Interspecific Relationships in Benthic Assemblages of a Large Lowland River : Co-existence or Competition as a Result of Habitat Characteristics

HR: 1330h
AN: B33E-08 [Abstracts]
TI: Interspecific Relationships in Benthic Assemblages of a Large Lowland River : Co-existence or Competition as a Result of Habitat Characteristics
AU: * Akopian, M
EM: akopian@ccr.jussieu.fr
AF: University Pierre and Marie Curie - UMR Sisyphe 7619 CNRS/Paris VI, Box 105, Tour 46-56, 4 Place Jussieu, Paris Cedex 05, 75252 France
AU: Usseglio-Polatera, P
EM: usseglio@sciences.univ-metz.fr
AF: University of Metz - Biodiversity and Ecosystem Functioning Lab. (LBFE), Campus Bridoux, Avenue GＯＳal Delestraint, Metz, 57070 France
AB: Macrobenthic assemblages of the lower, regulated and canalized Marne River (France) are dominated by several "exotic", recently introduced species. Arrival, installation and spread of such alien species were certainly promoted by (1) the close connection between French and other European river systems (Rhine, Danube), (2) the modification of natural river flow and benthic habitats. Both habitat characteristics (e.g. granulometric composition, organic content) and corresponding benthic assemblage structure were analysed to identify the substrate affinity of major taxa in the lower Marne River. The main aim of the study was to evaluate the possible biotic interactions (i.e. competition for food and/or space) among dominant taxa as function of habitat features and to predict the future development of newly established species, already known as potential invaders: Corbicula fluminea (Bivalvia), Hypania invalida (Polychaeta), Chelicorophium curvispinum (Amphipoda), etc. Most of the newly established species, coming from the same biogeographical area ("invasional meltdown" hypothesis?), are eurytopic, with high fecundity and large food spectrum. First results demonstrated the co-existence of such species in the Marne River. But the future ecological importance of these organisms in benthic assemblages of the river depends on their present population size, population dynamics, and ability to colonize bottom substrates.
DE: 4804 Benthic processes/benthos
SC: Biogeosciences [B]
MN: 2005 Joint Assembly