The interaction of retention areas and submarine ground water (SGD) in small bays: Implications for phytoplankton growth

Modified Davis drifters were deployed repeatedly over spring and neap tidal cycles in Kinvara Bay, a small semi-enclosed bay on the west coast of Ireland, in order to map circulation pathways and assess their implications for the transport and dispersal of nutrients and phytoplankton. The results showed that limited movement of water during neap tides created a retention area in the inner bay, trapping nutrients and any suspended particles. It is proposed that this retention, coupled with enhanced nutrient inputs via submarine ground water discharge driven by precipitation, leads to enhanced biological growth conditions for phytoplankton and is the likely cause of intense dinoflagellate blooms in summer that have historically occurred from time to time within the bay. This study has implications for all small bays with nutrient-rich freshwater inputs which may develop tidally driven retention areas.