Author: "Gérard Thouzeau" - Searchworks@Jio Institute Digital Library Search Results

Your search keyword '"Gérard Thouzeau"' showing total 77 results

Start Over Author "Gérard Thouzeau"

77 results on '"Gérard Thouzeau"'

1. Corals adapted to extreme and fluctuating seawater pH increase calcification rates and have unique symbiont communities

Author: Clément Tanvet, Emma F. Camp, Jill Sutton, Fanny Houlbrèque, Gérard Thouzeau, and Riccardo Rodolfo‐Metalpa
Subjects: adaptation, Bouraké, calcification, coral, natural analogue, New Caledonia, Ecology, QH540-549.5
Abstract: Abstract Ocean acidification (OA) is a severe threat to coral reefs mainly by reducing their calcification rate. Identifying the resilience factors of corals to decreasing seawater pH is of paramount importance to predict the survivability of coral reefs in the future. This study compared corals adapted to variable pHT (i.e., 7.23–8.06) from the semi‐enclosed lagoon of Bouraké, New Caledonia, to corals adapted to more stable seawater pHT (i.e., 7.90–8.18). In a 100‐day aquarium experiment, we examined the physiological response and genetic diversity of Symbiodiniaceae from three coral species (Acropora tenuis, Montipora digitata, and Porites sp.) from both sites under three stable pHNBS conditions (8.11, 7.76, 7.54) and one fluctuating pHNBS regime (between 7.56 and 8.07). Bouraké corals consistently exhibited higher growth rates than corals from the stable pH environment. Interestingly, A. tenuis from Bouraké showed the highest growth rate under the 7.76 pHNBS condition, whereas for M. digitata, and Porites sp. from Bouraké, growth was highest under the fluctuating regime and the 8.11 pHNBS conditions, respectively. While OA generally decreased coral calcification by ca. 16%, Bouraké corals showed higher growth rates than corals from the stable pH environment (21% increase for A. tenuis to 93% for M. digitata, with all pH conditions pooled). This superior performance coincided with divergent symbiont communities that were more homogenous for Bouraké corals. Corals adapted to variable pH conditions appear to have a better capacity to calcify under reduced pH compared to corals native to more stable pH condition. This response was not gained by corals from the more stable environment exposed to variable pH during the 100‐day experiment, suggesting that long‐term exposure to pH fluctuations and/or differences in symbiont communities benefit calcification under OA.
Published: 2023
Full Text: View/download PDF

2. High Coral Recruitment Despite Coralline Algal Loss Under Extreme Environmental Conditions

Author: Clément Tanvet, Francesca Benzoni, Christophe Peignon, Gérard Thouzeau, and Riccardo Rodolfo-Metalpa
Subjects: coral recruitment, crustose coralline algae (CCA), extreme environmental conditions, persistence, natural variability, Science, General. Including nature conservation, geographical distribution, QH1-199.5
Abstract: The crucial role of crustose coralline algae (CCA) in inducing hard coral larval settlement and ensuring the replenishment of coral reefs is widely accepted, and so are the negative effects of anthropogenic CO2 emissions on both CCA abundance and coral development. However, diversified and well-developed coral reef communities have been recently discovered in natural conditions where CCA and corals would not be expected to thrive. Back-reef pools, volcanic CO2 vents, mangrove estuaries, and semi-enclosed lagoons systems can present seawater pH, temperature, and dissolved oxygen values reaching or even exceeding the conditions currently predicted by the Inter Panel on Climate Change (IPCC) for 2100. In the semi-enclosed lagoon of Bouraké (New Caledonia, southwest Pacific Ocean), seawater pHT, dissolved oxygen, and temperatures regularly fluctuate with the tide reaching respectively minimum values of 7.23 pHT units, 2.28 mg O2 L-1, and maximum of 33.85°C. This study reports the effect of such extreme environmental conditions on hard coral recruitment and CCA originally settled at a forereef on artificial substrates that were transplanted over two years in two fringing reef and at the Bouraké lagoon. Our data emphasize the negative effects of the extreme conditions in our study sites on the CCA, which decreased in cover by ca. 80% and lost in the competition with turf algae, which, in turn, increased up to 162% at the end of the two years. Conversely, hard coral recruitment remained high at Bouraké throughout the study, three-fold higher than at two sites located outside Bouraké where environmental conditions were typical for coastal fringing reefs. Our findings show that while such extreme, climate change like-conditions have a direct and adverse effect on CCA abundance, and despite a certain persistence, coral larvae settlement was not affected. Based on previous findings from Bouraké, and the present observations, both coral recruits and adults seem to be unaffected despite the extreme environmental conditions. This study supports previous research illustrating how extreme natural and variable environments may reveal unexpected and positive insights on the processes underlying coral acclimatization and adaptation to global change.
Published: 2022
Full Text: View/download PDF

3. Easily Implemented Methods of Radiometric Corrections for Hyperspectral–UAV—Application to Guianese Equatorial Mudbanks Colonized by Pioneer Mangroves

Author: Marion Jaud, Guillaume Sicot, Guillaume Brunier, Emma Michaud, Nicolas Le Dantec, Jérôme Ammann, Philippe Grandjean, Patrick Launeau, Gérard Thouzeau, Jules Fleury, and Christophe Delacourt
Subjects: drone, hyperspectral imaging, radiometric calibration, reflectance, pioneer mangroves, intertidal sediments, Science
Abstract: Hyper-DRELIO (Hyperspectral DRone for Environmental and LIttoral Observations) is a custom, mini-UAV (unmanned aerial vehicle) platform (® and a field spectrometer, allowing performance of an initial calibration of the sensor in order to correct “vignetting effects” and a field standardization to convert digital numbers (DN) collected by the hyperspectral camera to reflectance, taking into account the time-varying illumination conditions. Radiometric corrections are applied to a subset of a dataset collected above mudflats colonized by pioneer mangroves in French Guiana. The efficiency of the radiometric corrections is assessed by comparing spectra from Hyper-DRELIO imagery to in situ spectrometer measurements above the intertidal benthic biofilm and mangroves. The shapes of the spectra were consistent, and the spectral angle mapper (SAM) distance was 0.039 above the benthic biofilm and 0.159 above the mangroves. These preliminary results provide new perspectives for quantifying and mapping the benthic biofilm and mangroves at the scale of the Guianese intertidal mudbanks system, given their importance in the coastal food webs, biogeochemical cycles, and the sediment stabilization.
Published: 2021
Full Text: View/download PDF

4. The Impossible Sustainability of the Bay of Brest? Fifty Years of Ecosystem Changes, Interdisciplinary Knowledge Construction and Key Questions at the Science-Policy-Community Interface

Author: Olivier Ragueneau, Mélanie Raimonet, Camille Mazé, Jennifer Coston-Guarini, Laurent Chauvaud, Anatole Danto, Jacques Grall, Frédéric Jean, Yves-Marie Paulet, and Gérard Thouzeau
Subjects: sustainability, land-ocean continuum, Bay of Brest, interdisciplinarity, science-policy-community interface, Science, General. Including nature conservation, geographical distribution, QH1-199.5
Abstract: In this contribution, the study of the Bay of Brest ecosystem changes over the past 50 years is used to explore the construction of interdisciplinary knowledge and raise key questions that now need to be tackled at the science-policy-communities interface. The Bay of Brest is subject to a combination of several aspects of global change, including excessive nutrient inputs from watersheds and the proliferation of invasive species. These perturbations strongly interact, affecting positively or negatively the ecosystem functioning, with important impacts on human activities. We first relate a cascade of events over these five decades, linking farming activities, nitrogen, and silicon biogeochemical cycles, hydrodynamics of the Bay, the proliferation of an exotic benthic suspension feeder, the development of the Great scallop fisheries and the high biodiversity in maerl beds. The cascade leads to today's situation where toxic phytoplankton blooms become recurrent in the Bay, preventing the fishery of the great scallop and forcing the fishermen community to switch pray and alter the maerl habitat and the benthic biodiversity it hosts, despite the many scientific alerts and the protection of this habitat. In the second section, we relate the construction of the interdisciplinary knowledge without which scientists would never have been able to describe these changes in the Bay. Interdisciplinarity construction is described, first among natural sciences (NS) and then, between natural sciences and human and social sciences (HSS). We finally ask key questions at the science-policy interface regarding this unsustainable trend of the Bay: How is this possible, despite decades of joint work between scientists and fishermen? Is adaptive co-management a sufficient condition for a sustainable management of an ecosystem? How do the different groups (i.e., farmers, fishermen, scientists, environmentalists), with their diverse interests, take charge of this situation? What is the role of power in this difficult transformation to sustainability? Combining natural sciences with political science, anthropology, and the political sociology of science, we hope to improve the contribution of HSS to integrated studies of social-ecological systems, creating the conditions to address these key questions at the science-policy interface to facilitate the transformation of the Bay of Brest ecosystem toward sustainability.
Published: 2018
Full Text: View/download PDF

5. Reproductive and larval cycle of the scallop Argopecten purpuratus (Ostreoida: Pectinidae), during El Niño-La Niña events and normal weather conditions in Antofagasta, Chile

Author: Miguel Avendaño, Marcela Cantillánez, Marcel Le Pennec, and Gérard Thouzeau
Subjects: Argopecten purpuratus, ciclo reproductivo, ciclo larval, bahía de Antofagasta, Chile, Biology (General), QH301-705.5
Abstract: Seasonality, amplitude, and magnitude of spawning events were determined for Argopecten purpuratus in the La Rinconada marine reserve, Antofagasta, Chile, between December 1995 and January 2004. During the same period, samples of scallop larvae were obtained in vertical plankton hauls recovered within this reserve in an area routinely exposed to circular, gyre-like currents which helped retain the larvae within the bay. The reproduction of this population in normal or cool (e.g. "La Niña", 1998-2000) years occurred throughout the year, with a more active period between September and April, declining in June and August; this contrasted with the warmer "El Niño" oceanographic period of 1997-98 in which reproductive activity was more intense and prolonged throughout the entire year. The reproductive events in this population were mostly synchronous, although one asynchronous period occurred each year following the more intense March to May spawnings. This reproductive activity generated a continuous presence of larvae in the area in which no strict relation could be found between the intensities of spawning and numbers of larvae in the water. Larval presence was, however, generally correlated with active spawning periods. Important increases in larval numbers recorded at the end of 1999 and the beginning of 2003 were correlated with census data showing a higher percentage presence of broodstock over 90 mm in shell length during these years. An adequate stock of this size class is needed for a successful seed capture program in the reserve (for mass culture). Rev. Biol. Trop. 56 (1): 121-132. Epub 2008 March 31.Entre 1995 y 2004 se determinó, con el índice gonadosomático, el ciclo reproductivo de Argopecten purpuratus en La Rinconada, Antofagasta, Chile. Paralelamente se realizaron muestreos larvales mediante arrastres verticales de plancton. La reproducción, en años normales y fríos (La Niña, 1998-2000), ocurre todo el año, con un período más intenso entre septiembre y abril, declinando en junio y agosto. En contraste, esta actividad no declina en condiciones de "El Niño" 1997-1998. En esta población los eventos reproductivos son sincrónicos, con un período altamente asincrónico entre marzo y mayo, al culminar los desoves más intensos. Esta actividad reproductiva, genera la presencia continua de larvas en el área. No hay relación entre intensidad de puestas y número de larvas, sin embargo, los períodos de mayor abundancia están directamente relacionados con períodos de mayor actividad reproductiva. Los incrementos importantes en el número de larvas entre fines de 1999 y comienzos del 2003 se asocian con un mayor número de reproductores sobre 90 mm de longitud. Esto indica la importancia de mantener un stock adecuado de este grupo demográfico, si se espera implementar programas de captación larval de esta especie en la reserva.
Published: 2008

6. Artificial collection and early growth of spat of the scallop Argopecten purpuratus (Lamarck, 1819), in La Rinconada Marine Reserve, Antofagasta, Chile

Author: Miguel Avendaño D., Marcela Cantillánez S., Gérard Thouzeau, and Juan B. Peña
Subjects: argopecten purpuratus, larvae, spat collection, growth, survival, chile, Aquaculture. Fisheries. Angling, SH1-691
Abstract: Artificial collection of early juveniles (“spat”) of the scallop Argopecten purpuratus in Japanese-type collectors was evaluated between January 2001 and July 2002 in the La Rinconada Marine Reserve, Antofagasta, Chile. This area of Antofagasta Bay has in the past been noted for the retention of scallop larvae by local gyres, in which their numbers can vary between 89 and 34175 larvae m-3, producing larval sets of 400 to 15340 post-larvae (spat) per collector. The results showed no quantitative relationship between larval abundance in the water and the spat density collected per day in the collectors, although high settlement rates were associated with high numbers of umboned larvae in the water. Allowing collectors to remain in situ for extended periods of 88 and 159 days resulted in a severe loss of seed which had settled in the collectors during the first 28 to 40 days of immersion. These losses varied between 50.9 and 99.6% of the spat collected, and were more prejudicial for the smaller cohorts that had settled in the collectors at the end of the first immersion period. The growth rates measured among different cohorts for each immersion period varied between 81.3 and 235.2 mm/day for the first cohort (C1) and between 64.0 and 167.4 mm/day for the second cohort (C2). The highest growth rates occurred in collectors containing the lowest numbers of spat after the occurrence of spat losses during the long periods of immersion. Occurrence of intraspecific competition within the collectors is discussed as potentially responsible for the decreases in spat numbers and the variations observed in their growth rates.
Published: 2007
Full Text: View/download PDF

7. Nematode diversity patterns in mangroves: a review of environmental drivers at different spatial scales

Author: Adriana Spedicato, Daniela Zeppilli, Gérard Thouzeau, and Emma Michaud
Subjects: Ecology, Ecology, Evolution, Behavior and Systematics, Nature and Landscape Conservation
Published: 2023
Full Text: View/download PDF

8. Corals adapted to extreme and fluctuating seawater pH increase calcification rates and have unique symbiont communities

Author: Clément Tanvet, Emma Camp, Jill Sutton, Fanny Houlbreque, Gérard Thouzeau, Riccardo Rodolfo-Metalpa, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Ecologie marine tropicale dans les Océans Pacifique et Indien (ENTROPIE [Réunion]), Institut de Recherche pour le Développement (IRD)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), CNRS (MITI interdisciplinary programs), and ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017)
Subjects: calcification, natural analogue, New Caledonia, Symbiodiniaceae, [SDV]Life Sciences [q-bio], Bourake, physiology, ocean acidification, adaptation, coral
Abstract: Ocean acidification (OA) is a severe threat to coral reefs mainly by reducing their calcification rate. Identifying the resilience factors of corals to decreasing seawater pH is of paramount importance to predict the survivability of coral reefs in the future. This study compared corals adapted to variable pHT (i.e., 7.23–8.06) from the semi-enclosed lagoon of Bouraké, New Caledonia, to corals adapted to more stable seawater pHT (i.e., 7.90–8.18). In a 100-day aquarium experiment, we examined the physiological response and genetic diversity of Symbiodiniaceae from three coral species (Acropora tenuis, Montipora digitata, and Porites sp.) from both sites under three stable pHNBS conditions (8.11, 7.76, 7.54) and one fluctuating pHNBS regime (between 7.56 and 8.07). Bouraké corals consistently exhibited higher growth rates than corals from the stable pH environment. Interestingly, A. tenuis from Bouraké showed the highest growth rate under the 7.76 pHNBS condition, whereas for M. digitata, and Porites sp. from Bouraké, growth was highest under the fluctuating regime and the 8.11 pHNBS conditions, respectively. While OA generally decreased coral calcification by ca. 16%, Bouraké corals showed higher growth rates than corals from the stable pH environment (21% increase for A. tenuis to 93% for M. digitata, with all pH conditions pooled). This superior performance coincided with divergent symbiont communities that were more homogenous for Bouraké corals. Corals adapted to variable pH conditions appear to have a better capacity to calcify under reduced pH compared to corals native to more stable pH condition. This response was not gained by corals from the more stable environment exposed to variable pH during the 100-day experiment, suggesting that long-term exposure to pH fluctuations and/or differences in symbiont communities benefit calcification under OA.
Published: 2022
Full Text: View/download PDF

9. Land-use changes in Amazon and Atlantic rainforests modify organic matter and black carbon compositions transported from land to the coastal ocean

Author: TASSIANA SERAFIM, Marcelo G. Almeida, Gérard Thouzeau, Emma Michaud, Michael Seidel, Jutta Niggemann, Thorsten Dittmar, and Carlos Eduardo de Rezende
Subjects: Environmental Engineering, Environmental Chemistry, Pollution, Waste Management and Disposal
Published: 2023
Full Text: View/download PDF

10. The Codevelopment of Mangroves and Infaunal Community Diversity in Response to the Natural Dynamics of Mud Deposition in French Guiana

Author: Emma Michaud, Adélaïde Aschenbroich, Olivier Gauthier, François Fromard, Josephine Y. Aller, Robert C. Aller, Guillaume Brunier, Edward J. Anthony, Antoine Gardel, Vincent Le Garrec, Aude Leynaert, Gérard Thouzeau, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Stony Brook University [SUNY] (SBU), State University of New York (SUNY), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Laboratoire Ecologie, Evolution, Interactions des Systèmes amazoniens (LEEISA), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Guyane (UG)-Centre National de la Recherche Scientifique (CNRS), Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), ANR-12-JSV7-0012,BIOMANGO,BIOdiversité et fonctionnement des écosystèmes dans les MANgroves de Guyane française : perspectives pour une gestion de l'écOsystème dans son contexte amazonien(2012), and ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010)
Subjects: [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, Renewable Energy, Sustainability and the Environment, mangroves, Geography, Planning and Development, benthos, Amazon influence, intertidal tropical mudflat, alpha and beta diversity, resilience, Management, Monitoring, Policy and Law, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract: International audience; The sustainability of mangrove ecosystems requires a knowledge of their spatiotemporal variability as a function of regional properties. The unique coastal ecosystems of the mangrove belt along the coast of the Guianas in South America are influenced by cycles of a massive accretion of mud supplied by the Amazon River and wave induced erosion. This study characterized, for the first time, how benthic infaunal assemblages, as proxies of mechanisms of mangrove resilience, were structured by the natural growth track of Avicennia germinans dominated mangroves in French Guiana. We sampled 4 mobile mud stations and 27 consolidated mud stations distributed over 9 tidal transects from bare to vegetated mudflats colonized by young mangroves during the dry season. We collected a complete dataset of sediment and vegetation variables together with the benthic meso- (>0.25 mm) and macrofauna (>1 mm). We used a combination of eigenvector based multivariate analyses and variance partitioning on this multiple set of variables to identify which environmental variables likely drive the benthic diversity patterns. Mangrove early development increased the alpha and beta diversities of the infaunal communities for the two size classes. A total of 20–30% and 7–12% of the beta diversity are explained by linear and nonlinear spatial variables, respectively. However, 7% to 9% of the variance partioning could be determined by other biotic/abiotic variables, biological interactions or neutral processes, not described here. This study has highlighted the necessity of taking into account mangrove dynamics at suitable spatial scales for benthic biodiversity evaluation and mangrove management or restoration plans.
Published: 2022
Full Text: View/download PDF

11. Predicting the energy budget of the scallop Argopecten purpuratus in an oxygen–limiting environment

Author: Frédéric Jean, Gérard Thouzeau, Laure Pecquerie, Jonathan Flye-Sainte-Marie, Arturo Aguirre-Velarde, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Instituto del Mar del Peru (IMARPE), Institut de Recherche pour le Développement (IRD), ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, Argopecten purpuratus, growth, [SDE.MCG]Environmental Sciences/Global Changes, Dynamic energy budget, hydrogen sulfide, Growth, Bioenergetics, Aquatic Science, bioenergetics, Oceanography, 010603 evolutionary biology, 01 natural sciences, reproduction, DEB theory, Water column, Aquaculture, Peru, 14. Life underwater, Hypoxia, Ecology, Evolution, Behavior and Systematics, Hydrogen sulfide, biology, hypoxia, business.industry, Reproduction, ACL, 010604 marine biology & hydrobiology, Hypoxia (environmental), biology.organism_classification, Energy budget, [SDE]Environmental Sciences, Scallop, Environmental science, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, business, Bay
Abstract: International audience; Low concentrations of oxygen determine marine species distribution and abundance along the Peruvian 1 coast with consequences for human activity such as fishing and aquaculture. In order to assess bioener-2 getic consequences of oxygen limitation on the Peruvian scallop Argopecten purpuratus, we first devel-3 oped a Dynamic Energy Budget (DEB) model of growth and reproduction calibrated on field experimen-4 tal datasets. Then, we included oxygen availability as an additional forcing variable using a simple rule 5 based on the ability of the scallop to regulate oxygen consumption. The resulting model was tested using 6 growth/reproduction monitoring and simultaneous high frequency environmental records in Paracas Bay 7 (Peru) at two different depths: suspended in the water column and on the sea bottom. Simulations indicated 8 that scallops growth and reproduction was not food-limited. The negative observed effects of hypoxia on 9 growth and reproduction could be explained by a decrease in both assimilation and reserve mobilization. 10 However, hypoxic conditions in summer were not sufficient to explain the observed losses in somatic tissue 11 weights and the disruption of reproduction. The latter two patterns were better simulated when assuming in-12 creased somatic maintenance costs due to the presence of H 2 S during milky turquoise water discolouration 13 events observed during summer. 14
Published: 2019
Full Text: View/download PDF

12. Comparison of benthic oxygen exchange measured by aquatic Eddy Covariance and Benthic Chambers in two contrasting coastal biotopes (Bay of Brest, France)

Author: Gérard Thouzeau, E. Amice, Sylvain Rigaud, Tom Cox, Thierry Le Bec, Bruno Deflandre, Pierre Polsenaere, Isabelle Bihannic, Olivier Maire, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Détection, évaluation, gestion des risques CHROniques et éMErgents (CHROME) / Université de Nîmes (CHROME), Université de Nîmes (UNIMES), Royal Netherlands Institute for Sea Research (NIOZ), The EDDYCO project (INSU EC2CO/DRIL program) provided financial support for this study. The Région Aquitaine (FEBBA project) and the IZOFLUX project from the French National Research Agency (white program) funded the EC system. The Région Aquitaine (FEBBA project) and the Vrije Universiteit Brussel supported the two-year postdoctoral fellowships awarded to P.P. The development of the new EC system, EC2, was realized in collaboration with Unisense A/S and the NIOZ-Yerseke. We would like to express our thanks to the INSU team from L’Albert Lucas and Henry Bouillard and Christian Portier from EPOC. This work has been carried out within the framework of the Cluster of Excellence COTE, ANR-10-BLAN-0612,IZOFLUX,Étude intégrée de l'Impact des herbiers de ZOstères sur les processus et FLUX benthiques en milieu côtier(2010), ANR-10-LABX-0045,COTE,COntinental To coastal Ecosystems: evolution, adaptability and governance(2010), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, Benthic Chambers, 010504 meteorology & atmospheric sciences, Fauna, Eddy covariance, Aquatic Science, 01 natural sciences, [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, Benthic O-2 fluxes, Aquatic Eddy Covariance, Maerl bed, 14. Life underwater, Maerl, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, Ecology, Benthic oxygen fluxes, 010604 marine biology & hydrobiology, Bay of Brest, Sediment, 15. Life on land, Spatial heterogeneity, Bare mudflat, Oceanography, 13. Climate action, Benthic zone, Environmental science, Animal Science and Zoology, Bay, Bioturbation
Abstract: To the best of our knowledge, the understanding of benthic metabolism of coastal sedimentary areas is still limited due to the complexity of determining their true in situ dynamics over large spatial and temporal scales. Multidisciplinary methodological approaches are then necessary to increase our comprehension of factors controlling benthic processes and fluxes. An aquatic Eddy Covariance (EC) system and Benthic Chambers (BC) were simultaneously deployed during the winter of 2013 in the Bay of Brest within a Maerl bed and a bare mudflat to quantify and compare O2 exchange at the sediment–water interface. Environmental abiotic parameters (i.e., light, temperature, salinity, current velocity and water depth) were additionally monitored to better understand the mechanisms driving benthic O2 exchange. At both sites, EC measurements showed short-term variations (i.e. 15 min) in benthic O2 fluxes according to environmental conditions. At the Maerl station, EC fluxes ranged from-21.0 mmol m−2 d−1 to 71.3 mmol m−2 d −1 and averaged 22.0 ± 32.7 mmol m−2 d−1 (mean ± SD), whilst at the bare muddy station, EC fluxes ranged from -43.1mmol m−2 d−1 to 12.1 mmol m−2 d −1 and averaged -15.9 ± 14.0 mmol m−2 d−1 (mean ± SD) during the total deployment. Eddy Covariance and Benthic Chambers measurements showed similar patterns of temporal O2 flux changes at both sites. However, at the Maerl station, BC may have underestimated community respiration. This may be due to the relative large size of the EC footprint (compared to BC), which takes into account the mesoscale spatial heterogeneity (e.g. may have included contributions from bare sediment patches). Also, we hypothesize that the influence of bioturbation induced by large-sized mobile benthic fauna on sediment oxygen consumption was not fully captured by BC compared to EC. Overall, the results of the present study highlight the importance of taking into account specific methodology limitations with respect to sediment spatial macro-heterogeneity and short-term variations of environmental parameters to accurately assess benthic O2 exchange in the various benthic ecosystems of the coastal zone.
Published: 2021
Full Text: View/download PDF

13. Easily Implemented Methods of Radiometric Corrections for Hyperspectral-UAV-Application to Guianese Equatorial Mudbanks Colonized by Pioneer Mangroves

Author: Emma Michaud, Nicolas Le Dantec, Marion Jaud, Guillaume Sicot, Jérôme Ammann, Christophe Delacourt, Philippe Grandjean, Gérard Thouzeau, Patrick Launeau, Jules Fleury, Guillaume Brunier, Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Géosciences Océan (LGO), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Equipe Marine Mapping & Metrology (Lab-STICC_M3), Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance (Lab-STICC), École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT), École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010), ANR-11-EQPX-0011,CRITEX,Parc national d'équipements innovants pour l'étude spatiale et temporelle de la Zone Critique des Bassins Versants(2011), Université de Bretagne Sud (UBS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique (IMT Atlantique), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, reflectance, hyperspectral imaging, Science, 0211 other engineering and technologies, 02 engineering and technology, drone, 01 natural sciences, [SPI.AUTO]Engineering Sciences [physics]/Automatic, Littoral zone, intertidal sediments, 14. Life underwater, Radiometric calibration, 021101 geological & geomatics engineering, 0105 earth and related environmental sciences, Remote sensing, Vignetting, Spectrometer, Orientation (computer vision), [SDE.IE]Environmental Sciences/Environmental Engineering, radiometric calibration, pioneer mangroves, Hyperspectral imaging, Benthic zone, General Earth and Planetary Sciences, Environmental science, Mangrove, [SPI.SIGNAL]Engineering Sciences [physics]/Signal and Image processing
Abstract: International audience; Hyper-DRELIO (Hyperspectral DRone for Environmental and LIttoral Observations) is a custom, mini-UAV (Unmanned Aerial Vehicle) platform (< 20 kg) equipped with a light push broom hyperspectral sensor combined with a navigation module measuring position and orientation. Because of the particularities of UAV surveys (low flight altitude, small spatial scale and high resolution), dedicated pre-processing methods have to be developed when reconstructing hy-perspectral imagery.This article presents light easy-implementation in-situ methods, using only two Spectralon® and a field spectrometer, allowing to perform an initial calibration of the sensor in order to correct “vignetting effects” and a field standardization to convert Digital Numbers (DN) collected by the hyperspectral camera to reflectance, taking into account the time-varying illumination con-ditions. Radiometric corrections are applied to a subset of a dataset collected above mudflats colonized by pioneer mangroves in French Guiana. The efficiency of the radiometric corrections is assessed by comparing spectra from Hyper-DRELIO imagery to in-situ spectrometer meas-urements above the intertidal benthic biofilm and mangroves. The shapes of the spectra are con-sistent and the Spectral Angle Mapper (SAM) distance is of 0.039 above the benthic biofilm and of 0.159 above the mangroves. These preliminary results provide new perspectives for quanti-fying and mapping the benthic biofilm and mangroves at the scale of the Guianese intertidal mudbanks system, given their importance in the coastal food webs, biogeochemical cycles and the sediment stabilization.
Published: 2021
Full Text: View/download PDF

14. Size‐based survival of cultured Argopecten purpuratus (L, 1819) under severe hypoxia

Author: Fred Jean, Arturo Aguirre-Velarde, Jonathan Flye-Sainte-Marie, Rosa Cueto-Vega, Patricia Gil-Kodaka, Gérard Thouzeau, Universidad Nacional Agraria La Molina (UNALM), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Instituto del Mar del Peru (IMARPE), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, severe hypoxia, Argopecten purpuratus, 010504 meteorology & atmospheric sciences, biology, 010604 marine biology & hydrobiology, [SDV.SA.ZOO]Life Sciences [q-bio]/Agricultural sciences/Zootechny, Lt(50), Severe hypoxia, Aquatic Science, biology.organism_classification, 01 natural sciences, Mass mortality, Andrology, size effect, mass mortality, 14. Life underwater, Lt50, [SDV.EE.BIO]Life Sciences [q-bio]/Ecology, environment/Bioclimatology, Agronomy and Crop Science, 0105 earth and related environmental sciences
Abstract: International audience; During recent years, mass mortalities of cultured scallops became more frequent in Peruvian bays. One of the main drivers related to these mortalities was hypoxic events. This study was designed to understand the hypoxia phenomenon in these bays and to assess how the Peruvian scallop, Argopecten purpuratus, can cope with reduced oxygen levels in seawater based on individual size. First, we analyzed the relationships between dissolved oxygen saturation and other environmental parameters (the Coastal El Niño Index, temperature, salinity and pH) in bottom seawater, the frequency and intensity of hypoxic events in two main culture areas (Sechura and Paracas Bays), and their relationship with scallop mass mortalities. Then, we performed experiments with two size groups of A. purpuratus (31 and 80 mm shell height; seed and commercial size, respectively) to assess their respective survival time under severe hypoxia (1% oxygen saturation) at 16°C and a salinity of 35. Finally, the results of the field records and the experimental data are used to suggest ways to improve scallop cultivation along the Peruvian coast.
Published: 2021
Full Text: View/download PDF

15. Mangrove‐Derived Organic and Inorganic Carbon Exchanges Between the Sinnamary Estuarine System (French Guiana, South America) and Atlantic Ocean

Author: Romain Walcker, Raghab Ray, Emma Michaud, Sylvain Morvan, Jérémy Devesa, Vincent Vantrepotte, Gerd Gleixner, Gérard Thouzeau, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Nord]), Laboratoire Ecologie, Evolution, Interactions des Systèmes amazoniens (LEEISA), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Guyane (UG)-Centre National de la Recherche Scientifique (CNRS), Max Planck Institute for Biogeochemistry (MPI-BGC), Max-Planck-Gesellschaft, ANR-10-LABX-0025,CEBA,CEnter of the study of Biodiversity in Amazonia(2010), ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010), ANR-12-JSV7-0012,BIOMANGO,BIOdiversité et fonctionnement des écosystèmes dans les MANgroves de Guyane française : perspectives pour une gestion de l'écOsystème dans son contexte amazonien(2012), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Institut national des sciences de l'Univers (INSU - CNRS), Centre National de la Recherche Scientifique (CNRS)-Université de Guyane (UG)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Institut de Recherche pour le Développement (IRD)-Institut Universitaire Européen de la Mer (IUEM), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, Atmospheric Science, 010504 meteorology & atmospheric sciences, Soil Science, Aquatic Science, 01 natural sciences, Tidal cycle, Total inorganic carbon, Organic matter, 14. Life underwater, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Water Science and Technology, Carbon flux, organic matter, [SDV.EE]Life Sciences [q-bio]/Ecology, environment, chemistry.chemical_classification, geography, geography.geographical_feature_category, Ecology, 010604 marine biology & hydrobiology, ACL, mangroves, Paleontology, Forestry, Estuary, 15. Life on land, French Guiana, carbon flux, Oceanography, chemistry, 13. Climate action, [SDE]Environmental Sciences, Environmental science, Mangrove, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, tidal cycle
Abstract: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2020JG005739; International audience; There is growing evidence that a substantial fraction of the dissolved organic and inorganic carbon (DOC and DIC) and particulate organic carbon (POC) can be exported from mangroves to the ocean. Yet our understanding of C fluxes in mangrove forests is limited to only few regional studies that exclude the world's longest sediment dispersal system connected to the Amazon River. The present study aims at (1) examining tidal fluctuations of DOC, POC, and DIC; their isotopes; and optical properties such as chromophoric dissolved organic matter (CDOM) and (2) estimating their exchange fluxes between the mangroves and adjacent coastal water in the Sinnamary estuary, French Guiana. Time series observation highlighted that physical processes coupled to tides controlled diel dynamics and sources of DOC (e.g., litter leaching and pore water seepage) and POC (microphytobenthos, sediment resuspension, and bioturbation activities). Intense benthic remineralization could account for high water column pCO2 and DIC exchange flux during the low tide. Mangrove-derived DOC export to inner shelf (8.14 g C m−2 day−1) was exceeding import of POC and DIC from the mud bank and marine sources to the mangroves (1.35 and 0.90 g C m−2 day−1, respectively). Because of specific dynamics of the Amazon mobile muds, local geomorphology, water column stratification, and environmental forcing, Guianese mangroves cannot be seen as simple C exporters to the Atlantic waters. These first data setting on C fluxes for the region should be included along with other studies to improve global mangrove C budget estimate.
Published: 2020
Full Text: View/download PDF

16. The sources and distribution of carbon (DOC, POC, DIC) in a mangrove dominated estuary (French Guiana, South America)

Author: Jérémy Devesa, Sylvain Morvan, V. Vantrepotte, Gerd Gleixner, Raghab Ray, Romain Walcker, Gérard Thouzeau, M. Le Goff, Robert C. Aller, Emma Michaud, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), School of Marine and Atmospheric Sciences [Stony Brook] (SoMAS), Stony Brook University [SUNY] (SBU), State University of New York (SUNY)-State University of New York (SUNY), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Centre National de la Recherche Scientifique (CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Institut national des sciences de l'Univers (INSU - CNRS), Max Planck Institute for Biogeochemistry (MPI-BGC), Max-Planck-Gesellschaft, Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Ecologie, Evolution, Interactions des Systèmes amazoniens (LEEISA), Centre National de la Recherche Scientifique (CNRS)-Université de Guyane (UG)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), ANR-12-JSV7-0012,BIOMANGO,BIOdiversité et fonctionnement des écosystèmes dans les MANgroves de Guyane française : perspectives pour une gestion de l'écOsystème dans son contexte amazonien(2012), ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010), ANR-10-LABX-0025,CEBA,CEnter of the study of Biodiversity in Amazonia(2010), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Nord]), Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), and Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Guyane (UG)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, 010504 meteorology & atmospheric sciences, 01 natural sciences, Carbon cycle, Dissolved organic carbon, Phytoplankton, Mangroves, Environmental Chemistry, Methanotrophy, Ecosystem, 14. Life underwater, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, Stable isotopes, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, Total organic carbon, geography, Amazonian system, geography.geographical_feature_category, ACL, 010604 marine biology & hydrobiology, Microphytobenthos, Estuary, 15. Life on land, Oceanography, 13. Climate action, Benthic zone, [SDE]Environmental Sciences, Environmental science, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Mangrove, Remineralization
Abstract: International audience; Mangrove forests are highly productive coastal ecosystems that significantly influence global carbon cycling. This study characterized the sources of dissolved organic carbon (DOC), particulate organic carbon (POC) and dissolved inorganic carbon (DIC) and the processes affecting their distributions in a mangrove-influenced estuary located in French Guiana (FG), a region representative of these dynamic systems down drift of the Amazon River. Four sampling cruises were carried out between 2013 and 2015 in surface waters of the estuary during dry and wet seasons. Stable isotopes (δ13DOC, δ13POC, δ13DIC), elemental ratios and optical properties (absorption) were used as proxies to identify different C sources. Property–salinity relationships revealed regions of approximately linear mixing (e.g., alkalinity) or net sources or sinks (e.g., DOC). DIC speciation and isotopic distributions demonstrated dynamic source–sink reaction processes within the estuary. DOC was the major form of organic carbon representing mixtures of terrestrial sources (e.g., pore water, litter leaching) and very high concentration (400–800 µM) compared to other mangrove settings (e.g. Brazilian, Sundarbans, African). Highly negative δ13POC (− 40‰) in the riverine part presumably suggests the role of freshwater phytoplankton in the dry season and methanotrophic sources derived from senescent mangrove deposits or upstream hydrothermal dam during the wet season. Microphytobenthos and marine phytoplankton were the primary sources of POC inshore and DOC offshore, respectively. Mangrove products and benthic microalgae dominated estuarine sources of C in FG coastal waters (~ 10 km, inner shelf region), and there was extensive exchange of C between forest and tidal flat and the estuarine reservoirs.
Published: 2018
Full Text: View/download PDF

17. Evidence of clandestine harvest and failure of conservation policies for Argopecten purpuratus in the Rinconada Marine Reserve (Chile)

Author: Marcela Cantillánez, Gérard Thouzeau, and Miguel Avendaño
Subjects: 0106 biological sciences, Argopecten purpuratus, Stock assessment, Ecology, biology, Overfishing, 010604 marine biology & hydrobiology, Population size, Fishing, Marine reserve, 04 agricultural and veterinary sciences, Aquatic Science, biology.organism_classification, 01 natural sciences, Fishery, Scallop, 040102 fisheries, 0401 agriculture, forestry, and fisheries, 14. Life underwater, Bay, Nature and Landscape Conservation
Abstract: The study of Argopecten purpuratus reproduction, post-larval settlement, stock size, and population size structure and shell growth was undertaken in the 2000s in the Rinconada marine reserve (Chile) to evaluate the effectiveness of scallop recruitment and self-sustainability. The results highlight strong seasonal and inter-annual variations of environmental conditions and scallop gonadosomatic index, spat collection, benthic distribution, total abundance and population size structure. The Von Bertalanffy growth parameters were L∞ = 120.12 mm and K = 0.9681; commercial size would be reached in about 17.2 months in the bay. Substrate availability, meteorological conditions, hydrodynamics and illegal harvesting explain spatial and temporal variations in scallop distribution and abundance. Recruitment strength depends on one main cohort from year to year. While recruitment made up 81% and 94% of total abundances in May 2002 and May 2003, respectively, there were no overall density-dependent relationships between stock size and recruitment. Spawning asynchrony in the bay supports the hypothesis that multiple gamete releases form part of a reproductive strategy in response to environmental variability. The massive disappearance of large-sized scallops during the study periods was direct evidence of overfishing owing to clandestine harvesting within the marine reserve. The failure of current legislation, strategies and policies for scallop conservation requires new regulations to restore scallop stock size, maintain its reproductive performance and limit illegal harvesting in the Rinconada. A scenario allowing harvesting regulated by stock-dependent fishing quotas would more efficiently ensure stock recovery and self-sustainability. The modalities of this new policy are discussed.
Published: 2017
Full Text: View/download PDF

18. The French National Committee on Scientific Diving (CNPS): a key actor for developing scientific diving in France

Author: Gérard Thouzeau, Régis Hocdé, Jean-Pierre Beurier, Laurent Borel, Mathieu Coulange, Alain Couté, Gérard Eldin, Jean-Pierre Féral, Eric Folcher, Stéphan Jacquet, Philippe Le Bras, Sébastien Legrand, Philippe Lenfant, Mario Lepage, Laurent Lévêque, Stéphane Nicolas, Valeriano Parravicini, Caroline Play, Gilles Saragoni, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD), Université de Nantes (UN), Centre Camille Jullian - Histoire et archéologie de la Méditerranée et de l'Afrique du Nord de la protohistoire à la fin de l'Antiquité (CCJ), Aix Marseille Université (AMU)-Ministère de la Culture et de la Communication (MCC)-Centre National de la Recherche Scientifique (CNRS), Hôpital Sainte-Marguerite [CHU - APHM] (Hôpitaux Sud ), Muséum national d'Histoire naturelle (MNHN), Institut national des sciences de l'Univers (INSU - CNRS), Institut méditerranéen de biodiversité et d'écologie marine et continentale (IMBE), Avignon Université (AU)-Aix Marseille Université (AMU)-Institut de recherche pour le développement [IRD] : UMR237-Centre National de la Recherche Scientifique (CNRS), Centre Alpin de Recherche sur les Réseaux Trophiques et Ecosystèmes Limniques (CARRTEL), Institut National de la Recherche Agronomique (INRA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Département des Recherches Archéologiques Subaquatiques et Sous-Marines [Marseille] (DRASSM), Ministère de la Culture (MC), Université de Perpignan Via Domitia (UPVD), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Station biologique de Roscoff [Roscoff] (SBR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS), École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL), Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland, Institute of Oceanology, Polish Academy of Sciences, Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO), Centre National de la Recherche Scientifique (CNRS)-Institut de recherche pour le développement [IRD] : UMR237-Aix Marseille Université (AMU)-Avignon Université (AU), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), cnrs délégation Provence et Corse, École pratique des hautes études (EPHE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut de Recherche pour le Développement (IRD)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SPI.OTHER]Engineering Sciences [physics]/Other, 032TECHNO, [SHS.ARCHEO]Humanities and Social Sciences/Archaeology and Prehistory, European standards, Scientific diving, Plongée scientifique, Oceanography, [SDE.ES]Environmental Sciences/Environmental and Society, Standards européens de l'exécution, Innovations technologiques, [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, [SDE]Environmental Sciences, Technology New/Modern/Innovation, Océanogaphie, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography
Abstract: International audience; The French National Committee for Scientific Diving (CNPS) is an inter-agency committee on scientific diving activities. French marine universities, research institutes (CNRS-INEE/INSU/INSHS, DRASSM, EPHE, IFREMER, INRA, INSERM, IPEV, IRD, IRSTEA) and the National Museum (MNHN) are involved or represented. The CNPS, created in 1999, is the scientific diving representative of the Ministry of Higher Education and Research to the Ministry of Labor. It includes personalities chosen for their expertise in the field of professional use of diving (scientific and technical diving, training), the law of the sea, the hyperbaric medicine and the European scientific diving panel (ESDP). The aims of this group of experts are: a) to observe the evolution of the professional scientific diving practices worldwide, b) to define common frameworks and promote the best practices, c) to provide high-level expertise and advices to Ministries of Labor and Research, d) to monitor the innovations in scientific diving, technology, field practices and hyperbaric medicine, e) to share informations and feedback with the French scientific divers community, f) to participate in the training of scientific divers, and g) to represent France at the ESDP. The CNPS has been fully involved since 2009 in the formulation of new laws and regulations dedicated to professional diving with the Ministry of Labor. The French scientific diving community is very diversified, for historical reasons, due to its 18 000 km long coastline and a strong presence overseas, through the involvement of researchers in global science issues and international collaborations. This poster presents the aims, activities and key results obtained by the CNPS. It also sets out some perspectives, especially actions in favour of a convergence of European practice patterns and standards.
Published: 2019
Full Text: View/download PDF

19. Feeding behaviour and growth of the Peruvian scallop ( Argopecten purpuratus ) under daily cyclic hypoxia conditions

Author: Jonathan Flye-Sainte-Marie, Fred Jean, Gérard Thouzeau, Arturo Aguirre-Velarde, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Instituto del Mar del Peru (IMARPE), and ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010)
Subjects: 0106 biological sciences, Argopecten purpuratus, 010504 meteorology & atmospheric sciences, Bioenergetics, Dynamic energy budget, [SDE.MCG]Environmental Sciences/Global Changes, Growth, Aquatic Science, Biology, Oceanography, 01 natural sciences, Animal science, Dry weight, 14. Life underwater, Hypoxia, Ecology, Evolution, Behavior and Systematics, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, 010604 marine biology & hydrobiology, ACL, Hypoxia (environmental), Aquatic animal, biology.organism_classification, Clearance rate, Fishery, Pectinidae, Scallop, Feeding behaviour, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract: International audience; As a secondary consequence of the high productivity of the upwelling system, organisms inhabiting Peruvian coastal bays are frequently exposed to hypoxic conditions. The aim of the present paper was to investigate the effects of daily-cyclic-severe hypoxia on energetics of a species presenting little escape ability when facing hypoxia. For this purpose, juvenile Peruvian scallops (Argopecten purpuratus) were exposed to four experimental conditions: fed and starved, combined or not to nightly severe hypoxia (5% oxygen saturation) for ≈ 12 h over a 21-day experiment. In both fed conditions, clearance rate was measured by the mean of an open-flow system. Our results indicate that the Peruvian scallop is able to maintain an active filtration even at low oxygen saturation, at least during expositions up to 12 h. During the first phase of exposure to hypoxia, clearance rate decreased abruptly when oxygen saturation dropped below 10%, but rapidly recovered to values close to those found under normoxia. As a consequence of this ability to feed during hypoxia, no difference in soft tissue dry weight (digestive gland not included) was observed at the end of the experimental period between oxic conditions among fed scallops. However, shell growth was negatively affected by hypoxic condition. Starved individuals exhibited similar weight loss between hypoxic and normoxic conditions indicating no or little effect of oxic condition on maintenance costs. Considering the observed responses for feeding, growth and maintenance, we can hypothesize that this species presents metabolic/bioenergetic efficient adaptations to deal with hypoxic conditions that are recurrent in Peruvian coastal bays. We hypothesize that the small observed effects might be modelled in the context of the Dynamic Energy Budget theory as a restriction of reserve mobilization under hypoxic conditions.
Published: 2018
Full Text: View/download PDF

20. A review of potential impacts of submarine power cables on the marine environment: Knowledge gaps, recommendations and future directions

Author: Morgane Lejart, Andrew Want, Nicolas Desroy, Gérard Thouzeau, Bastien Taormina, Antoine Carlier, Juan Bald, France Energies Marines [Brest], Laboratoire d'Ecologie Benthique Côtière (LEBCO), Dynamiques des Écosystèmes Côtiers (DYNECO), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), AZTI - Tecnalia, Heriot-Watt University [Edinburgh] (HWU), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Environnement Ressource Bretagne Nord (LERBN), LITTORAL (LITTORAL), Dynamiques de l'Environnement Côtier (DYNECO), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, Sociology of scientific knowledge, Project commissioning, 010603 evolutionary biology, 01 natural sciences, Nuclear decommissioning, Submarine power cables, Marine energy, 14. Life underwater, Environmental planning, Marine renewable energy, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, Renewable Energy, Sustainability and the Environment, business.industry, [SDE.IE]Environmental Sciences/Environmental Engineering, 010604 marine biology & hydrobiology, ACL, Submarine, Chemical pollution, Environmental impacts, Renewable energy, Habitat, 13. Climate action, Benthic habitats, Ecosystem functioning, Environmental science, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, business
Abstract: International audience; Submarine power cables (SPC) have been in use since the mid-19th century, but environmental concerns about them are much more recent. With the development of marine renewable energy technologies, it is vital to understand their potential impacts. The commissioning of SPC may temporarily or permanently impact the marine environment through habitat damage or loss, noise, chemical pollution, heat and electromagnetic field emissions, risk of entanglement, introduction of artificial substrates, and the creation of reserve effects. While growing numbers of scientific publications focus on impacts of the marine energy harnessing devices, data on impacts of associated power connections such as SPC are scarce and knowledge gaps persist. The present study (1) examines the different categories of potential ecological effects of SPC during installation, operation and decommissioning phases and hierarchizes these types of interactions according to their ecological relevance and existing scientific knowledge, (2) identifies the main knowledge gaps and needs for research, and (3) sets recommendations for better monitoring and mitigation of the most significant impacts. Overall, ecological impacts associated with SPC can be considered weak or moderate, although many uncertainties remain, particularly concerning electromagnetic effects.
Published: 2018
Full Text: View/download PDF

21. Marine Species Introduced on the French Channel-Atlantic Coasts: A Review of Main Biological Invasions and Impacts

Author: Gérard Thouzeau, Valérie Stiger-Pouvreau, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, Codium fragile, [SDE.MCG]Environmental Sciences/Global Changes, Halophyte, Biodiversity, Invasive Species, Remediation, Introduced species, Spartina alterniflora, 01 natural sciences, Invasive species, Macroalgae, 0502 economics and business, 14. Life underwater, Sargassum muticum, ACLN, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, Mollusks, biology, Ecology, 010604 marine biology & hydrobiology, 05 social sciences, 15. Life on land, biology.organism_classification, Fishery, French Channel-Atlantic Coasts, 13. Climate action, Benthic zone, Impacts, Biological dispersal, 050202 agricultural economics & policy, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract: International audience; The impacts of anthropogenisation modify permanently the distribution patterns of brackish and marine species. Globalization leads to a rapid increase of the numbers of introduced species anywhere in the world. Biological invasions often result in significant losses in the economic value, biological diversity and function of invaded ecosystems. This review presents the main pathways of introduction of non-indigenous species and the main benthic taxonomic groups being established and/or invasive along the French Channel-Atlantic coasts. A focus is put on main invasive marine species in the intertidal and subtidal zones of Brittany (France), among macroalgae (Sargassum muticum, Grateloupia turuturu, Undaria pinnatifida, Codium fragile and Gracilaria vermiculophylla), halophytes (Spartina alterniflora) and benthic invertebrates (Mollusks: Crepidula fornicata, Crassostrea gigas and Venerupis philippinarum). The species biology, introduction vectors, reproductive and dispersal capacities are considered, together with proliferation patterns along the Channel-Atlantic coasts. The ecological impacts of these species on the environment are also described, as well as the European regulations existing to limit alien species introduction and some examples of struggle against the invaders including eradication trials and biomass valorization. Last, the on-going impacts of global changes on alien species invasiveness along the Channel- Atlantic coasts are discussed.
Published: 2015
Full Text: View/download PDF

22. Bioturbation functional roles associated with mangrove development in French Guiana, South America

Author: Arthur Alt, Gérard Thouzeau, François Fromard, Franck Gilbert, Emma Michaud, Arnaud De Coninck, Vincent Le Garrec, Adélaïde Aschenbroich, Isabelle Bihannic, Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut Français de Recherche pour l'Exploitation de la MER - IFREMER (FRANCE), Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE), Institut National de la Recherche Scientifique - INRS (CANADA), Institut de Recherche pour le Développement - IRD (FRANCE), Université de Bretagne Occidentale - UBO (FRANCE), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), Université de Lorraine (FRANCE), Institut National Polytechnique de Toulouse - INPT (FRANCE), Université Toulouse III - Paul Sabatier - UPS (FRANCE), Laboratoire des Sciences de l'Environnement Marin - LEMAR (Plouzané, France), Laboratoire Ecologie fonctionnelle et Environnement - EcoLab (Toulouse, France), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Institut National de la Recherche Scientifique [Québec] (INRS), ANR-12-JSV7-0012,BIOMANGO,BIOdiversité et fonctionnement des écosystèmes dans les MANgroves de Guyane française : perspectives pour une gestion de l'écOsystème dans son contexte amazonien(2012), ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO), Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, 010504 meteorology & atmospheric sciences, Biodiversité et Ecologie, Aquatic Science, 01 natural sciences, Mesofauna, [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, Benthic community, Dry season, Dominance (ecology), Organic matter, 14. Life underwater, Sediment reworking, Soil mesofauna, 0105 earth and related environmental sciences, chemistry.chemical_classification, Amazonian system, Ecology, 010604 marine biology & hydrobiology, ACL, Community structure, 15. Life on land, Dynamic system, chemistry, Ecosystèmes, Mud bank, Environmental science, Species richness, Macrofauna, Mangrove, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Bioturbation
Abstract: International audience; This study aims to qualify, quantify, and compare the sediment reworking rates induced by the meso- (0.25–1 mm) and macro-infauna ([1 mm) along a mangrove growth gradient in the sedimentary dynamics of the French Guiana coast. The characterization of the role of small-infauna bioturbation in mangroves is new despite their known numerical dominance in tropical environments. Bare sediment, pioneer mangroves, and young mangroves were investigated during the dry season and spring tide to characterize their environment, infaunal functional community structure and sediment reworking rates. The biodiffusion differed significantly between mangrove stages, co-varying mainly with density and functional richness. On the contrary, the non-local transport remained similar, despite the mangrove-agespecificity of infauna functional compositions, which responded to modifications in the nature and content of organic matter. The first mangrove infaunal functional sequence is described: organisms that first colonize deposited mud generate the maximum biodiffusive mixing and induce a total downward particle flux (BDF) as high as in the young mangroves; in the pioneer mangroves, the infauna variables and BDF are stressed to minimum values. Our study sheds light on the functional contribution of the small infauna in a mangrove coastal area and quantifies its role in particle transport during mangrove development.
Published: 2017
Full Text: View/download PDF

23. Chronic and severe hypoxic conditions in Paracas Bay, Pisco, Peru: Consequences on scallop growth, reproduction, and survival

Author: Fred Jean, Jaime Mendo, Alex Vega-Espinoza, Arturo Aguirre-Velarde, Jazmín Vásquez-Spencer, Gérard Thouzeau, Midori Kawazo-Delgado, Diego Herrera-Sanchez, Rosa Cueto-Vega, Jonathan Flye-Sainte-Marie, Instituto del Mar del Peru (IMARPE), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Universidad Nacional Agraria La Molina (UNALM), LabexMER Marine Excellence Research: a changing ocean (2010), ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Argopecten purpuratus, [SDE.MCG]Environmental Sciences/Global Changes, media_common.quotation_subject, Growth, Aquaculture, Milky-turquoise water/aguas Blancas, Aquatic Science, 03 medical and health sciences, Scallop aquaculture, 14. Life underwater, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 030304 developmental biology, media_common, Hypoxic/anoxic conditions, [SDV.EE]Life Sciences [q-bio]/Ecology, environment, 0303 health sciences, biology, ACL, Reproduction, 04 agricultural and veterinary sciences, biology.organism_classification, High frequency monitoring, Anoxic waters, Fishery, Gonadosomatic Index, 13. Climate action, [SDE]Environmental Sciences, Scallop, 040102 fisheries, 0401 agriculture, forestry, and fisheries, Upwelling, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Bay, Coastal upwelling
Abstract: International audience; The response of Argopecten purpuratus (Peruvian scallop) to environmental conditions was studied in the upwelling-influenced Bay of Paracas (Peru). Scallops growth and reproduction were monitored weekly over a 7-month period under two conditions (culture depths): on the bottom and 2 m above (suspended culture). At the same time, a high-frequency environmental monitoring was realized at the aforementioned depths. The results indicate that environmental conditions in the Bay are highly variable, especially during the summer: temperature fluctuations up to 8∘C were recorded in less than one day while oxic conditions ranged from oversaturation to anoxia. Milky-turquoise waters discoloration events (sulphide presence suspected) were simultaneously observed together with anoxic conditions and sudden temperature drops. Increased stratification and upwelling favorable winds during the summer might be partly responsible for the observed environmental variability. Higher somatic and gonadal growth were observed in scallops growing in suspended culture compare with bottom culture. This pattern might be related to different environmental conditions at culture depth: turbidity was lower in suspended culture and hypoxic conditions occurred only 18% of the whole study period versus 48% on the bottom. The Gonadosomatic index varied according to an approx. 30-day cycle between winter and late spring and it was synchronous between the different scallop size groups. During summer, when milky waters and anoxic events occurred frequently, cessation of reproduction, somatic weight losses and increased scallop mortality were observed. Exposure to severe hypoxia and related environmental conditions clearly affected scallop bioenergetics and subsequently growth and reproduction. In addition, the occurrence of milky waters harmed the survival of the Peruvian scallop in culture. These results are discussed in terms of management strategies for sustainable scallop aquaculture in the Bay.
Published: 2019
Full Text: View/download PDF

24. Brachyuran crab community structure and associated sediment reworking activities in pioneer and young mangroves of French Guiana, South America

Author: Gérard Thouzeau, Emma Michaud, Marcos Tavares, Antoine Gardel, Adélaïde Aschenbroich, Thomas Stieglitz, François Fromard, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre for TropicalWater and Aquatic Ecosystem Research (TropWATER), School of Earth and Environmental Sciences [Australia], James Cook University (JCU)-James Cook University (JCU), Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Laboratoire Ecologie, Evolution, Interactions des Systèmes amazoniens (LEEISA), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Guyane (UG)-Centre National de la Recherche Scientifique (CNRS), University of São Paulo (USP), ANR-12-JSV7-0012,BIOMANGO,BIOdiversité et fonctionnement des écosystèmes dans les MANgroves de Guyane française : perspectives pour une gestion de l'écOsystème dans son contexte amazonien(2012), ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Nord]), and Universidade de São Paulo = University of São Paulo (USP)
Subjects: 0106 biological sciences, 010504 meteorology & atmospheric sciences, habitat, Crabs, Aquatic Science, Oceanography, 01 natural sciences, chasmagnathus-granulata, Mangroves, Community composition, 14. Life underwater, Amazon, organic-matter, 0105 earth and related environmental sciences, biodiversity, ecosystem, geography, geography.geographical_feature_category, Ecology, burrowing crabs, 010604 marine biology & hydrobiology, ACL, Sediment, Estuary, dynamics, 15. Life on land, Burrow, Spatial heterogeneity, French Guiana, Benthic zone, genus uca, salt-marsh, Salt marsh, DISCOVERY, ecological role, Mangrove, Bioturbation, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Geology
Abstract: 00001 ăWOS:000390627700006; International audience; This study in French Guiana evaluates the changes of crab assemblages and their bioturbation activities between mangrove early stages (pioneer and young mangrove) and within stages by taking their spatial heterogeneity (tidal channels, flat areas, pools) into account. The results show differences in crab assemblage structure between and within the early stages of mangrove in relation to microhabitat and sediment characteristics. The sediment reworking rates are a function of the biomass or density of particular species (Ucides cordatus, Uca cumulanta) and burrower functional groups. Crab species or functional interactions mediate changes in sediment reworking rates suggesting the need to consider entire benthic communities rather than single species. This study suggests that the role of the micro habitat in determining the biologically -induced sediment reworking rates depends on the age of the mangrove. Feeding activity results in a sediment turnover of 11.7 +/- 9.7 g(dw) m(-2) day(-1) and 6.8 +/- 3.0 g(dw) m(-2) day(-1) in the pioneer and young mangroves, respectively. Burrow maintenance excavates 40.5 +/- 7.4 g(dw) m(-2) day(-1) and 251.3 +/- 419.7 g(dw) m(-2) day(-1) in the pioneer and young mangroves, respectively. Upscaling to the studied area (Sinnamary estuary: 6 km(2)), shows that 500 tons.day(-1) and 20 tons.day(-1) of sediments could be excavated and pelletized, respectively, during the spring tides of the dry season. Thus, biological sediment reworking would greatly contribute to the sedimentary dynamics of the Guianese mangroves under Amazonian influence.
Published: 2016
Full Text: View/download PDF

25. Effects of progressive hypoxia on oxygen uptake in juveniles of the Peruvian scallop, Argopecten purpuratus (Lamarck, 1819)

Author: Gérard Thouzeau, Arturo Aguirre-Velarde, Fred Jean, Jonathan Flye-Sainte-Marie, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Instituto del Mar del Peru (IMARPE), ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, Argopecten purpuratus, Q10, chemistry.chemical_element, Aquaculture, Aquatic Science, 01 natural sciences, Oxygen, Animal science, Respiration, Peru, 14. Life underwater, Oxygen saturation, [SDV.EE]Life Sciences [q-bio]/Ecology, environment, Argopecten, biology, 010604 marine biology & hydrobiology, ACL, Hypoxia (environmental), 04 agricultural and veterinary sciences, Oxygen critical point, biology.organism_classification, Oceanography, chemistry, 13. Climate action, Scallop, 040102 fisheries, 0401 agriculture, forestry, and fisheries, Oxyregulation, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, circulatory and respiratory physiology
Abstract: International audience; A field survey performed in Paracas Bay (Peru), a major scallop culture area, showed that the Peruvian scallop, Argopecten purpu-ratus, periodically faces severe hypoxic events. Oxygen uptake rate (VO2) of A. purpuratus juveniles facing progressive decrease of environmental oxygen saturation (from 100% to 5%) was measured at two contrasting temperatures ("normal condition" = 16°C and "warm condition" = 25°C). In normoxia, (oxygen saturation >70%) average VO2 was significantly (p < 0.001) higher in warm condition (0.20 ±0.004 mgO 2 ind −1 h −1) than in normal condition (0.12 ±0.007 mgO 2 ind −1 h −1). The shape of the VO2 response curve during increasing hypoxic conditions was evaluated using a segmented linear regression. The break points between linear segments allowed estimating the oxygen critical points (PcO2 , oxygen saturation units), while the slopes of the various segments was used to assess the VO2 regulatory capacity. In both temperature conditions at oxygen saturation lower than PcO2 , VO2 was a fourth of the values recorded in normoxic condition. This trend was more pronounced in the warm condition. Paradoxically, the estimated PcO2 was lower in warm condition (21.4% ±0.7) compared to the normal condition (24.4% ±1.9). However, the study of the slopes at oxygen saturations higher than PcO2 revealed that A. purpuratus can regulate its respiratory rate similarly and efficiently at both 16 and 25°C. Moreover, for VO2 above PcO2 , the estimated Q10 between normal and warm conditions was 1.78 (Arrhenius temperature = 4983 K), highlighting a moderate effect of temperature on VO2. These results reflect the adaptive capacity of this species to the changing environment along the Peruvian-Chilean coasts influenced by upwelling system and ENSO events. However, results from this study indicate that, at least during some periods, A. purpuratus spend more than 70% of its time exposed to hypoxic conditions below the estimated PcO2. Such conditions could have negative consequences on the species metabolism and harm the performance of A. purpuratus culture.
Published: 2016
Full Text: View/download PDF

26. Diurnal heterogeneity in silicic acid fluxes in shallow coastal sites: Causes and implications

Author: Sorcha Ní Longphuirt, Aude Leynaert, Laurent Chauvaud, Olivier Ragueneau, Sophie Martin, Gérard Thouzeau, Frédéric Jean, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Marine Environment Laboratories, and International Atomic Energy Agency [Vienna] (IAEA)
Subjects: 0106 biological sciences, silicic acid, diurnal variations, microphytobenthos, 010504 meteorology & atmospheric sciences, Aquatic Science, Oceanography, 01 natural sciences, chemistry.chemical_compound, Benthos, Diurnal cycle, Phytoplankton, 14. Life underwater, Silicic acid, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, subtidal, migrations, 010604 marine biology & hydrobiology, Diurnal temperature variation, Bay of Brest, Pelagic zone, Plankton, chemistry, 13. Climate action, Benthic zone, Environmental science, France
Abstract: International audience; In shallow coastal areas the amplitude and range of benthic silicic acid fluxes can have a significant influence on benthic–pelagic coupling and the functioning of the pelagic system. To explore the oscillation in fluxes over the diurnal cycle and in particular the influence of microphytobenthos (MPB), an experiment was carried out in a shallow subtidal site in the Bay of Brest (France). Benthic chambers were employed over a 48 h period to measure the variability in silicic acid and oxygen fluxes; MPB migration was investigated using a diving Pulse Amplitude Modulated (PAM) fluorometer and uptake rhythms of silicic acid by natural MPB populations were measured using the 32Si isotope. It was discovered that silicic acid fluxes fluctuated greatly throughout the diurnal period resulting in an oscillation in the availability of this nutrient for phytoplankton communities. The uptake of silicic acid by the MPB was quantified for the first time and highlighted a 2-fold increase in the demand from night to afternoon periods. The combined silicic acid uptake and the concentration of cells at the sediment–water interface, forming a dense biofilm of MPB, were postulated to be the main processes reducing effluxes at midday. Our work highlighted the many processes which influence silicic acid effluxes in shallow coastal areas and the possible interaction between uptake and dissolution processes. The variations in benthic fluxes over the diurnal period were comparable to observations reported at the seasonal scale. Therefore, up-scaling hourly flux observations to daily and annual estimates should be undertaken with caution. Further we suggest that the main processes influencing flux oscillations over the diurnal period should be considered when planning sampling strategies and extrapolating to larger time scales.
Published: 2009
Full Text: View/download PDF

27. Response of a phytoplankton community to increased nutrient inputs: A mesocosm experiment in the Bay of Brest (France)

Author: Pascal Claquin, Stéphane L'Helguen, Philippe Pondaven, Aude Leynaert, Annick Masson, Pierre Fouillaron, Véronique Martin-Jézéquel, Gérard Thouzeau, Pierre Huonnic, Sorcha Ní Longphuirt, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO), Physiologie et Ecophysiologie des Mollusques Marins (PE2M), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS), Adaptation et diversité en milieu marin (AD2M), Station biologique de Roscoff [Roscoff] (SBR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Mer, molécules et santé EA 2160 (MMS), Université de Nantes - UFR des Sciences Pharmaceutiques et Biologiques, Université de Nantes (UN)-Université de Nantes (UN)-Le Mans Université (UM)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN), Région Bretagne and is part of an INVABIO 2 project that was funded by the Ministère de l'Ecologie et du Développement Durable, Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Le Mans Université (UM)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Université de Nantes - UFR des Sciences Pharmaceutiques et Biologiques, and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, 010504 meteorology & atmospheric sciences, biology, Ecology, 010604 marine biology & hydrobiology, Chaetoceros, Aquatic Science, biology.organism_classification, 01 natural sciences, Algal bloom, Mesocosm, Diatom, Benthic zone, Phytoplankton, Dominance (ecology), 14. Life underwater, Bay, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences
Abstract: International audience; In the Bay of Brest (France), benthic fluxes of silicic acid (DSi) are thought to be strongly involved in diatom dominance and their intensity depends on the density of an invasive gastropod, Crepidula fornicata. While the proliferation of this gastropod is likely to support diatom dominance, local fishermen have proposed its removal as it perturbs the development of the native Great Scallop, Pecten maximus. However, such a removal may be associated with potentially harmful algal blooms. The response of the phytoplankton community to modifications of the benthic fluxes of DSi, resulting from a further proliferation or the removal of C fornicata, was examined in a mesocosm nutrient enrichment experiment over a period of 16 days in the spring of 2004. Six mesocosms (5.4 m(3)) were filled using a natural planktonic assemblage from the Bay and received N, P and Si additions at the stoichiometric ratio of the in situ benthic fluxes (Si:N:P=16:16:1), with a gradient of enrichment ranging from 0 to almost 4 times the maximal benthic flux measured in the Bay. The diatom Chaetoceros (mainly C. debilis) rapidly outgrew non-siliceous species of microphytoplankton in all enclosures although kinetic experiments provided direct evidence of Si limitation. This dominance of diatoms at DSi concentrations
Published: 2007
Full Text: View/download PDF

28. Improving Argopecten purpuratus culture in northern Chile: Results from the study of larval and post-larval stages in relation to environmental forcing

Author: Gérard Thouzeau, Marcela Cantillánez Silva, and Miguel Avendaño
Subjects: education.field_of_study, Argopecten, Argopecten purpuratus, biology, Marine reserve, Population, Aquatic Science, Plankton, Bivalvia, biology.organism_classification, Fishery, Oceanography, Scallop, education, Bay
Abstract: Scallop management studies including a spat collection program have been carried out within the marine reserve of La Rinconada Bay to protect genetic diversity of scallops, to restock natural populations and to provide wild spat to culture activities in Chile. Plankton sampling and spat collection were used to characterize larval and post-larval stages of the Argopecten purpuratus population within this reserve, between December 1995 and March 2000. Main goals were to determine optimal scallop spat collection area, temporal variations of spat settlement and the effect of collector distance off the bottom, and spat growth within the collectors. Larval sampling showed the almost continuous presence, although in variable abundances, of scallop larvae, except for late August–September. Greatest larval abundances were consistently observed from November–December to April–May of the following year. This pattern was altered during the La Nina event of 1998–2000 with unusual peaks of larvae in late July 1999 and November–December 1999. A significant positive relationship was found between the abundance of the large-sized larvae and Chl a concentration ca. 2 weeks before, between February 1999 and February 2000. Larval growth rates ranged from 3.5 to 7.3 μm day − 1 . Shallow waters were not appropriate for spat collection; the best spat collection area was located in the northwestern part of the Reserve, in water depths ranging from 15 to 20–25 m. Spat settlement was significantly higher at 1 m and 2 m off the bottom, compared with 3 m off the seabed. There was no clear pattern of differential spat growth with collector distance from the bottom in a given site, but spatial variations were observed in the Bay at 1 m off the bottom depending on depth-related bottom-water temperature. Spat settlement occurred almost continuously between November 1997 and March 2000, but in variable proportions: spat abundance ranged from 12 to 6540 ind.coll. − 1 . Mean spat growth rate was 175 μm day − 1 during the ENSO period, vs. 143 μm day − 1 during La Nina. Culture improvements are discussed from these new insights on the reproductive cycle and spat collection of A. purpuratus . The former would facilitate future management practices and would help to restore stocks in the Rinconada Bay.
Published: 2007
Full Text: View/download PDF

29. Benthic community respiration in areas impacted by the invasive mollusk Crepidula fornicata

Author: Frédéric Jean, Marion Richard, Gérard Thouzeau, Laurent Chauvaud, Jacques Clavier, and Sophie Martin
Subjects: geography, geography.geographical_feature_category, Ecology, Estuary, Aquatic Science, Biology, biology.organism_classification, Water column, Oceanography, Benthos, Benthic zone, Environmental chemistry, Dissolved organic carbon, Phytoplankton, Crepidula, Bay, Ecology, Evolution, Behavior and Systematics
Abstract: The American slipper limpet Crepidula fornicata L. has been an invasive species in European bays and estuaries since the 1950s and can reach densities up to several thousands of individuals m -2 . The objective of this study was to estimate the impact of C. fornicata on benthic community metabolism by comparing 2 contrasting sites with high (>1000 ind. m -2 ) and low (
Published: 2007
Full Text: View/download PDF

30. Biological control of trace metal and organometal benthic fluxes in a eutrophic lagoon (Thau Lagoon, Mediterranean Sea, France)

Author: Jacques Grall, Frédéric Jean, David Point, David Amouroux, Gérard Thouzeau, Olivier F. X. Donard, Erwan Amice, Emmanuel Tessier, Mathilde Monperrus, Aude Leynaert, Jacques Clavier, Laurent Chauvaud, Laboratoire de Chimie Analytique Bio-Inorganique et Environnement (LCABIE), Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux (IPREM), Université de Pau et des Pays de l'Adour (UPPA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Pau et des Pays de l'Adour (UPPA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Université européenne de Bretagne - European University of Brittany (UEB)
Subjects: Biogeochemical cycle, mercury, 010504 meteorology & atmospheric sciences, trace metals, sediment–water exchanges, biota, 010501 environmental sciences, Aquatic Science, Oceanography, 01 natural sciences, Mediterranean Sea, Trace metal, 14. Life underwater, 0105 earth and related environmental sciences, [SDV.EE]Life Sciences [q-bio]/Ecology, environment, geography, geography.geographical_feature_category, Thau Lagoon, Trace element, Sediment, Estuary, Redox gradient, speciation, 13. Climate action, Benthic zone, Environmental science, Spatial variability, France, organotin
Abstract: International audience; In situ benthic chamber experiments were conducted in the Thau Lagoon that allowed the simultaneous determination of the benthic exchanges of trace metals (Cd, Co, Cu, Mn, Pb and U) and mercury species (iHg and MMHg). Fluxes of organotin compounds (MBT, DBT and TBT) were also investigated for the first time. The benthic incubations were performed during two campaigns at four stations that presented different macrobenthic and macrophytic species distribution and abundance (see [Thouzeau, G., Grall, J., Clavier, J., Chauvaud, L., Jean, F., Leynaert, A., Longpuirt, S., Amice, E., Amouroux, D., 2007. Spatial and temporal variability of benthic biogeochemical fluxes associated with macrophytic and macrofaunal distributions in the Thau lagoon (France). Estuarine, Coastal and Shelf Science 72 (3), 432–446.]). The results indicate that most of the flux intensity as well as the temporal and spatial variability can be explained by the combined influence of microscale and macroscale processes. Microscale changes were identified using Mn flux as a good indicator of the redox conditions at the sediment–water interface, and by extension, as an accurate proxy of benthic fluxes for most trace metals and mercury species. We also observed that the redox gradient at the interface is promoted by both microbial and macrobenthic species activity that governs O2 budgets. Macroscale processes have been investigated considering macrobenthic organisms activity (macrofauna and macroalgal cover). The density of such macroorganisms is able to explain most of the spatial and temporal variability of the benthic metal fluxes within a specific site. A tentative estimation of the flux of metals and organometals associated with deposit feeder and suspension feeder activity was found to be in the range of the flux determined within the chambers for most considered elements. Furthermore, a light/dark incubation investigating a dense macroalgal cover present at the sediment surface illustrates the role of photosynthetic activity in controlling benthic exchanges. Significant changes in benthic flux intensity and/or direction were reported for all redox sensitive elements (Cd, Co, Cu, Mn, Pb, U, and iHg). For MMHg and organotin species, other complimentary processes such as photodegradation/uptake and hydrophobic absorption/desorption need to be considered. This work demonstrates that the processes governing benthic exchanges are complex and that benthic organisms play a major role in the significant seasonal, diurnal and spatial variability of trace metals and organometals benthic fluxes in the lagoon.
Published: 2007
Full Text: View/download PDF

31. Benthic O2 distribution and dynamics in a Mediterranean lagoon (Thau, France): An in situ microelectrode study

Author: Jacques Clavier, Christophe Rabouille, Karine Dedieu, S. Ogier, Gérard Thouzeau, Laurent Chauvaud, Frédéric Jean, Valérie Mesnage, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Océan et Interfaces (OCEANIS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Morphodynamique Continentale et Côtière (M2C), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut Universitaire Européen de la Mer (IUEM), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO)
Subjects: 0106 biological sciences, Oyster, Biogeochemical cycle, 010504 meteorology & atmospheric sciences, coastal ocean, Oyster farming, Aquatic Science, Oceanography, 01 natural sciences, Bottom water, biology.animal, sedimentewater exchange, medicine, benthic recycling, Organic matter, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, 14. Life underwater, 0105 earth and related environmental sciences, Total organic carbon, chemistry.chemical_classification, biology, 010604 marine biology & hydrobiology, 15. Life on land, Seasonality, biology.organism_classification, medicine.disease, microelectrode, chemistry, 13. Climate action, Benthic zone, organic carbon mineralization, Environmental science, oxygen
Abstract: Benthic oxygen profiles were acquired using microsensors over two seasonal cycles (December 2001, April and August 2002, January and May 2003) at two stations differently affected by shellfish farming activity in the Thau lagoon (French Mediterranean coast). This study was part of the Microbent-PNEC Program on the study of biogeochemical processes at the sedimentewater interface in an eutrophicated environment. We explored seasonal and spatial heterogeneity as well as the biogeochemical drivers of oxygen uptake, such as in situ temperature, bottom water oxygenation and organic matter deposition. O2 consumption rates were determined by using a transport-reaction model. Maximum rates were reached in August and May and minimum rates in December, April or January. The effect of oyster farming on oxygen fluxes was clearly identified with higher diffusive oxygen uptake in the station inside the oyster parks (C5; 36.8 18.5e87.7 40.8 mmol m2 d1), compared with the station lying outside the oyster parks (C4; 8.6 2.1e30.7 8.3 mmol m2 d1). At C5, the large spatial heterogeneity was statistically concealing temporal variation, whereas a clear statistical difference between cold and warm periods appeared at C4. In these lagoon sediments, the seasonal dynamics of diffusive oxygen demand and consumption rates were mainly driven by seasonal temperature variation at both stations, as well as by seasonal organic matter delivery to the sediment at the station located outside the oyster parks. In the station located below the oyster parks, seasonal variation of organic matter deposition was dampened by oyster filtering activity. Seasonal temperature variation thus appeared as the major driver of oxygen dynamics in this station. Measurements of total O2 uptake rates indicated a significant fraction of microbial recycling and diffusive transport in oxygen uptake at the station located close to the oyster parks. In the open water site, fauna-mediated O2 transport prevailed in April 2002 (cold conditions), whereas the microbial recycling seemed to dominate in May 2003 (warm conditions). 2006 Elsevier Ltd. All rights reserved.
Published: 2007
Full Text: View/download PDF

32. Spatial and temporal variability of benthic biogeochemical fluxes associated with macrophytic and macrofaunal distributions in the Thau lagoon (France)

Author: David Amouroux, Erwan Amice, Gérard Thouzeau, Laurent Chauvaud, Frédéric Jean, Sorcha Ní Longphuirt, Jacques Clavier, Aude Leynaert, and Jacques Grall
Subjects: Biogeochemical cycle, biology, Ecology, Sediment, Biota, Aquatic Science, Oceanography, biology.organism_classification, Macrophyte, Seagrass, Benthos, Benthic zone, Environmental science, Spatial variability
Abstract: The aim of the present study in the Thau lagoon was to determine spatial and temporal variations of biogeochemical fluxes at the sediment–water interface (oxygen, nutrients and DIC) associated with macrophytic and/or macrofaunal distributions during spring time, which is a period of major vegetal growth. The pattern of benthic fluxes was studied in April 2002 and May 2003 for four main benthic biota of the lagoon, with one site subject to biodeposition by oysters cultured in suspension, one site representative of the central part of the lagoon that was only under general sedimentation, one site densely covered by macroalgae and one site located within a seagrass meadow. The results emphasize the role of oyster cultures on benthic fluxes and the impact of spatial heterogeneity of the benthos (macrophytes and macrofauna) distribution at various spatial scales. Hypoxic conditions were shown to develop at the sediment–water interface in May 2003 in the central part of the lagoon. Oxygen and DIC fluxes emphasized benthic respiration overall, and spatio-temporal variability mainly due to the presence/absence of the macroalgal cover on the sediment. The absence of benthic macroinfaunal organisms in the stations under the influence of oyster biodeposition and facing a dense macroalgal cover highlighted anoxic conditions in the sediments. Major benthic macrofauna community changes were observed in the central zone between April 2002 and May 2003, emphasizing sediment organic matter enrichment. The analysis of benthic fluxes over a productive period of the annual cycle provided a basis for describing spatial and temporal variations of the dynamics of sediment–water exchanges in the lagoon.
Published: 2007
Full Text: View/download PDF

33. Impact of an invasive species,Crepidula fornicata, on the hydrodynamics and transport properties of the benthic boundary layer

Author: Catherine Bourg, Karen Mulleners, Georges Chapalain, Katell Guizien, Gérard Thouzeau, and Frédéric Moulin
Subjects: biology, Ecology, Aquatic environment, Sediment–water interface, Benthic boundary layer, Forestry, Crepidula, Aquatic Science, biology.organism_classification, Erodability, Geology, Invasive species
Abstract: Nous avons etudie l'impact d'une espece invasive, Crepidula fornicata, sur l'hydrodynamique et les proprietes de transport de la couche limite benthique. Nous presentons les resultats obtenus au moyen de trois approches differentes : 1) des mesures in-situ du courant pres du fond et de la concentration de sediment en suspension sur deux sites en Baie de Brest (Bretagne, France), 2) des mesures de vitesse dans des experiences controlees en laboratoire d'ecoulements au-dessus de coquilles artificielles de Crepidula, et 3) des simulations numeriques d'un ecoulement au-dessus d'un fond bidimensionnel en forme de coquilles. Les simulations numeriques et les experiences de laboratoire ont montre que l'erosion du lit et la vitesse d'echange entre la canopee et l'ecoulement externe decroissaient lorsque la densite en coquillages augmentait. Ces resultats suggerent un effet de protection par les coquilles de Crepidula dont l'efficacite croit avec la densite en coquillages. Cette tendance a ete egalement trouvee dans les mesures de terrain : durant les marees d'equinoxe, la resuspension observee sur le fond de sable fin envase faiblement colonise par les crepidules est plus importante que sur le site a forte densite en crepidules. Neanmoins, d'autres processus peuvent expliquer ces donnees ; leur importance est donc discutee dans cette etude.
Published: 2007
Full Text: View/download PDF

34. Gregariousness and protandry promote reproductive insurance in the invasive gastropod Crepidula fornicata: evidence from assignment of larval paternity

Author: Lise Dupont, Joëlle Richard, Frédérique Viard, Gérard Thouzeau, and Yves-Marie Paulet
Subjects: 0106 biological sciences, biology, Sequential hermaphroditism, Reproductive success, Ecology, 010604 marine biology & hydrobiology, Zoology, Sex reversal, biology.organism_classification, 010603 evolutionary biology, 01 natural sciences, Intraspecific competition, Hermaphrodite, Genetics, Crepidula, Mating, Sperm competition, reproductive and urinary physiology, Ecology, Evolution, Behavior and Systematics
Abstract: According to the size-advantage hypothesis, protandric sequential hermaphroditism is expected when the increase in reproductive success with age or size is small for males but large for females. Interestingly, some protandrous molluscs have developed gregarious strategies that might enhance male reproductive success but at the cost of intraspecific competition. The gastropod Crepidula fornicata, a European invading species, is ideal for investigating mating patterns in a sequential hermaphrodite in relation to grouping behaviour because individuals of different size (age) live in perennial stacks, fertilization is internal and embryos are brooded. Paternity analyses were undertaken in stacks sampled in three close and recently invaded sites in Brittany, France. Paternity assignment of 239 larvae, sampled from a set of 18 brooding females and carried out using five microsatellite loci, revealed that 92% of the crosses occurred between individuals located in the same stack. These stacks thus function as independent mating groups in which individuals may reproduce consecutively as male and female over a short time period, a pattern explained by sperm storage capacity. Gregariousness and sex reversal are promoting reproductive insurance in this species. In addition, females are usually fertilized by several males (78% of the broods were multiply sired) occupying any position within the stack, a result reinforcing the hypothesis of sperm competition. Our study pointed out that mating behaviours and patterns of gender allocation varied in concert across sites suggesting that multiple paternities might enhance sex reversal depending on sperm competition intensity.
Published: 2006
Full Text: View/download PDF

35. Influence of suspended mussel lines on the biogeochemical fluxes in adjacent water in the Îles-de-la-Madeleine (Quebec, Canada)

Author: Philippe Archambault, Marion Richard, Gérard Thouzeau, and Gaston Desrosiers
Subjects: chemistry.chemical_classification, Biogeochemical cycle, biology, Ecology, Biogeochemistry, Mussel, Aquatic Science, Bivalvia, biology.organism_classification, Water column, Nutrient, chemistry, Environmental chemistry, Organic matter, Mollusca, Ecology, Evolution, Behavior and Systematics
Abstract: Oxygen consumption and nutrient fluxes were measured in 80 L enclosures containing water, 1- or 2-year-old mussels, or 1- or 2-year-old line sections (mussels plus associated fauna organic matter complex: AFOM) in August and September 2003 in the Îles-de-la-Madeleine. Mussel lines acted as nutrient sources and oxygen sinks in adjacent water. The magnitude of fluxes at the mussel line interface depended on the nutrient (NH4 >> Si(OH)4, PO4 > NO3 > NO2). Mussel metabolism contributed greatly to O2 consumption and NH4 and PO4 releases. Mussel influence was greater in stressful periods. The AFOM complex mainly contributed to NO3, NO2, and Si(OH)4 fluxes. These fluxes could originate from organic matter decomposition rather than from associated faunal metabolism. The influence of AFOM depended on its composition and thus on line immersion time. Mussel lines by ammonia releases could be a factor of reduction of N limitation in the water column. Mussel line should be integrated as a new interface of biogeochemical exchanges in environmental carrying capacity studies.
Published: 2006
Full Text: View/download PDF

36. Comparison of Zostera marina and maerl community metabolism

Author: Jean-Marc Guarini, Laurent Chauvaud, Jacques Grall, Joëlle Richard, Sophie Martin, Frédéric Jean, Gérard Thouzeau, Christian Hily, Jacques Clavier, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre de Recherche sur les Ecosystèmes Marins et Aquacoles (CREMA), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS), and Sanz, Frédérique
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 0106 biological sciences, biology, [SDU.OCEAN] Sciences of the Universe [physics]/Ocean, Atmosphere, Ecology, 010604 marine biology & hydrobiology, Plant Science, Aquatic Science, biology.organism_classification, 010603 evolutionary biology, 01 natural sciences, Seagrass, Benthic zone, Temperate climate, Zostera marina, Ecosystem, 14. Life underwater, Autotroph, Maerl, Bay
Abstract: The photosynthetic and repiratory metabolism of Zostera marina and maerl communities was compared, in the same area of the Bay of Brest in March–April, using benthic chambers. P–E curves for both oxygen and carbon were established for bottom irradiances between 0 and 525 μmol m−2 s−1. An exponential function was fitted to calculate daily production. Community metabolic quotients did not differ for maerl and seagrass beds. Community photosynthetic quotients were significantly higher (1.19) whereas community respiratory quotients were lower (0.70) than 1. Maerl and seagrass bed P–E curves mainly differed by the minimum saturating irradiance (Ek). Net community production was estimated to 26.8 mmol C m−2 d−1 for Z. marina meadows and 8.6 mmol C m−2 d−1 for maerl beds. The two communities can, therefore, be considered as autotrophic during the March–April period. Community respiration did not differ between Z. marina meadows and maerl beds, with an average value of 53.8 mmol C m−2 d−1 during a day. In similar environmental conditions, the production of maerl beds corresponds to approximately one third that of seagrass meadows. The maerl communities, therefore, form productive ecosystems, relevant to temperate coastal ecosystems functioning.
Published: 2005
Full Text: View/download PDF

37. Clams as CO2 generators: The Potamocorbula amurensis example in San Francisco Bay

Author: James E. Cloern, Janet K. Thompson, Gérard Thouzeau, and Laurent Chauvaud
Subjects: geography, geography.geographical_feature_category, biology, Ecology, Primary production, Estuary, Aquatic Science, Oceanography, Bivalvia, biology.organism_classification, Population density, chemistry.chemical_compound, chemistry, Benthic zone, Carbonate, Environmental science, Potamocorbula amurensis, Bay
Abstract: Cm Respiration and calcium carbonate production by the invasive Asian clam, Potamocorbula amurensis, were cal culated to assess their importance as CO2 sources in northern San Francisco Bay. Production, calculated using monthly population density and size structure measured at three sites over 7 yr and a shell length/CaCO3 conversion factor, averaged 221 (�184) g CaCO3 m �2 yr �1 . Net calcium carbonate production by this exotic bivalve releases CO2 at a mean rate of 18 (�17) g C m �2 yr �1 . Respiration by P. amurensis, estimated from secondary production, releases additional CO2 at a mean rate of 37 (� 34) gCm �2 yr �1 . Therefore, total net CO2 production by P. amurensis averages 55 (�51) g C m �2 yr �1 in an estuarine domain where net primary production consumes only 20 g inorganic �2 yr �1 .C O 2 production by P. amurensis in northern San Francisco Bay is an underestimate of the total CO2 supply from the calcified zoobenthic communities of San Francisco Bay, and results from other studies have sug gested that this rate is not unusual for temperate estuaries. Global extrapolation yields a gross CO2 production rate in the world's estuaries of 1 � 10 14 gCy r �1 , which suggests that calcified benthic organisms in estuaries generate CO2 equal in magnitude to the CO2 emissions from the world's lakes or from planetary volcanism (the net source is determined by the highly variable rate of CO2 consumption by carbonate dissolution). This biogenic CO2 source is increasing because of the continuing global translocation of mollusks and their successful colonization of new habitats.
Published: 2003
Full Text: View/download PDF

38. Rôle des interactions biotiques sur le devenir du pré-recrutement et la croissance de Pecten maximus (L.) en rade de Brest

Author: Gérard Thouzeau, Laurent Guerin, Jacques Grall, and Laurent Chauvaud
Subjects: Ecology, Limpet, media_common.quotation_subject, Biology, biology.organism_classification, General Biochemistry, Genetics and Molecular Biology, Competition (biology), Benthic zone, Scallop, Pecten maximus, Crepidula, Bay, Mollusca, media_common
Abstract: Biotic interactions within benthic megafauna were studied from quantitative dredge samples to investigate their role in the persistence of low scallop, Pecten maximus, stocks in the Bay of Brest. The distributions of 148 species of the megafauna and of four age classes of Pecten maximus were sampled. Suspension feeders dominate all megabenthic assemblages within the bay. This domination can be related to Crepidula fornicata spreading in the bay; however, no direct competition for food between scallops and the slipper limpet (introduced species) has been observed. On the other hand, Crepidula spreading leads to major changes in sediment type (silting) in the bay owing to biodeposit production, and silting would be a major factor inducing the decrease in Pecten maximus distribution. Predation would not be limiting. Within 10 years, one may predict a strong decrease in the area colonized by scallops in the bay.
Published: 2000
Full Text: View/download PDF

39. Long-term variation of the Bay of Brest ecosystem:benthic-pelagic coupling revisited

Author: Laurent Chauvaud, Gérard Thouzeau, Frédéric Jean, and Olivier Ragueneau
Subjects: Biomass (ecology), Ecology, biology, fungi, Pelagic zone, Aquatic Science, Spring bloom, Biogenic silica, biology.organism_classification, Oceanography, Diatom, Benthic zone, Phytoplankton, Bay, Ecology, Evolution, Behavior and Systematics
Abstract: Observations over the last 20 yr of the development of pelagic and benthic communities of a western European coastal ecosystem (Bay of Brest) provide complementary hypotheses to the 'silicic acid pump' hypothesis. An increase in nitrogen inputs, independent of silicic acid levels, has lowered the Si:N molar ratios during the last 20 yr in river discharges. Since 1981, maximum concen- trations of chlorophyll a during the first spring bloom of the annual cycle have decreased, in contrast to the subsequent spring and summer blooms. Concomitantly, extensive spreading of an exotic gas- tropod Crepidula fornicata has modified the trophic structure of benthic communities by increasing suspension-feeder biomass. The following hypotheses on ecosystem functioning are made: (1) the decrease of chlorophyll biomass during the first spring bloom results from silicic acid limitation and increased suspension feeder activity, (2) benthic filtration and biodeposition activities enhance bio- genic silica retention at the sediment-water interface, and (3) recycling of trapped biogenic silica maintains diatom populations by providing silicic acid in summer and reduces primary production seasonality. These hypotheses suggest that benthic organisms control the export rate of biogenic silica towards the open-water ocean and thus the specific composition of secondary phytoplankton blooms in the Bay.
Published: 2000
Full Text: View/download PDF

40. Effects of environmental factors on the daily growth rate of Pecten maximus juveniles in the Bay of Brest (France)

Author: Gérard Thouzeau, Laurent Chauvaud, and Yves-Marie Paulet
Subjects: biology, Ecology, Dinoflagellate, Zoology, Aquatic Science, Bivalvia, biology.organism_classification, Pecten (genus), Scallop, Pecten maximus, Gymnodinium, Bloom, Bay, Ecology, Evolution, Behavior and Systematics
Abstract: The study of the effects of environmental factors on the daily growth of Pecten maximus juveniles (one- and two-year olds) in the Bay of Brest was prompted by the decline of the scallop fishery in the Bay. Scallops over 30 mm in shell length were collected monthly from October 1994 to November 1995. Daily shell growth rings were counted using image analysis. Multiple stepwise regression analyses were performed to identify environmental parameters significantly affecting mean daily shell growth rates of one- and two-year-old juveniles in 1994 and 1995. Normal growth of Pecten shells is mainly regulated by bottom-water temperature, salinity and, to a lesser extent, river flow, rather than food. In 1995, three major toxic blooms of Gymnodinium cf. nagasakiense were recorded, leading to major reductions in shell growth rates. The effect of the toxic blooms on the natural Pecten populations was all the more important as no wild scallop spat settled on artificial collectors during the 1995 summer toxic events, and no pre-recruits originating from the 1995 spawnings were sampled on the bottom, despite good-quality spawnings. Two growth retardations were observed for one-year-old juveniles during the summer of 1995: the first one appears to be related to the sedimentation of a Rhizosolenia delicatula–Chaetoceros sociale bloom. It is suggested that the large aggregates of these diatoms led to clogging of the scallop gills. The second growth decrease was explained by the first bloom of G. cf. nagasakiense. The second and third dinoflagellate blooms were not associated with daily growth rate decreases in one-year-old scallops. The toxic effect of the dinoflagellate blooms was greater for two-year-old than for one-year-old juveniles; higher filtration rates and/or a differently oriented metabolism, compared with younger individuals, would explain these variations.
Published: 1998
Full Text: View/download PDF

41. MMHg production and export from intertidal sediments to the water column of a tidal lagoon (Arcachon Bay, France)

Author: Jacques Clavier, Pablo Rodríguez-González, Jonathan Deborde, Jacques Grall, Stéphane Bujan, David Amouroux, Pierre Anschutz, Emmanuel Tessier, Erwan Amice, Gérard Thouzeau, Sylvain Bouchet, Mathilde Monperrus, Laboratoire de Chimie Analytique Bio-Inorganique et Environnement (LCABIE), Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux (IPREM), Université de Pau et des Pays de l'Adour (UPPA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Pau et des Pays de l'Adour (UPPA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), and Université de Brest (UBO)
Subjects: 010504 meteorology & atmospheric sciences, Benthic reactivity, Tidal cycling, Sediment, Intertidal zone, 010501 environmental sciences, 01 natural sciences, 6. Clean water, Water column, Oceanography, 13. Climate action, Benthic zone, Bioaccumulation, [SDE]Environmental Sciences, Erosion, Environmental Chemistry, Environmental science, Ecosystem, 14. Life underwater, Mercury species, Coastal ecosystem, Bay, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology
Abstract: International audience; Hg cycling in biologically productive coastal areas is of special importance given the potential for bioaccumulation of monomethylmercury (MMHg) into aquatic organisms. Field experiments were performed during three different seasons in Arcachon Bay, a mesotidal lagoon (SW France), to assess the variability of the water column concentrations, sediment-water exchanges and potential formation and degradation of MMHg. The objectives were to evaluate the contribution of intertidal mudflats to MMHg production and the various pathways of Hg species export. Dissolved and bulk concentrations of Hg species in the water column downstream of tidal flats were measured throughout several tidal cycles. The Hg benthic fluxes at the sediment-water interface were determined by means of benthic chambers for three different stations. Hg methylation and demethylation potentials were determined in surficial sediments and the water column using isotopic tracers. The tidal surveys demonstrated that benthic remobilization of Hg occurs primarily in association with sediment erosion and advection during ebb tide. However, elevated dissolved Hg concentrations observed at low tide were found to be caused by a combination of pore-waters seeping, benthic fluxes and methylation in the water column. Benthic fluxes were more intense during late winter conditions (median MMHg and inorganic Hg (IHg) fluxes: 64 and 179 pmol m-2 h-1, respectively) and subsequently decreased in spring (median 0.7 and -5 pmol m-2 h-1, respectively) and fall (median -0.4 and -1.3 pmol m-2 h-1, respectively). The trends in methylation and demethylation potentials were at the opposite of the fluxes, two times lower during winter than for spring or fall conditions. In this tidal environment, MMHg production in surface sediments and its subsequent release is estimated to be the major source of MMHg to the water column during winter and spring time. However, during the more productive summer period, the Hg methylation extent in the water column may be very significant and equivalent to the sediment contribution.
Published: 2013
Full Text: View/download PDF

42. Measurements of gaseous mercury exchanges at the sediment-water, water-atmosphere and sediment-atmosphere interfaces of a tidal environment (Arcachon Bay, France)

Author: Gérard Thouzeau, Jacques Clavier, Romain Bridou, Emmanuel Tessier, Mathilde Monperrus, Sylvain Bouchet, David Amouroux, Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux (IPREM), Université de Pau et des Pays de l'Adour (UPPA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and ANR-06-BLAN-0040,PROTIDAL,Les processus biogéochimiques transitoires de la zone intertidale(2006)
Subjects: Geologic Sediments, 010504 meteorology & atmospheric sciences, Intertidal zone, 010501 environmental sciences, Management, Monitoring, Policy and Law, Atmospheric sciences, 01 natural sciences, Phase Transition, Wind speed, Flux (metallurgy), Water column, Seawater, 0105 earth and related environmental sciences, Hydrology, Air Pollutants, Gaseous mercury, Atmosphere, Public Health, Environmental and Occupational Health, Mercury, General Medicine, Contamination, 13. Climate action, [SDE]Environmental Sciences, Environmental science, France, Bay, Exchange model, Water Pollutants, Chemical, Environmental Monitoring
Abstract: International audience; The elemental mercury evasion from non-impacted natural areas is of significant importance in the global Hg cycle due to their large spatial coverage. Intertidal areas represent a dynamic environment promoting the transformations of Hg species and their subsequent redistribution. A major challenge remains in providing reliable data on Hg species variability and fluxes under typical transient tidal conditions found in such environment. Field experiments were thus carried out to allow the assessment and comparison of the magnitude of the gaseous Hg fluxes at the three interfaces, sediment-water, sediment-atmosphere and water-atmosphere of a mesotidal temperate lagoon (Arcachon Bay, Aquitaine, France) over three distinct seasonal conditions. The fluxes between the sediment-water and the sediment-atmosphere interfaces were directly evaluated with field flux chambers, respectively static or dynamic. Water-atmosphere fluxes were evaluated from ambient concentrations using a gas exchange model. The fluxes at the sediment-water interface ranged from −5.0 to 5.1 ng m−2 h−1 and appeared mainly controlled by diffusion. The occurrence of macrophytic covers (i.e.Zostera noltii sp.) enhanced the fluxes under light radiations. The first direct measurements of sediment-atmosphere fluxes are reported here. The exchanges were more intense and variable than the two other interfaces, ranging between −78 and 40 ng m−2 h−1 and were mostly driven by the overlying atmospheric Hg concentrations and superficial sediment temperature. The exchanges between the water column and the atmosphere, computed as a function of wind speed and gaseous mercury saturation ranged from 0.4 to 14.5 ng m−2 h−1. The flux intensities recorded over the intertidal sediments periodically exposed to the atmosphere were roughly 2 to 3 times higher than the fluxes of the other interfaces. The evasion of elemental mercury from emerged intertidal sediments is probably a significant pathway for Hg evasion in such tidal environments exhibiting background contamination level.
Published: 2011
Full Text: View/download PDF

43. Methane sources, sinks and fluxes in a temperate tidal lagoon: The Arcachon Lagoon (SW France)

Author: Guy Boucher, Mathieu Canton, Jonathan Deborde, Frédéric Guérin, Gwenaël Abril, Dominique Poirier, Gérard Thouzeau, Danielle Marty, Pierre Anschutz, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Mécanismes et Transfert en Géologie (LMTG), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Centre d'océanologie de Marseille (COM), Université de la Méditerranée - Aix-Marseille 2-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Biologie des organismes marins et écosystèmes (BOME), Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS), UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), French National Programme on Coastal Environment (PNEC 'Chantier Littoral Atlantique') and the ANR project PROTIDAL, ANR-06-BLAN-0040,PROTIDAL,Les processus biogéochimiques transitoires de la zone intertidale(2006), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Wetland, Aquatic Science, Oceanography, 01 natural sciences, Methane, Atmosphere, chemistry.chemical_compound, Pore water pressure, Water column, Arcachon Lagoon, 14. Life underwater, Water pollution, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, 010604 marine biology & hydrobiology, methane, Sediment, 6. Clean water, coastal environment, chemistry, chamber flux measurements, 13. Climate action, Environmental science, Water quality, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract: The Arcachon lagoon is a 156 km 2 temperate mesotidal lagoon dominated by tidal flats (66% of the surface area). The methane (CH 4 ) sources, sinks and fluxes were estimated from water and pore water concentrations, from chamber flux measurements at the sediment–air (low tide), sediment–water and water–air (high tide) interfaces, and from potential oxidation and production rate measurements in sediments. CH 4 concentrations in waters were maximal (500–1000 nmol l −1 ) in river waters and in tidal creeks at low tide, and minimal in the lagoon at high tide ( −1 ). The major CH 4 sources are continental waters and the tidal pumping of sediment pore waters at low tide. Methanogenesis occurred in the tidal flat sediments, in which pore water concentrations were relatively high (2.5–8.0 μmol l −1 ). Nevertheless, the sediment was a minor CH 4 source for the water column and the atmosphere because of a high degree of anaerobic and aerobic CH 4 oxidation in sediments. Atmospheric CH 4 fluxes at high and low tide were low compared to freshwater wetlands. Temperate tidal lagoons appear to be very minor contributor of CH 4 to global atmosphere and to open ocean.
Published: 2010
Full Text: View/download PDF

44. Benthic-pelagic coupling and the seasonal silica cycle in the Bay of Brest (France): new insights from a coupled physical-biological model

Author: Olivier Ragueneau, Goulven Gildas Laruelle, M. Kempa, Gérard Thouzeau, Brivaëla Moriceau, Pierre Regnier, Ni S.N. Longphuirt, Aude Leynaert, Laurent Chauvaud, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Mass distribution, 0106 biological sciences, 010504 meteorology & atmospheric sciences, Dissolved silica, Numerical models, Population, Aquatic Science, Biology, Coastal zone, 01 natural sciences, Algal bloom, 14. Life underwater, education, Crepidula fornicata, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, education.field_of_study, geography, geography.geographical_feature_category, Ecology, Harmful algal bloom, 010604 marine biology & hydrobiology, Silica, Pelagic zone, Estuary, ANE, France, Brittany, Brest Bay, Benthic-pelagic coupling, Plankton, Estuarine environment, Oceanography, 13. Climate action, Benthic zone, Nutrient cycles, [SDE]Environmental Sciences, Algal blooms, Heterogeneity, Crepidula fornicata (Linnaeus, 1758), Bay
Abstract: International audience; A fully transient, 2-dimensional physical and biological model has been developed to quantify the seasonal cycle of silica in the estuaries-coastal zone continuum of the Bay of Brest (France). The numerical model includes an explicit representation of the benthic-pelagic coupling, which is stimulated by the increasing density of an invasive megabenthic filter feeder, the slipper limpet Crepidula fornicata. The selected spatial resolution allows resolution of the heterogeneous density distribution of these organisms in the bay. Results show that the benthic nutrient dynamics are highly variable and strongly depend on the local conditions. This heterogeneity is not reflected in the pelagic phytoplankton Population dynamics because transport and mixing homogenize the distribution of nutrients and biomass. A seasonally resolved silica budget over the entire bay and estuaries emphasizes the important contribution of the benthic recycling fluxes to the supply of dissolved silica (dSi) during the productive period (similar to 50%, from 1 April to 1 September). In a prognostic scenario which forecasts the impact of removing the invasive benthic filter feeders, the dSi efflux is reduced by 63% and a pronounced harmful algal bloom of dinoflagellates develops in late summer.
Published: 2009
Full Text: View/download PDF

45. Diel variation of benthic respiration in a coral reef sediment (Reunion Island, Indian Ocean)

Author: Clémentine Esbelin, Jacques Clavier, Gérard Thouzeau, Laurent Chauvaud, Patrick Frouin, Pascale Cuet, Dorothée Taddei, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Ecologie Marine (ECOMAR), and Université de La Réunion (UR)
Subjects: 0106 biological sciences, 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Aquatic Science, Oceanography, 01 natural sciences, chemistry.chemical_compound, [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, Respiration, Dissolved organic carbon, 14. Life underwater, Reef, Diel vertical migration, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, 010604 marine biology & hydrobiology, fungi, sediments, carbon dioxide, Coral reef, chemistry, Benthic zone, Carbon dioxide, coral reef, Limiting oxygen concentration, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, metabolism, oxygen, Geology, geographic locations, respiration
Abstract: International audience; Oxygen and total dissolved inorganic carbon (DIC) fluxes at the water–sediment interface were measured using benthic chambers to assess the short-term variations of community respiration (CR) in the back reef sediments of Reunion Island (Indian Ocean). Benthic CR had a daily cycle of minimal (6:00 AM) and maximal values (6:00 PM), showing increases of oxygen and DIC fluxes of 2.8- and 3.8-fold, respectively. Average CR values were observed at midday and midnight. The evolution of fluxes was positively related to oxygen concentration in ambient water, but not to temperature changes. In the study area, high daytime primary production augments the amount of energy available for community metabolism and increases benthic respiration. The benthic communities are therefore subjected to short-term variable environmental conditions with oxygen supersaturation during the day, and moderately hypoxic conditions at the end of the night.
Published: 2008
Full Text: View/download PDF

46. Effects of seasonal dynamics in a Zostera noltiimeadow on phosphorus and iron cycles in a tidalmudflat (Arcachon Bay, France)

Author: Gérard Thouzeau, Jonathan Deborde, Guy Bachelet, Aurélia Mouret, Pierre Anschutz, Gwenaël Abril, Didier Jézéquel, Jacques Clavier, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, 010504 meteorology & atmospheric sciences, eelgrass growth, Intertidal zone, Aquatic Science, 01 natural sciences, Pore water pressure, Water column, Nutrient, [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Organic matter, Zostera, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Early diagenesis, Ecology, Evolution, Behavior and Systematics, Eelgrass growth, 0105 earth and related environmental sciences, intertidal zone, chemistry.chemical_classification, Ecology, biology, 010604 marine biology & hydrobiology, nutrient, Sediment, Lagoon, 15. Life on land, biology.organism_classification, 6. Clean water, lagoon, Oceanography, chemistry, Environmental chemistry, early diagenesis, Bay
Abstract: International audience; A study was conducted in Arcachon Bay, France, to determine the effect of seasonal dynamics in a Zostera noltii meadow on P and Fe cycles in the superficial sediments of a tidal mudflat. The redox-sensitive Fe particulate pool and associated P in the root zone showed a seasonal variation following the growth and decay of Z. noltii biomass, with a maximum content during the growth period. In comparison, the bare sediments did not show significant seasonal changes. A dissolved inorganic phosphorus (DIP) uptake was measured from the water column to the sediment in vegetated sediments, whereas a net DIP efflux was observed in the unvegetated sediments. During the growth period, the formation of an iron oxihydroxide-rich zone occurred and acted as a trap for dissolved phosphorus, constituting a reserve of available P for eelgrass growth. At the periphery of the rhizosphere, a strong reduction of the sediment occurred during the growth phase, probably due to increasing organic matter inputs via the roots. The iron oxihydroxide dissolution releases Fe(II) and the recently bound phosphorus to the pore water, making it available for assimilation by the eelgrass roots for growth metabolism. Fe(II) is re-oxidized to solid Fe(III) forms depleted in P into the root zone, or re-precipitated below as sulphur forms. The highest P uptake occurs by this process, and the seasonal variations in redox-sensitive P stock are sufficient to support the annual Z. noltii P requirement. During the decline period, as the P plant demand and the oxic layer thickness drop, the unused released DIP pool supplies large amounts of DIP to the pore water and water column.
Published: 2008
Full Text: View/download PDF

47. Growth of Argopecten purpuratus (Mollusca: Bivalvia) on a natural bank in Northern Chile: sclerochronological record and environmental controls

Author: Laurent Chauvaud, Miguel Avendaño, Marcela Cantillánez, Julien Thébault, Gérard Thouzeau, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Universidad de Antofagasta, Facultad de Recursos del Mar, Universidad de Antofagasta, This work was supported by international programs of cooperation between France and Chile (CNRS-CONICYT and ECOS-Sud C98B02 and C06B04) undertaken by the University of Antofagasta (Departamento de Acuicultura) and the University of Western Brittany (UMR 6539 CNRS)., and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, Argopecten purpuratus, Population, Aquatic Science, 01 natural sciences, Scallop aquaculture, 14. Life underwater, education, [SDV.EE]Life Sciences [q-bio]/Ecology, environment, education.field_of_study, biology, Ecology, 010604 marine biology & hydrobiology, Marine reserve, 04 agricultural and veterinary sciences, Bivalvia, biology.organism_classification, [SDV.BA.ZI]Life Sciences [q-bio]/Animal biology/Invertebrate Zoology, Oceanography, Scallop, [SDE]Environmental Sciences, 040102 fisheries, 0401 agriculture, forestry, and fisheries, Upwelling, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Bay
Abstract: The copyright to this article was transferred to EDP Sciences, IFREMER and IRD. The original publication is available at www.edpsciences.org/alr.; International audience; Daily striae on the shell of the scallop, Argopecten purpuratus, were used to investigate its growth in a protected population within La Rinconada Bay, near Antofagasta (2nd Region, Northern Chile), and to determine how environmental forcings control shell growth. This sclerochronological approach was useful to describe daily shell growth a posteriori. Mean shell growth rates were calculated daily between February and October 1999 from shells of six specimens harvested on 15 October 1999. A multiple regression analysis performed on shell growth and environmental data shows that a temperature increase stimulates shell growth whereas particulate organic carbon concentration might be stressful above 2.5 mg L-1. The lunar cycle might also have an effect on growth, most potent around New Moons, by synchronizing an endogenous oscillator. The age at commercial size (90 mm) was only 10–11 months in La Rinconada Marine Reserve and the von Bertalanffy growth parameters were K = 2.24 y-1 and Hoo = 117 mm. Differences in shell growth performances between this study and previous ones dealing with A. purpuratus growth may be explained by the different methods used for shell growth modelling, higher growth rate on the seabed compared to suspended cultures, and particular environmental forcings (e.g. El Niño Southern Oscillation-ENSO events). Growth performance seems better during La Niña than during El Niño events, probably because of the large temperature increase (above the highest temperatures recorded in “normal” conditions) and the decline in coastal upwelling (which affects food availability) during El Niño. La Rinconada Marine Reserve appears as a very favourable site for A. purpuratus growth, probably because of the active upwelling zone off Antofagasta. These new insights on A. purpuratus shell growth confirm the importance of La Rinconada Marine Reserve as an area supporting repopulation of endangered wild stocks and scallop aquaculture in Chile.
Published: 2008
Full Text: View/download PDF

48. Effects of water depth on survival and growth of Argopecten purpuratus (Lamarck, 1819) spat in Northern Chile

Author: Gérard Thouzeau, Marcela Cantillánez, Miguel Avendaño, Thouzeau, Gérard, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, Argopecten purpuratus, biology, 010604 marine biology & hydrobiology, Marine reserve, 04 agricultural and veterinary sciences, Aquatic Science, biology.organism_classification, 01 natural sciences, Water depth, Fishery, [SDE.BE] Environmental Sciences/Biodiversity and Ecology, stomatognathic diseases, [SDV.AEN] Life Sciences [q-bio]/Food and Nutrition, Scallop, otorhinolaryngologic diseases, 040102 fisheries, 0401 agriculture, forestry, and fisheries, Environmental science, 14. Life underwater, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Agronomy and Crop Science, Bay, [SDV.AEN]Life Sciences [q-bio]/Food and Nutrition, ComputingMilieux_MISCELLANEOUS
Abstract: Collection and suspended culture of Argopecten purpuratus spat in Japanese-type collectors was undertaken in the Rinconada Marine Reserve (Antofagasta, Chile) to determine growth variations between surface and bottom waters. Scallop spat was collected at 16-m depth and grown at 1- and 16-m depths. An initial settlement of ca. 13,000 post-larvae per bottom collector (2 cohorts) was observed on 3 February 2001. Two new cohorts settled in bottom collectors on 3 March, while no spat settlement occurred in surface collectors. The four cohorts exhibited substantial and different mortality rates over the study period, depending on the cohort and on-growing depth. The first and second cohorts exhibited mortality rates of 80.3 and 53.1% in bottom collectors, respectively, versus 29 and 43.6% in surface structures. The third and fourth cohorts exhibited mortality rates of 21.4 and 59.7% in bottom collectors, respectively. Mean shell height of scallop spat after 88 days of culture was 6.46 mm for the first cohort and 4.37 mm for the second cohort in bottom collectors, versus 10.33 and 7.31 mm in surface collectors, respectively. Mean post-larval growth rate in bottom collectors (86 μm day−1) was significantly lower than growth rate in surface collectors (146 μm day−1). Factors explaining the depth-related mortality and growth rates are discussed to improve scallop culture in the Reserve. It was concluded from the results that culture improvement in Antofagasta Bay would require collecting spat in bottom waters and raising it near the surface during initial cultivation stages.
Published: 2008

49. Seasonal variability of living benthic foraminifera from the outer continental shelf of the Bay of Biscay

Author: Gérald Duchemin, Gérard Thouzeau, Christian Hily, Françoise Andrieux-Loyer, Frans Jorissen, François Le Loc'h, and Thouzeau, Gérard
Subjects: 010506 paleontology, 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Aquatic Science, Oceanography, 01 natural sciences, Algal bloom, Foraminifera, Phytoplankton, 14. Life underwater, Ecology, Evolution, Behavior and Systematics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, biology, Continental shelf, Benthic foraminifera, Phytodetritus, Pelagic-benthic coupling, Bay of biscay, Seasonality, biology.organism_classification, [SDE.BE] Environmental Sciences/Biodiversity and Ecology, Cassidulina, [SDE.MCG] Environmental Sciences/Global Changes, Benthic zone, France, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Bay, Geology
Abstract: Living benthic foraminiferal faunas of six stations from the continental shelf of the Bay of Biscay have been investigated during three successive seasons (spring, summer and autumn 2002). For the three investigated stations, bottom water oxygen concentration, oxygen penetration into the sediment and sediment organic carbon contents are all relatively similar. Therefore, we think that the density and the composition of the foraminiferal faunas is mainly controlled by the quantity and quality of organic input resulting from a succession of phytoplankton bloom events, occurring from late February to early September. The earliest blooms are positioned at the shelf break, late spring and early summer blooms occur off Brittany, whereas in late summer and early autumn, only coastal blooms appear, often in the vicinity of river outlets. In spring, the benthic foraminiferal faunas of central (B, C and D) and outer (E) continental shelf stations are characterised by strong dominance in the first area and strong presence in the second area of Nonionella iridea. In fact, station E does not serve as a major depocenter for the remains of phytoplankton blooms. If station E is not considered, the densities of this taxon show a clear gradient from the shelf-break, where the species dominates the assemblages, to the coast, where it attains very low densities. We explain this gradient as a response to the presence, in early spring, of an important phytoplankton bloom, mainly composed of coccolithophorids, over the shelf break. This observation is supported by the maximum particles flux values at stations close to the shelf break (18.5 g m− 2 h− 1) and lower values in a station closer to the coast (6.8 g m− 2 h− 1). In summer, the faunal density is maximum at station A, relatively close to more varied phytoplancton blooms that occur off Brittany until early June. We suggest that the dominant species, Nonion fabum, Cassidulina carinata and Bolivina ex. gr. dilatata respond to phytodetritus input from these blooms. In autumn, the rich faunas of inner shelf station G are dominated by N. fabum, B. ex. gr. dilatata, Hyalinea balthica and Nonionella turgida. These taxa seem to be correlated with the presence of coastal blooms phenomena, in front of river outlets. They may be favoured by an organic input with a significant contribution of terrestrial, rather low quality organic matter.
Published: 2008

50. Capacitación artificial y crecimiento temprano de la 'semilla' de Argopecten purpuratus (Lamarck, 1819) en la reserva marina La Rinconada, Antofagasta, Chile

Author: Gérard Thouzeau, D Miguel Avendaño, S Marcela Cantillánez, Juan B. Peña, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Thouzeau, Gérard
Subjects: 0106 biological sciences, Argopecten purpuratus, Survival, captación de semilla, crecimiento, SH1-691, Growth, Aquatic Science, Oceanography, 01 natural sciences, lcsh:Aquaculture. Fisheries. Angling, Intraspecific competition, Larvae, Aquaculture. Fisheries. Angling, 14. Life underwater, larvas, Chile, [SDV.BDLR] Life Sciences [q-bio]/Reproductive Biology, ComputingMilieux_MISCELLANEOUS, lcsh:SH1-691, Larva, supervivencia, biology, 010604 marine biology & hydrobiology, Marine reserve, [SDV.BDLR]Life Sciences [q-bio]/Reproductive Biology, Spat collection, 04 agricultural and veterinary sciences, biology.organism_classification, [SDE.BE] Environmental Sciences/Biodiversity and Ecology, Fishery, Scallop, 040102 fisheries, 0401 agriculture, forestry, and fisheries, Scallop larvae, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Bay
Abstract: Artificial collection of early juveniles ("spat") of the scallop Argopecten purpuratus in Japanese-type collectors was evaluated between January 2001 and July 2002 in the La Rinconada Marine Reserve, Antofagasta, Chile. This area of Antofagasta Bay has in the past been noted for the retention of scallop larvae by local gyres, in which their numbers can vary between 89 and 34175 larvae m-3, producing larval sets of 400 to 15340 post-larvae (spat) per collector. The results showed no quantitative relationship between larval abundance in the water and the spat density collected per day in the collectors, although high settlement rates were associated with high numbers of umboned larvae in the water. Allowing collectors to remain in situ for extended periods of 88 and 159 days resulted in a severe loss of seed which had settled in the collectors during the first 28 to 40 days of immersion. These losses varied between 50.9 and 99.6% of the spat collected, and were more prejudicial for the smaller cohorts that had settled in the collectors at the end of the first immersion period. The growth rates measured among different cohorts for each immersion period varied between 81.3 and 235.2 mm/day for the first cohort (C1) and between 64.0 and 167.4 mm/day for the second cohort (C2). The highest growth rates occurred in collectors containing the lowest numbers of spat after the occurrence of spat losses during the long periods of immersion. Occurrence of intraspecific competition within the collectors is discussed as potentially responsible for the decreases in spat numbers and the variations observed in their growth rates., Un programa mensual de captación de A. purpuratus, implementado en la reserva marina de La Rinconada, entre enero de 2001 y julio de 2002, la caracterizó como zona de retención larvaria, con densidades variando entre 89 y 34175 larvas m-3, y de fijaciones entre 400 y 15340 post-larvas por colector. No se encontró una relación directa entre abundancia larvaria y asentamiento, sin embargo, las mayores captaciones estuvieron asociadas a la presencia de un elevado número de estados umbonados. La mantenimiento prolongado de colectores in situ, por periodos que variaron entre 88 y 159 días, provocó una fuerte reducción en el número de semillas que se asentaron en ellos durante los primeros 28 a 40 días de inmersión. Estas reducciones variaron entre el 99.6 y el 50.9% de la semilla fijada, siendo las más perjudicadas las cohortes más pequeñas, asentadas al final del primer periodo de inmersión. Las tasas de crecimiento registradas en estas cohortes, para cada periodo de inmersión, variaron entre 81.3 y 235.2 μm/día para las cohortes C1 y entre 64.0 y 167.4 μm/día para las cohortes C2. Las mayores tasas están directamente relacionadas con un menor número de semilla recuperada. Se discuten las competencias intraespecíficas ocurridas en los colectores, como responsables de la disminución del número de semilla y de las variaciones registradas en sus tasas de crecimiento., The present study was carried out within the framework of the FNDR project, Code BIP N°20127869-0.
Published: 2007
Full Text: View/download PDF

Catalog

Books, media, physical & digital resources

See catalog results

Searchworks

Select search scope, currently: Articles Catalog books, media & more in Jio Institute collections Articles journal articles & other e-resources

Search

Search Constraints

Refine your results

Search Limiters

Topic

Publication Year Range

Language

Publication Type

Journal

Database

Publisher

77 results on '"Gérard Thouzeau"'

Search Results

Catalog

Select search scope, currently: Articles

Catalog

books, media & more in Jio Institute collections

Articles

journal articles & other e-resources