Climate influence on Dinophysis spp. spatial and temporal distributions in Greek coastal water

Abstract

Presence of Dinophysis spp., the main phytoplankton genus responsible for the occurrence of lipophilic biotoxins of the okadaic acid group (Diarrhetic Shellfish Poisoning; DSP) in Greek mussels, was recorded in the pe- riod 2003-2008 in five major mussel culture areas of Greece. Dinophysis spp. abundances were simultaneously stud- ied with climatological parameters (air temperature, rainfall, wind direction and velocity) and the occurrence of DSP toxic episodes in mussels. Dinophysis spp. blooms occurred with a seasonal periodicity. Highest cell abundances of the bloom appeared steadily between late winter and spring, whereas occurrence of DSP toxicity in mussels followed a similar time pattern, with mouse bioassay-positive samples ranging between 10.2-28.1% of the total samples anal- ysed. Maximum mean Dinophysis spp. counts coincided with air temperatures in the range of 10-20°C; abundances higher than 1,000 cells L -1 were more frequently recorded at air temperatures in the range of 4-20°C in combination with low rainfall and low velocity winds (<Beaufort scale 4), blowing from the north (NW, N and NE) and south (SE and S). To our knowledge, this is the first report to correlate the occurrences and abundances of potentially toxic Dinophysis spp. and climatological data for the majority of the shellfish production areas studied. Such observations may contribute to the clarification of the occurrence patterns of DSP toxic episodes, hence bettering the economical management of mussel production.