engleski

Ecology and taxonomy of potentially toxic Pseudo-nitzschia species in Lim Bay (north-eastern Adriatic Sea)

The population dynamics of Pseudo-nitzschia in relation to environmental factors was investigated from March 2002 to July 2008 in Lim Bay, in the north-eastern Adriatic Sea. Domoic acid was monitored in the breeding population of Mytilus galloprovincialis from 2005 to 2008. The principal-component analysis of environmental parameters showed that the system is mostly temperature driven. The phytoplankton community was mainly composed of diatoms. Pseudo-nitzschia was the dominant diatom, present in 60 % of samples, with a maximum (1.6 x 106 cells L–1) contribution up to 97 % of the total diatom abundance. Morphological analysis revealed P. manii and potentially toxic P. pseudodelicatissima, P. pungens, P. fraudulenta and P. calliantha as the dominant species in blooms. Pseudo-nitzschia abundance positively correlated to temperature, phosphate and ammonia in accordance with its maximal abundance in the summer/autumn period when fish farms had a maximum impact on the environment. Domoic acid was detected in Mytilus galloprovincialis in concentrations below regulatory limits, ranging from 0.097 to 0.8721 µg g-1 in five cases from April to October 2005 in Lim Bay, but so far it is not clear which of the species was responsible for DA production. This study is also the first record of P. manii, P pungens and P. fraudulenta species in the Adriatic Sea.

Pseudo-nitzschia species ; domoic acid ; population dynamics ; Adriatic Sea

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