Zooplankton grazing impact in the plume of dilution of the Gironde estuary (France) prior to the spring bloom

The Bay of Biscay is a coastal area intensively exploited forfishing and is submitted to important human actions (proximityof important industrial and agricultural areas). Thus, the understandingof the materials and energy transfers in such ecosystems isof great interest. However, investigations on zooplankton (animportant component of the marine food web) are very scarcein this area. Our study concerns the grazing impact of the zooplanktonin shelf waters in the plume of dilution of the Gironde estuaryprior to the spring bloom. Samples were taken through the photiclayer in April 1993. Our results have shown that Temora longicornisand Paracalanus parvus dominated the ‘herbivorous’planktonic community. The grazing impact of the zooplanktoncommunity on the total phytoplankton stock and on the totalprimary production was low (9–14 and 17–21% day^–1,respectively) during this period, which is in accordance withmost results in coastal areas. However, due to the small sizeof the algae (