Abstract
Prevalence, impact on shellfish resources and interspecific, spatial, and temporal variabilities of domoic acid (DA) in bivalves from Galicia (NW Spain) have been studied based on more than 25 years of monitoring data. The maximum prevalence (samples in which DA was detected) (100%) and incidence (samples with DA levels above the regulatory limit) (97.4%) were recorded in Pecten maximus, and the minimum ones in Mytilus galloprovincialis (12.6 and 1.1%, respectively). The maximum DA concentrations were 663.9 mg kg−1 in P. maximus and 316 mg kg−1 in Venerupis corrugata. After excluding scallop P. maximus data, DA was found (prevalence) in 13.3% of bivalve samples, with 1.3% being over the regulatory limit. In general, the prevalence of this toxin decreased towards the North but not the magnitude of its episodes. The seasonal distribution was characterized by two maxima, in spring and autumn, with the later decreasing in intensity towards the north. DA levels decreased slightly over the studied period, although this decreasing trend was not linear. A cyclic pattern was observed in the interannual variability, with cycles of 4 and 11 years. Intoxication and detoxification rates were slower than those expected from laboratory experiments, suggesting the supply of DA during these phases plays an important role.
Highlights
In 1987, in Prince Edward Island, Canada, the intoxication of 104 people by consumption of mussels was reported [1,2]
In more than 13% of the samples obtained by the monitoring system from 1995 to 2020, domoic acid (DA) was detected
DA was found in all samples of P. maximus analyzed but in 12.6% of those of M. galloprovincialis
Summary
In 1987, in Prince Edward Island, Canada, the intoxication of 104 people by consumption of mussels was reported [1,2]. Temporal variation has several components: (a) short-term variation, which is mostly a product of the balance between uptake and release of the toxins from bivalves (intoxication, detoxification); (b) seasonal variation; and (c) trend. Prevalence (proportion of the analyzed samples in which DA was detected), incidence (proportion of the samples with DA concentrations above 20 μg kg−1), and the main sources of variability of the DA concentration in bivalves of the area (Figure 1) have been characterized This includes the apparent intoxication and detoxification rates of each species, the comparison of the levels in mussels (used in this case as the sentinel species) with other bivalves, and the analysis of the trends or cycles which might have taken place over a 25-year period. FFigiguurere1.1A. rAeareoaf ostfusdtyu.dEys.tuEasrtiuesarfrioesmfrwohmichwshaimchplseasmwperleestawkeenre(ltoawkeernr(iglohwt pearnreigl)h, atnpdamneuls),sealnd muss pprordoudcutciotnioanreaarse(atsw(otwotoheorthpeanr eplsa)n. els)
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