12th International Conference on Harmful Algae

INTERNATIONAL SOCIETY FOR THE STUDY OF HARMFUL ALGAE12 th <strong>International</strong> <strong>Conference</strong> on Harmful Algae, Copenhagen, Denmark, 4-8 September 2006used in this study may, in addition,produce another(s) secondarymetabolite(s) responsible for thedisruption of epithelial cell adhesionsystems, but not yet identified.PO.12-04Evolutionary relationshipsbetween two winter-bloomingphotosynthetic dinoflagellatesand heterotrophic Pfiesteria-likespeciesSession: PO.12 - Taxonomy and phylogenyRE Logares 1 , K Rengefors 1 , A Kremp 21 Lund University, LUND, Sweden2 Tvärminne Zoological Station, University ofHelsinki, HANKO, FinlandPeridinium aciculiferum is afreshwater dinoflagellate normallyfound in north-temperate lakes.Scrippsiella hangoei is a marinebrackishdinoflagellate endemicfrom the Baltic Sea. Bothmorphospecies are importantcomponents of the winterphytoplankton community andgenerally bloom below the ice-capat the end of the winter. The twomorphospecies differ in habitat,general morphology and physiology.However, they share identicalnuclear ribosomal DNA (SSU, ITS1-2, 5.8S and LSU) and very similarmitochondrial cytochrome b (COB)sequences, indicating a recentevolutionary divergence. AFLPfingerprinting shows that the twomorphospecies are presentlygenetically isolated. The SSU andCOB phylogenies indicate that bothmorphospecies are evolutionaryrelated to estuarine species similarto Pfiesteria. Morphological dataagree with phylogenies: the platepatterns of P. aciculiferum and S.hangoei are very similar to thePfiesteria-like Shepard’s-Crookspecies, and the three taxa appearas most closely related in the SSUphylogenies. Some Pfiesteria andPfiesteria-like species are wellknown toxin producers.Interestingly, P. aciculiferum is oneof the few freshwater dinoflagellatesknown to produce allelopathicsubstances, and there is someevidence that S.hangoei producetoxins. An interesting difference isthat Pfiesteria and Pfiesteria-likespecies are heterotrophic, while P.aciculiferum and S. hangoei havechloroplasts. We are presentlyinvestigating the origin of theirchloroplasts.PO.08-22Comparative pathogenicity ofCochlodinium polykrikoides fromthe York River, Virginia, USA andthe Gulf of CaliforniaSession: PO.08 - ToxicologyVJ Lovko, WK VogelbeinVirginia Institute of Marine Science,GLOUCESTER POINT, United States ofAmericaCochlodinium polykrikoides is aglobally distributed mixotrophicdinoflagellate that forms massiveblooms worldwide. These bloomshave been associated with fish killsin Japan, Korea, the Gulf of Mexicoand the northwest coast of NorthAmerica and C. polykrikoides isoften considered a toxic alga,although the mechanisms ofpathogenicity have not been clearlyidentified. Other regions includingthe east coast of North Americaalso experience blooms of C.polykrikoides, although noassociation with fish kills has beenreported. We conductedcomparative larval fish bioassays(Cyprinodon variegatus) with bloomderivedcultures of C. polykrikoidescollected from the York River,226