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 20063 Dalhousie University, HALIFAX, Canada4 Alfred Wegener Institute for Polar and M,BREMERHAVEN, Germany5 CSIC, BARCELONA, SpainCoastal embayments of the EbroDelta in the NW Mediterraneaninclude Fangar and Alfacs Bays.Both bays are active sites forshellfish production of mussels(Mytilus galloprovincialis) andoysters (Crassostrea gigas) andhave been subject over the years toextensive studies in relation toHABs. We present herein the firstyear results of a collaborativeresearch project between NRC(Canada), CSIC and IRTA (Spain)concerning HAB populationdynamics in Alfacs Bay. This projecthas recently started (2005) and inconjunction with the local monitoringprogram, aims to give knowledge onthe occurrence of HAB events usingAlfacs Bay as a pilot site for coastalembayments. For this purposemarine toxins in bivalves andphytoplankton were recordedtogether with environmental andphysical parameters that could becrucial for the understanding ofHABs dynamics. Evaluation oftoxicity over a 52-week periodshows DSP episodes with cooccurrenceof YTX in shellfish inAlfacs Bay. Complementary resultsinclude the distribution of harmfulspecies, the description of toxins inshellfish and phytoplankton throughanalytical chromatography, thecytotoxicity of phytoplanktonrecovered from net hawls,chlorophyll-a quantification, sestonestimation through light absorbanceevaluation and description ofenvironmental and physicalparameters.First study of Gymnodiniumcatenatum sexuality in naturalsamples from Galicia´s coasts(NW Spain)Session: PO.10 - Ecophysiology &autecologyRI Figueroa 1 , I Bravo 1 , I Ramilo 1 , EGarcés 2 , A Morono 3 , Y Pazos 31 Instituto Español de Oceanografía, VIGO,Spain2 Institut de Recercca i Tecnologia, SANTCARLES DE LA RÁPITA, Spain3 Instituto Tecnoloxico, SpainGymnodinium catenatum Graham isan unarmoured, cyst-formingdinoflagellate species responsiblefor outbreaks of paralytic shellfishpoisoning (PSP). During Novemberand December of 2005, G.catenatum bloomed in the Galiciancoasts (NW coast of Spain).Vegetative cells, fusing gametes,planozygotes and resting cystswere counted in fixed sampleswhich morphologies and sizes werepreviously compared for calibrationto the observed in living ones. Themaximum values recorded were of86.000 vegetative cells/L, 1000fusing gamete pairs/L, 18,000planozygotes/L and 480 cysts/L.Living sexual stages were isolatedto check behaviour and viability.Apart from the previously citedsexual stages, other unreportedbehaviours of G. catenatumsexuality in natural samples, suchus planozygote division, bilobulatedcysts and chains of resting cystswere documented, photographedand compared to laboratory studies.Sediment samples were taken 3months after the bloom. Up to671cysts/cc were counted, and afterisolation, high values ofgerminability and viability wereobtained.PO.10-33PO.13-80173