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Auteur Katsanevakis, S.; Coll, M.; Piroddi, C.; Steenbeek, J.; Ben Rais Lasram, F.; Zenetos, A.; Cardoso, A.C.
Titre Invading the Mediterranean Sea: biodiversity patterns shaped by human activities Type Article scientifique
Année 2014 Publication Revue Abrégée Front. Mar. Sci
Volume 1 Numéro Pages
Mots-Clés alien species; Aquaculture; biodiversity patterns; biological invasions; Lessepsian migrants; pathways; shipping
Résumé Human activities, such as shipping, aquaculture, and the opening of the Suez Canal, have led to the introduction of nearly 1000 alien species into the Mediterranean Sea. We investigated how human activities, by providing pathways for the introduction of alien species, may shape the biodiversity patterns in the Mediterranean Sea. Richness of Red Sea species introduced through the Suez Canal (Lessepsian species) is very high along the eastern Mediterranean coastline, reaching a maximum of 129 species per 100 km2, and declines toward the north and west. The distribution of species introduced by shipping is strikingly different, with several hotspot areas occurring throughout the Mediterranean basin. Two main hotspots for aquaculture-introduced species are observed (the Thau and Venice lagoons). Certain taxonomic groups were mostly introduced through specific pathways—fish through the Suez Canal, macrophytes by aquaculture, and invertebrates through the Suez Canal and by shipping. Hence, the local taxonomic identity of the alien species was greatly dependent on the dominant maritime activities/interventions and the related pathways of introduction. The composition of alien species differs among Mediterranean ecoregions; such differences are greater for Lessepsian and aquaculture-introduced species. The spatial pattern of native species biodiversity differs from that of alien species: the overall richness of native species declines from the north-western to the south-eastern regions, while the opposite trend is observed for alien species. The biodiversity of the Mediterranean Sea is changing, and further research is needed to better understand how the new biodiversity patterns shaped by human activities will affect the Mediterranean food webs, ecosystem functioning, and the provision of ecosystem services.
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Auteur Sequeira, A.M.M.; Mellin, C.; Floch, L.; Williams, P.G.; Bradshaw, C.J.A.
Titre Inter-ocean asynchrony in whale shark occurrence patterns Type Article scientifique
Année 2014 Publication Revue Abrégée Journal of Experimental Marine Biology and Ecology
Volume 450 Numéro Pages 21-29
Mots-Clés <!–; –><keyword; Handled; id=; Not; Tag
Résumé Abstract The whale shark (Rhincodon typus, Smith, 1828) is a migratory species (classed as Vulnerable by the IUCN) with genetic and circumstantial evidence for inter-ocean connectivity. Given this migratory behaviour, population-wide occurrence trends can only be contextualized by examining the synchrony in occurrence patterns among locations where they occur. We present a two-step modelling approach of whale shark spatial and temporal probability of occurrence in the Atlantic and Pacific Oceans using generalized linear mixed-effects models. To test the hypothesis that the probability of whale shark occurrence is asynchronous across oceans, as expected if inter-ocean migration occurs, we used long-term datasets of whale shark sightings derived from tuna purse-seine logbooks covering most of the central-east Atlantic (1980–2010) and western Pacific (2000–2010). We predicted seasonal habitat suitability to produce maps in each area, and then evaluated the relative effect of time (year) on the probability of occurrence to test whether it changed over the study period. We also applied fast Fourier transforms to determine if any periodicity was apparent in whale shark occurrences in each ocean. After partialling out the effects of seasonal patterns in spatial distribution and sampling effort, we found no evidence for a temporal trend in whale shark occurrence in the Atlantic, but there was a weak trend of increasing probability of occurrence in the Pacific. The highest-ranked model for the latter included a spatial predictor of occurrence along with fishing effort, a linear term for time, and a random temporal effect (year), explaining 15% of deviance in whale shark probability of occurrence. Fast Fourier transforms revealed a prominent 15.5-year cycle in the Atlantic. The increase in the probability of occurrence in the Pacific is concurrent with a decrease previously detected in the Indian Ocean. Cyclic patterns driven by migratory behaviour would better explain temporal trends in whale shark occurrence at the oceanic scale. However, despite cycles partially explaining observations of fewer sharks in some years, overall reported sighting rate has been decreasing. As a result, we suggest that the current {IUCN} status of the species should be re-assessed, but more data are needed to examine the flow of individuals across oceans and to identify possible reasons for asynchronous occurrences.
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ISSN 0022-0981 ISBN Médium
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Numéro d'Appel (up) LL @ pixluser @ collection 314
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Auteur Poisson, F.; Séret, B.; Vernet, A.-L.; Goujon, M.; Dagorn, L.
Titre Collaborative research: Development of a manual on elasmobranch handling and release best practices in tropical tuna purse-seine fisheries Type Article scientifique
Année 2014 Publication Revue Abrégée Marine Policy
Volume 44 Numéro Pages 312-320
Mots-Clés <!–; –><keyword; Handled; id=; Not; Tag
Résumé Abstract The reduction of by-catch mortality is an objective of the ecosystem approach to fisheries and a request made by consumers. Elasmobranchs, an important component of the French tropical tuna purse seine fishery by-catch, are currently thrown back into the sea. Fishers interact with various types of elasmobranchs that range widely in size, weight and shape, and could pose various degrees of danger to the crew. A diversity of discarding practices within the fleet were reported, some practices were considered suitable, others needed to be adapted and improved and others simply had to be banned. The majority of the crews were likely to improve their handling practices if they were presented with practical suggestions that were quick and easy. Combining scientific observations and empirical knowledge from skippers and crew, a manual, providing appropriate handling practices to ensure crew safety and increase the odds of survival for released animals has been developed and disseminated. Bringing these good practices onto the decks of fishing vessels should contribute to the reduction of the fishing mortality of some vulnerable species. It would be positively viewed by consumers as an act that reduces fishing's footprint on the environment and promoting animal welfare which would improve the image of fishing industry. Mitigation research is by definition an iterative process and different complementary methods must be carried out at different levels of the fishing process to significantly reduce the mortality of the by-catch.
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Numéro d'Appel (up) LL @ pixluser @ collection 315
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Auteur Ban, N.C.; Maxwell, S.M.; Dunn, D.C.; Hobday, A.J.; Bax, N.J.; Ardron, J.; Gjerde, K.M.; Game, E.T.; Devillers, R.; Kaplan, D.M.; Dunstan, P.K.; Halpin, P.N.; Pressey, R.L.
Titre Better integration of sectoral planning and management approaches for the interlinked ecology of the open oceans Type Article scientifique
Année 2014 Publication Revue Abrégée Marine Policy
Volume Numéro Pages
Mots-Clés Areas beyond national jurisdiction; Benthic-pelagic interlinkages; High seas; marine conservation; Marine Protected Areas; sustainable fisheries
Résumé Open oceans are one of the least protected, least studied and most inadequately managed ecosystems on Earth. Three themes were investigated that differentiate the open ocean (areas beyond national jurisdiction and deep area within exclusive economic zones) from other realms and must be considered when developing planning and management options: ecosystem interactions, especially between benthic and pelagic systems; potential effects of human activities in open oceans on ecological linkages; and policy context and options. A number of key ecological factors differentiate open oceans from coastal systems for planners and managers: (1) many species are widely distributed and, especially for those at higher trophic levels, wide ranging; (2) the sizes and boundaries of biogeographical domains (patterns of co-occurrence of species, habitats and ecosystem processes) vary significantly by depth; (3) habitat types exhibit a wide range of stabilities, from ephemeral (e.g., surface frontal systems) to hyper-stable (e.g., deep sea); and (4) vertical and horizontal linkages are prevalent. Together, these ecological attributes point to interconnectedness between open ocean habitats across large spatial scales. Indeed, human activities – especially fishing, shipping, and potentially deep-sea mining and oil and gas extraction – have effects far beyond the parts of the ocean in which they operate. While managing open oceans in an integrated fashion will be challenging, the ecological characteristics of the system demand it. A promising avenue forward is to integrate aspects of marine spatial planning (MSP), systematic conservation planning (SCP), and adaptive management. These three approaches to planning and management need to be integrated to meet the unique needs of open ocean systems, with MSP providing the means to meet a diversity of stakeholder needs, SCP providing the structured process to determine and prioritise those needs and appropriate responses, and adaptive management providing rigorous monitoring and evaluation to determine whether actions or their modifications meet both ecological and defined stakeholder needs. The flexibility of MSP will be enhanced by the systematic approach of SCP, while the rigorous monitoring of adaptive management will enable continued improvement as new information becomes available and further experience is gained.
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ISSN 0308-597x ISBN Médium
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Numéro d'Appel (up) LL @ pixluser @ collection 317
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Auteur Cuif, M.; Kaplan, D.M.; Lefèvre, J.; Faure, V.M.; Caillaud, M.; Verley, P.; Vigliola, L.; Lett, C.
Titre Wind-induced variability in larval retention in a coral reef system: a biophysical modelling study in the South-West Lagoon of New Caledonia Type Article scientifique
Année 2014 Publication Revue Abrégée Progress in Oceanography
Volume 122 Numéro Pages 105-115
Mots-Clés Biophysical model; Dascyllus aruanus; Homing; Larval dispersal; New Caledonia; Precompetency; Wind-driven transport
Résumé In the present work, a biophysical dispersal model is used to understand the role of the physical environment in determining reef fish larval dispersal patterns in the South-West Lagoon of New Caledonia. We focus on a reef fish species, the humbug damselfish Dascyllus aruanus, to investigate seasonal variability of simulated larval retention at the scale of a reef patch and at the scale of the lagoon, and to explore links between larval retention and wind variability. The model shows that retention exhibits considerable temporal variability and periodically reaches values much larger than anticipated. Non-zero larval settlement occurs over a large part of the lagoon. Nevertheless, settlement values decrease quickly away from the natal reef and mean dispersal distances are of order 25-35 km. Cross-correlation analyses indicate that weather conditions characterized by strong south east trade winds lead to low retention rates at both local (reef) and regional (lagoon) scales. By contrast, subtropical weather conditions characterized by weak winds result in high retention rates. These results suggest that large-scale weather regimes can be used as proxies for larval retention of the humbug damselfish in the South-West Lagoon of New Caledonia. Nevertheless, relatively small mean dispersal distances suggest that meta-population dynamics occur on relatively small spatial scales.
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ISSN 0079-6611 ISBN Médium
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Numéro d'Appel (up) LL @ pixluser @ collection 318
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