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Crise, A., Kaberi, H., Ruiz, J., Zatsepin, A., Arashkevich, E., Giani, M., et al. (2015). A MSFD complementary approach for the assessment of pressures, knowledge and data gaps in Southern European Seas: The PERSEUS experience. Marine Pollution Bulletin, 95(1), 28–39.
Résumé: PERSEUS project aims to identify the most relevant pressures exerted on the ecosystems of the Southern European Seas (SES), highlighting knowledge and data gaps that endanger the achievement of SES Good Environmental Status (GES) as mandated by the Marine Strategy Framework Directive (MSFD). A complementary approach has been adopted, by a meta-analysis of existing literature on pressure/impact/knowledge gaps summarized in tables related to the MSFD descriptors, discriminating open waters from coastal areas. A comparative assessment of the Initial Assessments (IAs) for five SES countries has been also independently performed. The comparison between meta-analysis results and IAs shows similarities for coastal areas only. Major knowledge gaps have been detected for the biodiversity, marine food web, marine litter and underwater noise descriptors. The meta-analysis also allowed the identification of additional research themes targeting research topics that are requested to the achievement of GES.
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Cruaud, P., Decker, C., Olu, K., Arnaud-Haond, S., Papot, C., Le Baut, J., et al. (2019). Ecophysiological differences between vesicomyid species and metabolic capabilities of their symbionts influence distribution patterns of the deep-sea clams. Mar. Ecol.-Evol. Persp., 40(3), e12541.
Résumé: This study provides an analysis of vesicomyid bivalve-symbiont community distribution across cold seep and hydrothermal vent areas in the Guaymas Basin (Gulf of California, Mexico). Using a combination of morphological and molecular approaches including fluorescent in situ hybridization (FISH), and electronic microscopy observations, vesicomyid clam species and their associated symbionts were characterized and results were analyzed in light of geochemical conditions and other on-site observations. A greater diversity of vesicomyids was found at cold seep areas, where three different species were present (Phreagena soyoae [syn. kilmeri], Archivesica gigas, and Calyptogena pacifica). In contrast, A. gigas was the only species sampled across the hydrothermal vent area. The same haplotype of A. gigas was found in both hydrothermal vent and cold seep areas, highlighting possible contemporary exchanges among neighboring vents and seeps. In either ecosystem, molecular characterization of the symbionts confirmed the specificity between symbionts and hosts and supported the hypothesis of a predominantly vertical transmission. In addition, patterns of clams could reflect potential niche preferences for each species. The occurrence of numerous traces of vesicomyid movements on sediments in the sites colonized by A. gigas seemed to indicate that this species might have a better ability to move. Furthermore, variation in gill sulfur content could reveal a higher plasticity and sulfur storage capacity in A. gigas. Thus, the distribution of vesicomyid species across the chemosynthetic areas of the Guaymas Basin could be explained by differences in biological traits of the vesicomyid species that would allow A. gigas to more easily exploit transient and punctual sources of available sulfide than P. soyoae.
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Dalleau, M., Kramer-Schadt, S., Gangat, Y., Bourjea, J., Lajoie, G., & Grimm, V. (2019). Modeling the emergence of migratory corridors and foraging hot spots of the green sea turtle. Ecol. Evol., .
Résumé: Environmental factors shape the spatial distribution and dynamics of populations. Understanding how these factors interact with movement behavior is critical for efficient conservation, in particular for migratory species. Adult female green sea turtles, Chelonia mydas, migrate between foraging and nesting sites that are generally separated by thousands of kilometers. As an emblematic endangered species, green turtles have been intensively studied, with a focus on nesting, migration, and foraging. Nevertheless, few attempts integrated these behaviors and their trade-offs by considering the spatial configurations of foraging and nesting grounds as well as environmental heterogeneity like oceanic currents and food distribution. We developed an individual-based model to investigate the impact of local environmental conditions on emerging migratory corridors and reproductive output and to thereby identify conservation priority sites. The model integrates movement, nesting, and foraging behavior. Despite being largely conceptual, the model captured realistic movement patterns which confirm field studies. The spatial distribution of migratory corridors and foraging hot spots was mostly constrained by features of the regional landscape, such as nesting site locations, distribution of feeding patches, and oceanic currents. These constraints also explained the mixing patterns in regional forager communities. By implementing alternative decision strategies of the turtles, we found that foraging site fidelity and nesting investment, two characteristics of green turtles' biology, are favorable strategies under unpredictable environmental conditions affecting their habitats. Based on our results, we propose specific guidelines for the regional conservation of green turtles as well as future research suggestions advancing spatial ecology of sea turtles. Being implemented in an easy to learn open-source software, our model can coevolve with the collection and analysis of new data on energy budget and movement into a generic tool for sea turtle research and conservation. Our modeling approach could also be useful for supporting the conservation of other migratory marine animals.
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Dalongeville, A., Andrello, M., Mouillot, D., Albouy, C., & Manel, S. (2016). Ecological traits shape genetic diversity patterns across the Mediterranean Sea: a quantitative review on fishes. J. Biogeogr., 43(4), 845–857.
Résumé: AimWe set out to identify the determinants of the variation in genetic diversity among fish species and test whether multi-species genetic diversity is randomly distributed in space. LocationMediterranean Sea. MethodsWe collected genetic diversity data from 39 published studies on Mediterranean fishes (31 species) along with the spatial coordinates of the sampling sites. We focused on microsatellite heterozygosity (151 data points) and mitochondrial haplotype diversity (201 data points). We used linear regressions to link genetic diversity and 11 ecological traits. We also tested for spatial autocorrelation and trends in the residuals. ResultsAmong-species variation in microsatellite heterozygosity was explained by three ecological traits: vertical distribution, migration type and body length. Variation in mitochondrial haplotype diversity was also explained by vertical distribution and migration type, and by reproductive strategy (semelparity). However, vertical distribution and migration type showed opposite effects on microsatellites and mitochondrial diversity. After accounting for the effects of ecological traits, no spatial pattern was detected, except for one of the species considered. Main conclusionsEcological factors explain an important proportion of the among-species genetic diversity. These results suggest that life history strategies of the species influence the variation of microsatellite diversity indirectly through their effect on effective population size, while the spatial variations of genetic diversity seem to be too complex to be identified in our analysis. We found very different effects of traits on mitochondrial and nuclear DNA diversity, which can be explained by the specificities of mitochondrial DNA (absence of recombination, maternal inheritance and non-neutrality).
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Dalongeville, A., Andrello, M., Mouillot, D., Lobreaux, S., Fortin, M. - J., Lasram, F., et al. (2018). Geographic isolation and larval dispersal shape seascape genetic patterns differently according to spatial scale. Evol. Appl., 11(8), 1437–1447.
Résumé: Genetic variation, as a basis of evolutionary change, allows species to adapt and persist in different climates and environments. Yet, a comprehensive assessment of the drivers of genetic variation at different spatial scales is still missing in marine ecosystems. Here, we investigated the influence of environment, geographic isolation, and larval dispersal on the variation in allele frequencies, using an extensive spatial sampling (47 locations) of the striped red mullet (Mullus surmuletus) in the Mediterranean Sea. Univariate multiple regressions were used to test the influence of environment (salinity and temperature), geographic isolation, and larval dispersal on single nucleotide polymorphism (SNP) allele frequencies. We used Moran's eigenvector maps (db-MEMs) and asymmetric eigenvector maps (AEMs) to decompose geographic and dispersal distances in predictors representing different spatial scales. We found that salinity and temperature had only a weak effect on the variation in allele frequencies. Our results revealed the predominance of geographic isolation to explain variation in allele frequencies at large spatial scale (>1,000km), while larval dispersal was the major predictor at smaller spatial scale (<1,000km). Our findings stress the importance of including spatial scales to understand the drivers of spatial genetic variation. We suggest that larval dispersal allows to maintain gene flows at small to intermediate scale, while at broad scale, genetic variation may be mostly shaped by adult mobility, demographic history, or multigenerational stepping-stone dispersal. These findings bring out important spatial scale considerations to account for in the design of a protected area network that would efficiently enhance protection and persistence capacity of marine species.
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