Plankton blooms, ocean circulation and the European slope current: Response to weather and climate in the Bay of Biscay and W English Channel (NE Atlantic)

Abstract The flow of upper-layer surface water and circulation for the Bay of Biscay, continental slope and in the wider region of the NE Atlantic is presented, as well as the seasonality of flow and internal tides. The marine plankton environments of Biscay Ocean , Biscay Eddies , Biscay Slope and Biscay Shelf are defined. The Shelf region (Armorican and Celtic) is further divided into Stratified Shelf , Frontal and Tidally Mixed . Seasonal distributions of chlorophyll a are given for all environment from in situ measurements and remote sensing data. Mixing and stabilisation of surface water in the euphotic layer for the start of the spring bloom using in situ profiling measurements is examined. Some regional responses for the slope current, dinoflagellate blooms and interannual variations in spring diatom numbers with respect to weather and climate in the Bay of Biscay and around the British Isles are suggested and discussed. An example of the Eastern European Ocean Margin continental slope response to winter weather (sea level atmospheric pressure forcing) resulting in warm winter water in the southern Bay of Biscay ( Navidad , with eddy production) and off the Shetland continental slopes (the warm-water supply route to the Arctic) is given from the slope climate observation series.