Spatial analysis of the trophic interactions between two juvenile fish species and their preys along a coastal-estuarine gradient Auteur(s) : Kopp, Dorothee Le Bris, Herve Grimaud, Lucille Nerot, Caroline Brind'Amour, Anik Éditeur(s) : Elsevier Science Bv Résumé : Coastal and estuarine systems provide nursery grounds for many marine fish species. Their productivity has been correlated with terrigeneous inputs entering the coastal-estuarine benthic food web, thereby favouring the establishment of fish juveniles. Studies in these ecosystems often describe the nursery as a single large habitat without verifying nor considering the presence of contiguous habitats. Our study aimed at identifying different habitats based on macrozoobenthic communities and morpho-sedimentary characteristics and assessing the trophic interactions between fish juveniles and their benthic preys within these habitats. It included 43 sampling sites covering 5 habitats in which we described taxonomically and quantitatively the invertebrates and fish communities with stable isotopes and gut contents. It suggested that the benthic common sole Solea solea displayed feeding plasticity at the population level, separating the juveniles (G0) from the older fish (G1) into different "feeding sub-populations". Size-based feeding plasticity was also observable in the spatial occupancy of that species in the studied bay. The demersal pouting, Trisopterus luscus, equally used the different habitats but displayed low feeding plasticity across and inside each habitat. Stable isotopes proved to be powerful tools to study the spatial distribution of trophic interactions in complex ecosystems like the bay of Vilaine and to define optimal habitats for fish that use the coastal-estuarine ecosystem as nursery grounds. Journal Of Sea Research (1385-1101) (Elsevier Science Bv), 2013-08 , Vol. 81 , P. 40-48 Droits : 2013 Elsevier B.V. All rights reserved http://archimer.ifremer.fr/doc/00151/26226/24327.pdf DOI:10.1016/j.seares.2013.03.013 http://archimer.ifremer.fr/doc/00151/26226/ | Partager |
Morphospecies and taxonomic sufficiency of benthic megafauna in scientific bottom trawl surveys Auteur(s) : Brind'Amour, Anik Laffargue, Pascal Morin, Jocelyne Vaz, Sandrine Foveau, Aurelie Le Bris, Herve Éditeur(s) : Pergamon-elsevier Science Ltd Résumé : Scientific fisheries surveys routinely identify a large diversity of commercial and non-commercial benthic megainvertebrates that could provide useful information for Marine Strategy Framework Directive (MSFD) descriptors. Species is obviously the basic taxonomic level to which most ecological studies and theories refer. Identification at this level of organization is indeed always preferred over any other taxonomic level. Nevertheless, aggregation of species to higher taxonomic levels may be unavoidable sometimes, since errors of identification are known or suspected to occur in many surveys. Using analyses of taxonomic sufficiency (identification of organisms at various taxonomic resolutions) and groups of morphospecies (taxa identified easily by non-experts on the basis of evident morphological traits), this study aims to quantify the loss of ecological information incurred by partial identification of benthic megafauna in bottom trawl surveys in order to put such data to good use. The analyses were conducted on five scientific surveys representing a large range of geographical areas (from 150 km2 to 150 000 km2) and environmental conditions. Results show that genus, family and, particularly, morphospecies are good surrogates for species identification in community analyses. We suggest that bottom trawl surveys can provide reliable megafauna data that may usefully complete those obtained by grab surveys. The use of morphospecies could lead to new strategies, combining different datasets to provide indicators for MSFD descriptors (e.g. D6). Continental Shelf Research (0278-4343) (Pergamon-elsevier Science Ltd), 2014-01 , Vol. 72 , P. 1-9 Droits : 2013 Elsevier Ltd. All rights reserved. http://archimer.ifremer.fr/doc/00162/27309/25538.pdf DOI:10.1016/j.csr.2013.10.015 http://archimer.ifremer.fr/doc/00162/27309/ | Partager Voir aussi Bay of Biscay English Channel North Sea Taxonomic sufficiency Benthic descriptor Bottom trawl surveys Télécharger |