Dynamics of Dinophysis sensu lato species (Dinophyceae) in a coastal Mediterranean environment (Adriatic Sea)

Species of Dinophysis Ehrenberg sensu lato were collected opportunistically along the southern Adriatic coasts (Apulia, Italy) during a survey of phytoplankton community structure and dynamics carried out from 1995 to 1997. Most previous reports of Dinophysis spp. in the Adriatic Sea concentrated on northern populations, with few data available on phytoplankton inhabiting the southern coastal areas. Thus, the present study is the first on Dinophysis sensu lato species composition and spatio-temporal distribution in these essentially oligotrophic waters. Twelve Dinophysis species were identified; some of which can be assigned to the genus Phalacroma. Dinophysis sacculus, D. fortii, D. caudata, Phalacroma rotundatum and P. mitra are potentially producers of diarrhetic shellfish poisoning. Seasonal changes in Dinophysis and Phalacroma populations are presented, as well as their relationships with hydrographic and biotic factors. These dinoflagellates were associated with mixing conditions, low water temperatures and high nutrient inputs. Furthermore, the statistical analysis evidenced significant correlations of Dinophysis species to chlorophyll a and phytoplankton. Ecological implications arising from the data are discussed.