engleski

Seasonal dynamics of potentially harmful microalgae in the coastal area of Rovinj, NE Adriatic Sea

A growth of concern toward microalgal species that produce toxins has been noticed in last few decades. These toxins accumulate in shellfish and fish, thus when consumed can cause a variety of gastrointestinal and neurological illnesses in humans. This report aims to contribute to the knowledge on the biogeographical distribution and seasonality patterns of potentially harmful microalgal species in the northern Adriatic. Microalgal community was investigated over a one year period, from September 2008 to October 2009, at a coastal station in the vicinity of the city of Rovinj. A total of 15 potentially harmful microalgae characterized as bloom-forming and/or potentially toxic were identified, including 8 diatoms, 7 dinoflagellates and 1 prymnesiophyte. The abundances of each species were analyzed in relation to environmental parameters. Diatoms included: Amphora coffaeformis and Pseudo- nitzschia species such as: P. subfraudulenta, P. fraudulenta, P. seriata, P. pungens, P. galaxiae and P. delicatissima “sensu lato”. Only one species, P.pseudodelicatissima “sensu lato”, formed blooms in autumn period exceeding cell concentrations of 105 cells L-1. Other species were recorded in low numbers, but clear succession patterns were evident in their appearance. Dinoflagellates Dinophysis acuminata, D. caudata. D. fortii, D. sacculus, Phalacroma rotundata, Lingulodinium polyedrum and Prorocentrum minimum appeared in low abundances and were recorded mostly in late spring and summer period. Among prymnesiophytes, Phaeocystis cordata was observed throughout the spring period and is for the first time recorded for the Adriatic Sea. As reported elsewhere we confirm a similar seasonal occurrence of toxic microalgae with highest risk periods of spring and summer.

HAB ; seasonal ; phytoplankton ; Pseudo-nitzschia

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