Morphogenetic and toxin composition variability of Alexandrium tamarense (Dinophyceae) from the east coast of Russia

Abstract

T.Y. Orlova, M.S. Selina, E.L. Lilly, D.M. Kulis and D.M. Anderson. 2007. Morphogenetic and toxin composition variability of Alexandrium tamarense (Dinophyceae) from the east coast of Russia. Phycologia 46: 534–548. DOI: 10.2216/06-17.1

Twenty-seven clones were established from elongate Alexandrium sp. cysts collected in six regions along the Russian Pacific coast. All isolates were identified as Alexandrium tamarense via detailed epifluoresence microscopy of thecal plates. Morphological differences of both cultured and wild cells from the study regions mainly occurred in the shape of the cell (length/width ratio), degree of development of the sulcal list, and the shape of the posterior sulcal (S.p.) and second antapical (2″″) plates. Cells were divided into two cell types: ‘short’ (isodiametrical or wide) and ‘tall’. Each cell type exhibits specific features of tabulation, mainly the shape of the S.p. and 2″″ plates and was dominant in each particular region of the study. The short type, with a wide S.p. and reduced length in the dorsoventral 2″″ plates, was characteristic of A. tamarense from Primorye and southern Sakhalin Island. The tall cells, i.e., with cell length exceeding width, and having and elongate S.p. and dorsoventrally elongate 2″″ plates, prevailed in Avachinskaya Guba Inlet and in the Bering Sea. The differences reported here between the two types are within the range of morphological variability of A. tamarense sensu Balech, 1995. The D1–D2 fragment of the large subunit nuclear ribosomal DNA was analyzed for 24 clones. Alexandrium tamarense from the Russian Pacific coast compose three genetically distinct populations that correspond to the Japanese temperate Asian, eastern North American, and western North American ribotypes of the ‘tamarensis’ complex. The presence and distribution of eastern and western North American ribotypes along the Russian Pacific coast suggest that dispersion to the temperate Asian region occurred long ago via natural currents and processes, and not through human-mediated introductions, as has been proposed. No strict correlation was observed between different morphological types of cells and ribotypes. High-performance liquid chromatography toxin analyses showed that all isolates were toxic and demonstrated variability in toxin content and composition among different populations. These data document the significant and previously uncharacterized risk of shellfish contamination with paralytic shellfish poisoning toxins from blooms of A. tamarense in Russian marine waters.

Key Words::

• Alexandrium tamarense
• Distribution
• Far Eastern seas of Russia
• LSU rRNA
• Morphology
• PSP
• Toxicity

ACKNOWLEDGMENTS

This research was supported in part by the U.S. National Science Foundation through grants OCE-0136861 and OCE-0430724 to D.M.A. and by RFBR 04-04-49747, RFBR-FEB RAS through grants 06-04-96039 and 06-04-96034; FEB RAS 06-I-II16-057, 06-I-II11-034, and 06-III-A06-167. We offer special thanks to Mr. Garry Comer and the Comer Science and Technology foundation. Without their support at a critical juncture in this study, this publication would not have been possible. The authors also acknowledge Dr. Galina Konovalova for critically reading the manuscript, useful comments and suggestions and for kindly providing samples from Avachinskaya Guba Inlet and Olytorskii Bay.