|Les changements à long terme de la diversité spécifique dans les séries macrobenthiques subtidales: quelle interprétation? Exemple du site de Gravelines (baie sud de la mer du Nord)|
Luczak, C. (2001). Les changements à long terme de la diversité spécifique dans les séries macrobenthiques subtidales: quelle interprétation? Exemple du site de Gravelines (baie sud de la mer du Nord). Océanis (Paris) 1999(25): 377-393
In: Océanis (Paris). Institut Océanographique: Paris. ISSN 0182-0745, more
Benthos; Geographical distribution; Sampling; Species diversity; ANE, France, Nord, Gravelines [Marine Regions]; Marine
Species richness and diversity (Shannon's index) were examined over two years in relation to sampling design at one station during long-term monitoring of subtidal soft-sediment macrobenthic communities. In the usual approach, ten 0.1 m² grabs (grain) are taken at each sampling date, densities of the replicates are added and the results are given as density or richness per square meter. Our results show that if grain, lag and extent are taken into account, there is a clear spatial heterogeneity in sampling design between dates and in community distribution on a small scale. These differences in spatial observation scale lead to an important potential perturbation of spatial structure in the interpretation of the evolution of the macrobenthic community, because this spatial observation scale can interact with several spatial scales of organisation of the community. lt appears of prime necessity that all characteristics of the spatial scale of observation (grain, lag and extent) be taken into account in the interpretation of benthic ecological phenomena. The spatial scales of organisation of benthic communities must, however, first be identified as accurately as possible.