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Auteur (up) Marre, G.; Deter, J.; Holon, F.; Boissery, P.; Luque, S.
Titre Fine-scale automatic mapping of living Posidonia oceanica seagrass beds with underwater photogrammetry Type Article scientifique
Année 2020 Publication Revue Abrégée Marine Ecology Progress Series
Volume 643 Numéro Pages 63-74
Mots-Clés Benthic habitat mapping; Monitoring; Posidonia oceanica; Reconstruction uncertainty; Submerged aquatic vegetation; Underwater photogrammetry
Résumé The Mediterranean seagrass Posidonia oceanica, which provides highly valuable ecosystem services, is subject to increasing anthropogenic pressures, causing habitat loss or fragmentation. Whilst airborne images and acoustic data can be used for monitoring seagrass coverage at a macro-scale and over long time periods, monitoring its health in the short term requires precision mapping in order to assess current regression/progression of individual meadows. However, current fine-scale underwater techniques in the field are imprecise and time-demanding. We propose an automatic classification approach based on underwater photogrammetry for an operational, cost- and time-effective fine-scale monitoring method. The method uses a property of the sparse cloud generated during bundle adjustment—the reconstruction uncertainty—to map seagrass patches. The mean precision, recall and F1 score of the method over 21 study sites with different morphologies were 0.79, 0.91 and 0.84, respectively. However, the fragmentation level of the meadows had a significant negative effect on classification performances. The temporal monitoring of 3 sites using this method proved its operability and showed a positive evolution index of the corresponding meadows over a period of 3 yr. This method is generalizable for most encountered configurations and can be integrated in a large monitoring system, as it enables the production of numerous seagrass maps over a short period of time. Moreover, our methodology could be generalized and applied in the study of other submerged aquatic vegetation by adjusting the method’s parameters.
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ISSN 0171-8630, 1616-1599 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2801
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Auteur (up) McLean, M.; Mouillot, D.; Auber, A.
Titre Ecological and life history traits explain a climate-induced shift in a temperate marine fish community Type Article scientifique
Année 2018 Publication Revue Abrégée Marine Ecology Progress Series
Volume 606 Numéro Pages 175-186
Mots-Clés
Résumé A better understanding of community dynamics and ecosystem functioning can be achieved by describing how community functional structure responds to environmental change over both time and space and by identifying which functional groups best mediate community responses. Here, we used a trait-based approach in combination with a newly developed application of principal response curves to functionally characterize a rapid taxonomic shift in the eastern English Channel fish community in the late 1990s. We identified the functional groups with the greatest contributions to the overall shift in fish functional structure and uncovered significant trait-environment relationships. We found that pelagic species with rapid life history cycles, characterized by broadcast spawning, small offspring size, and early maturation, declined considerably in abundance following an increase in sea surface temperature associated with a warming phase of the Atlantic Multidecadal Oscillation, which was likely exacerbated by historical fishing pressure. In contrast, species with late maturation, high parental care, and few, well-developed offspring increased in abundance, reinforcing that fish community responses to climate warming are strongly mediated through life history traits. By examining how environmental factors drove a community shift at the trait level, we provide a mechanistic understanding of how fish functional structure responds to rapid environmental change.
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ISSN 0171-8630 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2466
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Auteur (up) Peckham, S.H.; Maldonado-Diaz, D.; Tremblay, Y.; Ochoa, R.; Polovina, J.; Balazs, G.; Dutton, P.H.; Nichols, W.J.
Titre Demographic implications of alternative foraging strategies in juvenile loggerhead turtles Caretta caretta of the north Pacific Ocean Type Article scientifique
Année 2011 Publication Revue Abrégée Marine Ecology Progress Series
Volume 425 Numéro Pages 269-280
Mots-Clés Donnees; Du; Ethologie; habitat; juvenile; Migration; Nord; Pacifique; Peuplement; Sa℡Lite; structure; Trophique
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ISSN 1616-1599 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 158
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Auteur (up) Pethybridge, H.; BODIN, N.; Arsenault-Pernet, E.-J.; BOURDEIX, J.-H.; BRISSET, B.; BIGOT, J.-L.; ROOS, D.; Peter, M.
Titre Temporal and inter-specific variations in forage fish feeding conditions in the NW Mediterranean: lipid content and fatty acid compositional changes Type Article scientifique
Année 2014 Publication Revue Abrégée Marine Ecology Progress Series
Volume 512 Numéro Pages 39-54
Mots-Clés Clupeiformes; ecosystem health; Environmental variations; Nutritional condition; Prey Quality; Trophic markers
Résumé We describe the total lipid content, lipid class composition and fatty acid profiles of adult forage fishes (anchovy, sardine and sprat) sampled in the NW Mediterranean Sea in 2010 and 2011. Inter-and intra-species differences were mostly related to sampling period with limited effect of gender or total length. As an assemblage, total lipid content and relative levels of triacylglycerols and fatty acids 16:1n7, 20:5n3 and 14:0 in forage fish were highest in summer and autumn, indicating better feeding conditions and a more pronounced diatom-supported food web. In contrast, total lipid content was lowest at the end of winter and spring, and coincided with high levels of 22:6n3, indicating a more herbivorous diet based on dinoflagellates. Resource partitioning and niche separation, as inferred from fatty acid profiles, were apparent between species. Sardine showed a more diverse, temporally separated feeding strategy than anchovy, and dietary overlap was higher in winter than summer with sardine having higher markers of copepods, 22:1n11 and 20:1n9. Sprat collected in winter occupied a separate niche area to both sardine and anchovy with higher total lipid content and carnivory biomarker 18:1n9. Our results show that the lipid dynamics of forage fishes can be used to gain quantitative insights into sub-system level changes in species interactions, including prey and predator productivity.
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1129
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Auteur (up) Trenkel, V.M.; Vaz, S.; Albouy, C.; Brind’Amour, A.; Duhamel, E.; Laffargue, P.; Romagnan, J.B.; Simon, J.; Lorance, P.
Titre We can reduce the impact of scientific trawling on marine ecosystems Type Article scientifique
Année 2019 Publication Revue Abrégée Marine Ecology Progress Series
Volume 609 Numéro Pages 277-282
Mots-Clés Ecosystem-based management; Genetic methods; Impacts of bottom trawling; Marine surveying; Monitoring ethics
Résumé The negative impacts that scientific monitoring may have on marine ecosystems has been a neglected topic, mainly on the basis that its magnitude is minor compared to commercial fisheries, even though this raises ethical and, in certain cases, conservation issues. We argue that ethical principles should lead us to reconsider marine wildlife resource monitoring such as the fish and shellfish trawl surveys providing the science-based evidence needed for fisheries management and assessment of how environmental change affects marine shelf communities worldwide. Recent scientific and technological progress has provided methods and tools which might now be harnessed to reduce the impact of marine monitoring. We review these alternative methods, consider modifications to current practices and identify areas requiring further research.
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Langue en Langue du Résumé Titre Original
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ISSN 0171-8630, 1616-1599 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2519
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