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1. Assessment of Ba/Ca in Arctica islandica shells as a proxy for phytoplankton dynamics in the Northwestern Atlantic Ocean

Author

Philippe Archambault, Laurent Chauvaud, Pierre Poitevin, Pascal Lazure, Julien Thébault, Justine Doré, Gwénaëlle Chaillou, André Poirier, 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), Institut des Sciences de la MER de Rimouski (ISMER), Université du Québec à Rimouski (UQAR), 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), Centre de recherche sur la dynamique du système Terre (GEOTOP), Université de Montréal (UdeM)-McGill University = Université McGill [Montréal, Canada]-École Polytechnique de Montréal (EPM)-Concordia University [Montreal]-Université du Québec à Rimouski (UQAR)-Université du Québec à Montréal = University of Québec in Montréal (UQAM)-Université du Québec en Abitibi-Témiscamingue (UQAT), Departement de Biologie [Québec], Université Laval [Québec] (ULaval), This research is a contribution of LIA-BeBEST, an international collaboration between French (IUEM-UBO, LEMAR - Brest) and Canadian (ISMER-UQAR, Rimouski) academic institutions. We thank the LEMAR and the DFO for their help. We are sincerely grateful to Dr. Virginie Roy (MLI, Quebec-Canada) for her relevant advice and her kindness. In addition, we express our sincere gratitude to Dr. Simon B.elanger (UQAR) and Dr. Peter Galbraith (MLI) for their help to disentangle the information and Herl.e Goraguer (Ifremer delegate in SPM) for his commitment to the preparation and sending of a part of the samples. We show our appreciation to Laure Devine and Hannah Whitby for their useful comments. We also thank Eric Dabas for his technical assistance in the sclerochronology process. Finally, we would like to thank the two anonymous reviewers for their valuable comments and suggestions in a previous version of the manuscript. This research was supported by a grant from the Natural Sciences and Engineering Research Council of Canada (to G.C.) and the Canada Research Chair Program (to G.C.) as well as the Region Bretagne and the Cluster of Excellence LabexMER. This research was carried out as part of the Ph.D. thesis of Justine Dore for the University of Western Brittany. All the data used to produce the results of this paper may be obtained by contacting the corresponding author., 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), and École Polytechnique de Montréal (EPM)-McGill University = Université McGill [Montréal, Canada]-Université de Montréal (UdeM)-Université du Québec en Abitibi-Témiscamingue (UQAT)-Université du Québec à Rimouski (UQAR)-Concordia University [Montreal]-Université du Québec à Montréal = University of Québec in Montréal (UQAM)

Subjects
0106 biological sciences, Chlorophyll, Chlorophyll a, 010504 meteorology & atmospheric sciences, Global climate, Aquatic Science, Oceanography, 01 natural sciences, Proxy (climate), Cross-dating, chemistry.chemical_compound, Food chain, Northwestern Atlantic, Phytoplankton, A. islandica, 14. Life underwater, Master chronology, Arctica islandica, 0105 earth and related environmental sciences, biology, 010604 marine biology & hydrobiology, ACL, biology.organism_classification, chemistry, 13. Climate action, Ba/Ca, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Geology, Chronology
Abstract

International audience; Despite its major role as a global climate regulator, little is known about the recent evolution of the North Atlantic Ocean, especially prior to the fifties, principally because of the lack of long-term instrumental data. Moreover, the North Atlantic Ocean is undergoing rapid changes at the physical scale leading to modifications at the biological scale increasing interest to monitor the environment. The phytoplankton is the base of the ocean life and its perturbation can lead to further changes in the food chain. Recording its dynamics implies to observe both its spatial and temporal variations. This study brings forward the use of the Ba/Ca ratio from shells of the long-living bivalve Arctica islandica collected in the Northwestern Atlantic Ocean near Saint-Pierre and Miquelon (SPM) as a recorder of the past and present phytoplankton dynamics. A high inter and intra-reproducibility and synchrony between Ba/Cashell profiles were demonstrated allowing the reconstruction of a 124 years annually-resolved Ba/Cashell master chronology (from 1893 to 2016). This master chronology was positively correlated to the surface chlorophyll a measured by satellite sensor at regional (around SPM) and global scales (Northwestern Atlantic).

Published
2020

2. Comparison of the Effects of Two Herbicides and an Insecticide on Tropical Freshwater Plankton in Microcosms

Author

Philippe Cecchi, Laurence Amalric, Christophe Leboulanger, G. Sarazin, Agnès Bouchez, Marc Bouvy, Marc Pagano, Claire Carré, Ecosystèmes lagunaires : organisation biologique et fonctionnement (ECOLAG), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de géochimie des Eaux (LGE), Université Paris Diderot - Paris 7 (UPD7)-Institut de Physique du Globe de Paris, Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), 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]), Cyanobactéries des milieux aquatiques tropicaux peu profonds. Rôles et contrôles (CYROCO), This paper is a contribution to the ECOMET project, funded by the French Ministry of Ecology, Energy, Sustainable Development, and Sea (MEEDDM), grant no. CV070000783. The authors would like to thank the Forestry and Agriculture Office at Mamoudzou (DAF Mayotte) and SOGEA-Mayotte for their help with fieldwork. We are grateful to the staff of the Gite du Mont Combani for their support during our stay. Anonymous referees are acknowledged for improvement of an earlier version of the manuscript., and Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut National de la Recherche Agronomique (INRA)

Subjects
Paraquat, 0106 biological sciences, Insecticides, Food Chain, Health, Toxicology and Mutagenesis, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 010501 environmental sciences, Biology, 01 natural sciences, Zooplankton, Fenitrothion, chemistry.chemical_compound, Phytoplankton, Animals, Biomass, Mozambique, 0105 earth and related environmental sciences, 2. Zero hunger, Herbicides, 010604 marine biology & hydrobiology, fungi, General Medicine, Bacterioplankton, Plankton, Pesticide, environmental monitoring/analysis, Pollution, [SDE.ES]Environmental Sciences/Environmental and Society, 6. Clean water, chemistry, 13. Climate action, Diuron, Environmental chemistry, environmental sciences and ecology, Microcosm, natural plankton communities, tropical freshwater reservoir, Water Pollutants, Chemical, Environmental Monitoring, toxicology
Abstract

International audience; Natural plankton communities from a tropical freshwater reservoir (Combani Reservoir, Mayotte Island, Mozambique Channel) were exposed, in 20-l nutrient-enriched microcosms, to two nominal concentrations of three pesticides: the herbicides diuron (2.2 and 11 mu g/l) and paraquat (10 and 40.5 mu g/l) and the insecticide fenitrothion (10 and 100 mu g/l), commonly used in the tropics for agriculture and disease vector control. Bacterioplankton, phytoplankton, and zooplankton communities were monitored for 5 days after exposure, and the concentrations of toxicant and major nutrients were measured. Bacterioplankton growth was noticeable in all systems and was slightly affected by pesticide at any concentration. A transitory increase in thymidine-based bacterial production was observed in diuron- and fenitrothion-treated microcosms, followed by a marked decrease in all microcosms after 5 days. The functional diversity of bacterioplankton, evaluated using BIOLOG ECO (R) microplates, was reduced by exposure to the highest pesticide concentrations. Phytoplankton was affected by pesticides in different ways. Chlorophyll biomass and biovolumes were increased by diuron addition and decreased by paraquat, whereas fenitrothion-treated microcosms remained unaffected relative to controls. Phytoplankton taxonomic diversity was decreased by paraquat and high doses of fenitrothion but was unaffected by addition of diuron. The decrease in diversity was due to a reduction in the number of species, whereas the density of small cells increased, especially after addition of paraquat. Heterotrophic flagellates were sensitive to paraquat and to the highest diuron concentration; a reduction in biomass of up to 90% was observed for 40.5 mu g/l paraquat. Zooplankton, dominated by Thermocyclops decipiens and Diaphanosoma excisum, was slightly sensitive to diuron, and very sensitive to paraquat. High concentrations of the insecticide fenitrothion were effective only on young stages. The potential direct and indirect effects of pesticide contamination on such a simplified plankton food web, typical of newly constructed reservoirs, appear to differ significantly depending on the biological compartment considered. The overall sensitivity of tropical plankton is comparable to the sensitivity for temperate systems, and direct and indirect effects appeared rapidly, within 5 days of exposure.

Published
2011