Spatial distribution of dinoflagellates from the tropical coastal waters of the South Andaman, India: Implications for coastal pollution monitoring.

Dinoflagellate community structure from two semi-enclosed areas along the South Andaman region, India, was investigated to assess the anthropogenic impact on coastal water quality. At the densely inhabited Port Blair Bay, the dominance of mixotrophs in water and Protoperidinoids in sediments was attributed to anthropogenic nutrient enrichment and prey availability. A significant decrease in dinoflagellate abundance from inner to outer bay emphasize the variation in nutrient availability. The dominance of autotrophs and Gonyaulacoid cysts at the North Bay highlight low nutrient conditions with less anthropogenic pressure. The occurrence of oceanic Ornithocercus steinii and Diplopsalis sp. could evince the oceanic water intrusion into the North Bay. Nine potentially harmful and red-tide-forming species including Alexandrium tamarense complex, A. minutum were identified in this study. Although there are no harmful algal bloom (HABs) incidences in this region so far, increasing coastal pollution could support their candidature towards the future HABs initiation and development.