engleski

Diversity of the potentially toxic diatom genus Pseud- nitzschia in the northern Adriatic Sea

Phytoplankton samples were collected at two stations in the northern Adriatic Sea from 1972 to 2017. The analysis of this 45 years long data set provided significant insights in the phytoplankton dynamics, species succession and changes in the phytoplankton community. Species from the genus Pseudo-nitzschia were among the most abundant and most frequent diatoms during the entire investigated period. The genus Pseudo-nitzschia is associated with the production of domoic acid (DA), a strong neurotoxin. Changes in the species composition within the genus have been observed. In the 1980ies the phytoplankton community was dominated by the P. seriata group. While the group P. delicatissima first appeared in the '80s and since then their frequency continuously increased. P. delicatissima grup has a frequency of appearance from 76-97% in the last decade. Pseudo-nitzschia are important costituents of HAB blooms worldwide as well as a DA producers which in turn calls for in depth analysis of the species diversity of the genus for the area. Monoclonal cultures were established for taxonomical and molecular identification. The existence of 7 different Pseudo-nitzschia species is confirmed in the northern Adriatic on the basis of detailed morphological characteristics and/or molecular feautures. P. fraudulenta, P. pungens and P. subfraudulenta as a rapresentatives from P. seriata group, and five species in P. delicatissima group: P. mannii, P. pseudodelicatissima, P. delicatissima, P. calliantha.

diatoms ; alkaline phosphatase ; northern Adriatic ; phosphorus limitation

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