Distribution and impacts of Harmful Algal Blooms in the ICES area

Summary Harmful Algal Blooms (HABs) represent a major hazard for the exploitation of coastal resources in ICES countries. Blooms of toxin-producing (low biomass) HABs are recurrent throughout the whole ICES region leading to prolonged shellfish harvesting bans when regulatory levels are exceeded; fishkilling (high biomass) HABs affect intensive caged-fish aquaculture in Scandinavia, Scotland and western Canada. Emerging benthic HABs have caused isolated events of Ciguatera Fish Poisoning (CFP) in Macaronesia (Canary, Madeira Islands) and outbreaks of toxic sea-spray on Mediterranean beaches. In the Baltic Sea, cyanobacteria aggregate in surface scums in tourist areas, and may kill domestic animals. Since the establishment of HAB related ICES activities (1984), we have witnessed the decline of some toxin-producers and PSP outbreaks in Iberia, the wax and wane of DSP outbreaks in Europe, and their emergence in North America, and the description of new lipophilic toxins (i.e. azaspiracids) that were unnoticed before, co-extracted with the most common diarrhetic shellfish toxins. Here we provide a checklist of the causative agents of harmful microalgal outbreaks in the ICES area, and a qualitative appraisal of the most outstanding patterns observed in the two last decades and reported to the ICES-IOC Working Group on Harmful Algal Bloom Dynamics.