Toxin-Producing Ostreopsis cf. ovata are Likely to Bloom Undetected along Coastal Areas

Abstract

Mass appearances of the toxic dinoflagellate genus Ostreopsis are known to cause dangerous respiratory symptoms in humans exposed to aerosols. The outbreaks can appear in shallow marine waters of temperate regions around the globe. We followed a massive bloom event on a public beach on the northern Adriatic coast near Rovinj, Croatia. We identified the responsible species and the produced toxins as well as the dynamics of the event with respect to environmental conditions. Ostreopsis cf. ovata appeared in masses from September through October 2010 on a public beach near Rovinj, Croatia but stayed undetected by public health organizations. Respiratory symptoms were observed whenever humans were exposed to substrate samples containing large numbers of Ostreopsis cells. During the mass abundance of O. cf. ovata also exposure to the aerosols on the beach evoked respiratory symptoms in humans. Our measurements showed high cell abundances and high toxin contents with a stable relative contribution of putative Palytoxin and Ovatoxins a-e. Artificial beach structures proved to dramatically reduce settling of the observed Ostreopsis biofilm. Blooms like those reported herein have a high potential to happen undetected with a high potential of affecting the health of coastal human populations. Increased monitoring efforts are therefore required to understand the ecology and toxicology of those bloom events and reduce their negative impact on coastal populations.

Sanitary problems related to the presence of Ostreopsis spp. in the Mediterranean Sea: a multidisciplinary scientific approach

“…Similar symptoms were observed along the Spanish and French Mediterranean coasts, accompanied by ocular irritation, headache and, in some cases, by fever [41,42]. Other anecdotal descriptions of respiratory problems following marine aerosol exposure during Ostreopsis blooms have also been reported along the Mediterranean coast [25,43,44]. The most serious sanitary problems occurred on the Liguria coast in summer of 2005 [22,40] and repeated, with a lower intensity, in 2006 [40].…”

Development of periphytic diatoms on different artificial substrates in the Eastern Adriatic Sea

“…Also, epiphytes on shoots of seagrass have better availability to light, as well as to nutrients from the water column and the substrate (HUTCHINSON 1975). Additionally, macrophytes as an elastic substrate can sustain wave energy and reduce turbulent effects on the biofi lm surface, which could promote biofi lm formation (PFANNKUCHEN et al 2012).…”

“…Recent periphytic studies in the Adriatic Sea have focused on epiphytic diatoms of the northern Adriatic (MUNDA 2005) and the toxic bloom of benthic dinofl agellates Ostreopsis (TOTTI et al 2007, PFANNKUCHEN et al 2012, whilst in the middle Adriatic research is focused on the ecology and taxonomy of periphytic diatoms in the estuary of rivers, like the River Zrmanja (BURIĆ et al 2004, CAPUT et al 2005.…”

Establishing the link between <em>Ostreopsis</em> cf.<em>ovata</em> blooms and human health impacts using ecology and epidemiology

“…Hence, the recurrent Ostreopsis blooms are not always accompanied by concomitant symptoms that would generate health reports. This causes underdiagnosis and, thus, under-reporting to the surveillance health system (Tichadou et al 2010, Pfannkuchen et al 2012. Second, the estimations of the Ostreopsis concentrations in the affected area were usually conducted only after symptoms were reported.…”

“…Thus, the direct link with the O. cf. ovata blooms remains unclear due to the temporal mismatch between the ecological and the epidemiology studies, as noted earlier (Tichadou et al 2010, Pfannkuchen et al 2012.…”