47 results on '"Duarte, Carlos M."'
Search Results
2. Dissolved organic matter release in a Posidonia oceanica meadow
- Author
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Barrón, Cristina and Duarte, Carlos M.
- Published
- 2009
3. Effects of sediment sulfides on seagrass Posidonia oceanica meristematic activity
- Author
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Garcias-Bonet, Neus, Marbà, Núria, Holmer, Marianne, and Duarte, Carlos M.
- Published
- 2008
4. Sulfide invasion in the seagrass Posidonia oceanica at Mediterranean fish farms : assessment using stable sulfur isotopes
- Author
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Frederiksen, Morten S., Holmer, Marianne, Díaz-Almela, Elena, Marba, Núrià, and Duarte, Carlos M.
- Published
- 2007
5. Diversity of European seagrass indicators: patterns within and across regions
- Author
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Marbà, Núria, Krause-Jensen, Dorte, Alcoverro, Teresa, Birk, Sebastian, Pedersen, Are, Neto, Joao M., Orfanidis, Sotiris, Garmendia, Joxe M., Muxika, Iñigo, Borja, Angel, Dencheva, Kristina, and Duarte, Carlos M.
- Published
- 2013
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6. Mediterranean Seagrass Growth and Demography Responses to Experimental Warming
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Olsen, Ylva S., Sánchez-Camacho, María, Marbà, Núria, and Duarte, Carlos M.
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- 2012
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7. Distribution and Pathogenicity of the Protist Labyrinthula sp. in western Mediterranean Seagrass Meadows
- Author
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Garcias-Bonet, Neus, Sherman, Timothy D., Duarte, Carlos M., and Marbà, Núria
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- 2011
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8. Seagrass Meadows Modify Drag Forces on the Shell of the Fan Mussel Pinna nobilis
- Author
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Hendriks, Iris E., Cabanellas-Reboredo, Miguel, Bouma, Tjeerd J., Deudero, Salud, and Duarte, Carlos M.
- Published
- 2011
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9. Comparative Analysis of Stability—Genetic Diversity in Seagrass (Posidonia oceanica) Meadows Yields Unexpected Results
- Author
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Arnaud-Haond, Sophie, Marbà, Núria, Diaz-Almela, Elena, Serrão, Ester A., and Duarte, Carlos M.
- Published
- 2010
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10. Bacterial Community Dynamics in a Seagrass (Posidonia oceanica) Meadow Sediment
- Author
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García-Martínez, Micaela, López-López, Arantxa, Calleja, María Ll., Marbà, Núria, and Duarte, Carlos M.
- Published
- 2009
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11. Seagrass (Halophila stipulacea) invasion enhances carbon sequestration in the Mediterranean Sea.
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Wesselmann, Marlene, Geraldi, Nathan R., Duarte, Carlos M., Garcia‐Orellana, Jordi, Díaz‐Rúa, Rubén, Arias‐Ortiz, Ariane, Hendriks, Iris E., Apostolaki, Eugenia T., and Marbà, Núria
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POSIDONIA ,CARBON sequestration ,SEAGRASSES ,CARBON cycle ,CARBON isotopes ,POSIDONIA oceanica ,INTRODUCED species - Abstract
The introduction and establishment of exotic species often result in significant changes in recipient communities and their associated ecosystem services. However, usually the magnitude and direction of the changes are difficult to quantify because there is no pre‐introduction data. Specifically, little is known about the effect of marine exotic macrophytes on organic carbon sequestration and storage. Here, we combine dating sediment cores (210Pb) with sediment eDNA fingerprinting to reconstruct the chronology of pre‐ and post‐arrival of the Red Sea seagrass Halophila stipulacea spreading into the Eastern Mediterranean native seagrass meadows. We then compare sediment organic carbon storage and burial rates before and after the arrival of H. stipulacea and between exotic (H. stipulacea) and native (C. nodosa and P. oceanica) meadows since the time of arrival following a Before‐After‐Control‐Impact (BACI) approach. This analysis revealed that H. stipulacea arrived at the areas of study in Limassol (Cyprus) and West Crete (Greece) in the 1930s and 1970s, respectively. Average sediment organic carbon after the arrival of H. stipulacea to the sites increased in the exotic meadows twofold, from 8.4 ± 2.5 g Corg m−2 year−1 to 14.7 ± 3.6 g Corg m−2 year−1, and, since then, burial rates in the exotic seagrass meadows were higher than in native ones of Cymodocea nodosa and Posidonia oceanica. Carbon isotopic data indicated a 50% increase of the seagrass contribution to the total sediment Corg pool since the arrival of H. stipulacea. Our results demonstrate that the invasion of H. stipulacea may play an important role in maintaining the blue carbon sink capacity in the future warmer Mediterranean Sea, by developing new carbon sinks in bare sediments and colonizing areas previously occupied by the colder thermal affinity P. oceanica. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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12. Seagrass Posidonia oceanica diel pH fluctuations reduce the mortality of epiphytic forams under experimental ocean acidification.
- Author
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Ramajo, Laura, Lagos, Nelson A., and Duarte, Carlos M.
- Subjects
POSIDONIA ,OCEAN acidification ,POSIDONIA oceanica ,FORAMINIFERA ,SEAGRASSES ,MORTALITY - Abstract
It is hypothesized that pH fluctuations produced by seagrasses metabolism may confer marine calcifiers resistance to ocean acidification. Here, we tested this thesis by comparing the net population growth rate (NPGR) of a foraminifer species (Rosalina sp.) epiphytic of Mediterranean seagrass (Posidonia oceanica) to average current and projected pH scenarios under either stable conditions or diel fluctuations in pH of 0.3 units; variations similar to that experienced in their habitat. No significant differences were found in NPGRs between the fluctuating and stable pH treatments at current pH levels. NPGRs in treatments where pH fluctuated did not present significant differences to the treatment with high and stable pH conditions. In contrast, foraminifers exposed to stable low pH regimes experienced a steep decline in NPGR. These results suggest that diel pH fluctuations generated by P. oceanica photosynthetic activity could confer resistance to ocean acidification to Rosalina sp. • Forams epiphyte of Posidonia oceanica are resistant to ocean acidification scenarios. • Seagrasses may provide "refugia" from ocean acidification to associated biota. • There is an urgent need to incorporate pH fluctuations in the experimental designs. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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13. Dramatic loss of seagrass habitat under projected climate change in the Mediterranean Sea.
- Author
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Chefaoui, Rosa M., Duarte, Carlos M., and Serrão, Ester A.
- Subjects
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SEAGRASSES , *MARINE ecology , *CLIMATE change , *ECOLOGICAL niche , *PHYTOGEOGRAPHY - Abstract
Abstract: Although climate warming is affecting most marine ecosystems, the Mediterranean is showing earlier impacts. Foundation seagrasses are already experiencing a well‐documented regression in the Mediterranean which could be aggravated by climate change. Here, we forecast distributions of two seagrasses and contrast predicted loss with discrete regions identified on the basis of extant genetic diversity. Under the worst‐case scenario, Posidonia oceanica might lose 75% of suitable habitat by 2050 and is at risk of functional extinction by 2100, whereas Cymodocea nodosa would lose only 46.5% in that scenario as losses are compensated with gained and stable areas in the Atlantic. Besides, we predict that erosion of present genetic diversity and vicariant processes can happen, as all Mediterranean genetic regions could decrease considerably in extension in future warming scenarios. The functional extinction of Posidonia oceanica would have important ecological impacts and may also lead to the release of the massive carbon stocks these ecosystems stored over millennia. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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14. Thresholds of irradiance for seagrass Posidonia oceanica meadow metabolism
- Author
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Gacia, Esperança, Marbà, Núria, Cebrián, J., Vaquer-Sunyer, Raquel, Garcias-Bonet, Neus, and Duarte, Carlos M.
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Ecology ,biology ,Respiration ,Compensation Irradiance ,fungi ,Irradiance ,Sediment ,Carbon sink ,Production ,Aquatic Science ,Mediterranean ,biology.organism_classification ,Seagrass ,Agronomy ,Posidonia oceanica ,Botany ,Ecosystem ,Shading ,Ecology, Evolution, Behavior and Systematics - Abstract
11 páginas, 5 figuras., Meadows of the endemic seagrass Posidonia oceanica are threatened in the Mediterranean due to a general deterioration of the light environment that becomes critical when light irradiance is insufficient to meet the carbon requirements of the system. Here, we conduct a 3 wk, in situ shading experiment (8 levels plus controls) to determine the threshold of irradiance for balanced metabolism in a shallow P. oceanica meadow and further assess the recovery of the system 1 wk later. Reduced light irradiance decreased the net community production of the meadow, which may turn negative (i.e. respiration exceeded gross community primary production) under 338 μE m−2 s−1. Shading throughout the experiment did not appear to cause sustained physiological damage to the system since values of net community production after the cessation of shading were similar to pre-experimental, ambient levels. Sediment acid volatile sulfide pools ranged between 0.002 and 0.058 mol m−2 across shading treatments, and the highest pools were observed in the most shaded sediments. At high light impairment, meristematic cell divisions were low, and carbohydrate content in young rhizomes decreased throughout the experiment. Eight days after the cessation of shading, reduced rhizome carbohydrate stores and elevated sediment sulfide levels still persisted in the previously intensively shaded areas. The present study provides evidence of resistance and resilience of the seagrass Posidonia oceanica to light impairment for short (3 wk) periods of time. Although the compensation irradiance of the system varied by ~2-fold, it provides a quantitative estimate of the irradiance threshold at which seagrass meadows may shift from being coastal carbon sinks to CO2 sources., This research is a contribution to the project ‘Praderas’ funded by the Fundación BBVA.
- Published
- 2012
15. Effect of environmental factors (wave exposure and depth) and anthropogenic pressure in the C sink capacity of Posidonia oceanica meadows.
- Author
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Mazarrasa, Inés, Marbà, Núria, Garcia ‐ Orellana, Jordi, Masqué, Pere, Arias ‐ Ortiz, Ariane, and Duarte, Carlos M.
- Subjects
POSIDONIA oceanica ,CARBON cycle ,MEADOWS ,ANTHROPOGENIC effects on nature ,BIOACCUMULATION - Abstract
Seagrass are among the most important natural carbon sinks on Earth with Posidonia oceanica (Mediterranean Sea) considered as the most relevant species. Yet, the number of direct measurements of organic carbon burial rates in P. oceanica is still scarce and the effect of local environmental factors remains largely unexplored. In addition, P. oceanica meadows are declining due to the increase in anthropogenic pressure in coastal areas during the last century. The aim of this study is to assess the recent carbon sink capacity of P. oceanica and particularly the effect of human pressure and two environmental factors, water depth and exposure to wave energy (based on a fetch index), on the carbon burial rate since 1900. We conducted an extensive survey of sediment cores in meadows distributed across a gradient of depth, fetch, and human pressure around The Balearic Islands. Sediment and carbon accumulation rates were obtained from
210 Pb concentrations profiles. Top-30 centimeters carbon stocks (6.1 ± 1.4 kg C m−2 ) and burial rates (26 ± 6 g C m−2 yr1 ) varied up to fivefold across meadows. No significant effect of water depth in carbon burial rates was observed. Although fetch was significantly correlated with sediment mean grain size, confirming the effect of wave exposure in the patterns of sedimentation, fetch alone could not explain the differences in carbon burial rates among the meadows examined. Human pressure affected carbon burial rates, leading to increased rates since the onset of the rise in anthropogenic pressure, particularly so in sheltered meadows supporting high human pressure. [ABSTRACT FROM AUTHOR]- Published
- 2017
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16. Seagrass as major source of transparent exopolymer particles in the oligotrophic Mediterranean coast.
- Author
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Iuculano, Francesca, Duarte, Carlos M., Marbà, Núria, and Augustí, Susana
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POSIDONIA oceanica ,SEAGRASSES ,SEAWATER ,TERRITORIAL waters - Abstract
The role of seagrass, Posidonia oceanica, meadows as a source of transparent exopolymer particles (TEP) to Mediterranean coastal waters was tested by comparing the TEP dynamics in two adjacent coastal waters in the oligotrophic NW Mediterranean Sea, one characterized by oligotrophic open-sea waters and the other accumulating seagrass leaf litter, together with an experimental examination of TEP release by seagrass litter. TEP concentrations ranged from 4.6 µg XG Eq L
-1 to 90.6 µg XG Eq L-1 , with mean (±SE) values of 38.7 (±2.02) µg XG Eq L-1 in the site devoid of seagrass litter, whereas the coastal beach site accumulating leaf litter had > 10-fold mean TEP concentrations of 487.02 (±72.8) µg XG Eq L-1 . Experimental evaluation confirmed high rates of TEP production by P. oceanica litter, allowing calculations of the associated TEP yield. We demonstrated that P. oceanica is an important source of TEP to the Mediterranean Sea, contributing an estimated 0.10 Tg C as TEP annually. TEP release by P. oceanica seagrass explains the elevated TEP concentration relative to the low chlorophyll a concentration in the Mediterranean Sea. [ABSTRACT FROM AUTHOR]- Published
- 2017
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17. El cambio climático y sus consecuencias para los ecosistemas costeros de las Islas Baleares
- Author
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Duarte, Carlos M. and Tintoré, Joaquín
- Subjects
Posidonia oceanica ,Climatic changes ,Natural History - Abstract
El cambio climático es el problema medioambiental más importante del siglo XXI, afectando a todas las actividades humanas, incluídas la provisión de agua y alimento para la humanidad. Este cambio afectará de manera particularmente importante a las áreas insulares, ya que tienen una mayor dependencia de las zonas costeras, las cuales se veran fuertemente afectadas por el cambio climático. Esta dependencia se materializa, en el caso de las Islas Baleares, en una dependencia económica, derivada del papel clave de la industria turística. Esta industria es especialmente sensible al cambio climático, por 10 que las consecuencias para los ecosistemas costeros que se discuten en este capítulo tendran también importantes repercusiones sobre la economia y sociedad baleares. En este capítulo examinamos primero los conceptos de cambio climático y cambio global, revisamos las consecuencias de los cambios que se han producido durante el siglo XX para los ecosistemas costeros y finalmente evaluamos los cambios adicionales que se esperan sobre la base de las predicciones de escenarios posibles para el siglo XXI, y las actuaciones que debieran emprenderse para minimizar las consecuencias negativas del cambio climático. Todo este ejercicio se lleva a cabo bajo una notable carència de datos específicos para las Islas Baleares, 10 que revela de inmediato la necesidad de contar con una base observacional, sujeta a un control de calidad riguroso, capaz de permitir, a traves de su integración en un sistema interdisciplinar de analisis, la deteccion de cambios en los ecosistemas costeros de las Islas Baleares., El canvi climàtic és el problema mediambiental més important del segle XXI, afectant a totes les activitats humanes, incloses la provisió d'aigua i aliment per a la humanitat. Aquest canvi afectarà de forma particularment important a les àees insulars, ja que tenen una major dependència de les zones costeres, que es veuran intensament afectades pel canvi climàtic. Aquesta dependència es materialitza, en el cas de les Illes Balears, en una dependència econòmica, derivada del paper clau de la industria turística. Aquesta industria es especialment sensible al canvi climàtic, pel que les conseqüències per als ecosistemes costaners que se discuteixen en aquest capítol tendran també importants repercusions sobre l'economia i la societat de les Balears. En aquest capítol s'examinen primer els conceptes de canvi climátic i canvi global, revisam les conseqüències dels canvis que s'han produït durant el segle XX per als ecosistemes costaners i finalment avaluam els canvis addicionals que s'esperen sobre la base de les prediccions d'escenaris possibles per al segle XXI, i les actuacions que es tendrien que emprendre per a minimitzar les conseqüències negatives del canvi climàtic. Tot aquest exercici es du a terme sota una notable carència de dades especifiques per a les Illes Balears, el que revela la necessitat de comptar amb una base observacional, subjecta a un control de qualitat rigurós, capaç de permetre, a través de la seva integració en un sistema interdisciplinar d'anàlisi, la detecció de canvis en els ecosistemes costaners de les Illes Balears., The climatic change is the most relevant environmental problem of the XXI century, affecting all human activities, including water and food supplies to mankind. This change will dramatically affect insular areas, since they have a greater dependence on coastal areas that will be strongly affected by the climatic change. In the case of the Balearic Islands, this dependence will be mainly economical, derived from its key role on the tourist industry. This industry is specially sensitive to the climatic change, and therefore aftermath for coastal ecosystems discussed in this chapter will also have important effects on the Balearic economy and society. In this chapter the concepts of climatic and global change will be examined first, consequences of changes suffered by coastal ecosystems through the XX century will be revised, and finally we will evaluate the added changes that can be expected based on the different scenarios predicted for the XXI century, and the actions to undertake to minimize the negative consequences of the climatic change. All this exercise is done under a remarkable lack of specific data for the Balearic Islands, thereby revealing the need to count with an observational basis, subject to a thorough quality control, able to permit, through its integration in an interdisciplinary analysis system, the detection of changes in the coastal ecosystems of the Balearic Islands.
- Published
- 2001
18. Annual growth of Posidonia oceanica: contribution of large-scale versus local factors to seasonality
- Author
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Alcoverro, Teresa, Duarte, Carlos M., and Romero, Javier
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Primary production ,Posidonia oceanica ,Nutrients ,Seasonality ,Growth ,Seagrass - Abstract
Este artículo contiene 8 páginas, 3 tablas, 5 figuras, The seasonal growth pattern of the seagrass Posidonia oceanica (L.) Delile was examined in 5 meadows in NE Spain to assess the relative importance of large-scale versus local factors in controbng the seasonal patterns observed. Large-scale seasonal forcing, resulting from changes in light and temperature associated with the solar cycle, was assessed from the coherence of seasonal growth palterns among the meadows and accounted for 46 and 43% of variability in shoot size and growth, respectively. The local component of seasonality, which results from local variation in environmental variables (e.g. nutrients, dissolved inorganic carbon, redox potential) was assessed as the differences in the annual time course of shoot size and growth among the meadows, and accounted for 9 and 12% of the variability, respectively. These results support the contention that seagrass seasonality is primarily controlled by the solar cycle, and secondarily by seasonal changes in the environment which are at leas1 in part caused by the temporal variability of seagrass growth. This indirect link between light and temperature and local conditions needs to be taken into account to interpret correlations between such variables and seagrass growth., This work was supported by the grant STEP-0063-C of the ECC.
- Published
- 1995
19. Degradative potential of marine bacterial isolates from the aquatic plant Posidonia oceanica.
- Author
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Marco-Noales, Ester, Ordax, Mónica, Garcias-Bonet, Neus, López, María M., Marbá, Núria, and Duarte, Carlos M.
- Subjects
STARCH ,ENZYMATIC analysis ,ALTEROMONAS ,POSIDONIA oceanica ,SEAGRASSES - Published
- 2009
20. Evolutionary and Ecological Trees and Networks.
- Author
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Hernández-García, Emilio, Herrada, E. Alejandro, Rozenfeld, Alejandro F., Tessone, Claudio J., Eguíluz, Víctor M., Duarte, Carlos M., Arnaud-Haond, Sophie, and Serrão, Ester
- Subjects
SPECIES ,PHYLOGENY ,CLADISTIC analysis ,GENETICS ,POSIDONIA oceanica ,BIOLOGICAL evolution ,GENOMICS - Abstract
Evolutionary relationships between species are usually represented in phylogenies, i.e. evolutionary trees, which are a type of networks. The terminal nodes of these trees represent species, which are made of individuals and populations among which gene flow occurs. This flow can also be represented as a network. In this paper we briefly show some properties of these complex networks of evolutionary and ecological relationships. First, we characterize large scale evolutionary relationships in the Tree of Life by a degree distribution. Second, we represent genetic relationships between individuals of a Mediterranean marine plant, Posidonia oceanica, in terms of a Minimum Spanning Tree. Finally, relationships among plant shoots inside populations are represented as networks of genetic similarity. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]
- Published
- 2007
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- View/download PDF
21. Meristematic activity of Mediterranean seagrass (Posidonia oceanica) shoots
- Author
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Garcias-Bonet, Neus, Duarte, Carlos M., and Marbà, Núria
- Subjects
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MERISTEMS , *SEAGRASSES , *POSIDONIA oceanica , *PLANT shoots , *MEADOWS , *CIRCADIAN rhythms - Abstract
Abstract: Shoot meristematic activity of Mediterranean seagrass Posidonia oceanica has been assessed in eleven different meadows located around Balearic Islands (Spanish Mediterranean). Moreover, in six of them, the meristematic activity has been determined hourly (or every 2 or 3h, depending on the meadow) for at least 24h, with the aim of detecting a possible circadian rhythm in the % of dividing nuclei. Meristematic activity was inferred by applying flow cytometry techniques combined with DNA labeling to determine the percentage of nuclei in each phase of the cell cycle (i.e. G0+G1, S, G2). The percentage of nuclei in G2 phase of the cell cycle reflects the percentage of nuclei that are dividing in a specific moment. In the meristems of vertical shoots of P. oceanica the percentage of nuclei in G2 phase was on average 7±0.11%, and it ranged from 2% to 12% across the meadows studied. The average percentage of nuclei in the G2 phase in P. oceanica meristems is lower than reported for other plants. No circadian rhythms were detected in meristems of P. oceanica. The variability observed for meristematic activity across meadows suggests that it could be used as indicator of seagrass stress and, thus, to assess impacts to meristems before population declines could be observed. [Copyright &y& Elsevier]
- Published
- 2012
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22. Uncertainty analysis along the ecological quality status of water bodies: The response of the Posidonia oceanica multivariate index (POMI) in three Mediterranean regions.
- Author
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Mascaró, Oriol, Bennett, Scott, Marbà, Núria, Nikolić, Vedran, Romero, Javier, Duarte, Carlos M., and Alcoverro, Teresa
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ECOLOGICAL assessment ,BODIES of water ,POSIDONIA oceanica ,WATER quality ,UNCERTAINTY (Information theory) ,MULTIVARIATE analysis - Abstract
Abstract: Uncertainty analyses allow the identification and quantification of the factors that contribute to the potential misclassification of the ecological status of water bodies, helping to improve the sampling design used in monitoring. Here we used a Posidonia oceanica multivariate index (POMI) bio-monitoring dataset covering a total of 81 sites distributed throughout 28 water bodies from the coast of Catalonia, Balearic Islands and Croatia to determine the levels of uncertainty associated with each region and how they change according to the quality status of water bodies. Overall, variability among sites (meadows) within water bodies was the factor that generated the greatest risk of misclassification among the three regions, within which the Balearic Islands had the lowest uncertainty, followed by Croatia and Catalonia. When water bodies classified in good/high quality were separated from those in moderate/poor status classes, we found that the latter displayed higher levels of uncertainty than the former. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
23. Mediterranean warming triggers seagrass ( Posidonia oceanica) shoot mortality.
- Author
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MARB, NÚRIA and Duarte, Carlos M.
- Subjects
- *
HEAT waves (Meteorology) , *CLIMATE change , *MARINE biodiversity , *POSIDONIA oceanica , *ANGIOSPERMS , *POPULATION - Abstract
Rapid warming of the Mediterranean Sea threatens marine biodiversity, particularly key ecosystems already stressed by other impacts such as Posidonia oceanica meadows. A 6-year monitoring of seawater temperature and annual P. oceanica shoot demography at Cabrera Archipelago National Park (Balearic Islands, Western Mediterranean) allowed us to determine if warming influenced shoot mortality and recruitment rates of seagrasses growing in relative pristine environments. The average annual maximum temperature for 2002–2006 was 1 °C above temperatures recorded in 1988–1999 (26.6 °C), two heat waves impacted the region (with seawater warming up to 28.83 °C in 2003 and to 28.54 °C in 2006) and the cumulative temperature anomaly, above the 1988–1999 mean annual maximum temperature, during the growing season (i.e. degree-days) ranged between 0 °C in 2002 and 70 °C in 2003. Median annual P. oceanica shoot mortality rates varied from 0.067 year−1 in 2002 to 0.123 year−1 in 2003, and exceeded recruitment rates in all stations and years except in shallow stations for year 2004. Interannual fluctuations in shoot recruitment were independent of seawater warming ( P>0.05). P. oceanica meadows experienced a decline throughout the study period at an average rate of −0.050±0.020 year−1. Interannual variability in P. oceanica shoot mortality was coupled ( R2>0.40) to seawater warming variability and increasing water depth: shoot mortality rates increased by 0.022 year−1 (i.e. an additional 2% year−1) for each additional degree of annual maximum temperature and by 0.001 year−1 (i.e. 0.1% year−1) for each accumulated degree water temperature remained above 26.6 °C during the growing season. These results demonstrate that P. oceanica meadows are highly vulnerable to warming, which can induce steep declines in shoot abundance as well indicating that climate change poses a significant threat to this important habitat. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
24. Seasonal dynamics of Posidonia oceanica in Magalluf Bay (Mallorca, Spain): Temperature effects on seagrass mortality.
- Author
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Díaz-Almela, Elena, Marbà, Núria, Martínez, Regino, Santiago, Rocío, and Duarte, Carlos M.
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POSIDONIA oceanica ,SEAGRASSES ,PLANT population measurement ,PLANT mortality ,COASTAL ecology - Abstract
We recorded seasonal and interannual population dynamics of the endemic Mediterranean seagrass Posidonia oceanica in a shallow meadow, Magalluf Bay, Spain (39°30.25′N, 2°32.59′E), performing direct monthly-bimonthly censuses from June 2001 to November 2004, in 12 permanent plots. Initially, there were 568 ± 54 (mean 6 SE) shoots m22. An average decline of -63 ± 10 SE shoots m
−2 yr−1 was detected. Shoot mortality (median: 1.2% month−1 ; range: 0% to 12.1% month−1 ) increased in summer, enhanced by seawater temperature. There was also substantial interannual variability characterized by very high mortality in summer-autumn 2001 and in autumn-winter 2003-2004, coinciding with hot summers and meadow flowering in autumn (2001: 2.0% ± 1.4% of shoots; 2003: 53.8% ± 10.4% of shoots), but fruiting and seedling recruitment were only observed in 2004. Annual vegetative recruitment (0.034 ± 0.007 yr−1 ) was 53 times higher than annual sexual recruitment (0.0006 ± 0.0007 yr−1 ), and total recruitment (vegetative + sexual) was on average 4.5 times lower than mortality. Specific net population growth was always negative during the study. No seasonality was detected in shoot recruitment (median: 0.002 month−1 ; range: 0 to 0.021 month−1 ), which did not correlate with solar radiation or temperature. Shoots recruited during the study had a steeper exponential depletion rate ( rr = -0.34 ± 0.05 SE yr−1 ) than the global population ( rN0 = -0.16 ± 0.01 SE yr−1 ). Shoot probability to survive to the next age class ( px ) increased with shoot age. Our results suggest that the general decline of P. oceanica meadows could be enhanced by the decadal Mediterranean warming trend. [ABSTRACT FROM AUTHOR]- Published
- 2009
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25. Deterioration of Sediment Quality in Seagrass Meadows (Posidonia ocean ica) Invaded by Macroalgae (Caulerpa sp.).
- Author
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Holmer, Marianne, Marbà, Núria, Lamote, Morgane, and Duarte, Carlos M.
- Subjects
MARINE sediments ,POSIDONIA oceanica ,SEAGRASSES ,ORGANIC compounds ,CAULERPA taxifolia - Abstract
Species of the macroalgae Caulerpa sp. are increasingly being observed in meadows of the endemic Mediterranean seagrass Posidonia oceanica, and in particular Caulerpa taxifoIia, has been considered as an invasive species leading to seagrass decline. Studies have so far failed to reveal the underlying mechanisms of the success of the macroalgae, and here, we examine how biogeochemical changes of the environment associated to indigenous (Caulerpa prolifera) and non-indigenous (Caulerpa race-mosa and C. taxijblia) species affect the habitat of P oceanica. Two of the species (C. prolifera and C. race- mosa) affect the sediment biogeochemical conditions by increasing organic matter pools, microbial activity, and sulfide pools of the sediments, and limited effects were found for C. taxifolia. Biomass of the macroalgae contributed to the extent of impacts, and high sulfide invasion into the seagrasses and regression of the meadow were pronounced at the location with the highest Caulerpa biomass. This suggests that Caulerpa invasion contributes to seagrass decline probably because Caulerpa thrives better than the seagrasses in the modified environment. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
26. Effects of fish farm waste on Posidonia oceanica meadows: Synthesis and provision of monitoring and management tools
- Author
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Holmer, Marianne, Argyrou, Marina, Dalsgaard, Tage, Danovaro, Roberto, Diaz-Almela, Elena, Duarte, Carlos M., Frederiksen, Morten, Grau, Antoni, Karakassis, Ioannis, Marbà, Nuria, Mirto, Simone, Pérez, Marta, Pusceddu, Antonio, and Tsapakis, Manolis
- Subjects
ENVIRONMENTAL impact analysis ,AGRICULTURE & the environment ,FISH farming ,POSIDONIA oceanica ,SEAGRASSES ,AQUATIC habitats ,ENVIRONMENTAL indicators ,ORGANIC water pollutants ,NUTRIENT pollution of water - Abstract
This paper provides a synthesis of the EU project MedVeg addressing the fate of nutrients released from fish farming in the Mediterranean with particular focus on the endemic seagrass Posidonia oceanica habitat. The objectives were to identify the main drivers of seagrass decline linked to fish farming and to provide sensitive indicators of environmental change, which can be used for monitoring purposes. The sedimentation of waste particles in the farm vicinities emerges as the main driver of benthic deterioration, such as accumulation of organic matter, sediment anoxia as well as seagrass decline. The effects of fish farming on P. oceanica meadows are diverse and complex and detected through various metrics and indicators. A safety distance of 400 m is suggested for management of P. oceanica near fish farms followed by establishment of permanent seagrass plots revisited annually for monitoring the health of the meadows. [Copyright &y& Elsevier]
- Published
- 2008
- Full Text
- View/download PDF
27. Sedimentary iron inputs stimulate seagrass (Posidonia oceanica) population growth in carbonate sediments
- Author
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Marbà, Núria, Duarte, Carlos M., Holmer, Marianne, Calleja, Maria Ll., Álvarez, Elvira, Díaz-Almela, Elena, and Garcias-Bonet, Neus
- Subjects
- *
SEAGRASSES , *MARINE plants - Abstract
Abstract: The relationship between sedimentary Fe inputs and net seagrass population growth across a range of Posidonia oceanica meadows growing in carbonate Mediterranean sediments (Balearic Islands, Spain; SE Iberian Peninsula, Spain; Limassol, Cyprus; Sounion, Greece) was examined using comparative analysis. Sedimentary Fe inputs were measured using benthic sediment traps and the net population growth of P. oceanica meadows was assessed using direct census of tagged plants. The meadows examined ranged from meadows undergoing a severe decline to expanding meadows (specific net population growth, from −0.14yr−1 to 0.05yr−1). Similarly, Fe inputs to the meadows ranged almost an order of magnitude across meadows (8.6–69.1mgFem−2 d−1). There was a significant, positive relationship between sedimentary iron inputs and seagrass net population growth, accounting for 36% of the variability in population growth across meadows. The relationship obtained suggested that seagrass meadows receiving Fe inputs below 43mgFem−2 d−1 are vulnerable and in risk of decline, confirming the pivotal role of Fe in the control of growth and the stability of seagrass meadows in carbonate sediments. [Copyright &y& Elsevier]
- Published
- 2008
- Full Text
- View/download PDF
28. Feed-backs between genetic structure and perturbation-driven decline in seagrass (Posidonia oceanica) meadows.
- Author
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Diaz-Almela, Elena, Arnaud-Haond, Sophie, Vliet, Mirjam S., Álvarez, Elvira, Marbà, Núria, Duarte, Carlos M., and Serrão, Ester A.
- Subjects
GENETIC polymorphisms ,ECOLOGICAL disturbances ,POSIDONIA oceanica ,MICROSATELLITE repeats ,FISH farming ,CHROMOSOMES ,NUCLEOTIDE sequence ,PLANT genetics ,SEAGRASSES - Abstract
We explored the relationships between perturbation-driven population decline and genetic/ genotypic structure in the clonal seagrass Posidonia oceanica, subject to intensive meadow regression around four Mediterranean fish-farms, using seven specific microsatellites. Two meadows were randomly sampled (40 shoots) within 1,600 m
2 at each site: the ''impacted'' station, 5-200 m from fish cages, and the ''control'' station, around 1,000 m downstream further away (considered a proxy of the pre-impact genetic structure at the site). Clonal richness (R), Simpson genotypic diversity (D*) and clonal sub-range (CR) were highly variable among sites. Nevertheless, the maximum distance at which clonal dispersal was detected, indicated by CR, was higher at impacted stations than at the respective control station (paired ttest: P < 0.05, N = 4). The mean number of alleles (Â) and the presence of rare alleles (Âr ) decreased at impacted stations (paired t-test: P < 0.05, and P < 0.02, respectively, N = 4). At a given perturbation level (quantified by the organic and nutrient loads), shoot mortality at the impacted stations significantly decreased with CR at control stations (R2 = 0.86, P < 0.05). Seagrass mortality also increased with  (R2 = 0.81, P < 0.10), R (R2 = 0.96, P < 0.05) and D* (R2 = 0.99, P < 0.01) at the control stations, probably because of the negative correlation between those parameters and CR. Therefore, the effects of clonal size structure on meadow resistance could play an important role on meadow survival. Large genotypes of P. oceanica meadows thus seem to resist better to fish farm-derived impacts than little ones. Clonal integration, foraging advantage or other size-related fitness traits could account for this effect. [ABSTRACT FROM AUTHOR]- Published
- 2007
- Full Text
- View/download PDF
29. Iron Additions Reduce Sulfide Intrusion and Reverse Seagrass ( Posidonia oceanica) Decline in Carbonate Sediments.
- Author
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Marbà, Núria, Calleja, Maria Ll., Duarte, Carlos M., Álvarez, Elvira, Díaz-Almela, Elena, and Holmer, Marianne
- Subjects
IRON ,SULFIDES ,IGNEOUS intrusions ,SEDIMENTS ,CARBONATES ,SEAGRASSES ,PLANT growth ,GROWTH rate ,BIOTIC communities - Abstract
We conducted a 2-year in situ experiment to test the capacity of iron additions to reverse the decline experienced by a Posidonia oceanica meadow colonizing carbonate, iron poor sediment. Iron additions improved the sediment conditions that support seagrass growth by decreasing the sediment sulfide concentration and sulfate reduction rates, and decreased sulfide intrusion into the plants. Iron additions for 2 years did not significantly change survivorship of shoots present at the onset of the experiment, but significantly increased shoot recruitment and survivorship of shoots recruited during the experiment. After 2 years, iron additions reversed seagrass decline and yielded positive growth rates of shoots relative to control populations where seagrass continued to decline. This research demonstrates that seagrass decline in carbonate sediments may be reversed by targeting critical processes such are sediment sulfide pools and seagrass nutritional status, controlling the functioning of the ecosystem. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
30. Vicariance patterns in the Mediterranean Sea: east–west cleavage and low dispersal in the endemic seagrass Posidonia oceanica.
- Author
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Arnaud-Haond, Sophie, Migliaccio, Marianna, Diaz-Almela, Elena, Teixeira, Sara, van de Vliet, Mirjiam Susanne, Alberto, Filipe, Procaccini, Gabriele, Duarte, Carlos M., and Serrão, Ester A.
- Subjects
POSIDONIA oceanica ,SEAGRASSES ,MARINE plants ,MONOCOTYLEDONS ,POSIDONIA ,MICROSATELLITE repeats ,GENETIC polymorphisms ,PLEISTOCENE stratigraphic geology - Abstract
Aim The seagrass, Posidonia oceanica is a clonal angiosperm endemic to the Mediterranean Sea. Previous studies have suggested that clonal growth is far greater than sexual recruitment and thus leads to low clonal diversity within meadows. However, recently developed microsatellite markers indicate that there are many different genotypes, and therefore many distinct clones present. The low resolution of markers used in the past limited our ability to estimate clonality and assess the individual level. New high-resolution dinucleotide microsatellites now allow genetically distinct individuals to be identified, enabling more reliable estimation of population genetic parameters across the Mediterranean Basin. We investigated the biogeography and dispersal of P. oceanica at various spatial scales in order to assess the influence of different evolutionary factors shaping the distribution of genetic diversity in this species. Location The Mediterranean. Methods We used seven hypervariable microsatellite markers, in addition to the five previously existing markers, to describe the spatial distribution of genetic variability in 34 meadows spread throughout the Mediterranean, on the basis of an average of 35.6 (± 6.3) ramets sampled. Results At the scale of the Mediterranean Sea as a whole, a strong east–west cleavage was detected (amova). These results are in line with those obtained using previous markers. The new results showed the presence of a putative secondary contact zone at the Siculo-Tunisian Strait, which exhibited high allelic richness and shared alleles absent from the eastern and western basins. F statistics (pairwise θ ranges between 0.09 and 0.71) revealed high genetic structure between meadows, both at a small scale (about 2 to 200 km) and at a medium scale within the eastern and western basins, independent of geographical distance. At the intrameadow scale, significant spatial autocorrelation in six out of 15 locations revealed that dispersal can be restricted to the scale of a few metres. Main conclusions A stochastic pattern of effective migration due to low population size, turnover and seed survival is the most likely explanation for this pattern of highly restricted gene flow, despite the importance of an a priori seed dispersal potential. The east–west cleavage probably represents the outline of vicariance caused by the last Pleistocene ice age and maintained to this day by low gene flow. These results emphasize the diversity of evolutionary processes shaping the genetic structure at different spatial scales. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
31. Consequences of Mediterranean warming events in seagrass ( Posidonia oceanica) flowering records.
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DIAZ-ALMELA, ELENA, MARB, NURIA, and Duarte, Carlos M.
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SEAGRASSES ,POSIDONIA oceanica ,EFFECT of global warming on plants ,WATER temperature ,THERMAL stresses ,MEDITERRANEAN-type ecosystems ,CLIMATE change - Abstract
Posidonia oceanica, a seagrass endemic to the Mediterranean forms extended and extremely persistent meadows. It is a clonal plant with an apparently irregular pattern of flowering events. An extensive bibliographic review allowed the reconstruction of past flowering events of this species around the Mediterranean, with a high degree of confidence for the last 30 years. The data series on annual flowering prevalence (FP, flowering records per total records) and flowering intensity (FI, fraction of flowering shoots) produced have been compared with four series on Sea Surface annual Temperature maxima (SST
max ) obtained for the NW Mediterranean (averaged from the local data series of l'Estartit and Villefranche: 1957–2005) and for the Eastern, Western basin and the whole Mediterranean sea (extracted from NCEP Reynolds interpolated SST maps: 1982–2005). Significant warming trends are detected in the Mediterranean SSTmax series, at a rate of (mean+SE) 0. 04±0. 01°C yr−1 ( R2 =0. 24, P<0. 01, N=24 years), in the Eastern basin series (0. 06±0. 01°C yr−1 , R2 =0. 43, P<0. 001, N=24 years) and in the long SSTmax series of the NW Mediterranean (0. 02±0. 01 C yr−1 , R2 =0. 12, P<0. 02, N=49 years). The magnitudes of the SSTmax anomalies around the absolute warming trend do not increase with time in any SSTmax series. Peaks of FP and FI in the Mediterranean seem to occur each 9–11 years, and coincide with peaks of annual SSTmax . Annual FP and FI increase with the residuals of annual SSTmax warming trend in all Mediterranean basins (FPMED : R2 =0. 27, P<0. 01, N=23; FPNW : R2 =0. 34, P<0. 01, N=31; FPE : R2 =0. 20; P<0. 10, N=23). An outstanding event of P. Oceanica flowering across the Mediterranean has been registered in Autumn 2003; 1 month after the highest annual SSTmax recorded in the series. The hypothesis of flowering induction by thermal stress as the possible cause of this relationship is discussed, as well as the potential use of P. Oceanica flowering record as early indicator of biological change induced by global sea warming in Mediterranean marine ecosystems. [ABSTRACT FROM AUTHOR]- Published
- 2007
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32. Organic Carbon Metabolism and Carbonate Dynamics in a Mediterranean Seagrass (Posidonia oceanica) Meadow.
- Author
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Barrón, Cristina, Duarte, Carlos M., Frankignoulle, Michel, and Borges, Alberto Vieira
- Subjects
MARINE productivity ,SEAGRASSES ,POSIDONIA oceanica ,MARINE plants ,MONOCOTYLEDONS ,MARINE ecology - Abstract
We measured monthly dissolved oxygen (DO) changes in situ benthic incubations from March 2001 to October 2002 in a Posidonia oceanica meadow and unvegetated sediments of Magalluf Bay (Mallorca Island, Spain) to determine gross primary production (GPP), community respiration (R), and net community production (NCP). From June 2001 to October 2002, we also measured fluxes of dissolved inorganic carbon (DIC) and total alkalinity (TAlk). The yearly integrated metabolic rates based on DO changes show that the P. oceanica communities are net autotrophic while the metabolic rates in the unvegetated benthic communities are nearly balanced. Higher calcium carbonate (CaCO
3 ) cycling, both in terms of production and dissolution, was observed in P. oceanica communities than in unvegetated benthic communities. In the P. oceanica meadow, the annual release of CO2 from net CaCOs production corresponds to almost half of the CO2 uptake by NCP based on DIC incubations. In unvegetated benthic communities, the annual uptake of CO2 from net CaCO3 dissolution almost fully compensates the CO2 release by NCP based on DIC incubations. CaCO3 dynamics is potentially a major factor in CO2 benthic fluxes in seagrass and carbonate-rich temperate coastal ecosystems. [ABSTRACT FROM AUTHOR]- Published
- 2006
33. Patterns of seagrass (Posidonia oceanica) flowering in the Western Mediterranean.
- Author
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Diaz-Almela, Elena, Marbà, Nuria, Álvarez, Elvira, Balestri, Elena, Ruiz-Fernández, Juan M., and Duarte, Carlos M.
- Subjects
POSIDONIA oceanica ,POSIDONIA ,SEAGRASSES ,MONOCOTYLEDONS ,ANGIOSPERMS ,PLANTS ,PLANT reproduction ,REPRODUCTION ,MARINE biology - Abstract
The intensive reconstructive sampling (1957–2004, 39 localities), a systematic direct observation (1992–2004, 1 locality) and particular direct observations (66 localities) of Posidonia oceanica meadows were analysed together with temporal series of flowering available in the literature (19 localities). This allowed the examination of temporal and spatial variability in annual flowering prevalence (FP, the fraction of meadows flowering in a given year) and of annual meadow flowering intensity (FI, number of inflorescences per shoot) for the period 1979–2004 across the Western Mediterranean, as well as spatial variability of flowering frequency (FF, the fraction of years that a given meadow has flowered) and shoot flowering probability (Pf, fraction of flowering stalks appeared per annual segment). Each year, on an average 17% of the investigated meadows flowered, ranging from 3 to 86% of meadows among the years. The highest annual FP and FI values were obtained in 2003 (FP=0.86 and mean FI=0.23±0.03 inflorescences shoot
−1 ). A secondary peak of FP and mean FI occurred 9 years earlier, in 1994 (FP=0.44 and mean FI=0.08±0.02). Both peaks of flowering occurred after hot summers. Flowering synchrony in particular years across the Western Mediterranean and clines of increased meadow flowering frequency towards the North and East, suggests the existence of large-scale environmental mechanisms controlling the floral induction. On the other hand, meadow FF and Pf were highly heterogeneous among and within the meadows, indicating that local factors also may play a significant role in flowering induction. When flowering, the Western Mediterranean meadows showed an average 0.11±0.02 inflorescences shoot−1 , but FI greatly varied among and along the series (from 0.002 to 0.54 inflorescences shoot−1 ) and decreased significantly with depth but was independent of meadow shoot density and meadow latitude or longitude. The shoot flowering probability was quite low (0.007±0.002 inflorescences shoot−1 year−1 ) and exponentially increased with shoot age. [ABSTRACT FROM AUTHOR]- Published
- 2006
- Full Text
- View/download PDF
34. Benthic primary producers––a neglected environmental problem in Mediterranean maricultures?
- Author
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Holmer, Marianne, Pérez, Marta, and Duarte, Carlos M.
- Subjects
MARINE fishes ,FISH farming ,POSIDONIA oceanica ,SPECIES - Abstract
Marine fish farming is increasing rapidly in the Mediterranean and in contrast to the Atlantic the coastal zone in the Mediterranean is characterized by clear waters with high transparency. This allows benthic primary producers such as the slow-growing seagrass Posidonia oceanica to grow at large depths at locations suitable for fish farming and generating a conflict between the conservation of these meadows and the growth of aquaculture operations in the Mediterranean. In this paper we review the current knowledge on environmental interactions between fish farming and benthic primary producers with particular focus on P. oceanica, as this seagrass is a key component along Mediterranean coasts. The recovery times of P. oceanica are very long, in the order of centuries, and losses of this species are thus considered to be irreversible at managerial time scales. [Copyright &y& Elsevier]
- Published
- 2003
- Full Text
- View/download PDF
35. Posidonia oceanica as a Source of Chromophoric Dissolved Organic Matter for the Oligotrophic NW Mediterranean Coast.
- Author
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Iuculano, Francesca, Duarte, Carlos M., Otero, Jaime, Álvarez-Salgado, Xosé Antón, and Agustí, Susana
- Subjects
POSIDONIA oceanica ,POSIDONIA ,DISSOLVED organic matter ,ORGANIC compounds ,COASTS ,SEAGRASSES - Abstract
Posidonia oceanica is a well-recognized source of dissolved organic matter (DOM) derived from exudation and leaching of seagrass leaves, but little is known about its impact on the chromophoric fraction of DOM (CDOM). In this study, we monitored for two years the optical properties of CDOM in two contrasting sites in the Mallorca Coast (Balearic Islands). One site was a rocky shore free of seagrass meadows, and the second site was characterized by the accumulation of non-living seagrass material in the form of banquettes. On average, the integrated color over the 250–600 nm range was almost 6-fold higher in the beach compared with the rocky shore. Furthermore, the shapes of the CDOM spectra in the two sites were also different. A short incubation experiment suggested that the spectral differences were due to leaching from P. oceanica leaf decomposition. Furthermore, occasionally the spectra of P. oceanica was distorted by a marked absorption increase at wavelength < 265 nm, presumably related to the release of hydrogen sulfide (HS
− ) associated with the anaerobic decomposition of seagrass leaves within the banquettes. Our results provide the first evidence that P. oceanica is a source of CDOM to the surrounding waters. [ABSTRACT FROM AUTHOR]- Published
- 2020
- Full Text
- View/download PDF
36. Author Correction: Palaeoclimatic conditions in the Mediterranean explain genetic diversity of Posidonia oceanica seagrass meadows.
- Author
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Chefaoui, Rosa M., Duarte, Carlos M., and Serrão, Ester A.
- Subjects
- *
POSIDONIA oceanica , *SEAGRASS restoration - Abstract
An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
37. Disentangling the Influence of Mutation and Migration in Clonal Seagrasses Using the Genetic Diversity Spectrum for Microsatellites.
- Author
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Arnaud-Haond, Sophie, Moalic, Yann, Hernández-García, Emilio, Eguiluz, Victor M., Alberto, Filipe, Serrão, Ester A., and Duarte, Carlos M.
- Subjects
SEAGRASSES ,POSIDONIA oceanica ,CYMODOCEACEAE ,MICROSATELLITE repeats ,GENETIC mutation - Abstract
The recurrent lack of isolation by distance reported at regional scale in seagrass species was recently suggested to stem from stochastic events of large-scale dispersal. We explored the usefulness of phylogenetic information contained in microsatellite loci to test this hypothesis by using the Genetic Diversity Spectrum (GDS) on databases containing, respectively, 7 and 9 microsatellites genotypes for 1541 sampling units of Posidonia oceanica and 1647 of Cymodocea nodosa. The simultaneous increase of microsatellite and geographic distances that emerges reveals a coherent pattern of isolation by distance in contrast to the chaotic pattern previously described using allele frequencies, in particular, for the long-lived P. oceanica. These results suggest that the lack of isolation by distance, rather than the resulting from rare events of large-scale dispersal, reflects at least for some species a stronger influence of mutation over migration at the scale of the distribution range. The global distribution of genetic polymorphism may, therefore, result predominantly from ancient events of step-by-step (re)colonization followed by local recruitment and clonal growth, rather than contemporary gene flow. The analysis of GDS appears useful to unravel the evolutionary forces influencing the dynamics and evolution at distinct temporal and spatial scales by accounting for phylogenetic information borne by microsatellites, under an appropriate mutation model. This finding adds nuance to the generalization of the influence of large-scale dispersal on the dynamics of seagrasses. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
- View/download PDF
38. Light availability and temperature, not increased CO2, will structure future meadows of Posidonia oceanica.
- Author
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Hendriks, Iris E., Olsen, Ylva S., and Duarte, Carlos M.
- Subjects
- *
PHOTOSYNTHESIS , *POSIDONIA oceanica , *EFFECT of carbon dioxide on plants , *EFFECT of light on plants , *PLANT growth - Abstract
We evaluated the photosynthetic performance of Posidonia oceanica during short-term laboratory exposures to ambient and elevated temperatures (24–25 °C and 29–30 °C) warming and p CO 2 (380, 750 and 1000 ppm p CO 2 ) under normal and low light conditions (200 and 40 μmol photons m −2 s −1 respectively). Plant growth was measured at the low light regime and showed a negative response to warming. Light was a critical factor for photosynthetic performance, although we found no evidence of compensation of photosynthetic quantum efficiency in high light. Relative Electron Rate Transport (rETR max ) was higher in plants incubated in high light, but not affected by p CO 2 or temperature. The saturation irradiance (I k ) was negatively affected by temperature. We conclude that elevated CO 2 does not enhance photosynthetic activity and growth, in the short term for P. oceanica , while temperature has a direct negative effect on growth. Low light availability also negatively affected photosynthetic performance during the short experimental period examined here. Therefore increasing concentrations of CO 2 may not compensate for predicted future conditions of warmer water and higher turbidity for seagrass meadows. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
39. Phytoplankton trapped within seagrass (Posidonia oceanica) sediments are a nitrogen source: An in situ isotope labeling experiment.
- Author
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Barrón, Cristina, Middelburg, Jack J., and Duarte, Carlos M.
- Subjects
PHYTOPLANKTON ,SEAGRASSES ,MARINE plants ,POSIDONIA oceanica ,NITROGEN - Abstract
We examined the retention of nitrogen associated with sedimented planktonic material trapped within a Mediterranean seagrass (Posidonia oceanica) meadow with the use of
15 N-enriched algal material injected into vegetated and nonvegetated sediment as a tracer. The retention of labeled nitrogen material in the sediment and the appearance in P. oceanica leaves, rhizomes, and roots was examined 3, 5, 9, and 21 d after injection. More than 80% of the label material added to the bare sediment was lost within 5 d. Labeled material was retained better in vegetated sediments. Labeled material from the sediment was taken up rapidly by the roots, translocated through the rhizomes, and accumulated in the new leaves. The amount of15 N recovered during the experiment in P. oceanica meadow was fourfold higher than that recovered in unvegetated sediment, demonstrating that the P. oceanica meadow was more efficient in retaining the nitrogen deposited as algal material than unvegetated sediments. Enhanced trapping of sestonic particles by seagrass canopies can be an efficient nutrient acquisition strategy in the oligotrophic environments that seagrasses inhabit. [ABSTRACT FROM AUTHOR]- Published
- 2006
40. Mediterranean seagrass (Posidonia oceanica) loss between 1842 and 2009.
- Author
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Marbà, Núria, Díaz-Almela, Elena, and Duarte, Carlos M.
- Subjects
- *
POSIDONIA oceanica , *SEAGRASSES , *PLANT shoots , *EUTROPHICATION , *BIOLOGICAL invasions - Abstract
We compiled published data in peer-review articles and grey literature reports, which we appended with our own data, to assess the changes in areal extent, cover and shoot density that P. oceanica meadows have experienced between years 1842 and 2009 in the Mediterranean basin. Our results demonstrate an overall tendency towards decline of the areal extent, cover and shoot density of P. oceanica meadows during the last 50 years, the period with the largest availability of records. Available estimates indicated that between 13% and 50% of seagrass areal extent of P. oceanica in the Mediterranean basin appear to be lost, and that the remaining meadows of the Mediterranean may have thinned shoot density by 50% for the last 20 years and have became more fragmented. Considering the changes quantified in P. oceanica areal extent, cover and density, about 6.9% of the potential P. oceanica vegetation would have been lost annually over the last 50 years. The loss of P. oceanica meadows in the Mediterranean may have lead to a substantial (between 11% and 52%) reduction of the capacity of this key coastal ecosystem to sequester carbon in the last 50 years, hence reducing the carbon sink capacity of the entire Mediterranean Sea. The major causes of P.oceanica loss were widespread local disturbances, but recently, global disturbances, such as climate change and the spread of invasive exotic species, were also seriously threatening Posidonia meadows in the Mediterranean. These findings urgently call for implementation of management measures aiming at mitigating coastal deterioration by combining local and global actions. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
41. Modelling formation of complex topography by the seagrass Posidonia oceanica
- Author
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Kendrick, Gary A., Marbà, Núria, and Duarte, Carlos M.
- Subjects
- *
ECOLOGICAL heterogeneity , *LANDSCAPE ecology , *FRAGMENTED landscapes , *MEADOWS - Abstract
Abstract: Posidonia oceanica is a slow growing seagrass species that extends via growing rhizomes that grow only centimetres both horizontally and vertically each year. Posidonia oceanica forms topographically complex biogenic reefs of dead rhizome and sediments that are up to 4m in height that are called “matte”. This study investigates the role of slow horizontal and vertical growth of rhizomes in the formation of topographic complexity in P. oceanica matte using agent-based modelling. The simulated infilling of landscapes by P. oceanica was run over 600 iterations (years) for 10 random starts of 150 agents each. Initial infilling rates were very slow and P. oceanica had limited cover after a century of growth. Growth accelerated after 100years but plateaued after 400years such that after 600years only two-thirds of the landscape was occupied by P. oceanica. The pattern of spread of agents was initially random in direction but after larger patches were formed spread was radial from these patches. The seagrass landscape was initially highly fragmented with many small separate patches made up of a few agents each, with a Landscape Division index close to 1. Between 300 and 600years Landscape Division declined sharply to 0.42, indicating patches had coalesced into larger more continuous meadows forming a less fragmented landscape. Perimeter to area ratio of seagrass patches declined exponentially from >1 to approximately 0.2 over 600years of simulation. The matte developed from growth of patches and its greatest height occurred in more continuously occupied cells of the grid. The topography of the reef that occupied two-thirds of the landscape after six centuries of growth could be described as a pattern of channels between reef plateaus elevated 1–2m above channels. These results demonstrate that development in P. oceanica meadows of three-dimensional structure, in the formation of biogenic reefs, can be explained by, and is an emergent property of, slow horizontal and vertical rhizome growth rates combined with the time it takes for the accumulation of rhizomes in any region of the landscape. As such, the model provides a parsimonious explanation for the development of complex matte topography. [Copyright &y& Elsevier]
- Published
- 2005
- Full Text
- View/download PDF
42. 9
- Author
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Romero, Javier, Lee, Kun-Seop, Pérez, Marta, Mateo, Miguel A., Alcoverro, Teresa, LARKUM, ANTHONY W.D., ORTH, ROBERT J., and DUARTE, CARLOS M.
- Published
- 2006
- Full Text
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43. 7
- Author
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Mateo, Miguel A., Cebrián, Just, Dunton, Kenneth, Mutchler, Troy, LARKUM, ANTHONY W.D., ORTH, ROBERT J., and DUARTE, CARLOS M.
- Published
- 2006
- Full Text
- View/download PDF
44. Epiphytes of Seagrasses
- Author
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Borowitzka, Michael A., Lavery, Paul S., van Keulen, Michael, LARKUM, ANTHONY W.D., ORTH, ROBERT J., and DUARTE, CARLOS M.
- Published
- 2006
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45. Biology of Posidonia
- Author
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Gobert, Sylvie, Cambridge, Marion T., Velimirov, Branco, Pergent, Gérard, Lepoint, Gilles, Bouquegneau, Jean-Marie, Dauby, Patrick, Pergent-Martini, Christine, Walker, Diana I., LARKUM, ANTHONY W.D., ORTH, ROBERT J., and DUARTE, CARLOS M.
- Published
- 2006
- Full Text
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46. Patch dynamics of the Mediterranean seagrass Posidonia oceanica: Implications for recolonisation process
- Author
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Almela, Elena Diaz, Marbà, Nuria, Álvarez, Elvira, Santiago, Rocío, Martínez, Regino, and Duarte, Carlos M.
- Subjects
- *
SEAGRASSES , *POSIDONIA oceanica , *DEMOGRAPHIC surveys , *MARINE plants - Abstract
Abstract: Patch dynamics of the Mediterranean slow-growing seagrass Posidonia oceanica was studied in two shallow sites (3–10m) of the Balearic Archipelago (Spain) through repeated censuses (1–2year−1). In the sheltered site of Es Port Bay (Cabrera Island), initial patch density (October 2001) was low: 0.05patchesm−2, and the patch size (number of shoots) distribution was bimodal: most of the patches had less than 6 shoots or between 20 and 50 shoots. Mean patch recruitment in Es Port Bay (0.006±0.002patchesm−2 year−1) exceeded mean patch loss (0.001±0.001patchesm−2 year−1), yielding positive net patch recruitment (0.004±0.003patchesm−2 year−1) and a slightly increased patch density 3 years later (July 2004, 0.06patchesm−2). In the exposed site of S’Estanyol, the initial patch density was higher (1.38patchesm−2, August 2003), and patch size frequency decreased exponentially with size. Patch recruitment (0.26patchesm−2 year−1) and loss (0.24patchesm−2 year−1) were high, yielding a slightly increased patch density in the area 1 year later (October 2004, 1.40patchesm−2). Most recruited patches consisted of rooting vegetative fragments of 1–2 shoots. Seedling recruitment was observed in Summer 2004 at both sites. Episodic, seedling recruitment comprised 30% and 25% of total patch recruitment in Es Port Bay and S’Estanyol, respectively. Patch survival increased with patch size and no direct removal was observed among patches of 5 shoots or more. Most patches grew along the study, shifting patch distribution towards larger sizes. Within the size range studied (1–150 shoots), absolute shoot recruitment (shootsyear−1) increased linearly with patch size (R 2 =0.64, p <4×10−5, N =125), while specific shoot recruitment was constant (about 0.25±0.05year−1), although its variance was large for small patches. Given the slow growth rate and the high survival of patches with 5 or more shoots, even the low patch recruitment rates reported here could play a significant role in the colonisation process of P. oceanica. [Copyright &y& Elsevier]
- Published
- 2008
- Full Text
- View/download PDF
47. Seagrass (Posidonia oceanica) vertical growth as an early indicator of fish farm-derived stress
- Author
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Marbà, Núria, Santiago, Rocío, Díaz-Almela, Elena, Álvarez, Elvira, and Duarte, Carlos M.
- Subjects
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POSIDONIA oceanica , *FISH growth , *AQUACULTURE - Abstract
Abstract: The usefulness of vertical rhizome growth as an early indicator of fish farm impacts to Posidonia oceanica meadows was tested by comparing annual estimates of vertical rhizome growth, quantified retrospectively, at distances ranging between 5 and 1200m from fish cages at four Mediterranean locations (Cyprus, Greece, Italy and Spain). The studied fish farms had been operating since, at least, 1997, producing between 150 and 1150tonsyr−1 of sea bream (Sparus aurata) and sea bass (Dicentrachus labrax), and, at Italy, also sharpsnout sea bream (Diplodus puntazzo). The reconstructed vertical rhizome growth spanned from 19 to 25 years of growth, depending on sites, and the average vertical rhizome growth before the onset of fish farm operations ranged between 4.48 and 8.79mmyr−1. The vertical rhizome growth after the onset of farming activities declined significantly (t-test, P <0.05) from the control station (at >800m from the farm; vertical growth rate averaged 6.79, 5.52, 3.89 and 3.70mmyr−1 at Cyprus, Greece, Italy and Spain control stations, respectively) to the impacted one (at 5–300m from the farm; vertical growth rate was 4.82, 3.52, 2.77 and 1.92mmyr−1 at Cyprus, Greece, Italy and Spain impacted stations, respectively) at each farm. Moreover, vertical growth significantly (t-test, P <0.05) declined by about twofold following the onset of fish farm operations for the extant meadow nearest to the cages, as well as those supporting intermediate impacts at distances 35–400m from the cages. Vertical rhizome growth was not significantly affected after the onset of fish farm operations for the meadows located more than 800m from the farm, except in those from the Italian site, the largest farm. Examination of the time course of vertical growth for individual rhizomes in the areas of the meadow nearest to the farms, except for those at Cyprus, showed that the decline in vertical growth was initiated within the year of the onset of farming activities, suggesting a negligible resistance of seagrass meadows to fish farm impacts. The results obtained confirm that fish farm activities strongly affect seagrass health on the surrounding meadows, and clearly demonstrate the value of reductions in vertical rhizome growth as an early warning symptom of stress and impacts to P. oceanica meadows. [Copyright &y& Elsevier]
- Published
- 2006
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