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The participants at ICM-CSIC and IAEA-CSIC are studying the dynamics of Ostreopsis blooms in the NW Mediterranean, Catalan coast. In particular, their research is focused on a hot spot were recurrent events occur every summer and are associated to mild respiratory disorders in beach users, workers and inhabitants in the area. We are characterizing the ecology of the blooms, the chemical composition of some Ostreopsis metabolites and conducting epidemiology studies on the affected human population.

We work in coordination with the regional and local authorities and end users in Catalonia, and in particular, with the French partners of CoCliME at the Laboratoire Océanographique de Villefranche-sur-mer (France) that also investigates similar Ostreopsis blooms in their area. Together, we are elaborating a database on Ostreopsis past events and impacts, to determine the associated social and economic costs and along with other CoCliME partners determine the future trends of these events and potential effects under climate change scenarios.

The CSIC partners are investigating the presence of the harmful dinoflagellate Ostreopsis in the Catalan coast, with a particular focus on the beaches of Sant Andreu de Llavaneres beach (41°33.13′N; 2°29.54′E, located 38 km north of Barcelona). This locality constitutes an Ostreopsis hot spot where annual blooms have been occurring in the last decades. At this sampling station, Ostreopsis cf. ovata blooms (defined by concentrations above 105 cells·g-1 FW of macroalgae) span for at least two months every year, mainly along July and August, with sometimes a second peak in October.

The first outbreak in 1998 was associated to benthic fauna mortality. Since 2004, respiratory disorders are recorded (with up to 200 people potentially affected), coinciding with the presence of the microalgae. The Ostreopsis blooms occur in a long, open, shallow fossilized sedimentary beach that is intensively colonized by a macroalgae mat (composed mainly by Rhodophyceae and Phaeophyceae). Ostreopsis cf. ovata grows as epiphyte of the macroalgae and is also found swimming in the plankton community. This rock-solid beach constitutes a unique habitat that contrasts with the nearby sandy beaches. In front of this beach, certain buildings are directly exposed to aerosols that seem to contain irritative compounds that cause mild symptoms in the upper tract respiratory system, eye irritation, headache, general malaise, and in some cases, fever. Most of the symptoms disappear within a few hours without specific medication when people move away from the affected area in the vicinity of the Ostreopsis bloom; so far, no hospitalization has been required.

Map of the presence of Ostreopsis in the Mediterranean and noxious events.

The ICM-CSIC has a 20 year well established communication with the Water Catalan Agency (Agència Catalana de l'Aigua, ACA) in order to address environmental problems at the Catalan beaches and also to meet the European Environmental Directives (e.g. MWFD and MWS). Since the first Ostreopsis-related health outbreak in 2004, a communication network was established to investigate and manage this problem in the region. In particular, during the Ostreopsis bloom period, ICM-CSIC always contacts ACA when Ostreopsis abundances are close to the defined bloom conditions. Then, ACA determines management actions, including information to the medical authority, the Public Health Agency of Catalonia (PHAC) and the Llavaneres City Hall, and informative notes are installed in the beach area to prevent bath and recreation activities. In addition, ACA invites ICM-CSIC researchers to attend the meetings of the “Beaches Permanent Commission”. These meetings are organized several times during the summer period to facilitate the communication and coordination between ACA and the environmental technicians of the city councils of coastal Catalan villages, other environmental authorities and sea researchers to cope potential problems on coastal waters during the summer beach season. The ICM-CSIC researchers have informed about the Ostreopsis problem and offered different ways of contact. In the particular case of the Sant Andreu de Llavaneres locality several meetings have been conducted participated by personnel of the town hall, the PHAC, the Catalan Health Institute-Primary Health Care Department (CHI-PHCD), the ACA and ICM-CSIC researchers. These meetings have allowed establishing epidemiology studies in the locality, especially in the beach area.