Conditions d'apparition de densités accrues de dinoflagellés Dinophysis dans le pertuis d'Antioche et les eaux adjacentes. Campagnes Dinopertuis 89

Environmental and species features which lead to increases in cell density of the D.S.P. Dinoflagellate Dinophysis in inshore and offshore waters of the île de Ré - île d'Oléron area, France (cruises "Dinopertuis89"). Four weekly sampling series have been carried out, within 10 May – 31 May 1989, at 24 stations located from inshore to offshore waters of the "île de Ré" - "île d’Oléron" area, with the aim to investigate (i) whether Dinophysis increases in cell density occur first in offshore waters and then, eventually, are pushed to the coast, or develop simultaneously in the whole area, and (ii) whether there are some environmental conditions which are related to Dinophysis blooms. Depths of sampling have been stated on the bas is of STD profiles. All measurement and ana1ysis data obtained are tabled in the present paper. They pertain to temperature, salinity, light energy, inorganic nutrient contents (NH4, NO2, NO3, PO4. SiO3), organic nutrient contents (urea, DON, dissolved primary amines. DOP), chlorophyll a and pheophytin in contents, bacteria-cell density. Dinophysis spp. cell densities, and cell densities of main phvtoplancton species. These data obviously show that Dinophysis increases in cell density are associated with warm and stratified waters. and occur first in offshore areas.