Environmental, human health and socioeconomic impacts of Ostreopsis spp. blooms in the NW Mediterranean

19th International Conference on Harmful Algae (ICHA 2021), 10-15 october 2021, La Paz, Baja California Sur, MéxicoThis presentation summarizes the research conducted by the CoCliME project to ascertain the impacts of Ostreopsis (mainly O. cf. ovata) blooms in the NW Mediterranean beached and to design strategies to prevent, mitigate and, if necessary, adapt to the impacts of these events in the future. Noxious effects of Ostreopsis proliferations in the Mediterranean include massive mortalities of benthic organisms. Still, the involved deleterious mechanisms are poorly understood, requiring standardized ecotoxicology tests. Also, the chemical nature of the harmful compounds synthesized by Ostreopsis is unknown. There is a need to understand the toxin transfer through the marine food webs, and to evaluate the real risk of seafood poisonings in the area. The main effects on human health are, by now, associated to direct exposure to seawater with high Ostreopsis cell concentrations and to inhalation of aerosols containing unknown irritative chemicals produced under certain circumstances during the blooms. A six-year epidemiologic study confirmed the mild acute symptoms, affecting mainly the ophthalmologic, digestive, respiratory and dermatologic systems but the risk of chronic exposure as well. Beach monitoring and surveillance systems in summer (such as the surveillance Network on the French Mediterranean coast since 2006) constitutes an effective strategy to prevent Ostreopsis impacts on human health. Nowadays, the general public has a poor knowledge about the occurrence of Ostreopsis blooms. However, considering hypothetical future scenarios of increased Ostreopsis blooms, a large part of coastal rcreational and tourist activities could be negatively impacted. Tourist and residents might continue to go to the beaches during Ostreopsis proliferations, and this be exposed to associated health risk