Spatial patterns of ichthyoplankton assemblages along the eastern English Channel French coast during spring 1995

Two surveys were conducted during April and May 1995 along the French coast of the eastern English Channel. They aimed to describe the influence of en vironmental features-water advection through the Straits of Dover and the h ydrological coastal front-on ichthyoplankton assemblages. Multivariate analysis, using the non-metric multi-dimensional scaling and b ased on the Bray-Curtis dissimilarity index, was associated with multiple r egression to characterize the spatial larval distribution and to relate it to the environmental factors. During the April survey only young larvae wer e found. They were separated into a coastal larvae assemblage, characterize d by high water temperature and fluorescence of chlorophyll a and two offsh ore assemblages limited to high salinity water. During the May survey, youn g larvae were mainly located in offshore waters, in the south of the Picard e Bay and in the Straits, where high offshore chlorophyll a fluorescence wa s found. In contrast old larvae were found along the coast, near estuaries. This pattern shows a spatial segregation of developmental stages of larvae in this area due to adult spawning migration, larval drift and ontogentic migration. Larval distributions can be explained by salinity, temperature a nd concentration of chlorophyll a, but the spatial evolution of those param eters during spring have also to be taken into account for the comparison o f the distributions between both surveys. (C) 1999 Academic Press.