Facteurs hydroclimatiques et apparitions d'eaux colorées, en baie de Vilaine, durant l'année 1985

In 1985 the spring bloom of the diatom Skeletonema costatum did not show a brown discoloration of superficial waters like in 1983 and 1984. Somme factors being unfavorable between mid march and mid april , low sea water temperature, high frequency of moderate and strong winds, rough sea. The summer bloom of Thalassiosira sp. and Rhizosolenia delicatula which appears in may has been enhanced , by the strong rainfails between mid march and mid april, the increase of sea temperature at the end of may and at the beginning of june, the low mixing of sea waters correlated with the predominance of light and moderate winds in may and june, the low salinity and high nutrient load of upper layers. The bloom disappeared at the end of june mainly by the action of the winds wich have stired up the water masses, destraying the thermo-halin stratification.