Abstract
Galicia is an area with a strong mussel aquaculture industry in addition to other important bivalve mollusc fisheries. Between 2014 and 2017, 18,862 samples were analyzed for EU regulated marine lipophilic toxins. Okadaic acid (OA) was the most prevalent toxin and the only single toxin that produced harvesting closures. Toxin concentrations in raft mussels were generally higher than those recorded in other bivalves, justifying the use of this species as an indicator. The Rías of Pontevedra and Muros were the ones most affected by OA and DTX2 and the Ría of Ares by YTXs. In general, the outer areas of the Rías were more affected by OA and DTX2 than the inner ones. The OA level reached a maximum in spring, while DTX2 was almost entirely restricted to the fall–winter season. YTXs peaked in August–September. The toxins of the OA group were nearly completely esterified in all the bivalves studied except mussels and queen scallops. Risk of intoxication with the current monitoring system is low. In less than 2% of cases did the first detection of OA in an area exceed the regulatory limit. In no case, could any effect on humans be expected. The apparent intoxication and depuration rates were similar and directly related, suggesting that the rates are regulated mainly by oceanographic characteristics.
Highlights
Some phytoplankton species produce substances that are toxic to humans [1,2]
Pectenotoxin 2 (PTX2) was rarely found (0.18%) and DTX1 was only found in two samples
Toxicity was higher than the EU legal limit in 570 out of the 5561 samples (10.3%) in which toxins of the Okadaic acid (OA) group were quantified after alkaline hydrolysis, with other toxins being quantified without this treatment
Summary
Some phytoplankton species produce substances that are toxic to humans [1,2]. These species can bloom during certain periods of the annual cycle of phytoplankton and may be ingested by bivalve molluscs (cultured or in natural beds) which retain and ingest most of the particles suspended in the water, including toxin-containing cells [3,4,5,6,7,8,9]. A proportion of the toxins is absorbed by the bivalves, which frequently accumulate it to levels that are toxic to humans [3,10]. In such cases, the risk to human health from consuming bivalves is high and the harvesting and marketing of these animals must be prohibited, leading to losses for both the fisheries and aquaculture sectors [11]. Many countries run monitoring programs for marine biotoxins to minimize this risk as well as the economic impact of the presence of toxins [12,13,14].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
