Toxic marine microalgae and noxious blooms in the Mediterranean Sea: A contribution to the Global HAB Status Report

We review the spatial distribution of toxic marine microalgal species and impacts all types harmful algal events (Harmful Algal Blooms, HABs) in Mediterranean Sea (MS), including Black Sea, Marmara, coastal lagoons transitional waters, based on two databases compiled Ocean Biogeographic Information System (OBIS). Eighty-four potentially have been detected MS (2,350 records), which 16 described from these waters between 1860 2014 a few suspected to introduced. More than half (46) produce toxins that may affect human health, remainders ichthyotoxic substances (29) or other (9). Nevertheless, toxicity-related are not frequent (308 records 31 years), mainly consist aquaculture, caused by dinoflagellates Dinophysis Alexandrium, along with actual shellfish poisoning cases. Pseudo-nitzschia blooms widespread, but domoic acid rarely exceeds regulatory levels. Fish kills probably less sporadic reported, representing problem at places southern coasts Ebro River Delta. Since last decade 20th century, benthic Ostreopsis cf. ovata regularly occurred rocky shores MS, times health problems aerosol. New Gambierdiscus Fukuyoa, until now reported for westernmost easternmost coasts, raise concerns about risk ciguatera, syndrome so far known only subtropical tropical areas. Recent discoveries Vulcanodinium rugosum, responsible presence pinnatoxins French lagoons’ shellfish, azaspiracid-producers Azadinium spp. Mucilages discolorations major impact tourism summer. Reports HABs apparently increased over is likely related awareness monitoring operations rather an increase phenomena. Indeed, while case appears as sudden upsurge trend, no noxious has emerged intensively studied areas, such Spanish Adriatic Sea. Moreover, some cases decrease e.g., Alexandrium minutum disappearing Harbour Alexandria. Overall, main HAB risks derive massive development biomass consequent reduced water quality tourism, represents largest part economy coasts.