Small-scale spatial variability of food partitioning between cultivated oysters and associated suspension-feeding species, as revealed by stable isotopes

S Dubois,F Orvain,Jc Marin-Léal,M Ropert,S Lefebvre

doi:10.3354/meps336151

Abstract

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 336:151-160 (2007) - doi:10.3354/meps336151 Small-scale spatial variability of food partitioning between cultivated oysters and associated suspension-feeding species, as revealed by stable isotopes Stanislas Dubois1,*, Francis Orvain1, Julio César Marin-Léal1, Michel Ropert2, Sébastien Lefebvre1 1Laboratoire de Biologie et Biotechnologies Marine, Université de Caen, Esplanade de la Paix, 14032 Caen cedex, France 2Laboratoire Environnement Ressource de Normandie, IFREMER, Avenue du Général de Gaulle, BP 32, 14520 Port en Bessin, France *Email: stanislas.dubois@unicaen.fr ABSTRACT: Oyster culture structures support a host of epibionts belonging to the same suspension-feeding guild, which are considered to be potential competitors for food with cultivated oysters. In an intertidal shellfish ecosystem on the northern French coast, an approach based on stable isotopes (13C and 15N) was used to investigate intra- and interspecific food resource partitioning among cultivated oysters and the main associated wild sessile epibionts such as polychaetes, barnacles, mussels and ascidians. The main objective of the present study was to determine inter- and intraspecific food partitioning, along with small-scale spatial variability, within the guild of suspension feeders. We demonstrated that interspecific competition was limited among co-occurring suspension-feeders (ascidians, serpulid and terebellid polychaetes, bivalves and barnacles). None of the studied species had similar δ13C and δ15N signatures, indicating that relative contributions of organic matter sources may differ for each suspension-feeding species. Spatial variability was investigated both from the view of intra- and interspecific variability. Intraspecific variability was examined with regard to species’ feeding biology and the trophic plasticity of co-occurring suspension-feeders. Mantel tests indicated that spatial heterogeneity resulted not only from environmental conditions, such as elevation above sea level (a.s.l.) and sediment features, but also from the inherent spatial structure of isotopic signatures. Our results show that isotopic approaches that are limited to sampling in one area and at one time are at risk of mistaking trophic interactions. KEY WORDS: Shellfish · Oysters · Sessile epibionts · Stable isotopes · Spatial variability · Trophic plasticity Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 336. Online publication date: April 27, 2007 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2007 Inter-Research.

Highlights

In many estuarine and coastal ecosystems, commercial farming of shellfish is an important industry (Crawford et al 2003)
In an intertidal shellfish ecosystem on the northern French coast, an approach based on stable isotopes (13C and 15N) was used to investigate intra- and interspecific food resource partitioning among cultivated oysters and the main associated wild sessile epibionts such as polychaetes, barnacles, mussels and ascidians
Bivalves Crassostrea gigas and Mytilus edulis both had δ15N values lower than those of polychaetes, but C. gigas was slightly enriched in δ15N and slightly depleted in δ13C relative to M. edulis

Summary

Introduction

In many estuarine and coastal ecosystems, commercial farming of shellfish is an important industry (Crawford et al 2003). The carrying capacity of shellfish ecosystems has been investigated with models that assumed these species to feed in the same trophic niche and compete for the same food resources (see review by Prins et al 1998). Shellfish culture structures are known to support a range of associated organisms (mainly suspension-feeders), generally found on surrounding hard substrata and suspected of competing with farmed species for food (Lesser et al 1992). Since it was shown that diet and trophic relationships among organisms could be inferred from comparisons of natural abundances of stable isotopes with those in consumers’.

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