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Auteur Valls, A.; Coll, M.; Christensen, V. url  doi
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  Titre Keystone species : toward an operational concept for marine biodiversity conservation Type Article scientifique
  Année 2015 Publication Ecological Monographs Revue Abrégée  
  Volume 85 Numéro 1 Pages 29-47  
  Mots-Clés classification tree; Ecopath model; food-web structure; index of keystoneness; keystone species; marine ecosystems; Meta-analysis; mixed-trophic impact; rank correlation tests; scoring method  
  Résumé Various definitions and indices have been proposed in the literature to identify keystone species. In this study, we intended to make the concept of keystone species operational for marine biodiversity conservation. We used an exclusive definition of keystone species, based on the original concept of keystone predator, and derived a new functional index of keystoneness (KS) from an ecosystem-modeling approach. First, several KS indices were formulated, by combining measures of the mixed-trophic impact (MTI) and biomass of species. Then, a meta-analysis was performed, based on 101 published Ecopath food-web models, selected with a scoring method, and representative of the variety of marine ecosystems worldwide. The indices were applied to the models, and two statistical methods were compared to select the most promising KS index. Rank correlation tests were performed to assess the balance between the contribution of the impact and biomass components to the different KS indices. In addition, a classification tree was implemented, based on ecosystem-specific thresholds applied to the latter species traits, and used to confirm the identified keystone species. The selected index obtained the highest number of models with positive results from both the rank correlation tests and the classification tree. We also demonstrated the limitations of existing KS indices previously applied in the literature. Species were ranked according to their estimates of keystoneness with the selected KS index, so that potential keystone species were quantitatively identified in the 101 modeled food webs. The standardized modeling approach allowed for a comparison of the identified keystone species across models: cartilaginous fishes and toothed whales obtained the highest occurrences. Finally, the selected KS index was applied to the well-known case study of Prince William Sound (Alaska, USA). Potentially significant anthropogenic (fishing) impacts on keystone species were also considered and discussed. The operational methodology presented is directly applicable to marine food webs, and may be adapted to other (freshwater or terrestrial) systems.  
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  ISSN 0012-9615 ISBN Médium  
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  Numéro d'Appel (up) MARBEC @ isabelle.vidal-ayouba @ collection 1114  
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Auteur Ben Othman, H.; Leboulanger, C.; Le Floc'h, E.; Mabrouk, H.H.; Hlaili, A.S. url  doi
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  Titre Toxicity of benz(a)anthracene and fluoranthene to marine phytoplankton in culture: Does cell size really matter? Type Article scientifique
  Année 2012 Publication Revue Abrégée J. Hazard. Mater.  
  Volume 243 Numéro Pages 204-211  
  Mots-Clés Benz(a)anthracene; Ecotoxicity; Fluoranthene; Size-sensitivity relationship; aquatic organisms; biodegradation; chlorophyll; fluorescence; food-web; fresh-water phytoplankton; in-vitro; organic pollutants; pahs; phytoplankton; polycyclic aromatic-hydrocarbons; surface sediments  
  Résumé The toxicity of benz(a)anthracene and fluoranthene (polycyclic aromatic hydrocarbons, PAHs) was evaluated on seven species of marine algae in culture belonging to pico-, nano-, and microphytoplankton, exposed to increasing concentrations of up to 2 mg L-1. The short-term (24 h) toxicity was assessed using chlorophyll a fluorescence transients, linked to photosynthetic parameters. The maximum quantum yield Fv/Fm was lower at the highest concentrations tested and the toxicity thresholds were species-dependent. For acute effects, fluoranthene was more toxic than benz(a)anthracene, with LOECs of 50.6 and 186 mu g L-1, respectively. After 72 h exposure, there was a dose-dependent decrease in cell density, fluoranthene being more toxic than benz(a)anthracene. The population endpoint at 72 h was affected to a greater extent than the photosynthetic endpoint at 24 h. EC50 was evaluated using the Hill model, and species sensitivity was negatively correlated to cell biovolume. The largest species tested, the dinoflagellate Alexandrium catenella, was almost insensitive to either PAH. The population endpoint EC50s for fluoranthene varied from 54 mu g L-1 for the picophytoplankton Picochlorum sp. to 418 mu g L-1 for the larger diatom Chaetoceros muelleri. The size/sensitivity relationship is proposed as a useful model when there is a lack of ecotoxicological data on hazardous chemicals, especially in marine microorganisms. (C) 2012 Elsevier B.V. All rights reserved.  
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  ISSN 0304-3894 ISBN Médium  
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  Numéro d'Appel (up) MARBEC @ isabelle.vidal-ayouba @ collection 915  
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Auteur Danovaro, R.; Fanelli, E.; Canals, M.; Ciuffardi, T.; Fabri, M.-C.; Taviani, M.; Argyrou, M.; Azzurro, E.; Bianchelli, S.; Cantafaro, A.; Carugati, L.; Corinaldesi, C.; de Haan, W.P.; Dell'Anno, A.; Evans, J.; Foglini, F.; Galil, B.; Gianni, M.; Goren, M.; Greco, S.; Grimalt, J.; Guell-Bujons, Q.; Jadaud, A.; Knittweis, L.; Lopez, J.L.; Sanchez-Vidal, A.; Schembri, P.J.; Snelgrove, P.; Vaz, S. doi  openurl
  Titre Towards a marine strategy for the deep Mediterranean Sea: Analysis of current ecological status Type Article scientifique
  Année 2020 Publication Revue Abrégée Mar. Pol.  
  Volume 112 Numéro Pages 103781  
  Mots-Clés atmospheric deposition; Deep-sea ecosystems; downward particle fluxes; food-web structure; Marine strategy framework directive; Mediterranean basin; mercury bioaccumulation; particulate matter; polycyclic aromatic-hydrocarbons; seismic surveys; stable-isotopes; submarine canyons; trophic ecology  
  Résumé The Marine Strategy Framework Directive (MSFD), introduced in June 2008, was adopted to achieve a Good Environmental Status (GES) in the Ell's marine waters and to protect resources of socio-economic interest. The MSFD exerts to the marine area over which a Member State exercises jurisdictional rights in accordance with the United Nations Convention on the Law of the Sea (UNCLOS), including the deep-sea waters, seafloor and subseafloor of the Exclusive Economic Zones (EEZ). However, currently the MSFD focuses on coastal habitats and the shallow-water seafloor to the detriment of the deeper habitats. Despite the huge dimension of the deep sea (below 200 m of depth) covering more than 65% of the Earth's surface and including >95% of the global biosphere, the relevance of the dark portion of the seas and oceans is still almost completely neglected. Given the important bi-directional links between shallow and deep ecosystems, there is a clear need for extending the implementation of the MSFD into the deep sea, to define a sound ecosystem-based approach for the management and protection of deep-sea ecosystems and attain GES. We assembled data on drivers, anthropogenic pressures and impacts concerning the MSFD descriptors pertaining to the Mediterranean deep sea. We list deep-sea monitoring activities and the main sources providing benchmark conditions, and discuss knowledge and geographic coverage gaps. MSFD descriptors apply to the deep sea as to coastal waters, and ought to be monitored contemporaneously. We provide recommendations for guidelines for future deep-sea monitoring in the Mediterranean Sea.  
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  ISSN 0308-597x ISBN Médium  
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  Numéro d'Appel (up) MARBEC @ isabelle.vidal-ayouba @ collection 2749  
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Auteur Albo-Puigserver, M.; Navarro, J.; Coll, M.; Aguzzi, J.; Cardona, L.; Saez-Liante, R. doi  openurl
  Titre Feeding ecology and trophic position of three sympatric demersal chondrichthyans in the northwestern Mediterranean Type Article scientifique
  Année 2015 Publication Revue Abrégée Mar. Ecol.-Prog. Ser.  
  Volume 524 Numéro Pages 255-268  
  Mots-Clés Chimaera monstrosa; chimera-monstrosa; discrimination factors; Etmopterus spinax; etmopterus-spinax linnaeus; Feeding niche; fishing impacts; food-web; Galeus melastomus; galeus-melastomus; interpreting stable-isotopes; Isotope analysis; Mediterranean Sea; portuguese continental-slope; sea; top predators  
  Résumé Understanding how marine predators interact is a scientific challenge. In marine ecosystems, segregation in feeding habits has been largely described as a common mechanism to allow the coexistence of several competing marine predators. However, little is known about the feeding ecology of most species of chondrichthyans, which play a pivotal role in the structure of marine food webs worldwide. In this study, we examined the trophic ecology of 3 relatively abundant chondrichthyans coexisting in the Mediterranean Sea: the blackmouth catshark Galeus melastomus, the velvet belly lanternshark Etmopterus spinax and the rabbit fish Chimaera monstrosa. To examine their trophic ecology and interspecific differences in food habits, we combined the analysis of stomach content and stable isotopes. Our results highlighted a trophic segregation between C. monstrosa and the other 2 species. G. melastomus showed a diet composed mainly of cephalopods, while E. spinax preyed mainly on shrimps and C. monstrosa on crabs. Interspecific differences in the trophic niche were likely due to different feeding capabilities and body size. Each species showed different isotopic niche space and trophic level. Specifically, C. monstrosa showed a higher trophic level than E. spinax and G. melastomus. The high trophic levels of the 3 species highlighted their important role as predators in the marine food web. Our results illustrate the utility of using complementary approaches that provide information about the feeding behaviour at short (stomach content) and long-term scales (stable isotopes), which could allow more efficient monitoring of marine food-web changes in the study area.  
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  ISSN 0171-8630 ISBN Médium  
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  Numéro d'Appel (up) MARBEC @ isabelle.vidal-ayouba @ collection 1245  
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Auteur Shannon, L.J.; Coll, M.; Yemane, D.; Jouffre, D.; Neira, S.; Bertrand, A.; Diaz, E.; Shin, Y.J. url  doi
openurl 
  Titre Comparing data-based indicators across upwelling and comparable systems for communicating ecosystem states and trends Type Article scientifique
  Année 2010 Publication Revue Abrégée ICES J. Mar. Sci.  
  Volume 67 Numéro 4 Pages 807-832  
  Mots-Clés adriatic sea; central chile; comparative approach; demersal resources; fishing impacts; food-web; global fisheries; humboldt current system; indicator; nw mediterranean sea; pelagic fish; regime shifts; southern benguela; upwelling  
  Résumé Shannon, L. J., Coll, M., Yemane, D., Jouffre, D., Neira, S., Bertrand, A., Diaz, E., and Shin, Y-J. 2010. Comparing data-based indicators across upwelling and comparable systems for communicating ecosystem states and trends. – ICES Journal of Marine Science, 67: 807-832.  
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  ISSN 1054-3139 ISBN Médium  
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  Numéro d'Appel (up) MARBEC @ isabelle.vidal-ayouba @ collection 482  
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