Parallel monitoring of Ostreopsis cf. ovata blooms and human respiratory irritations in the NW Mediterranean

The 16th International Conference on Harmful Algae (ICHA 2014 New Zealand), Advancement Through Shared Science, 27-31 October 2014, Wellington, New Zealand.-- 1 page

Since the last decade, there has been an increase in the bloom occurrences of the toxic dinoflagellate genus Ostreopsis in temperate areas. In the Mediterranean Sea, massive blooms of Ostreopsis cf. ovata in some localities have been related to respiratory and dermatological symptoms in humans. Until now, the available health data comprise outbreaks of human affectation registered concurrently to high Ostreopsis cell densities. Because the blooms last for some months and symptoms are detected only occasionally, the direct link between the two kinds of events has not been clearly established yet. In order to address this discrepancy, in summer-autumn 2013, a joint epidemiology and ecology study was conducted in Sant Andreu de Llavaneres, a hot spot of Ostreopsis blooms in the NW Mediterranean Sea. Health disorders of a human cohort situated in front of the sampling station were continuously recorded along the whole Ostreopsis bloom period. In the water column, the highly variable cell numbers showed no link with human symptoms. In contrast, O. cf. ovata abundances in the macroalgae presented a well-defined temporal bloom pattern, and human health disorders peaked coinciding with the transition from the exponential to the stationary growth phase. We hypothesize that palytoxins, other secondary metabolites and/or potentially allergenic substances from the associated microbial community, could be released to the environment coinciding with that particular physiological state of the Ostreopsis cells. Thereafter, despite high cell densities were found in the macroalgae, the risk of potential respiratory impacts would be minor

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