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 IRTA, Centre d'Aqüicultura, SANTCARLES DE LA RAPITA, Spain2 Biological Institute, Univ Copenhagen,COPENHAGEN, Denmark3 CSIC-IEO, VIGO, SpainDinoflagellates belonging to thegenus Prorocentrum collected inSabah, East Malaysia (P.rhathymum, P. cf. faustiae andthree strains of P. lima), LaRéunion, (P. belizeanum) and inAlfacs Bay and Vigo, Spain (P. cf.mexicanum, P. lima) were culturedto study their toxicological and toxinproduction properties, by cellassays and liquid chromatographicmethods, using either fluorescenceor mass-spectrometry detection(LC-FD, LC-MS). Cytotoxicity,characterised by IC 50 andmorphological changes, is studiedand compared.IC 50 ranged from 2103 cellequivalents for P. cf. faustiae to133,103 for P. rhathymum.Morphological changes such asrounding and membrane blebbing,observed in cells exposed to allProrocentrum lima from Malaysiaand to Prorocentrum belizeanum,suggest the presence of okadaicacid (OA). Analytical measurementsconfirmed the production of OA bythese species. However, toxicity notcorrelated with the presence of OAsuggests the production of derivatesof OA or other toxins.PO.07-10Convergent blooms of Kareniabrevis along the Texas coastSession: PO.07 - Ecology andoceanographyL Campbell, RD HetlandTexas A&M University, COLLEGESTATION, TX, United States of AmericaA numerical model of wind-drivensurface flow in the Gulf of Mexico isused to examine physical controlson harmful algal bloom formationalong the Texas coast. Kareniabrevis, which blooms sporadicallythroughout the Gulf of Mexico, hasa relatively slow growth rate(doubling times of 2-3 days).Increases in K. brevis concentrationcannot be explained simply in termsof growth. We hypothesize that theprimary mechanism responsible forbloom formation is convergencedue to downwelling at the coast.Convergence along the Texas coastcaused by seasonal downwellingwinds can concentrate the planktonup to 1000 times. This is surprisingbecause the modelled cells do notgrow; the simulated increase inconcentration is due to physicalprocesses alone. The numericalmodel does a reasonably good jobat predicting the timing andmagnitude of bloom initiation alongthe coast, but does not predict thedetails of the migration of the bloomalong the coast after it has formed,or the destruction of the bloom. Thisresult is significant because itimplies that K. brevis blooms maybe caused primarily by physicalprocesses, and that cell division isnot an important factor in bloomformation.PO.13-46Dinophysis sacculus from AlfacsBay, NW Mediterranean. Toxinprofiles and cytotoxic potentialSession: PO.13 - Regional eventsE Cañete 1 , A Caillaud 1 , M Fernández 1 ,E Mallat 1 , J Blanco 2 , J Diogène 11 Centre Aqüicultura IRTA, SANT CARLESDE LA RÀPITA, Spain2 CIMA, Centro de Investigacións Mariñas,VILANOVA DE AROUSA, Galicia, 36620,SpainDinophysis sacculus is commonlypresent at the Mediterranean and145