The benthic dinoflagellate genus Ostreopsis has been known for long in shallow habitats (rocky coasts, coral reefs) of tropical seas. Ostreopsis produces potent toxins (palytoxin and analogues) that contaminate marine fauna (shellfish, sea urchins, starfishes, fishes) whose ingestion often has fatal consequences in humans in the tropics. In some cases, damage and mortality on benthic macrofauna concurrent to Ostreopsis outbreaks have also been documented in temperate areas. Since the 2000's, recurrent and massive outbreaks of this genus occur in Mediterranean beaches in summer. Those blooms have been associated to respiratory problems and skin irritations. It is not clear whether these health disorders are caused by toxin(s) released into the water and aerosolized or by allergenic reaction after direct exposure to Ostreopsis cells or fragments or even compounds originated from the benthic community during the bloom period. Given the potential risks to human health associated to emergent harmful benthic microalgae blooms in developed temperate countries, it is urgent to implement its effective monitoring. The dynamics of Ostreopsis blooms have been intensively studied since 2007 in Sant Andreu de Llavaneres beach (NW Mediterranean Sea). In this hot spot, the abundances of the organism (mainly O. cf. ovata) follow a clear seasonal pattern: it is present from late spring to autumn, with the highest numbers usually reached during the summer months (July-August). During the outbreak season health-related impacts are detected in humans, including respiratory, dermatological, ophthalmological and general symptoms, with different routes and periods of exposure. Given the empirical coincidence of the two events, we designed a multidisplinary (environmental and epidemiological) procedure -the Ostreo-health protocol- addressed to explore their possible cause-effect relationship. With this aim, marine samples were taken regularly from June to October 2013 (with high frequency samplings during the hottest period) to track Ostreopsis abundances in the phytoplankton and phytobenthos communities. Other ecological and meteorological parameters were also monitored. Finally, a daily record of human symptomatologies was performed in a human cohort inhabiting in closest proximity to the marine hot spot

Symposium on Integrating New Advances in Mediterranean Oceanography and Marine Biology, 26-29 November 2013, Institut de Ciències del Mar (CSIC), Barcelona, Catalunya, Spain

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