Chemical and microbiological contamination in limpets (Patella aspera) of the Portuguese coast

Abstract

Coastal production areas can be impacted by anthropogenic contamination from urban, agroindustrial and leisure activities. Some contaminants, such as chemical substances might also have a telluric origin. Non filter feeding univalve mollusks, such as limpets, which are collected in rocky shores either for sale or for auto-consumption, are very appreciated in Portugal, but have been excluded from provisions on the classification of production areas, although can present relevant contamination.Thus, the aim of this study was to assess the microbiological and toxic metal contaminations in limpets (Patella spp) of the Portuguese coast, taking into account the production area and seasonal variation, and comparing their contamination levels with those occurring in bivalve mollusk indicator species, mussel (Mytilus edulis). The risks associated to the consumption of limpet meals were also assessed. For that, microbial total and fecal levels and cadmium, lead and mercury contents in limpets and mussels samples from three coastal areas over several months were analyzed based on standard methodologies.Contents of mercury and lead in limpets from the three areas studied, were always below the limits of 0.50 mg kg -1 and 1.5 mg kg -1 allowed by the EU, respectively. Regarding cadmium, levels in limpet were always above the limit of 1.0 mg kg -1 , reaching about 3.0 mg kg -1 in some samples. These values probably indicate contamination from telluric origin (soil or rocks) in the coastal studied areas. Results indicated that microbiological contamination of fecal origin was low and in general below the detection level. Contamination levels did not show a clear seasonal pattern. The two mollusk species, limpets and mussels, differed statistically in all contaminants analyzed, being cadmium the most of concern, and always higher in limpets than in mussel samples. Thus, the potential risk associated with limpet consumption, taking into account the cadmium tolerable weekly intake (TWI), was investigated, being possible to reach a reliable recommendation of less than a monthly meal of 160 g. As recreational picking of limpets is common in Portugal, official recommendations of maximum periodic human consumption should be published and enforcement increased in forbidden areas.

Shellfish consumption preferences in an oceanic archipelago

“…This is particularly important since these molluscs tend to bioaccumulate metals from both geogenic and anthropogenic origins (e.g. cadmium) (Pedro et al, 2021).…”

“…Nonetheless, the cadmium content in limpets depends on different factors, including geographic location (Collado et al, 2006;Reinecke et al, 2012), season (Reinecke et al, 2012), type of substrate on which it feeds (Mbandzi et al, 2021) and size of the limpet (Cubadda et al, 2001). Therefore, the tolerable weekly quantity of limpet soft tissue should not be considered linearly, since the cadmium content in certain batches may overwrite the maximum legislated content reaching, in some cases, 3 times this maximum content (Pedro et al, 2021).…”

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

“…Live animals were washed and brushed under potable running water in order to remove material adherent to the shells, drained and dried using absorbent paper. Shells were aseptically opened and the flesh and intervalvar liquid were aseptically extracted and collected into a sterile container, in order to weigh around 100 g. The quantification of beta-glucuronidase-positive E. coli was performed using the most probable number (MPN) technique in a five-tube format according to ISO 16649-3 [ 53 ], as described in detail by Pedro et al [ 54 ], with a detection limit of 18 MPN/100g. When appropriate, microbiological results were log 10 transformed.…”

Active and passive biomonitoring of trace elements, polycyclic aromatic hydrocarbons, and polychlorinated biphenyls in small Mediterranean harbours

“…These highly chlorinated congeners are generally predominant in marine molluscs (Benali et al 2017;EFSA 2010;Giandomenico et al 2016;Herceg-Romanić et al 2014;Kožul et al 2009;Perugini et al 2004;Scarpato et al 2010) due to their molecular structure and high lipophilicity, which facilitate their accumulation in aquatic food web (Naso et al 2005) and make them resistant to metabolic degradation by molluscs (Vidal-Liñán et al 2016). Contaminant levels in soft tissues of molluscs are influenced by abiotic parameters (e.g., contaminant concentration in the water) (Pérez-López et al 2003) and biotic factors such as age, size, and reproductive status (Boyden 1977;Cabral-Oliveira et al 2015;Fattorini et al 2008;González-Fernández et al 2016;Pedro et al 2021). The origin of the organisms can also affect contaminant bioaccumulation since sampled populations may exhibit adaptative responses to a chronic contamination or environmental conditions, and distinct initial physiological status (Lacroix et al 2015;Mersch et al 1996;Silva et al 2018).…”