Bivalve Shellfish Safety in Portugal: Variability of Faecal Levels, Metal Contaminants and Marine Biotoxins during the Last Decade (2011–2020)

Abstract

Bivalves are a high-value product whose production has markedly increased, reaching 9863 tonnes in Portugal in 2021. Bivalves’ habitats—lagoons, estuaries and coastal waters—are exposed to biological and anthropogenic contaminants, which can bioaccumulate in these organisms and pose a significant public health risk. The need to obtain a safe product for human consumption led to the implementation of standardised hygiene regulations for harvesting and marketing bivalve molluscs, resulting in routine monitoring of bivalve production areas for microbial quality, metal contaminants, and marine biotoxins. While excessive levels of biotoxins and metal contamination lead to temporary harvesting bans, high faecal contamination leads to area reclassification and impose post-harvest treatments. In this study, the seasonal and temporal variability of these parameters were analysed using historical data generated by the monitoring programme during the last decade. Moreover, the impact of the monitoring program on bivalve harvesting from 2011 to 2020 was assessed. This program presented a considerable improvement over time, with an increase in the sampling effort and the overall program representativeness. Finally, contamination risk, revising control measures, and defining recommendations for risk mitigation measures are given in the light of ten years’ monitoring.

The Potential of Chitosan-Based Composites for Adsorption of Diarrheic Shellfish Toxins

“…By mixing selected adsorbents with specific and complementary adsorption properties, such as CH and AC or CH and MMT [24], it is possible to design a hybrid material that synergistically combines the single remediation Although the intoxications caused by these toxins are not lethal, their presence in marine ecosystems above the legal limits-160 µg OA-eq/kg [2]-leads to the prohibition of shellfish harvesting. Such bans may last for weeks or months [7] and entail high economic losses for shellfish catchers and producers, as well as other players in the sector, such as purification centers or the processing industry. Aiming to solve this problem, different approaches to eliminating DSP toxins from shellfish have been tested, such as thermal treatments, ozonation, γ-irradiation, and feeding with non-toxic algae [8][9][10], but all were devoid of successful outcomes since these lipophilic molecules are not rapidly depurated by bivalves.…”