| Summary: | Fernández-Tejedor, Margarita . et al.-- 12th International Conference on Harmful Algae, Copenhagen, Denmark, 4-8 September 2006.-- 3 pages, 7 figures Coastal embayments of the Ebro Delta in the NW Mediterranean include Fangar and Alfacs Bays. Both bays are active sites for the production of mussels (Mytilus galloprovincialis) and oysters (Crassostrea gigas) and have been subjected to extensive studies of HABs. We present herein the first year results of a collaborative research project concerning HAB population dynamics in Alfacs Bay. In conjunction with the local monitoring programme, this project uses Alfacs Bay as a pilot site for comparative studies of HABs in coastal embayments within the GEOHAB programme. The distribution of harmful species was measured by direct counting along with chlorophyll-a, biooptical characteristics of the water column, and key environmental and physical parameters that could be crucial for understanding HAB dynamics. Toxicity was measured by analytical chromatography and by assessing cytotoxicity of phytoplankton recovered from net hauls. Evaluation of toxicity over a 52-week period showed that diarrhetic shellfish poisoning (DSP) episodes co-occurred with yessotoxins (YTX) in the shellfish from Alfacs Bay. The presence of DSP correlated with the abundance of Dinophysis species in only about half the incidences where DSP was measured. The source of the remaining DSP events is unknown and no environmental triggers for toxin production is yet evident. There was no evidence that the abundant Pseudo-nitzschia species were producing domoic acid This project was funded by the NRC-SEPOCYT agreement between Canada and Spain, Ministry of Education and Science, Spanish Government DGPi-AM, Fisheries Department, Generalitat de Catalunya, IFOP Programme, and the European Union Peer reviewed
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