Spring zooplankton distribution and production of the copepod Euterpina acutifrons in Marennes-Ol�ron Bay (France)

Abstract

Short term variations of zooplankton populations were studied during an algal spring bloom in two characteristic areas of the Marennes-Oleron Bay (France). The sampling sites were chosen in the north of the bay, one close to the neritic zone, the other close to the estuarine zone. Five distinct zooplanktonic communities were observed: two typical neritic and estuarine assemblages, two eurytopic groups (linked to neritic or estuarine water masses) and an autochtonous community, widely distributed in the north of the bay. The copepod Euterpina acutifrons dominated the zooplankton community during this period of the year in terms of abundance (up to 83% of the zooplankton community). Its production differed between water masses: the highest production occurred at the estuarine station (3.48 ± 0.65 mg C m−3 d−1), where nauplii accounted for a large part of these high values. Its P/B ratio was similar at the two stations (0.196 and 0.209 d−1).