COMPARISON OF THE LONG-TERM EVOLUTION (19 77-1990) OF 2 MACROBENTHIC COMMUNITIES IN THE BAY-OF-MORLAIX (WESTERN ENGLISH-CHANNEL) - RELATIONS WITH HYDROCLIMATIC FACTORS

The quantitative changes of two benthic communities from the bay of Mo rlaix in the western part of the English Channel since 1977 have been determined. General trends of the main species were extracted by the E igen-Filtering method. Principal component analysis and hierarchical c lassifications were used to identify the successive periods of the ser ies. A comparative analysis of the trend of both series has been made in relation to the hydroclimatic changes observed during the sampling. The patterns were in phase in both communities. Five main periods wer e identified. The long-term temporal changes of both communities were affected by the Amoco Cadiz oil spill: high mortality in 1978 and reco nstitution of the populations destroyed by the hydrocarbons, but also by the climatic changes with a 3-4 yr period and the warming of the se awater over the last decade in relation to the sun Spots.