LONG-TERM VARIATIONS OF 4 MACROBENTHIC COMMUNITY STRUCTURES

This study examines whether meso-scale meteorological events, in parti cular the alternation of cold and mild periods, influenced the structu re of four Abi cr alba communities, sampled from 1977 to 1992 on the n orthwest French coast. We propose a new numerical procedure to describ e temporal variations in the structure of each assemblage, using some niche-oriented models recently developed by Tokeshi (1993). The descri ption of the temporal changes in the structure of each community was s ummarized into a 2D-plot of an ordination, performed on observed and s imulated patterns. Results showed that important changes occurred in t hese four assemblages, which were not directly related to the meso-sca le climatic events, but mainly to the local environmental factors and biotic interactions. Furthermore, it appears that stable environmental conditions would favour more stable structures, but do not determine the precise type of the structure.