Réseau de surveillance du phytoplancton (REPHY). Observations sur le bassin d'Arcachon de 1991 à 1994

A part from the human health protection, the REPHY monitoring produced an important microplanktonic algae database. After a first investigation of the data from 1987 to 1990 at the site Teychan in Arcachon bay (MASSON, 94), it was interesting to continue. Other data processing is used in this second report. So, ail the series from 1987 to 1994 has been analysed. The eight years data revealed : - Microplanktonic algae were quantitatively poor compared to the other areas monitored along the who1e French coast. The lowest abundances were measured from June 1992 to the end of 1994; - Species which preferred this area according to Sanders' index were Chaetoceros spp., Asterionella glacialis, Leptocylindrus danicus, Skeletonema costatum and Thalassionema nitzschioides; - Dinoflagelate dominance increased in 1993 and continued in 1994; - In spite of the presence of harmful algae, shellfish toxicity were rare.