Temporal stability of spatial structures of fish community in Languedoc-Roussillon and Provence-Alpes-Cote d'Azur regions.

Fish community of 35 stations of both Languedoc-Roussillon and Provence-Alpes-Cote d'Azur regions (France) were sampled from 1993 to 1996 during the survey program (Reseau Hydrobiologique et Piscicole) conducted by the Conseil Superieur de la Peche. The species-station-date data set was analysed using two K-tables (4 dates) statistical methods : Partial Triadic Analysis (THIOULOUSE and CHESSEL, 1987; BLANC et al., 1998) and series of contingency tables (FOUCART, 1978, 1983). With both methods, results suggested that there was a common spatial structure for all dates of sampling. The first method revealed an opposition between stations characterized by trout and stations where Cyprinidae species were dominant. The second method highlighted an upstream downstream structure of fish community similar to those considered as references (HUET, 1954; VERNEAUX, 1973, 1981). The analysis of temporal variation around the compromise structure showed that fish assemblages were stable over the studied period.