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 20061 Alfred-Wegener-Institute,BREMERHAVEN, Germany2 Stazione Zoologica 'Anton Dohrn',NAPLES, ItalyDense raphidophyte blooms are acause of mass fish mortalities incoastal areas throughout the world.The recent dramatic global growthof aquaculture, especially fishfarming, has led to increasedrequirement for knowledge oncharacterization and toxigenicity ofraphidophyte blooms. In theMediterranean, raphidophytes formannual blooms in coastal waters,thereby posing a threat to fishaquaculture. We investigated amixed bloom event involving theraphidophytes Chattonella sp. andFibrocapsa sp. on the Adriatic coastof Italy, including molecular genetic,morphological and ecologicalaspects. Light and electronmicroscopy revealed one of thespecies to be Chattonella subsalsaas described by Biecheler (1936).Nevertheless, genetic markers fornuclear and ribosomal DNA (LSU,SSU, ITS, psaA and RubisCo)differentiated this Chattonella, andwith less distinctness, Fibrocapsasp., from other known strains of therespective genera. Phenotypicdifferences among isolated cloneswere determined from profiles ofpolyunsaturated fatty acids (PUFAs)and activity of reactive oxygenspecies (ROS), which are putativelyresponsible for ichthyotoxicity.Strains were bioassayed with a fisherythrocyte lytic assay and the brineshrimp Artemia salina test. Therelationship (if any) between toxicityand phenotypic and genotypiccharacteristics is complex and notyet resolved.O.15-04How many different species arein the Alexandrium tamarense/catenella / fundyense complex?Session: O.15 - TaxonomyPresentation time: 12:40 - 13:00S Fraga 1 , RI Figueroa 1 , I Bravo 1 , NSampedro 2 , JM Franco 3 , A Penna 4 , IRamilo 1 , A Fernández-Villamarín 11 Instituto Español de Oceanografía, VIGO,Spain2 Institut de Ciències del Mar, CSIC,BARCELONA, Spain3 Instituto de Investigacións Mariñas, CSI,VIGO, Spain4 University of Urbino, PESARO, ItalyThe Alexandrium tamarense/catenella / fundyense speciescomplex comprises four geneticallydifferent clades in which thesimilarity between strains is larger ingeographically related species thanbetween geographically distantstrains of the same species. Theseclades are the North Atlantic, theWestern European, the TemperateAsian and the Mediterraneanclades. The morphologicalcharacters currently used todifferentiate the species within thiscomplex are the presence orabsence of a ventral pore in 1’ plate,the ability to form chains, and therelation between the transdiameterand the length of the cells. InAlexandrium minutum the presenceof the ventral pore is not a constantcharacter, and in other species theability to form longer or shorterchains is strain dependent, and therelation between the transdiameterand length of cells depends onwhether or not they form chains.These characters alone are nolonger valid to differentiate amongspecies of this complex. In ouropinion the four clades correspondto four different cryptic species, andnew morphological criteria arenecessary to define them. We64