MESOZOOPLANKTON COMMUNITY INDICATES CLIMATE CHANGES IN A SHELF AREA OF THE INNER BAY OF BISCAY THROUGHOUT 1988 TO 1990

The mesozooplankton community was monitored at both coastal and offsho re sites of the Basque shelf (inner Bay of Biscay) during 1988-1990. T his was considered of interest because the local climate change toward dry conditions was found to be responsible for changes in shelf-water properties. In addition to seasonal changes, interannual variations i n mesozooplankton abundance and composition were evident, and primaril y related to the year-to-year increase in water temperature and salini ty. The increasing trends in copepod dominance, coupled with the incre asing abundance of species with oceanic affinity (e.g. Euchaeta hebes) , were presumably a response to the increase in oceanic features in th e shelf area. In the same way, the substantial year-to-year increase i n the abundance of species with summer-autumn development was attribut ed to the progressive warming. Among these species, the case of Temora stylifera is discussed specifically because this species was very sca rce in 1988, but showed unusual high abundances for the study area, an d dominated the summer-autumn assemblage in 1990. We think that T.styl ifera can be a key species in monitoring climate-oceanological changes affecting the Bay of Biscay. Results are also discussed in the contex t of the long climate-oceanological series for the Bay of Biscay, and its biogeographical status.