Statistical analysis of heavy metals in Cerastoderma edule glaucum and Venerupis aurea laeta from Ganzirri Lake, Messina (Italy)

Mineral content in clam species from Sicily and Sardinia: A geographical, temporal and species-specific statistical comparison

Clams are bivalves molluscs that have been exploited as food since ancient times. They contain high-quality nutrients, including essential minerals that have a great influence on human health. However, clams absorb and bioaccumulate potentially toxic elements, characterized by persistence in the environment, toxicity, and ability to accumulate and magnify within biological systems. For the first time, three co-occurring clam species (Ruditapes decussatus, Cerastoderma glaucum and Polititapes aureus) were investigated in their concentration of 20 mineral elements by inductively coupled plasma mass spectrometry (ICP-MS). The samples were collected in 2023 and 2024 from transitional water environments in Sicily, characterized by different levels of anthropogenic pressure. Additionally, R. decussatus samples from commercially exploited beds in two Sardinian lagoons were compared with samples of the locally consumed Sicilian stocks. Aim of the study was to carry out a geographical, temporal and species-specific statistical comparison of a wide range of elements, providing a novel contribution to the field. The clams showed an important level of essential elements, including Fe and Zn. The concentration of potentially toxic elements, being very low (Hg, Pd and Cd below the legal limits), does not cause health problems, according to risk assessment. The main potentially toxic element found in all samples is Al. The results showed a high variability in mineral concentrations among the different samples, in terms of time, species and, mostly, location, as proved by the PCA statistical model which discriminated Sicilian clams from Sardinian clams, due to the higher concentration of potentially toxic elements in the latter.

Mineral composition in mussel Mytilus galloprovincialis and clam Tapes decussatus from Faro Lake of Messina: risk assessment for human health

Bivalve are exposed to a wide range of contaminants, some of which may be toxic to human health. The aim of this study was to detect essential and non-essential elements such as Na, Ca, Mg, Cr, Mn, Fe, Ni, Cu, Zn, As, Cd, Pb, Hg, Be and Co in water, sediments, and Mytilus galloprovincialis and Tapes decussatus from Faro Lake. It is a lake of marine origin located on the northern coast of Messina (Sicily), where shellfish farming has been practiced for many years. Metals were analysed by a single quadrupole inductively coupled plasma mass spectrometer (ICP-MS), except for Hg, which was quantified using a direct mercury analyser (DMA-80). The study evaluated the nutritional intake of elements through the ingestion of clams and mussels and the potential health risks to consumers. The lead levels found in M. galloprovincialis were below the LOQ, while in T. decussatus the concentrations were below the limit indicated by European Regulation 915/2023. Statistical analysis was carried out on M. galloprovincialis and T. decussatus samples using SPSS 27 and the data showed highly significant differences between the two species (p < 0.001). Cadmium (Cd) and mercury (Hg) concentrations were also below the legal limit in all samples analyzed. This study has shown that clams and mussels are a source of sodium (Na) with a Recommended Dietary Allowance (RDA) of 36% in M. galloprovincialis and 77% in T. decussatus. The percentages obtained for calcium (Ca) and magnesium (Mg) were 17%-19% and 18%-8%, respectively. The RDA of chromium (Cr) was of 191% for M. galloprovincialis and of 405% for T. decussatus. The Fe percentages were 92% and 169% for M. galloprovincialis and T. decussatus, respectively. The concentrations of the other metals observed in the two bivalve species of Lake Faro were generally lower than the Tolerable Weekly Intake (TWI) values estimated as a risk to human health.

Heavy Metals Bioaccumulation in Mytilus galloprovincialis and Tapes decussatus from Faro Lake (Messina), Italy

The aim of this study was to evaluate the potential bioaccumulation of arsenic (As), copper (Cu), zinc (Zn), cadmium (Cd), lead (Pb) and mercury (Hg) in the haemolymph and corpus of Mytilus galloprovincialis and Tapes decussatus from Lake Faro. The lake is particularly prone to the accumulation of substances that are potentially toxic to aquatic organisms, due to the input of pollutants from urban and agricultural sources and the low rate of water exchange. The combination of saltwater from the Tyrrhenian Sea, the Strait of Messina and freshwater from hilly aquifers has created brackish conditions in the lake, resulting in an area of high commercial shellfish productivity. As, Cd, Cu, Pb and Zn were determined using a single quadrupole inductively coupled plasma mass spectrometer; Hg was determined using a direct mercury analyser (DMA-80). Physicochemical parameters of the water from Lake Faro were also performed. Statistical analysis was carried out using GraphPad Prism 9.0 (GraphPad Software, Inc., Boston, MA, USA) and Shapiro-Wilk normality was applied. Concentrations of Cd, Hg and Pb below the permitted MRLs in Mytilus galloprovincialis and Tapes decussatus used as ''biological indicators'' show that Lake Faro is not at risk of contamination by these pollutants and, moreover, is free of health problems for the consumer based on regulatory limits.

Trace elements assessment in Cerastoderma glaucum from port areas in the Tunisian Mediterranean coast: The influence of parasites on bioaccumulation

In the present study, the seasonal concentration of seven trace elements was investigated in sediment and the cockle Cerastoderma glaucum tissues from two port areas in the North-East and South of Tunisia comparing cockles non-parasitized (NP) and parasitized (P) with digenean parasites. Elements concentration in sediments analyzed in both sites revealed that Zinc (Zn), Chromium (Cr), and Lead (Pb) were the most abundant ones, while Cadmium (Cd) and Mercury (Hg) were less abundant. The bioaccumulation of trace metals and Arsenic (As) in the tissues of cockles seems to be modulated by both the infection state and the parasite species. The relationship between bioaccumulation of metals and As, trematode species and abiotic parameters showed that the availability of certain metals for uptake by P cockles of both sites was influenced by the salinity and temperature of the water. Our results corroborate the possibility of using digenean infecting bivalves in biomonitoring aquatic ecosystems.

Do Freshwater and Marine Bivalves Differ in Their Response to Wildfire Ash? Effects on the Antioxidant Defense System and Metal Body Burden

Wildfires constitute a source of contamination to both freshwater and marine ecosystems. This study aimed to compare the antioxidant defense response of the freshwater clam Corbicula fluminea and the marine cockle (Cerastoderma edule) to wildfire ash exposure and the concomitant metal body burden. Organisms were exposed to different concentrations (0%, 12.5%, 25%, 50%, and 100%) of aqueous extracts of Eucalypt ash (AEAs) from a moderate-to-high severity wildfire. The activity of various enzymes, as well as lipid peroxidation, protein content, and metal body burden, were determined after 96 h of exposure. A significant increase in the protein content of soft tissues was observed for C. edule at AEA concentrations ≥ 25%, unlike for C. fluminea. Similarly, significant effects on lipid peroxidation were observed for cockles, but not for clams. For both species, a significant effect in the total glutathione peroxidase activity was observed at AEA concentrations ≥ 25%. Relative to the control, AEAs-exposed clams showed higher Cd content, whereas AEAs-exposed cockles showed higher Cu content, thus exhibiting different responses to the exposure to wildfire ash. The susceptibility of bivalves to ashes, at environmentally relevant concentrations, raises concern about the effects of post-fire runoff to bivalve species.

Surface sediment enrichment with trace metals in a heavily human-impacted lagoon (Bizerte Lagoon, Southern Mediterranean Sea): Spatial distribution, ecological risk assessment, and implications for environmental protection

Although several studies previously assessed the contents of trace metals in the sediments of the heavily human-impacted lagoon of Bizerte (northern Tunisia), multi-analytical approaches have not been, so far, used to assess the ecological risks in this water body. This study attempts to provide a comprehensive ecological risk assessment related to the enrichment of the lagoon sediments with seven metals (As, Cd, Cr, Cu, Hg, Pb, and Zn). Significant spatial variations were found in the metal concentrations in sediments, in relation to the degree of coastal human activities and hydrodynamics. This was confirmed with the results of the three pollution indices, C_f, PLI, and I_geo. Concordant results were found with most of the indices used to assess the ecological risks (PERI, PEL, ERL, ERM, M-ERM-Q, TU), indicating higher risks in the southern part of the lagoon. These findings can help to improve the environmental management plan of the socio-economic important lagoon of Bizerte.

Organic pollutants in marine samples from Tunisian coast: Occurrence and associated human health risks

140 contaminants belonging to various classes (organochlorine and organophosphorus pesticides, pyrethroid insecticides, carbamates, fungicides, acaricides, herbicides, synergists, insect growth regulators, polychlorobiphenyls, polycyclic aromatic hydrocarbons) were simultaneously analysed by GC-MS/MS in marine sediments, aquatic plant leaves and fish tissues samples. A total of 260 samples from five stations along the coast of Tunisia were evaluated. The results highlight that only 28 residues (12 polychlorobiphenyls, 8 organochlorine pesticides, 7 polycyclic aromatic hydrocarbons and triphenyl phosphate) were detected at levels higher than relative LOQ values. The amounts in sediment samples were compared with Sediment Quality Guidelines (SQGs) showing that the values are acceptable and no toxic effect is expected on aquatic organisms. A little variation of contaminant residues in sediment samples among coastal stations was recorded. Namely, with respect to almost all polychlorobiphenyls and organochlorine pesticides, higher values were recorder in summer. With respect to almost all polycyclic aromatic hydrocarbons, higher values were recorder in autumn. Aquatic plant leaves showed a residue accumulation higher than that of other compartments of marine system. The data about fish samples (Sparus aurata and Sarpa salpa, the two most frequently caught fish species at five sites on the central coast of Tunisia) do not pose direct hazard to human health because values were lower than protection limits.

Potentially Toxic Elements in Xiphias gladius from Mediterranean Sea and risks related to human consumption

Swordfish is a widely consumed fish worldwide. The aim of this work was to evaluate levels of As, Zn, Mn, Fe, Cu, Al, Cr, Ni, Se, Cd, Pd and Hg in 28 samples of swordfish muscles, coming from zone of Food and Agriculture Organization (FAO) namely 37.1 and 37.2, in order to assess potential public health risks. 100% of the samples had Cd levels not detectable, 32.14% of samples exceeded European maximum limits set for Hg. Health risk assessment showed a not dangerous condition for Al (0.65% of Tolerable Weekly Intake), Ni (0.27% of Tolerable Daily Intake) and Pb (0.68% of Provisional Tolerable Weekly Intake), but very hazardous states for Hg (159.69% of Tolerable Weekly Intake) and As (1099.45% for minimum value of Benchmark Dose Limit). Target Hazard Quotient (THQ) showed dangerous values only for As and Hg. Analytical data of the present study suggest a swordfish prudent consumption.

Effects of waterborne exposure to cadmium on biochemical responses in the freshwater gastropod, Bellamya aeruginosa

The biochemical responses of Bellamya aeruginosa as a dominant and widespread freshwater gastropod throughout China to waterborne cadmium (Cd) were investigated to explore the impacts of exposure concentration and duration in this potential sentinel species. After the 7 days' test of dosage-mortality relationship, gastropods were exposed for either 7 days at the LC₅₀ (1.7 mg/L), the LC₁₀ (0.7 mg/L) and 0.02 mg/L Cd, or 28 days at 0.02 mg/L Cd. A suite of biochemical indicators including metallothionein-like protein (MTLP), reduced glutathione (GSH), catalase (CAT), contents of tissue metal (Cd, Fe, Mn, Cu, Zn), and the compartments of these metals bound to MTLP were examined. The treatment of 0.02 mg/L Cd led to the increase of Cd bound to MTLP (Cd-MTLP) levels, the decrease of GSH content, and the upregulation of CAT activity, but no induction of MTLP, indicating that the intrinsic MTLP and GSH worked together for the detoxification of Cd at the low exposure. When the exposure concentration increased, GSH was depleted severely and synthesis of MTLP was triggered, leading to a strong and significant relationship between MTLP level and Cd accumulation. At the lethal concentrations (1.7 mg/L), both MTLP induction and CAT activity were inhibited while the proportion of Cd-MTLP to total Cd were increased, suggesting more intrinsic MTLP were utilized to sequester free Cd ions. Therefore, the content of Cd-MTLP in digestive glands of B. aeruginosa was recommended as a reliable biomarker for Cd contamination.

Pituitary Transcriptomic Study Reveals the Differential Regulation of lncRNAs and mRNAs Related to Prolificacy in Different FecB Genotyping Sheep

Long non-coding RNA (LncRNA) have been identified as important regulators in the hypothalamic-pituitary-ovarian axis associated with sheep prolificacy. However, their expression pattern and potential roles in the pituitary are yet unclear. To explore the potential mRNAs and lncRNAs that regulate the expression of the genes involved in sheep prolificacy, we used stranded specific RNA-seq to profile the pituitary transcriptome (lncRNA and mRNA) in high prolificacy (genotype FecB BB, litter size = 3; H) and low prolificacy sheep (genotype FecB B+; litter size = 1; L). Our results showed that 57 differentially expressed (DE) lncRNAs and 298 DE mRNAs were found in the pituitary between the two groups. The qRT-PCR results correlated well with the RNA-seq results. Moreover, functional annotation analysis showed that the target genes of the DE lncRNAs were significantly enriched in pituitary function, hormone-related pathways as well as response to stimulus and some other terms related to reproduction. Furthermore, a co-expression network of lncRNAs and target genes was constructed and reproduction related genes such as SMAD2, NMB and EFNB3 were included. Lastly, the interaction of candidate lncRNA MSTRG.259847.2 and its target gene SMAD2 were validated in vitro of sheep pituitary cells. These differential mRNA and lncRNA expression profiles provide a valuable resource for understanding the molecular mechanisms underlying Hu sheep prolificacy.

Monitoring metal pollution on coastal lagoons using Cerastoderma edule-a report from a moderately impacted system in Western Portugal (Óbidos Lagoon)

The main goal of this monitoring program was to evaluate the contamination in the intertidal environment of Óbidos Lagoon by the metals Cd, Pb, and Ni on water, sediments, and on biological samples, using the bivalve Cerastoderma edule (common name: cockle) as a biomonitor. Since C. edule is an edible mollusc, the risk of their consumption by humans from this lagoon was also evaluated. The study was performed in a restricted area of the lagoon-the ML station-where human activities, such as shellfish harvesting, intersect with the natural processes occurring in this system. The results obtained revealed that the water samples were polluted with Cd and Pb with concentrations (0.00025 mg l^-1 and 0.0072 mg l^-1) above the maximum legislated on the Directive 2008/105/EC, while for Ni, this occurred only on one of the seasons sampled (summer 2010: 0.029 mg l^-1). The sediments were not contaminated with Cd and Ni, and the contamination detected for the metal Pb, allowed the classification of this station as an unpolluted site ([Pbmin] = 7.477 mg.kg^-1 and [Pbmax] = 19.875 mg.kg^-1). On biological samples, comparing the results of metal contaminations with the values of the maximum levels fixed by European Commission Regulation (EC) No 1881/2006 and USFDA, all the results were below the legal value. Therefore, during the period of study, the consumption of this bivalve by humans was safe. Also, BAF and CF calculations suggest that C. edule can be used as a biomonitor to determine the source of the contaminations. This study supported the use of C. edule as a biomonitor to assess the contamination by the metals Pb and Ni at the Óbidos Lagoon and allowed to predict the potential transfer of metals to higher trophic levels with potential impacts on the natural and human communities.

Spatial distribution, bioaccumulation profiles and risk for consumption of edible bivalves: a comparison among razor clam, Manila clam and cockles in the Venice Lagoon

Despite their ecological and economical relevance, a lack of data is still occurring about the distribution, abundance, bioaccumulation and risks for consumption of some edible bivalves. The present study has been carried out in the Venice Lagoon taking into account three bivalve species to investigate i) the possible relationship among the biological features-distribution, abundance and bioaccumulation patterns- of razor clams (Solen marginatus Pulteney, 1799), Manila clams (Ruditapes philippinarum Adams and Reeve, 1850) and lagoon cockles (Cerastoderma glaucum Poiret, 1789) and the hydrological features, namely sediment physico-chemical characteristics and contamination; ii) their specific role as bioindicators of inorganic contamination; iii) the possible risks for human health associated with the consumption of these edible bivalves. Results showed that species distribution and abundance, especially for razor clams, was mainly influenced by environmental conditions and sediment granulometric composition, above metal(loid) contamination. The contamination patterns were different among species, as Manila clam generally showed higher bioaccumulation values for most of the metal(loid)s, whilst lagoon cockles preferentially accumulated Ni. Eventually, a serious concern exists for the human consumption, for all species and investigated sites regarding As. This study will raise attention on the effects of bioaccumulation of inorganic pollutants by edible bivalves and risks for consumers' safety, especially concerning razor clams and cockles, for which a critical lack of data on metal(loid) bioaccumulation occurs from the Northern Adriatic Sea.

Heavy metals in soils and sediments from Dongting Lake in China: occurrence, sources, and spatial distribution by multivariate statistical analysis

Heavy metal contamination in soils/sediments and its impact on human health and ecological environment have aroused wide concerns. Our study investigated 30 samples of soils and sediments around Dongting Lake to analyze the concentration of As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn in the samples and to distinguish the natural and anthropogenic sources. Also, the relationship between heavy metals and the physicochemical properties of samples was studied by multivariate statistical analysis. Concentration of Cd at most sampling sites were more than five times that of national environmental quality standard for soil in China (GB 15618-1995), and Pb and Zn levels exceeded one to two times. Moreover, Cr in the soil was higher than the national environmental quality standards for one to two times while in sediment was lower than the national standard. The investigation revealed that the accumulations of As, Cd, Mn, and Pb in the soils, and sediments were affected apparently by anthropogenic activities; however, Cr, Fe, and Ni levels were impacted by parent materials. Human activities around Dongting Lake mainly consisted of industrial activities, mining and smelting, sewage discharges, fossil fuel combustion, and agricultural chemicals. The spatial distribution of heavy metal in soil followed the rule of geographical gradient, whereas in sediments, it was significantly affected by the river basins and human activities. The result of principal component analysis (PCA) demonstrated that heavy metals in soils were associated with pH and total phosphorus (TP), while in sediments, As, Cr, Fe, and Ni were closely associated with cation exchange capacity (CEC) and pH, where Pb, Zn, and Cd were associated with total nitrogen (TN), TP, total carbon (TC), moisture content (MC), soil organic matter (SOM), and ignition lost (IL). Our research provides comprehensive approaches to better understand the potential sources and the fate of contaminants in lakeshore soils and sediments.

Mapping toxic mineral contamination: the southern oyster drill, S. haemastoma (L., 1767), as evaluable sentinel species

The nickel, chromium, arsenic, cadmium, and lead content have been evaluated, by ICP-MS, in digestive gland of the amphiatlantic gastropod Stramonita haemastoma, sampled along the highly anthropized Gulf of Milazzo (Central Mediterranean). Concentrations notably higher than those reported in literature for other Mediterranean Muricidae have been recorded. The results also indicated a different impact in different sites, according to distribution and typology of human activities, whilst recorded seasonal variations might relate with rapid metabolic response. Such preliminary results suggest S. haemastoma may be considered a promising sentinel species for inorganic contamination in marine environment, especially in terms of short-medium-term exposure.