Response of the Brest bay towards the increase of nutrients imputs

Abstract

In order to analyse the response of phytoplankton stocks to increasing enrichment in the bay of Brest, a survey of the cycle of nutrients and chlorophyll concentrations has been performed in 1993 and compared to earlier measurement. With regards to the seventies, a two-fold nitrate loading is now entering this ecosystem. As a result of these anthropogenic modifications, Si/N ratios have decreased but phytoplankton stocks have not increased. Both data analysis and ecological modelling show that several non anthropogenic factors have hindered the emergence of eutrophication effects in spite of increasing nitrate loading.