ASSESSING THE HARMFUL MICROALGAE OCCURRENCE AND TEMPORAL VARIATION IN A COASTAL AQUACULTURE AREA, SOUTHERN BRAZIL.

The occurrence of harmful microalgae in aquaculture areas is a potential cause of human health problems and economic and environmental losses. In southern Brazil, coastal aquaculture activities are increasing and the assessment of harmful algal risk is critical. Here, we report the occurrence of six dinoflagellate and two diatom toxic species and other potentially harmful microalgae in a prominent mussel culture area (Armação do Itapocoroy Bight). The highest risk of paralytic and diarrhetic shellfish poisoning was associated with dinoflagellate blooms of Gymnodinium catenatum (1.6 104 cells L-1) in autumn, and of Dinophysis acuminata complex (>103 cells L-1) from mid-winter through spring. Other potentially toxic microalgae observed were Pseudo-nitzschia spp. (diatoms) and Alexandrium sp. (dinoflagellate). Stochastic events related to dynamic oceanographic features appear to play an important role in triggering and determining the magnitude of toxic blooms inside the bight. Our results strongly support the need for official monitoring programs in this and other Brazilian coastal aquaculture areas to ensur