Finescale nearshore physico-chemical variability and associated plankton communities

55 Conference Estuarine Coastal Sciences Association (ECSA 55), Unbounded boundaries and shifting baselines: Estuaries and coastal seas in a rapidly changing world, 6-9 September 2015, London
The innershelf is a transitional, highly variable and productive area being also relevant for the physical, chemical, and biological processes and the transport of nutrients, plankton, and sediment offshore. This region contains well differentiated ecosystems spatially structured as cross-shore gradients. In low energy environments such as many Mediterranean coastal areas, phytoplankton biomass is frequently enhanced in nearshore waters, occasionally giving rise to intense blooms. Here, we characterize the fine scale variability of different nearshore coastal areas in the NW Mediterranean Sea during the stratified season. Data from 54 continuous high resolution cross-shore transects extending up to 3 km form the shoreline was used to investigate changes in biomass trends and its variability. Most of the sampled profiles displayed a differentiated nearshore environment consisting on changes on T, S and fluorescence as well as in their spatial scales of variation. These changes are accompanied by marked cross-shore differences in the composition of plankton communities (from micro to picoplankton). Variations in the nearshore gradients often respond to changes in the natural and anthropogenic forcings that regulate the ecosystem at each time and to the structure of the plankton assemblage. The heterogeneous nature of this nearshore ecosystem has profound repercussion on coastal ecosystem assessment and management