Multivariate analysis of the longitudinal variation of the zooplankton community structure in a riverine reservoir

The longitudinal variation in the zooplankton community of the riverine res ervoir of Esch-sur-Sure (Luxembourg) was studied in 1989, 1992 and 1993. Zo oplankton community structure, analysed by multidimensional scaling using t he Bray and Curtis index of similarity, showed clear differences among year s. Within each year, a clear longitudinal gradient along the reservoir was observed for the zooplankton in 1989 and 1993 with the highest similarity o bserved for stations located in the intermediate parts of the reservoir. A limited number of species was responsible for this longitudinal variation. For the environmental variables, the temporal variation from year to year w as also more pronounced than spatial variation within each year, indicating a correlation between environmental factors and zooplankton community stru cture.