engleski

Are the potentially toxic Pseudo-nitzschia populations found in the Adriatic geographically and genetically isolated?

Planktonic diatoms from the genus Pseudo-nitzschia are frequent and abundantconstituent of the marine phytoplankton worldwide. At least fourteenPseudo-nitzschia species have been proved to produce domoic acid, a strongneurotoxin responsible for Amnesic Shellfish Poisoning (ASP). Therefore, considerable scientific interest in Pseudo-nitzschia morphology and taxonomy hasbeen generated. Only recently genetical and phylogenic studies are revealing newimportant findings to the ecology of this genus.Morphological, ecological and toxic properties of the genus Pseudo-nitzschia were studied in the northern and middle Adriatic. 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. Three in the P.seriata group: P.fraudulenta, P.pungens and P.subfraudulenta, and four species in P.delicatissima group: P.mannii, P.pseudodelicatissima, P.delicatissima and P.calliantha. Most of the identified species were confirmed by molecular methods with different genetic markers (18S, ITS1-5, 8S- ITS2, 28S). Similarity representation after Neighbourjoininganalysis, most parsimoneous phylogenetic reconstruction and analysis of populationsconfirmed that populations from the Northern Adriatic are separated and genetically different from the rest of the Mediterranean and the world (ITS1-5.8S-ITS2). It could be demonstrated that the investigated Pseudo-nitzschia populations of the northern Adriatic are indigenous and genetically separated from populations in the Mediterranean and other regions of the world.

Adriatic Sea; Pseudo-nitzschia; populations

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