Fine scale zooplankton distribution in the Bay of Biscay in spring 2004

A fine scale spatial resolution survey (3 x 15 nautical miles) was conducted during May 2004 in the Bay of Biscay (43.32-46.12°N and 1.29-4.31°W), to study the zooplankton community during the onset of spring stratification. Cluster analysis classified the 45 most abundant taxa into seven major groups. In the southern part of the surveyed area, a front separating neritic waters from eddies off the shelf delimited distinct zooplankton communities. On the northern side of the surveyed area, river plumes and the generation of internal waves over the shelf break were the main mesoscale structures determining the composition and abundance of the zooplankton assemblages. Canonical correspondence analysis (CCA) and generalized additive models (GAMs) were used to investigate the relationship between zooplankton species distribution and selected environmental variables (sea surface temperature and salinity along with water column stratification and fluorescence pattern). Surface salinity and stratification index were the variables explaining the higher percentage of the deviance. The results of the survey conducted during May 2004 in the Bay of Biscay suggest that a limited number of environmental variables may be sufficient to attempt statistical modeling of zooplankton distribution.