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A procedure based on dispersive liquid-liquid microextraction (DLLME) for cobalt (Co) quantification in an Iraqi environmental matrix by flame atomic absorption spectroscopy (FAAS) was applied in this work. A case-study approach was chosen to obtain further in-depth information on the Co levels and to evaluate the effectiveness of N-salicylideneaniline (SAN) as a complexing agent for pre-concentration and extraction of Co. An univariate strategy was utilized to achieve the optimum extraction conditions. The estimated limits of detection (LOD) and quantification (LOQ) under optimum conditions were 1.04 and 3.47 µg L−1, respectively. The results achieved by the proposed system were compared with those using the microwave digestion/graphite furnace atomic absorption spectrometer (MWD/GF-AAS) for digest samples and also for some water samples (Direct GF-AAS). The proposed procedure was applied for analyzing eleven environmental samples. The detectable Co levels for water samples ranged from 0.72 to 4.30 µg L−1 with a relative standard deviation of 3.7–8.8%, while the concentration for solid samples ranged from 0.17–4.51 µg g−1 (2.4–11.8 RSD %). DLLME/FAAS proposed procedure is effective, simple, and has the benefit of minimizing the organic solvent consumption by a few microliters, which results in little waste.

In this work, a procedure based on dispersive liquid-liquid micro-extraction for lead (Pb) pre-concentration and quantification in an environmental matrix by flame atomic absorption spectroscopy (FAAS) was applied. A case-study approach was chosen to obtain further in-depth information on the Pb levels. The green chemistry principles have been applied for the pretreatment and preparation of real samples by focusing on some features such as the volume of reagents/sample, employ of energy efficient equipment, and production of waste. A univariate strategy was utilized to achieve the optimum extraction conditions. 1750 mL of acetonitrile containing 100 mL of carbon tetrachloride, were rapid injection into: 12.0 mL of a sample solution adjusted the pH at 9.0 and 0.07% (m v-1) Dithizone. The estimated limits of detection (LOD) and quantification (LOQ) under optimum conditions were 2.85 and 9.5 mg L-1, respectively. The enrichment factors EFs were found to be 60.6 (aqueous standards/DLLME-FAAS) and 30.8 (matrix matched/DLLME-FAAS). It was applied for the analyzing eleven environmental samples. The detectable Pb levels for water samples were ranged from 1.87 to 8.11 mg L-1, while in solid samples were ranged 0.39e4.66 mg g-1. The relative standard deviation for three concentrations (low, medium, and high) were found to be 10.64, 6.87, and 2.7, respectively. The presented system was validated by analyzing eleven environmental samples (water, bivalve molluscs, lettuce, and medicinal plants). The results indicated that high recoveries were obtained in the range of 92e104 %. The lead concentration was found in these samples always lower than permissible maximum levels stipulated by Iraqi Standards Specifications 2009 (number 417) for neutral water. The DLLME/FAAS procedure has proven to be a fast, simple, low-cost, and efficient analytical protocol, therefore allowing for employing this protocol in routine analysis of trace metals in such matrixes. [ABSTRACT FROM AUTHOR]

Simple Summary: Microplastics (MPs) are anthropogenic microscopic pieces of plastic in marine sediments and the water column that can originate from two different sources. Primary MPs are industrially produced microbeads, while secondary MPs result from the fragmentation of larger plastic debris by physical, chemical, and biological processes. Although not yet considered a food contaminant, they are readily ingested by marine organisms at several trophic levels, thus entering the food chain and representing a risk to consumers of fishery products. In this study, Donax trunculus (Truncate donax) specimens collected from Class A production areas in the Tyrrhenian Sea (Mediterranean Sea), and therefore destined directly for the final consumer, were analyzed for the presence of MPs. First, all items were morphologically classified and measured, and some of these were chemically identified. Then, the MPs' mean abundance (MA) was calculated, and a risk assessment of human exposure to MPs was carried out. Both the MA of MPs and human exposure to MPs were found to be low. However, given the magnitude of the problem, the collection of further data using standardized methods is essential for a better risk assessment. Microplastics (MPs) (0.1 µm–5 mm particles) have been documented in oceans and seas. Bivalve molluscs (BMs) can accumulate MPs and transfer to humans through the food chain. BMs (especially mussels) are used to assess MPs' contamination, but the genus Donax has not been thoroughly investigated. The aim of this study was to detect and characterize MPs in D. trunculus specimens collected along the Tuscan coast (Italy), and to assess the potential risk for consumers. The samples (~10 g of tissue and intervalval liquid from 35 specimens) were digested using a solution of 10% KOH, subjected to NaCl density separation, and filtered through 5 μm pore-size filters. All items were morphologically classified and measured, and their mean abundance (MA) was calculated. Furthermore, 20% of them were analyzed by Raman spectroscopy and, based on the obtained results, the MA was recalculated (corrected MA) and the annual human exposure was estimated. In the 39 samples analyzed, 85 items fibers (n = 45; 52.94%) and fragments (n = 40; 47.06%) were found. The MA was 0.23 ± 0.17 items/grww. Additionally, 83.33% of the items were confirmed as MPs (polyethylene and polyethylene terephthalate). Based on the correct MA (0.18 MPs/grww), D. trunculus consumers could be exposed to 19.2 MPs/per capita/year. The health risk level of MPs was classified as level III (moderate). [ABSTRACT FROM AUTHOR]

In recent field studies, suspected gymnophallid metacercariae were histologically located in the mantle of mussels from the Norwegian Sea. Mussels from the sites in which that infection was detected also presented abnormally high pearl numbers. It has been previously described that gymnophallid metacercariae could cause pearl formation processes in mussels, as a host reaction to encapsulate these metacercariae. Given the pathological host reaction these parasites elicit, a study was performed to identify gymnophallid metacercariae found in mussels collected from Tromsø at morphological and molecular level and to assess, by the use of molecular tools, the relationship between the parasite and the biological material inside the pearls. As a result, Gymnophallus bursicola metacercariae infecting Norwegian Mytilus edulis were identified according to morphological characters, along with the first 18S rDNA and COI sequences for this trematode species. In addition, parasite DNA from the core of the pearls was extracted and amplified for the first time, confirming the parasitological origin of these pearls. This procedure could allow identifying different parasitic organisms responsible for the generation of pearls in bivalves.

Concentrations of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) were investigated in six species of bivalve mollusc purchased on the Polish retail market. The risk to consumers was calculated as a percentage of the tolerable weekly intake (TWI) (2 pg World Health Organization toxic equivalent (WHO-TEQ) kg−1 body weight (b.w.)).

Purpose: To analyze and summarize information on the problem of contamination of aquatic ecosystems with antibiotics. Findings: The presented work describes global risks associated with the presence of antibiotics in the aquatic environment and aquatic organisms, and demonstrates quantitative and qualitative assessment of contamination with antibiotic residues in ocean aquatic resources using bivalves. Practical value. The review can be useful for the public engaged in ecology, agriculture, veterinary medicine, and fisheries; for experts in the field of pharmacology and microbiology. This paper can also be interesting for teachers and students of field-oriented universities.

Microplastics (MPs) (0.1 µm–5 mm particles) have been documented in oceans and seas. Bivalve molluscs (BMs) can accumulate MPs and transfer to humans through the food chain. BMs (especially mussels) are used to assess MPs’ contamination, but the genus Donax has not been thoroughly investigated. The aim of this study was to detect and characterize MPs in D. trunculus specimens collected along the Tuscan coast (Italy), and to assess the potential risk for consumers. The samples (~10 g of tissue and intervalval liquid from 35 specimens) were digested using a solution of 10% KOH, subjected to NaCl density separation, and filtered through 5 μm pore-size filters. All items were morphologically classified and measured, and their mean abundance (MA) was calculated. Furthermore, 20% of them were analyzed by Raman spectroscopy and, based on the obtained results, the MA was recalculated (corrected MA) and the annual human exposure was estimated. In the 39 samples analyzed, 85 items fibers (n = 45; 52.94%) and fragments (n = 40; 47.06%) were found. The MA was 0.23 ± 0.17 items/grww. Additionally, 83.33% of the items were confirmed as MPs (polyethylene and polyethylene terephthalate). Based on the correct MA (0.18 MPs/grww), D. trunculus consumers could be exposed to 19.2 MPs/per capita/year. The health risk level of MPs was classified as level III (moderate).

Endobiotic microalgae inhabit various groups of organisms, including bivalves. In this group, the association between the giant molluscs Tridacna and Symbiodinium is one of the most recognizable. This consortium allows hydrobionts to survive in oligotrophic waters by regulating their metabolism. The available research has provided an understanding of the interaction and adaptation of these symbionts, but the problem of the beginning of the formation of these relationships remains unresolved. In the case of Tridacninae, symbiosis is essential for the survival of bivalves, in contrast to representatives of the Mytilidae and the Coccomyxa found in them. A few works devoted mainly to the morphological aspects of invasion have shown that endobiont causes inflammation and pathology. Having data to clarify the exact “diagnosis” of the interaction of these organisms is not enough. It is possible that the relationship between bivalves and Coccomyxa is in the early stages of being established, which may lead to mutualism or parasitism in the future. We assume that the analysis of works on the symbiosis of Symbiodinium and bivalves will facilitate the course of research for the less studied Coccomyxa and their hosts. By postulating the Coccomyxa represent a unique evolutionary model for the formation of a symbiotic system, it is possible to use this system to study the interaction of organisms during their initial contact. The identified signalling pathways and mechanisms that allow the photobionts to evade host immunity can be useful for constructing new forms of symbiosystems.

The Barmur Group (informally Tjörnes beds) sedimentary succession of northern Iceland is key to reconstructing the opening of the Bering Strait oceanic gateway because these rocks record migration of bivalve molluscs from the Pacific to the Atlantic via the Arctic. However, the timing of the migration event is poorly constrained owing to a lack of reliable absolute ages. To address this problem, we present the first Ar‐Ar radiometric dates from four basaltic lavas that underlie, are intercalated with, and overlie the Barmur Group, and integrate them with existing paleomagnetic records. We show that the Barmur Group has a latest Miocene to early Pliocene age range (c. 6.0–4.4 Ma; C3r–C3n.2n), older than all previous age models. Thus, the Barmur Group does not record the mid‐Piacenzian Warm Period, contra some previous suggestions. Abundant Pacific bivalve molluscs appeared in the Barmur Group during subchrons C3n.4n–C3n.3r at 5.235–4.896 Ma, over 1.3 million years earlier than previously suggested. Appearance of Pacific bivalves in the northern Atlantic occurred shortly after the 5.6–5.4 Ma age previously inferred for first appearance of Arctic bivalves in the Pacific. Thus, our data suggest that first opening of the Bering Strait gateway by the latest Miocene (c. 5.5 Ma) was soon followed by bidirectional trans‐Arctic faunal exchange, and argue against a hypothesized two‐stage faunal exchange process spanning c. 2 million years. Our results also confirm that first opening of the Bering Strait gateway was not directly associated with the growth of large northern hemisphere icesheets, which occurred several million years later. Plain Language Summary: The extent to which global climate change is influenced by the flow of seawater between the world's oceans is an important question in Earth science. Sedimentary rocks from the Tjörnes Peninsula in northern Iceland record the opening of the Bering Strait oceanic gateway, which connects the Pacific and Atlantic Oceans via the Arctic. The signature of this gateway opening event is the sudden appearance in Iceland of bivalve mollusc fossils that previously lived only in the Pacific Ocean. However, the timing of their arrival is uncertain owing to the lack of reliable age measurements. To solve this problem, we applied radioisotope dating methods to a succession of rocks called the Barmur Group from the Tjörnes Peninsula. We found that the sudden appearance of Pacific fossils occurred over a million years earlier than previously thought. Our data show that first opening of the Bering Strait gateway was soon followed by migration of marine faunas in both directions, in contrast to the existing hypothesis that Pacific‐to‐Atlantic migration significantly post‐dated Atlantic‐to‐Pacific migration. Our results also confirm the hypothesis that establishment of the Pacific‐Arctic‐Atlantic oceanic connection did not directly trigger development of large northern hemisphere icecaps, which occurred several million years later. Key Points: New Ar‐Ar dating shows a late Miocene to early Pliocene (6.0–4.4 Ma) age range for the Barmur Group (Tjörnes beds), northern IcelandArrival of Pacific bivalves in Iceland is dated at 5.2–4.9 Ma (chrons C3n.4n–C3n.3r), soon after first Bering Strait opening at 5.6–5.4 MaOpening of the Bering Strait gateway did not directly cause the development of large northern hemisphere icecaps [ABSTRACT FROM AUTHOR]

Twelve trace elements were studied in four economically important bivalve molluscs (Mediterranean mussel, manila clam, striped venus clam, and truncated wedge clam) from the southern Marmara Sea for seasonal bioaccumulation and human health risk assessment. According to the findings, Fe and Zn were the most accumulative and element concentrations changed considerably (P < 0.05) between seasons and species. Daily, weekly, monthly intake and target hazard quotients of the trace elements were estimated and compared with maximum limits. The results revealed that consuming these bivalve molluscs from the southern Marmara Sea could be considered safe for human consumption. Nevertheless, further monitoring is needed in order to better follow the development in time of elemental pollution due to increasing environmental pressure on the Marmara Sea basin, together with research on other different bioaccumulative organisms. [ABSTRACT FROM AUTHOR]

This study aimed to assess the presence of thermotolerant Campylobacter spp., as one of the most important foodborne zoonotic pathogens, in three shellfish species: mussels (Mytilus galloprovincialis), oysters (Ostrea edulis) and queen scallops (Aequipecten opercularis). The samples were collected from nine locations in the Istrian aquatory, Croatia. Isolation of Campylobacter was done according to standard ISO method, and species were identified using multiplex PCR. Isolates identified as C. jejuni and C. lari were genotyped using multilocus sequence typing (MLST) to determine the potential source of contamination. Among 108 examined samples of bivalve molluscs, mussels dominated and were the only ones found positive for the presence of Campylobacter (25.6%). In total, 19 C. lari and 1 C. jejuni strains were isolated. C. lari isolates found in this study belong to 13 sequence types (STs), and 9 of them are newly described in this paper. Two out of the four previously described C. lari STs that were found in this study were previously found in human stool. The only C. jejuni isolate was found to be sequence type 1268, which belongs to ST-1275 clonal complex that is almost exclusively found in seabirds and can sporadically cause infection in humans. Regarding the obtained results, introducing surveillance of thermotolerant Campylobacter in shellfish in the Republic of Croatia is advised as an improvement for public health safety. [ABSTRACT FROM AUTHOR]

Marine biotoxins are toxic substances that may cause illness and death in marine organisms and humans. This article disseminates the results of a 4-year study on the occurrence of marine biotoxins in raw bivalve molluscs purchased from Polish suppliers.

Over the past decades, research on bivalve immune system is focused on studying the effect of environmental factors on the basal status of defense systems. The immune system of bivalves is greatly affected by abiotic factors, and the most significant ones are water temperature, salinity, and level of dissolved oxygen. Hypoxia is widespread in the coastal waters of the World Ocean since the 1950s. Hypoxic zones (with dissolved oxygen concentration < 0.5 mL O2·L−1) occur in shelf areas for a long time corresponding to the life cycle of many hydrobionts. Being benthic organisms, bivalve molluscs often experience reduced dissolved oxygen concentrations. This group of aquatic invertebrates both plays an important role in aquatic ecosystem functioning and is actively used in aquaculture. The efficiency of bivalve cultivation directly depends on its immune status determining resistance to diseases. The immune system of bivalve molluscs is based on a complex of nonspecific reactions of cellular and humoral components. Hemocytes circulating in the hemolymph are the key effectors of the cellular immune response which, along with the barrier tissues of molluscs, synthesize humoral factors with a wide spectrum of antimicrobial activity. The hemolymph of various bivalve species contains different cell types differing by size, morphology, and granulation of cytoplasm. Most bivalve species have 2 types of hemocytes – granular and agranular ones; those can be subdivided into morphotypes depending on number and color of granules, size of the nucleus, and presence of organelles in the cytoplasm. Granulocytes are considered the main immune cells that perform phagocytosis and (or) encapsulation of infectious agents, as well as their subsequent neutralization by releasing reactive oxygen species, lysing enzymes, and humoral antimicrobial proteins. Moreover, the complex of defense systems includes an antioxidant system which is closely related to mollusc immunity since it neutralizes reactive oxygen species releasing during cellular immune mechanism activation. An excess of these compounds damages mollusc cells by oxidizing proteins, cytoplasmic membrane lipids, and DNA. This article provides data on an oxygen deficiency effect on the cellular and humoral components of the immune system, as well as the tissue antioxidant complex of bivalve molluscs.

A new parasitic microalga has been discovered in the commercial bivalve Anadara broughtonii from the Peter the Great Bay of the Sea of Japan. Infected molluscs had an abnormal shell that was more rounded and had a pale orange-green body coloration. Microalgae can be found in all organs of Anadara, depending on the degree of invasion. However, the main places of their localization were the mantle, the hindgut, and the gills, which had the greatest histopathological abnormalities. In haemolymph detection of parasites was extremely rare and only in the amoebocytes. Morphological observations of cultures of this microalga using light and transmission electronic microscopy, and phylogenetic analyses, carried out using 18S rDNA and ITS1 loci, revealed that green alga from Anadara is a new species of the genus Coccomyxa, described here as Coccomyxa veronica sp. nov. [ABSTRACT FROM AUTHOR]

This research work was devoted to studying the ability of hyaluronic acid (HA) to treat skin wounds in rats. HA, an immune-neutral polysaccharide, is widespread in the human body as it is necessary for several tissues and cellular functions and has been used in the clinical practice for more than three decades. For this purpose, we attempted to obtain and enrich HA-containing extracts from two species of molluscs collected at Bizerte lagoon, namely Mytilus galloprovincialis and Crassostrea gigas. Then, the wound healing potential of purified HA (hyaluronan) was tested on Wistar rats which were separated into 4 groups: control, treated with a marketed healing cream "Avene Cicalfate", treated with HA isolated from M. galloprovincialis, and treated with HA isolated from C. gigas. After anesthesia, rats were submitted to back skin lesions (diameter 2 cm) and then treated daily until recovery. During the experiment, variation of the wound area was monitored. Results showed that the obtained net yield of HA was 3.8 mg/g dry weight and 1.9 mg/g dry weight for M. galloprovincialis and C. gigas respectively. Morphological analysis demonstrated that HA significantly accelerated wound repair through reepithelization. The mean wound surface was completely absent after 15 days of treatment with C. gigas hyaluronan. Based on these findings, it appears that mollusc HA has an obvious healing activity completely in accordance with its recognized effectiveness in dermo-cosmetology. [ABSTRACT FROM AUTHOR]

Aims: Bivalve molluscs are filter feeders that tend to accumulate and concentrate any suspended particles or bacteria from the water environment. Although they have been proven to accumulate heavy metals, investigation on the presence of antibiotic-resistant bacteria is still lacking. Therefore, this study examines the occurrence of antibioticresistant bacteria isolated from bivalve shellfish, namely, blood cockles (Anadara granosa) and green-lipped mussel (Perna viridis) purchased from markets in Johor, Malaysia. Methodology and results: Samples purchased were homogenized and then diluted. Viable cell count and bacterial isolation were performed using diluted samples followed by an antibiotic susceptibility test (ampicillin, ciprofloxacin and tetracycline) conducted on the pure isolates. The total viable count of bacterial colonies for cockle and mussel samples ranged from 1.1 × 107 to 4.4 × 109 CFU/mL and 1.2 × 109 to 4.3 × 109 CFU/mL. The numbers of colonies isolated from respective bivalves were 11 and 6. Generally, cockles isolates revealed higher resistance towards all three antibiotics at or above the Clinical and Laboratory Standard Institute (CLSI) threshold value. Meanwhile, mussel isolates showed full susceptibility to any ciprofloxacin concentration and tetracycline but exhibited resistance to ampicillin at a concentration exceeding the CLSI value. The number of drug resistance isolates in cockle and mussel samples decreased with increasing antibiotic concentration. The maximum number of antibiotics the mussel isolates were resistant to was two, whereas cockle isolates achieved three. Conclusion, significance and impact of study: The outcome of this study concludes that some isolates from cockle and mussel samples can resist antibiotic concentration above the CLSI threshold value. Resistance of more than the CLSI threshold level revealed that these isolates could pose significant health risks especially when the bivalves are ingested raw or undercooked. [ABSTRACT FROM AUTHOR]

Ukraine has a unique natural resources potential and is one of the world's richest agricultural countries in terms of soil composition and land bioproductivity. More than 2/5 of its agricultural land is located within the steppe zone – a zone of unstable and insufficient humidification. The production of agricultural products under arid conditions largely depends on solving the problem of agricultural land artificial irrigation. Due to this, since the 1960s large-scale construction of amelioration facilities took place in Southern Ukraine, including construction of the Kakhovka Reservoir and the Kakhovka Irrigation System, the largest one in Europe. The quality of water intended for irrigation depends on a water source and internal physicochemical/biological processes observed in the amelioration system. The attached bivalve molluscs present an important biotic component of hydrotechnical amelioration systems. They form dense settlements on solid artificial substrates and are usually considered as a source of biological barriers that should be constantly fought against. However, their filtration and sedimentation role can exert influence on the processes of water self-purification. The study aims at evaluating the role of filtering molluscs fouling process when it comes to treatment of irrigation water from suspensions and removal of some heavy metals from the water column. The research is based on the results of field analysis of deposits sedimentation processes in the water column with the help of sedimentation traps at 5 stations along Kakhovka Main Channel. It was found that the total biomass of settlements of attached bivalve molluscs Dreissena polymorpha and Dreissena bugensis that are present in the channel constitutes about 370 – 463 tons and they contribute to precipitation of 11.6 – 27.5 tons of suspended matter to the bottom sediments during summer months. This process is manifested in a decrease of suspended matter concentration in the water along the channel. Together with suspended matter 1.8 – 3.9 kg of Cr, 0.3 – 0.6 kg of Ni, 0.09 – 0.24 kg of Co, 0.08 – 0.18 kg of Pb, 0.088 – 0,144 kg of Cd also join the bottom sediments every month. Thus, the settlements of molluscs attached to the hydraulic structures can be considered as biological amelioration agents contributing to the improvement of irrigation water quality.

Highly populated coastal environments receive large quantities of treated and untreated wastewater from human and industrial sources. Bivalve molluscs accumulate and retain contaminants, and their analysis provides evidence of past contamination. Rivers and precipitation are major routes of bacteriological pollution from surface or sub-surface runoff flowing into coastal areas. However, relationships between runoff, precipitation, and bacterial contamination are site-specific and dependent on the physiographical characteristics of each catchment. In this work, we evaluated the influence of precipitation and river discharge on molluscs' Escherichia coli concentrations at three sites in Central Italy, aiming at quantifying how hydrometeorological conditions affect bacteriological contamination of selected bivalve production areas. Rank-order correlation analysis indicated a stronger association between E. coli concentrations and the modelled Pescara River discharge maxima (r = 0.69) than between E. coli concentration and rainfall maxima (r = 0.35). Discharge peaks from the Pescara River caused an increase in E. coli concentration in bivalves in 87% of cases, provided that the runoff peak occurred 1–6 days prior to the sampling date. Precipitation in coastal area was linked to almost 60% of cases of E. coli high concentrations and may enhance bacterial transportation offshore, when associated with a larger-scale weather system, which causes overflow occurrence. HIGHLIGHTS Using a grid-distributed hydrological model to assess hydrometeorological conditions in the absence of direct measurements.; Analysis of a previous uninvestigated area.; New discharge threshold determining Escherichia coli concentration peaks found in Central Italy in order to allow the development of an early warning system for risk assessment.;

Seafood is a major group associated with foodborne illnesses, with Salmonella spp. and E. coli being pathogens of great importance. The use of natural preservatives, such as essential oils, is gaining traction in the food industry to combat pathogenic microorganisms. This study aimed to evaluate the antimicrobial activity of oregano essential oil (OEO) against pathogenic strains of E. coli and Salmonella Enteritidis, experimentally inoculated in mussels (Perna perna). The antagonism test for OEO against Salmonella Enteritidis and E. coli was conducted using the agar well diffusion method, and the Minimum Inhibitory Concentration (MIC) was determined by microdilution. Mussels were experimentally contaminated and treated with OEO, then stored at 5 °C and analysed over ten days. Results showed OEO effectively reduced bacterial counts, with higher efficacy against Salmonella Enteritidis, with an average count difference of 2.252 log CFU/g over the 10-day storage period. The study concludes OEO as a natural preservative, with its effectiveness dependent on oil concentration and microbial load. • Essential oils are natural preservatives with antimicrobial characteristics. • The concentration of 1% OEO is effective for the in vitro inhibition of microorganisms. • OEO is effective as a natural preservative in mussels. • Salmonella Enteritidis showed the greatest reduction in count during 10 days of storage. • Intrinsic and extrinsic factors can influence the inhibitory effect of OEO. [ABSTRACT FROM AUTHOR]

This work describes a method for the determination of paralytic shellfish toxins in mussels (M. galloprovincialis) , oysters (Crassostrea gigas), and clams (Ruditapes decussatus) samples. The acetic acid extraction method is used for simultaneous analysis of Paralytic Shellfish Poisoning (PSP) and the separation of these compounds was achieved on ethylene bridged hybrid (BEH) Amide column with gradient mobile phase composed of acetonitrile (MeCN) and water (as eluent A and eluent B) both containing 2 mM ammonium formate and 50 mM formic acid. The method specificity, linearity, sensitivity, precision, and accuracy were successfully evaluated towards the detection of 13 hydrophilic marine biotoxins analyzed together (single run) in different sample matrixes such as mussels. oysters. and clams. Calibration curves were found to be linear (R2 ≥ 0.98). average Recovery% of 98.5–99.9%. limits of detection (LODs): 0.16–1.92 µg·kg−1; limits of quantitation (LOQs): 0.54–6.41 µg·kg−1) and the relative standard deviation (RSD%) of the precision was ≤ 2.8%. The method was applied for the determination of PSP in shellfish collected from several Tunisian locations. All LC-MS/MS results of analyzed molluscs collected from different Tunisia locations, reveal no PSP toxin group contamination and that the amount found does not exceeding the threshold of 800 µg STXequ·kg−1. [Display omitted] • A proposed official alternative method of analysis for regulatory control and food safety. • Simultaneous determination of paralytic shellfish toxins using LC-MSMS. • A highly sensitive detection of shellfish biotoxins. • Validation of the method for paralytic shellfish toxins determination. • Effectiveness of proficiency testing within 34 different laboratories. [ABSTRACT FROM AUTHOR]

We examined the occurrence and levels of 19 legacy and emerging per- and polyfluoroalkyl substances (PFASs) in 7 species of marine bivalve molluscs collected from four coastal cities of Shandong Province, China. Perfluorooctanoic acid (PFOA) was the most prevalent component, accounting for 68.1 % of total PFASs. The total PFASs in bivalve molluscs ranged from 0.86 to 6.55 ng/g wet weight, with the highest concentration found in Meretrix meretrix L. The concentration of total PFASs in bivalve molluscs showed the following trend: clams > scallops > oysters > mussels. Estimation on the human intake of PFASs from consumption of bivalve molluscs resulted in hazard ratios (HR) ranging from 0.12 to 6.40. Five of the seven species had HR >1, indicating high exposure risks associated with PFASs. Therefore, the occurrence of PFASs in marine biota is particularly concerning and further investigations on the sources of PFASs in Shandong are warranted. • First time detection of 19 PFASs in bivalve molluscs in Shandong Province • PFASs levels in bivalve molluscs varied from 0.86 to 6.55 ng/g wet weight. • PFOA, PFBA, PFNA and PFOS were the compounds most frequently detected. • Frequent consumption of bivalve molluscs may pose health risk. [ABSTRACT FROM AUTHOR]

Contaminants of Emerging Concerns (CECs) are defined as chemicals not commonly monitored in aquatic ecosystems, but with the potential to cause adverse effects on biota. CECs include Endocrine Disrupting Chemicals (EDCs) and Neuro-Endocrine disruptors (NEDs) of vertebrates. However, most invertebrates only rely on neuroendocrine systems to maintain homeostatic processes. Although conserved neuroendocrine components have been characterized in ecologically relevant groups, limited knowledge on invertebrate neuroendocrinology makes it difficult to define EDCs and NEDs in most species. The monoamine serotonin (5-hydroxytryptamine, 5-HT) acts both as a neurotransmitter and as a peripheral hormone in mammals. In molluscs, 5-HT is involved in multiple physiological roles and molecular components of the serotonergic system have been identified. This review is focused on the effects of CECs on the serotonergic system of bivalve molluscs. Bivalves are widespread in all aquatic environments, estuarine and coastal areas in particular, where they are exposed to a variety of chemicals. In bivalves, 5-HT is involved in gametogenesis and spawning, oocyte maturation and sperm motility, regulates heart function, gill ciliary beating, mantle/siphon function, the "catch" state of smooth muscle and immune responses. Components of 5-HT transduction (receptors and signaling pathways) are being identified in several bivalve species. Different CECs have been shown to affect bivalve serotonergic system. This particularly applies to antidepressants, among the most commonly detected human pharmaceuticals in the aquatic environment. In particular, selective serotonin reuptake inhibitors (SSRIs) are frequently detected in seawater and in bivalve tissues. Information available on the effects and mechanisms of action of SSRIs on the serotonergic system of adult bivalves is summarized. Data are also reported on the effects of CECs on development of neuroendocrine pathways of early larval stages, in particular on the effects of model EDCs in the marine mussel Mytilus galloprovincialis. Overall, available data point at the serotonergic system as a sensitive target for neuroendocrine disruption in bivalves. The results contribute drawing Adverse Outcome Pathways (AOPs) for model EDCs and SSRIs in larvae and adults. However, basic research on neuroendocrine signaling is still needed to evaluate the potential impact of neuroendocrine disruptors in key invertebrate groups of aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Contaminants of Emerging Concerns (CECs) are defined as chemicals not commonly monitored in aquatic ecosystems, but with the potential to cause adverse effects on biota. CECs include Endocrine Disrupting Chemicals (EDCs) and Neuro-Endocrine disruptors (NEDs) of vertebrates. However, most invertebrates only rely on neuroendocrine systems to maintain homeostatic processes. Although conserved neuroendocrine components have been characterized in ecologically relevant groups, limited knowledge on invertebrate neuroendocrinology makes it difficult to define EDCs and NEDs in most species. The monoamine serotonin (5-hydroxytryptamine, 5-HT) acts both as a neurotransmitter and as a peripheral hormone in mammals. In molluscs, 5-HT is involved in multiple physiological roles and molecular components of the serotonergic system have been identified. This review is focused on the effects of CECs on the serotonergic system of bivalve molluscs. Bivalves are widespread in all aquatic environments, estuarine and coastal areas in particular, where they are exposed to a variety of chemicals. In bivalves, 5-HT is involved in gametogenesis and spawning, oocyte maturation and sperm motility, regulates heart function, gill ciliary beating, mantle/siphon function, the ‘‘catch’’ state of smooth muscle and immune responses. Components of 5-HT transduction (receptors and signaling pathways) are being identified in several bivalve species. Different CECs have been shown to affect bivalve serotonergic system. This particularly applies to antidepressants, among the most commonly detected human pharmaceuticals in the aquatic environment. In particular, selective serotonin reuptake inhibitors (SSRIs) are frequently detected in seawater and in bivalve tissues. Information available on the effects and mechanisms of action of SSRIs on the serotonergic system of adult bivalves is summarized. Data are also reported on the effects of CECs on development of neuroendocrine pathways of early larval stages, in particular on the effects of model EDCs in the marine mussel Mytilus galloprovincialis. Overall, available data point at the serotonergic system as a sensitive target for neuroendocrine disruption in bivalves. The results contribute drawing Adverse Outcome Pathways (AOPs) for model EDCs and SSRIs in larvae and adults. However, basic research on neuroendocrine signaling is still needed to evaluate the potential impact of neuroendocrine disruptors in key invertebrate groups of aquatic ecosystems.

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Microplastic content (MPs) in mussels (Mytilus spp.) from two areas of the north coast of Spain was measured for the first time. Additionally, a comparison of microplastic levels observed in mussels digested with nitric acid and with potassium hydroxide was carried out. The average microplastic concentration in mussels digested with nitric acid was significantly lower than that observed in mussels digested with potassium hydroxide (p < 0.05). The average concentration of microplastics in mussels from the Cantabrian Sea (2.55±2.80 MPs g–1 WW) was slightly higher than that in mussels from the Ria of Vigo (1.59±1.28 MPs g–1 WW). Both in the Ria of Vigo and in the Cantabrian Sea the observed pattern of pollution was fitted to the one expected. Consequently, mussels have been confirmed as suitable sentinel organisms for microplastic pollution.

This study aimed to assess the presence of thermotolerant Campylobacter spp., as one of the most important foodborne zoonotic pathogens, in three shellfish species: mussels (Mytilus galloprovincialis), oysters (Ostrea edulis) and queen scallops (Aequipecten opercularis). The samples were collected from nine locations in the Istrian aquatory, Croatia. Isolation of Campylobacter was done according to standard ISO method, and species were identified using multiplex PCR. Isolates identified as C. jejuni and C. lari were genotyped using multilocus sequence typing (MLST) to determine the potential source of contamination. Among 108 examined samples of bivalve molluscs, mussels dominated and were the only ones found positive for the presence of Campylobacter (25.6%). In total, 19 C. lari and 1 C. jejuni strains were isolated. C. lari isolates found in this study belong to 13 sequence types (STs), and 9 of them are newly described in this paper. Two out of the four previously described C. lari STs that were found in this study were previously found in human stool. The only C. jejuni isolate was found to be sequence type 1268, which belongs to ST-1275 clonal complex that is almost exclusively found in seabirds and can sporadically cause infection in humans. Regarding the obtained results, introducing surveillance of thermotolerant Campylobacter in shellfish in the Republic of Croatia is advised as an improvement for public health safety.

Highly populated coastal environments receive large quantities of treated and untreated wastewater from human and industrial sources. Bivalve molluscs accumulate and retain contaminants, and their analysis provides evidence of past contamination. Rivers and precipitation are major routes of bacteriological pollution from surface or sub-surface runoff flowing into coastal areas. However, relationships between runoff, precipitation, and bacterial contamination are site-specific and dependent on the physiographical characteristics of each catchment. In this work, we evaluated the influence of precipitation and river discharge on molluscs' Escherichia coli concentrations at three sites in Central Italy, aiming at quantifying how hydrometeorological conditions affect bacteriological contamination of selected bivalve production areas. Rank-order correlation analysis indicated a stronger association between E. coli concentrations and the modelled Pescara River discharge maxima (r= 0.69) than between E. coli concentration and rainfall maxima (r= 0.35). Discharge peaks from the Pescara River caused an increase in E. coli concentration in bivalves in 87% of cases, provided that the runoff peak occurred 1-6 days prior to the sampling date. Precipitation in coastal area was linked to almost 60% of cases of E. coli high concentrations and may enhance bacterial transportation offshore, when associated with a larger-scale weather system, which causes overflow occurrence. [ABSTRACT FROM AUTHOR]

The production of aquaculture products in closed water supply plants is becoming more widespread, and the volume of cultivation with such systems of freshwater fish is increasing. The use of closed water supply plants is the most promising global trend. When growing in closed water supply facilities, all parameters of the technological process are supported by automated devices, and the influence of natural factors on the process of the process is minimal. However, such systems require complex technological support, which needs constant improvement. When working in closed water supply plants, a precipitate is formed that needs to be recycled. It is expedient to utilize these sediments using methods that allow to receive additional heat and electricity for the needs of closed water supply plants in the production of aquaculture. On the basis of generalization and analysis of literary sources, it was found that the average value of the coefficient of conversion of mixed fodder during fattening of pigs is from 2.8 to 3.2 kg of feed per kg of weight gain. The average value of the coefficient of conversion of mixed fodder during fattening cattle is from 6.3 to 7.2 kg of feed per kg of weight gain. When growing broilers, the feed conversion rate is from 1.6 to 2 kg per kg of weight gain. The average value of the coefficient of conversion of mixed fodder during the cultivation of trout was 1.6 kg of feed per kg of weight gain, and at feeding sows – 1.2 kg of feed per kg of weight gain. The results of the development of block diagrams for the installation of closed water supply for the production of aquaculture with the provision of partial energy autonomy due to heat and electricity generated during the cogeneration of biogas generated during methane digestion of organic constituents of the sediment formed during the operation of the closed water supply system are presented.

Human noroviruses are a major cause for gastroenteritis outbreaks. Filter-feeding bivalve molluscs, which accumulate noroviruses in their digestive tissues, are a typical vector for human infection. RT-qPCR, the established method for human norovirus detection in food, does not allow discrimination between infectious and non-infectious viruses and can overestimate potentially infectious viral loads. To develop a more accurate method of infectious norovirus load estimation, we combined intercalating agent propidium monoazide (PMAxx™)-pre-treatment with RT-qPCR assay using in vitro-cultivable murine norovirus. Three primer sets targeting different genome regions and diverse amplicon sizes were used to compare one-step amplification of a short genome fragment to three two-step long-range RT-qPCRs (7 kbp, 3.6 kbp and 2.3 kbp amplicons). Following initial assays performed on untreated infectious, heat-, or ultraviolet-inactivated murine noroviruses in PBS suspension, PMAxx™ RT-qPCRs were implemented to detect murine noroviruses subsequent to their extraction from mussel digestive tissues; virus extraction via anionic polymer-coated magnetic beads was compared with the proteinase K-dependent ISO norm. The long-range RT-qPCR process detecting fragments of more than 2.3 kbp allowed accurate estimation of the infectivity of UV-damaged murine noroviruses. While proteinase K extraction limited later estimation of PMAxx™ pre-treatment effects and was found to be unsuited to the assay, magnetic bead-captured murine noroviruses retained their infectivity. Genome copies of heat-inactivated murine noroviruses differed by 2.3 log10 between RT-qPCR and PMAxx™-RT-qPCR analysis in bivalve molluscs, the PMAxx™ pre-treatment allowing a closer approximation of infectious titres. The combination of bead-based virus extraction and PMAxx™ RT-qPCR thus provides a more accurate model for the estimation of noroviral bivalve mollusc contamination than the conjunction of proteinase K extraction and RT-qPCR and has the potential (once validated utilising infectious human norovirus) to provide an added measure of security to food safety authorities in the hazard assessment of potential bivalve mollusc contamination. [ABSTRACT FROM AUTHOR]

Monoalgal and bialgal diet were tried in 2 stages of larval development of Striostrea prismatica: phase I from mixotrofic to early umbonated veliger larva and phase II until eyespot larvae. The monoalgal diets in phase I were Tisochrysis lutea, Pavlova lutheri and Nannochloropsis sp. In phase II, Tetraselmis suecica, T. chuii, Chaetoceros gracilis and Ch. muelleri were incorporated. The bialgal diets (combination of P. lutheri + Ch. gracilis in proportions 1:3, 1:1 and 3:1) were chosen according to the results of the monoalgal trials and were evaluated against the classic diet = control (T. lutea + Ch. gracilis). The microalgae size and their fatty acid composition were determined. We recommend the combination T. lutea + Ch. gracilis, initially using T. lutea for mixotrophic larvae (6 days Post Fertilization‐PF), then incorporating Ch. gracilis in a ratio of 1:1 until completing phase I (8–10 PF). In phase II, the ratio should change to 1:3 until larvae with eyespot are obtained (18–20 PF). Suggestions were based on the higher demand for DHA in initial larvae and the need for EPA from the early umbonated phase. Finally, as a third experiment, microsubstrates (pieces of shells, sandpaper, polycarbonate and ground rubber) were evaluated to promote the settlement of pediveliger larvae. A settlement of 20% was obtained in pieces of shells of the same species. We consider that the settlement technology has not been optimized; therefore, evaluations directed at the behaviour of the species are recommended. [ABSTRACT FROM AUTHOR]

Human noroviruses are recognized as the leading worldwide cause of sporadic and epidemic viral gastroenteritis, causing morbidity and mortality in impoverished developing countries and engendering enormous economic losses in developed countries. Transmitted faecal‐orally, either via person‐to‐person contact, or by consumption of contaminated foods or water, norovirus outbreaks are often reported in institutional settings or in the context of communal dining. Bivalve molluscs, which accumulate noroviruses via filter feeding and are often eaten raw or insufficiently cooked, are a common food vehicle implicated in gastroenteritis outbreaks. The involvement of bivalve molluscs in norovirus outbreaks and epidemiology over the past two decades are reviewed. The authors describe how their physiology of filter feeding can render them concentrated vehicles of norovirus contamination in polluted environments and how high viral loads persist in molluscs even after application of depuration practices and typical food preparation steps. The global prevalence of noroviruses in bivalve molluscs as detected by different monitoring efforts is determined and the various methods currently utilized for norovirus extraction and detection from bivalve matrices described. An overview of gastroenteritis outbreaks affirmatively associated with norovirus‐contaminated bivalve molluscs as reported in the past 18 years is also provided. Strategies for risk reduction in shellfish contamination and subsequent human infection are discussed. [ABSTRACT FROM AUTHOR]

In this study, an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was originally developed for simultaneously quantitative analysis of twelve paralytic shellfish poisoning toxins, referring to STX, NEO, dcSTX, GTX1, GTX2, GTX3, GTX4, GTX5, C1, C2, dcGTX2, and dcGTX3 in bivalve molluscs. Chromatographic separations were performed on a TSK-Gel Amide-80 column (5 μm, 2.0 × 150 mm, Tosoh Corporation) by gradient elution with 2 mmol L−1 ammonium formate solution-acetonitrile (containing 0.1% formic acid) as mobile phases. The samples were pretreated by extraction with acetonitrile-water (80:20, v/v; containing 0.1% formic acid), followed by cleaning up using an Oasis HLB extraction cartridge (500 mg/6 mL). The present method showed good linearity (r2 > 0.99) with the limits of detection (LODs) and limits of quantification (LOQs) ranged from 1.03 to 10.65 μg/kg and 3.43–35.46 μg/kg, respectively for these toxins. Owing to its sensitivity and rapid properties, the presented method was applied to the determination of PSP toxins in bivalve molluscs involved in a food poisoning incident occurred in Zhangzhou, China, in June 2017. • New ultra-performance liquid chromatography-tandem mass spectrometry method. • Simultaneously quantitative analysis of twelve paralytic shellfish poisoning toxins. • Determine of the toxins in bivalve molluscs involved in a food poisoning incident. • The method is sensitive and rapid in comparison to previous ones. [ABSTRACT FROM AUTHOR]

The presence of heavy metals in bivalve molluscs implies a serious problem for the consumers health of this type of food. Therefore, the objective of the present investigation was to determine the presence of heavy metals in Anadara tuberculosa, mollusc of commercial importance at Puerto Bolívar, Ecuador. Atomic absorption spectrophotometry was the method used to quantify the concentration of heavy metals. The concentration of six metals was determined: lead (Pb), arsenic (As), mercury (Hg), cadmium (Cd), chromium (Cr) and cobalt (Co). The average values obtained, expressed in mg.kg-1 were: Pb (7.52 ± 0.46); As (1.55 ± 0.14); Hg (364.38 ± 91.39); Cd (1.68 ± 0.28); Cr (3,89 ± 1,82) and Co (2,71 ± 0,34 in A. tuberculosa The results show that Pb, As, Cd, and Hg exceed the maximum permissible limits, mercury exceeds by more than 100 times the limit value. The smaller size (3-4 cm) studied mollusc, has the capacity to bioaccumulate higher concentration of Pb, Cd and Cr.

Bivalve molluscs possess effective cellular and humoral defence mechanisms against bacterial infection. Although the immune responses of mussels to challenge with pathogenic vibrios have been largely investigated, the effects at the site of injection at the tissue level have not been so far evaluated. To this aim, mussels Mytilus galloprovincialis were herein in vivo challenged with Vibrio splendidus to assess the responses induced in hemolymph and posterior adductor muscle (PAM), being the site of bacterial infection. The number of living intra-hemocyte bacteria increased after the first hour post-injection (p.i.), suggesting the occurrence of an intense phagocytosis, while clearance was observed within 24 h p.i. A recruitment of hemocytes at the injection site was found in mussel PAM, together with marked morphological changes in the volume of muscular fibers, with a recovery of muscle tissue organization after 48 h p.i. A concomitant impairment in the osmoregulatory processes were observed in PAM by an initial inhibition of aquaporins and increased immunopositivity of Na+/K+ ATPase ionic pump, strictly related to the histological alterations and hemocyte infiltration detected in PAM. Accordingly, an intense cell turnover activity was also recorded following the infection event. Overall, results indicated the hemolymph as the system responsible for the physiological adaptations in mussels to stressful factors, such as pathogenicity, for the maintenance of homeostasis and immune defence. Also, the osmotic balance and cell turnover can be used as objective diagnostic criteria to evaluate the physiological state of mussels following bacterial infection, which may be relevant in aquaculture and biomonitoring studies. Unlabelled Image • Mussels Mytilus galloprovincialis were in vivo challenged with Vibrio splendidus. • The number of living intra-hemocyte bacteria increased after 1 h post-infection. • Histological changes and recruitment of hemocytes occurred at the injection site. • Impairment of osmoregulation and cell turnover activity were found in mussel muscles. [ABSTRACT FROM AUTHOR]

A method based on single-particle inductively coupled plasma mass spectrometry (sp-ICPMS) using a dwell time 50 μs for acquisition has been developed for silver nanoparticles (Ag NPs) determination and characterization in bivalve molluscs. Ultrasound assisted enzymatic hydrolysis has been proposed for a fast isolation of Ag NPs from seafood using pancreatin and lipase as extracting enzymes. Optimum extraction conditions imply ultrasonication at 80% amplitude for 10 min, using 10 mL of enzymatic solution (2 g L−1/2 g L−1 pancreatin:lipase, pH 7.4). Repeatability of the over-all procedure was 8%, and the limit of detection (LOD) in Ag NPs concentration was 0.417 × 107 NPs g−1 (the LOD in size was 13.6–16.2 nm). The analytical recovery was 92 and 103% when using Ag NPs standards of 40 and 60 nm, respectively. Several bivalve molluscs (clams, cockles, mussels, razor clams, oysters and variegated scallops) were analysed for total silver content (ICP-MS after microwave assisted acid digestion), and for Ag NPs by the proposed method. Ag NPs concentrations were from 1.56 × 107 to 59.2 × 107 NPs g−1. Mean sizes were within the 26–35 nm range. • Ag nanoparticles (number of particles and size distribution) in bivalve molluscs • Ultrasound assisted enzymatic hydrolysis as sample pre-treatment for silver nanoparticle isolation • Single particle – inductively coupled plasma – mass spectrometry for silver nanoparticle assessment [ABSTRACT FROM AUTHOR]

Clostridium difficile is a major cause of infectious diarrhea associated to healthcare settings. Community-acquired infections are increasingly reported in the last decade and exposure other than to symptomatic patients rather to contaminated foods or animals is feasible. Occurrence of C. difficile in shellfish raises concern because spores can survive the cooking temperatures given that shellfish is often consumed poorly cooked or raw. Aim of our study was to investigate whether shellfish represents a reservoir of C. difficile human PCR-ribotypes (RTs). 702 shellfish samples of farmed and wild bivalve mollusc species were collected over the 2015–2017 period in North Adriatic Italian Sea to investigate contamination with C. difficile and characterize the isolates in terms of genotypic variability and antimicrobial resistance profile. C. difficile was detected in 16.9% (CI: 14.1%–19.8%) samples: 11.6% mussels and 23.2% clams. Compared to mussels, clams were significantly associated with detection of C. difficile (OR = 2.4, P < 0.01). Overall 113 C. difficile isolates were genotyped and 75 (66.4%) were toxigenic. Fifty-three different RTs were identified. 40.7% C. difficile isolates were among the RTs most commonly involved in human infection in Europe. The profile of antimicrobial susceptibility was determined by E-test; microbiological resistance was frequent against clindamycin (17%), erythromycin (23%), rifampicin (8.8%) and moxifloxacin (10.6%). All isolates were susceptible to metronidazole and one showed MIC > ECOFF for vancomycin. C. difficile strains showed high variety in RTs, most of them already detected in other animals or known as highly virulent and epidemic in humans. These results prompt towards investigating on specific risk mitigation measures against C. difficile and are preliminary for any source attribution and risk assessment study. • 118/702 (16.9%, CI: 14.1%–19.8%) marine bivalve mollusc samples contaminated with C. difficile • High genotypic diversity of C. difficile isolates (53 PCR-ribotypes/113 isolates) • 66.4% C. difficile isolates toxigenic, some hypervirulent • 40.7% of C. difficile isolates overlap with PCR-ribotypes commonly isolated from C. difficile infection (CDI) in Europe. • Compared to mussels, clams have 2.4 more odds to be contaminated with C. difficile. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Natural radionuclides and 137Cs in different types of bivalve molluscs were determined by alpha and gamma spectrometry. • 137Cs was below the minimum detectable activity concentration in all bivalves samples. • The annual ingestion doses due to bivalves ingestion were assessed. • A statistical analysis of natural radioactivity was used to discriminate between molluscs of Atlantic and Mediterranean. Abstract The presence of natural and artificial radionuclides in the marine environment produces the accumulation of radionuclides in bivalve molluscs consumed by humans, and therefore it could result in a radiological hazard. In this study, the activity concentrations of 210Po, 40K, 210Pb and 234Th were determined in different types of bivalve molluscs sampled during the period of May 2014–June 2015, along coastal areas from the Andalusian region (South of Spain), through alpha-particle spectrometry and low-level gamma-ray spectrometry. The activity concentrations of 210Po; 40K; 210Pb and 234Th varied between 40 ± 2 and 515 ± 9 Bq kg−1 dry weight (d.w.); 121 ± 7 and 674 ± 34 Bq kg−1 d.w.; ND (lower than limit of detection) and 73 ± 10 Bq kg−1 d.w.; and ND and 126 ± 27 Bq kg−1 d.w., respectively. The committed effective dose to humans was calculated to range from 41 to 479 μSv year−1. Both activity concentrations and dose levels were comparable to previous studies from other countries. Finally, a multivariate statistical analysis of natural radioactivity content allowed the discrimination between bivalve molluscs from Atlantic and Mediterranean coasts. [ABSTRACT FROM AUTHOR]

Abstract Worldwide bivalve production has increased significantly in recent years. Bivalve meat is recommended in dietary regimens due to the benefits associated with their consumption but, at the same time, is internationally recognized as a potential vehicle for outbreaks of foodborne disease. To reduce food risk exposure, consumers must pay close attention when purchasing, handling and consuming bivalves. This study aimed to collect information on consumers' perceptions and practices related to bivalve purchasing, managing and consumption at home. A focus group methodology was adopted to better understand consumers' food practices and risk perceptions regarding molluscs. Four focus groups involving 42 consumers were conducted in Veneto and Marche region. The core analysis was then applied to each focus group discussion in order to identify, categorize and rank the information collected. The most important factors that came to light during the focus groups concerned the personal reasons for preparing bivalves at home; the place of purchase; the elements guiding consumers when purchasing bivalves; the bivalve preparation, cooking and storage conditions at home; the consumption of raw molluscs and the health risks; the consumers' categories most at risk; and the production chain control by the authorities. The data reported in the article can provide useful information to public authorities working on food safety for developing effective risk communication strategies. Highlights • Consumers play a crucial role in food risk reduction. • The focus group methodology collected information from Italian consumers. • The study analysed consumers' purchasing, handling and consumption of bivalves. • The data provide useful information for implementing risk communication activities. [ABSTRACT FROM AUTHOR]

Highlights • Bivalve molluscs species were analyzed by ICP OES and ICP-MS. • Most Lucina pectinata samples had higher concentrations of Cu, Cr and Pb. • Concentrations of As obtained in most samples were above the legal limit recommended by ANVISA. • PCA and HCA showed separation between Lucina pectinata and Trachycardium muricatum species. Abstract Four species of bivalve molluscs (Anomalocardia brasiliana , Iphigenia brasiliana , Lucina pectinata and Trachycardium muricatum) were collected in the Todos os Santos Bay (TSB), Bahia, Brazil, in order to evaluate As, Cd, Co, Cu, Cr, Fe, Mn, Ni, Pb, Se, V and Zn levels and, consequently, the risk of bivalve mollusc consumption in humans. The samples were analyzed by inductively coupled plasma optical emission spectrometry (ICP OES) and inductively coupled plasma mass spectrometry (ICP-MS) after closed-vessel microwave digestion. The accuracy was confirmed using the certified reference materials of oyster tissue (NIST 1566b) and mussel tissue (NIST 2977), and the results were statistically equivalent to the certified values. Application of principal component analysis (PCA) and hierarchical cluster analysis (HCA) showed a tendency to form two groups between samples of Lucina pectinata and Trachycardium muricatum. All species showed As and Cr concentrations higher than the maximum tolerable limit specified in Brazilian legislation. [ABSTRACT FROM AUTHOR]

The study aimed to evaluate the chemical composition and nutraceutical potential of two commercially significant edible bivalve mollusc species (Anadara broughtonii and Mactra chinensis). The edible parts (motor muscle, mantle and adductor) of these molluscs were analyzed for their proximate composition, collagen content, amino acid profile, chemical score and elemental constituents. Both molluscs had low fat content (2.43-6.91 g/100 g dry weight), and protein (55.36-68.01 g/100 g dry weight) and carbohydrates (11.36-20.37 g/100 g dry weight) were their main components. Total collagen content of the edible bivalve molluscs varied from 30.5 to 39 mg/g wet weight, accounting for approximately half of their total protein content. Among amino acids, glycine, glutamate, aspartic acid, alanine, leucine, lysine and arginine were present at high levels in the edible parts of both bivalve molluscs, while the major elements present were sodium, potassium, magnesium, calcium, iron, zinc and nickel. Having high-quality protein content, edible bivalve molluscs could be excellent sources of nutritive ingredients and, after further study, may find applications in nutricosmetics and functional foods. [ABSTRACT FROM AUTHOR]

Norovirus (NoV) and Hepatitis A virus (HAV) are the most important viral hazards associated with human illness following consumption of contaminated bivalve molluscs. The effectiveness of the current EU criteria for heat processing of bivalve molluscs (i.e. raising the temperature of the internal mollusc flesh to at least 90°C for a minimum of 90 seconds) was evaluated using predictive microbiology. A HAV thermal inactivation model was developed based on literature data in mollusc matrices during isothermal heat treatment. Application of the developed model demonstrated that the 90°C-90 s requirement may lead to significantly different virus inactivation depending on the commercial process design. This shows the need for the establishment of a Performance Criterion for bivalve molluscs heat processing which will assure a common specified level of consumer protection. A risk-based approach is described that allows for an effective processing design providing a more transparent and objective relation between the thermal processing targets and public health. Model simulations demonstrate that the F-value is a more appropriate Process Criterion than a single time-temperature combination since it enables the food business operators to design a process that is compliant with the safety requirements while at the same time achieving a desired product quality. [ABSTRACT FROM AUTHOR]

Klebsiella spp. are a major cause of both nosocomial and community acquired infections, with K. pneumoniae being responsible for most human infections. Although Klebsiella spp. are present in a variety of environments, their distribution in the sea and the associated antibiotic resistance is largely unknown. In order to examine prevalence of K. pneumoniae and related species in the marine environment, we sampled 476 batches of marine bivalve molluscs collected along the Norwegian coast. From these samples, K. pneumoniae (n = 78), K. oxytoca (n = 41), K. variicola (n = 33), K. aerogenes (n = 1), Raoultella ornithinolytica (n = 38) and R. planticola (n = 13) were isolated. The number of positive samples increased with higher levels of faecal contamination. We found low prevalence of acquired resistance in all isolates, with seven K. pneumoniae isolates showing resistance to more than one antibiotic class. The complete genome sequence of cefotaxime-resistant K. pneumoniae sensu stricto isolate 2016-1400 was obtained using Oxford Nanopore and Illumina MiSeq based sequencing. The 2016-1400 genome had two contigs, one chromosome of 5,088,943 bp and one plasmid of 191,744 bp and belonged to ST1035. The β-lactamase genes blaCTX-M-3 and blaTEM-1, as well as the heavy metal resistance genes pco, ars and sil were carried on a plasmid highly similar to one found in K. pneumoniae strain C17KP0055 from South-Korea recovered from a blood stream infection. The present study demonstrates that K. pneumoniae are prevalent in the coastal marine environment and that bivalve molluscs may act as a potential reservoir of extended spectrum β-lactamase (ESBL)-producing K. pneumoniae that may be transmitted through the food chain.

The analysis of the natural variability of seawater (Ta, Ω aragonite and pCO2) at Rodas Beach (NW Iberian Peninsula, Spain) revealed an increase of acidification. However, such pH change was not linked to any detrimental effect of the shell taphonomic characteristics of live razor clams harvested during distinct temporal series (length, thickness, organic content or strength). Temperature affected negatively shell strength and thickness, although the large correlation between the environmental variables would limit the individual characterization. Modelled trends in pH (and Ω aragonite) showed a significant decrease in the last 20 years, despite Ω > 1. Therefore, more recent shells are being secreted in a progressively less saturated carbonate environment and, consequently, more prone to suffer dissolution (and weakening) in projected climatic scenarios. When shells of harvested razor clams were exposed to projected climatic scenarios in the laboratory, dissolution rates were significantly greater for cold-acidic scenarios (more corrosive) as compared to warm-acidic. The median dissolution time (DT50) for shells under the cold-acidic scenario was reduced by half (15 years) when compared to the values observed for shells under current water chemistry conditions (30 years). Galician coastline, often characterised by p CO2-rich and cold waters due to upwelling system, would represent the most corrosive scenario for the shells according to the responses monitored in our survey which highlight future compromise for the ecosystem services supplied by these hard skeletons. Future climate scenarios might condition performance of bivalves but also more complex processes related to carbonate structures. Local biodiversity may be lowered which may reduce the possibility that many species find shelter and feeding grounds, diminishing the optimal substrate for other organisms as needed elements for optimal services in the ecosystems. • Variability in Ta, Ω aragonite and pCO 2 revealed an increase of acidification but no changes were noted in shell taphonomy. • Temperature affected negatively shell strength and thickness, despite large correlation between environmental variables. • Dissolution was greater for cold-acidic tests, mean DT 50 being reduced by half as compared to current conditions. • Recent shells are being secreted in a progressively less saturated carbonate environment, therefore more prone to be dissolved. • Marine shells support ecosystem services that may change in future conditions and affect biodiversity and optimal functioning. [ABSTRACT FROM AUTHOR]

In 2015, tetrodotoxins (TTXs) were considered a potential threat in Europe since several studies had shown the presence of these toxins in European bivalve molluscs. In this study, we investigated the occurrence of TTXs in 127 bivalve samples (mussels and oysters) and in 66 gastropod samples (whelks) collected all along the French mainland coasts in 2017 and 2018. Analyses were carried out after optimization and in-house validation of a performing hydrophilic interaction liquid chromatography associated with tandem mass spectrometry (HILIC-MS/MS) method. The concentration set by European Food Safety Authority (EFSA) not expected to result in adverse effects (44 µg TTX equivalent/kg) was never exceeded, but TTX was detected in three mussel samples and one whelk sample (1.7–11.2 µg/kg). The tissue distribution of TTX in this whelk sample showed higher concentrations in the digestive gland, stomach and gonads (7.4 µg TTX/kg) than in the rest of the whelk tissues (below the limit of detection of 1.7 µg TTX/kg). This is the first study to report the detection of TTX in French molluscs.