Annual and interannual dynamics of shellfish toxins and associated harmful algal species (HAS) were analyzed from 2015 to 2020 in Tortolì Lagoon (Sardinia, west Mediterranean Sea). Analysis of seasonal occurrence of different harmful algae, such as Dinophysis spp., Prorocentrum spp., Pseudo-nitzschia spp. and Alexandrium minutum, was performed. The species Dinophysis acuminata and Dinophysis sacculus were responsible for the accumulation of lipophilic toxins belonging to the okadaic acid group (OAs) and pectenotoxins2 (PTX2) in bivalve mollusks. The highest HAS detection was recorded in the winter months; in particular, Dinophysis spp. was mostly present in January–February. Out of 1090 analyzed mollusk samples, 39 were non-compliant, exceeding the legal limits (160 μg OA eq/kg e.p.) reported in Regulation 853/2004 of the European Commission. A statistical analysis related to the presence of OA and PTX2 in mollusks with various environmental parameters (pH, water temperature, dissolved oxygen, algal density) was implemented, proving a clear winter seasonality. The present study highlights the necessity to better understand the different factors able to influence the production and accumulation of toxins in bivalve mollusks bred in an important Sardinian production area. The contribution of this research is important not only from an environmental and productive point of view but also from the view of implementing management in order to mitigate any harm to human health.

Contaminants of emerging concern (CECs) are compounds found in several environmental compartments whose ubiquitous presence can cause toxicity for the entire ecosystem. Several personal care products, including antibiotics, have entered this group of compounds, constituting a major global threat. It is essential to develop simple and reliable methods by which to quantify these contaminants in several matrices. In this work, mussels were chosen as sentinel organisms to assess environmental pollution and the safety of bivalve mollusk consumption according to the “One Health perspective”. A liquid chromatographic tandem mass spectrometry method (LC-MS/MS) was developed for the quantification of two macrolides, erythromycin (ERY) and azithromycin (AZI), in mussels. This new method was validated according to international guidelines, showing high selectivity, good recoveries (>60% for both of them), sensitivity, and precision. The method was successfully applied for ERY and AZI research in mussels farmed along the Sardinian coasts (Italy), demonstrating itself to be useful for routine analysis by competent authorities. The tested macrolides were not determined in the analyzed sites at concentrations above the limits of detection (LODs). These results demonstrate the food safety of mussels (as concerns the studied antibiotics) and a negligible amount of pollution derived from these drugs in the studied area.

Paralytic shellfish poison algal biotoxins: Sardinia report 2002-2011 and non-compliance management

Bivalve mollusk production represents the principal aquaculture activity in Sardinia (40°03′ N, 9°05′ E). In 2021, 859 water samples and 1270 mollusk samples were analyzed. The species Alexandrium minutum caused the accumulation of Paralytic Shellfish Toxins (PST) in three samples of bivalve mollusks. Dinophysis acuminata complex caused the accumulation of lipophilic toxins (LTs) belonging to the okadaic acid group (OAs) in 18 samples of bivalve mollusks. The research of paralytic shellfish toxins (PSTs) in shellfish samples has been carried out with LC-FLD, as mentioned in the AOAC 2005 Official Method 2005.06. The determination of LTs was carried out by LC-MS/MS analysis. DTX2, belonging to the group of OA toxins, was detected for the first time in Sardinia, in mussels sampled in Tortolì. The presence of Dinophysis and Prorocentrum species was correlated with the accumulation of the OA toxin group in bivalve mollusks, showing a certain repeatability at certain times of the year in the areas included in the study. The results of the present study can help to plan and organize more effective bio-monitoring sampling strategies.

The objective of the present study was the determination of microplastics in Gilthead Seabream (Sparus aurata) reared in Italy and the assessment of consumer exposure. A total of sixty specimens were collected from four aquaculture facilities (A–D) located along the Sardinian coastal environment (Italy) and selected according to the principles of the risk assessment. From each Gilthead Seabream specimen, samples of gastro-intestinal tract (GI) and muscle (M) were obtained and digested using KOH 10% (1:10). The isolated microplastics were examined under the Stereomicroscope and characterized by Fourier transform infrared microscopy (μ-FTIR). Microplastics were identified in 25% of the samples. Positive fish showed plastic polymers in GI (22% and M (8%) respectively. The contamination was very limited, with a mean abundance of microplastics of 0.3 ± 0.56 and 1.2 ± 0.41 per fish and positive fish, respectively. Polypropylene, mainly blue, red and green in color, was the most detected polymer (72%). Consumers are exposed to plastic polymers via fish consumption, but so far, the implications for consumer exposure have not yet been quantified and are still being studied. The results of the present study represent the first contribution to the assessment of consumer exposure associated with the consumption of Gilthead Seabream (Sparus aurata) reared in Sardinian coastal environments, Italy.

The main objective of the present study was to assess the contamination level and nature of microplastics and their role as vectors of trace elements in Mediterranean mussels (Mytilus galloprovincialis). A total of 39 samples were collected from four farming areas (1–4) located in Sardinia (Italy) and selected according to the principles of the risk assessment. The concentrations of 22 trace elements (Be, Tl, Sb, Ag, Hg, Th, U, Sn, Co, Cd, Li, Mo, Cr, Ba, V, Ni, Pb, Se, Mn, Cu, As, Zn) in mussels and plastic particles extracted from mussels was determined by inductively coupled plasma mass spectrometry (ICP-MS/MS). The isolated plastic particles were characterized by Fourier Transform Infrared Spectroscopy (µ-FTIR). All samples were compliant with the European Union official limits set for Hg, Cd and Pb (Reg. UE 915/2023). Plastic particles were identified in all the samples with a total of 1007 isolated microfibers. Qualitative characterization of microplastics showed that natural polymers predominated, accounting for over 85% of the isolated microfibers. Cellulose was the most abundant polymer (55.29%), followed by cotton (30.59%). Synthetic polymers were present only as a minor fraction (~15%). These results support the use of Mytilus galloprovincialis as a reliable bioindicator of microplastics pollution. Heavy metal concentrations associated with microplastics ingested by Mytilus galloprovincialis were markedly lower than those measured directly in the edible tissues of the mussels, highlighting that microplastics likely contribute minimally as vectors of metals to human consumers. The results of the present study allowed for a comprehensive evaluation of both microplastics contamination and the distribution of heavy metals in mussels reared in Sardinia, providing a robust framework for subsequent risk assessment studies.