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Grenie, M., Mouillot, D., Villeger, S., Denelle, P., Tucker, C. M., Munoz, F., et al. (2018). Functional rarity of coral reef fishes at the global scale: Hotspots and challenges for conservation. Biol. Conserv., 226, 288–299.
Résumé: Characterizing functional diversity has become central in ecological research and for biodiversity assessment. Understanding the role of species with rare traits, i.e. functionally rare species, in community assembly, ecosystem dynamics and functioning has recently gained momentum. However, functional rarity is still ignored in conservation strategies. Here, we quantified global functional and evolutionary rarity for 2073 species of coral reef fishes and compared the rarity values to IUCN Red List status. Most species were functionally common but geographically rare. However, we found very weak correlation between functional rarity and evolutionary rarity. Functional rarity was highest for species classified as not evaluated or threatened by the IUCN Red List. The location of functional rarity hotspots (Tropical Eastern Pacific) did not match hotspots of species richness and evolutionary distinctiveness (Indo-Australian Archipelago), nor the currently protected areas. We argue that functional rarity should be acknowledged for both species and site prioritization in conservation strategies.
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Gruss, A., Kaplan, D., Guenette, S., Roberts, C. M., & Botsford, L. W. (2011). Consequences of adult and juvenile movement for marine protected areas. Biological Conservation, 144, 692–702.
Résumé: Adult and juvenile mobility has a considerable influence on the functioning of marine protected areas. It is recognized that adult and juvenile movement reduces the core benefits of protected areas, namely protecting the full age-structure of marine populations, while at the same time perhaps improving fisheries yield over the no-reserve situation through export of individuals from protected areas. Nevertheless, the study of the consequences of movement on protected area functioning is unbalanced. Significant attention has been paid to the influence of certain movement patterns, such as diffusive movement and home ranges, while the impacts of others, such as density-dependent movements and ontogenetic migrations, have been relatively ignored. Here we review the diversity of density-independent and density-dependent movement patterns, as well as what is currently known about their consequences for the conservation and fisheries effects of marine protected areas. We highlight a number of 'partially addressed' issues in marine protected area research, such as the effects of reserves targeting specific life phases, and a number of essentially unstudied issues, such as density-dependent movements, nomadism, ontogenetic migrations, behavioral polymorphism and 'dynamic' reserves that adjust location as a realtime response to habitat changes. Assessing these issues will be essential to creating effective marine protected area networks for mobile species and accurately assessing reserve impacts on these species.
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Grüss, A., Kaplan, D. M., & Robinson, J. (2013). Evaluation of the effectiveness of marine reserves for transient spawning aggregations in data-limited situations. ICES J. Mar. Sci., .
Résumé: Grüss, A., Kaplan, D. M., and Robinson, J. Evaluation of the effectiveness of marine reserves for transient spawning aggregations in data-limited situations. – ICES Journal of Marine Science, doi:10.1093/icesjms/fst028. Many coral reef fish species form predictable, transient spawning aggregations. Many aggregations are overfished, making them a target for spatial management. Here, we develop a per-recruit model to evaluate the performance of no-take marine reserves protecting transient spawning aggregations. The model consists of only 14 demographic and exploitation-related parameters. We applied the model to a protogynous grouper and a gonochoristic rabbitfish from Seychelles and tested six scenarios regarding the extent of protected areas, the level of fish spawning-site fidelity, and fishing effort redistribution post reserve implementation. Spawning aggregation reserves improve spawning-stock biomass-per-recruit and reduce the sex ratio bias in protogynous populations for all scenarios examined. However, these benefits are often small and vary among the different scenarios and as a function of sexual ontogeny. In all scenarios, increases in yield-per-recruit do not occur or are negligible. The long-term yield increases due to spawning aggregation reserves may still occur, but only if spawning-stock biomass recovery results in a recruitment subsidy. Given these limited benefits, the value of no-take reserves must be weighed against those of other management options, such as fishing effort reduction and seasonal fishery closures. The latter is particularly appropriate when spawning and non-spawning areas overlap in space.
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Jimenez, H., Dumas, P., Mouillot, D., Bigot, L., & Ferraris, J. (2016). Harvesting effects on functional structure and composition of tropical invertebrate assemblages. ICES J. Mar. Sci., 73(2), 420–428.
Résumé: Anthropogenic disturbances affect ecosystem structure and functioning. The quantification of their impacts on highly diverse and structurally complex ecosystems, such as coral reefs, is challenging. These communities are facing rising fishing pressure, particularly on Pacific Islands such as New Caledonia. The main objective was to quantify harvesting effects on invertebrate assemblages across two contrasting habitats (soft- and hard-bottom), by comparing communities in marine protected areas (MPAs) with non-MPAs using 10 biological and ecological traits. Patterns of trait composition were compared with those of species composition by non-metric multidimensional scaling and permutational analysis of variance analyses. Traits most responsible for differences between MPAs and non-MPAs were determined using SIMPER analysis, and predictions on shellfishing effects were discussed. A total of 248 species were recorded in hard-bottom communities, mainly characterized by mobile epifauna living on corals, crawling, and possessing a shell (molluscs) or a cuticle (crabs and echinoderms). Soft-bottom habitats contained 166 species, dominated by burrowing and sedentary species, especially shelled (largely bivalves) and worm-like organisms. Clear differences in species and trait composition between MPA and non-MPAs were highlighted in both habitats. Harvesting activities have community-wide effects that change the functional composition of invertebrate assemblages, in particular in terms of living habits and mobility. The observed shifts in benthic communities can affect the functioning of tropical coastal ecosystems and need to be included in small-scale fisheries management in poorly known tropical environments.
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Juhel, J. - B., Vigliola, L., Wantiez, L., Letessier, T. B., Meeuwig, J. J., & Mouillot, D. (2019). Isolation and no-entry marine reserves mitigate anthropogenic impacts on grey reef shark behavior. Sci Rep, 9, 2897.
Résumé: Reef sharks are vulnerable predators experiencing severe population declines mainly due to overexploitation. However, beyond direct exploitation, human activities can produce indirect or sublethal effects such as behavioral alterations. Such alterations are well known for terrestrial fauna but poorly documented for marine species. Using an extensive sampling of 367 stereo baited underwater videos systems, we show modifications in grey reef shark (Carcharhinus amblyrhynchos) occurrence and feeding behavior along a marked gradient of isolation from humans across the New Caledonian archipelago (South-Western Pacific). The probability of occurrence decreased by 68.9% between wilderness areas (more than 25 hours travel time from the capital city) and impacted areas while the few individuals occurring in impacted areas exhibited cautious behavior. We also show that only large no-entry reserves (above 150 km(2)) can protect the behavior of grey reef sharks found in the wilderness. Influencing the fitness, human linked behavioral alterations should be taken into account for management strategies to ensure the persistence of populations.
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