Akashiwo sanguinea (Dinophyceae) blooms in a sub-tropical estuary: An alga for all seasons

Abstract

Akashiwo sanguinea is a cosmopolitan dinoflagellate that has been observed to form major blooms in coastal ecosystems around the world. A. sanguinea plays a major role in the ecology of many marine environments, including coastal ecosystems with variable salinities, where its euryhaline character makes it competitive. The study involved monthly water sampling and measurement of physical-chemical parameters at four sites from the upper reaches of the Caloosahatchee Estuary to San Carlos Bay bordering the Gulf of Mexico. Major A. sanguinea blooms were observed in the Caloosahatchee estuary, with biovolume up to 30.5 × 106μm3mL-1, equivalent to 740 cells mL-1, in the upper estuary. The latter regions of the estuary also had the greatest range of salinity and the highest total nitrogen and total phosphorus concentrations. The dynamics of blooms are discussed within the context of spatial and temporal patterns of salinity, temperature and nutrient concentrations, as they relate to hydrologic and climatic conditions.