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Introduction: Coastal marine ecosystems, are particularly susceptible to climate change. One such threat is atmospheric heatwaves, which are predicted to increase in frequency, duration, and intensity. Many intertidal organisms already live at the edge of their thermal tolerance limits and heatwaves can outstretch an organism's ability to compensate in the short term. In June 2021 the Pacific Northwest region of North America, including the Salish Sea, experienced a significant atmospheric heatwave during some of the lowest tides of the year. This was followed by numerous reports of dead and dying intertidal marine organisms region-wide. A semi-quantitative rapid assessment found a range of both species- and location-specific effects but generally recorded widespread negative impacts to intertidal shellfish species across the Salish Sea. Methods: Following these results, we opportunistically analyzed data collected by intertidal bivalve resource managers from the region. These datasets allowed us to examine regional density and size data for clam and oyster populations before and after the heatwave to increase our quantitative understanding of heatwave effects. Results: We found a range of responses including positive and negative effects of the heatwave on clam and oyster density. While we generally found small changes in bivalve size, some site-species combinations displayed large shifts in size frequency. Many of our analyses did not indicate even moderate statistical support, even with large changes in the mean, driven in part by high variability in the data. Time intervals between surveys, ranging from 2 to over 25 months, had little effect on observed variability indicating that any heatwave-induced effects may be masked by variability inherent to the population ecology and/or survey methodology. Discussion: This analysis has highlighted the need for intertidal resource managers, and the greater research community, to consider alternative survey approaches designed to constrain variability in order to detect the effects of acute or extreme events. With the effects of climate change predicted to become more intense, targeted survey approaches may be needed to detect the effects and implications of such events and to continue effective management of intertidal bivalves in the Salish Sea and worldwide. [ABSTRACT FROM AUTHOR]

The grooved carpet-shell clam is one of the most economically relevant shellfish species living in the Mediterranean and nearby Atlantic coasts. Previous studies using different types of genetic markers showed a remarkable genetic divergence of the eastern Mediterranean, western Mediterranean, and Atlantic populations, but important details remained unclear. Here, data from six nuclear introns scored for restriction fragment size polymorphisms in eight populations that have not been studied before have been pooled for the analysis with data scattered through three previous studies, totaling 32 samples from 29 locations. The results show lower levels of heterozygosity, higher mean number of alleles, and alleles with restricted distribution in the Mediterranean populations, suggesting the existence of a large, isolated population in the eastern Mediterranean at the middle Pleistocene. The data also confirm the similarity of populations from Tunisia to Western Mediterranean populations. Finally, a genetic mosaic is apparent in the Atlantic coasts of the Iberian Peninsula, with a divergence of Rias Baixas populations from more northern populations and Central Portugal populations. The effects of oceanic fronts, seasonal upwellings, river plumes, and/or fishery management operations could explain this and other features of the Atlantic populations.

The grooved carpet-shell clam is one of the most economically relevant shellfish species living in the Mediterranean and nearby Atlantic coasts. Previous studies using different types of genetic markers showed a remarkable genetic divergence of the eastern Mediterranean, western Mediterranean, and Atlantic populations, but important details remained unclear. Here, data from six nuclear introns scored for restriction fragment size polymorphisms in eight populations that have not been studied before have been pooled for the analysis with data scattered through three previous studies, totaling 32 samples from 29 locations. The results show lower levels of heterozygosity, higher mean number of alleles, and alleles with restricted distribution in the Mediterranean populations, suggesting the existence of a large, isolated population in the eastern Mediterranean at the middle Pleistocene. The data also confirm the similarity of populations from Tunisia to Western Mediterranean populations. Finally, a genetic mosaic is apparent in the Atlantic coasts of the Iberian Peninsula, with a divergence of Rias Baixas populations from more northern populations and Central Portugal populations. The effects of oceanic fronts, seasonal upwellings, river plumes, and/or fishery management operations could explain this and other features of the Atlantic populations. [ABSTRACT FROM AUTHOR]

IntroductionCoastal marine ecosystems, are particularly susceptible to climate change. One such threat is atmospheric heatwaves, which are predicted to increase in frequency, duration, and intensity. Many intertidal organisms already live at the edge of their thermal tolerance limits and heatwaves can outstretch an organism’s ability to compensate in the short term. In June 2021 the Pacific Northwest region of North America, including the Salish Sea, experienced a significant atmospheric heatwave during some of the lowest tides of the year. This was followed by numerous reports of dead and dying intertidal marine organisms region-wide. A semi-quantitative rapid assessment found a range of both species- and location-specific effects but generally recorded widespread negative impacts to intertidal shellfish species across the Salish Sea. MethodsFollowing these results, we opportunistically analyzed data collected by intertidal bivalve resource managers from the region. These datasets allowed us to examine regional density and size data for clam and oyster populations before and after the heatwave to increase our quantitative understanding of heatwave effects. ResultsWe found a range of responses including positive and negative effects of the heatwave on clam and oyster density. While we generally found small changes in bivalve size, some site-species combinations displayed large shifts in size frequency. Many of our analyses did not indicate even moderate statistical support, even with large changes in the mean, driven in part by high variability in the data. Time intervals between surveys, ranging from 2 to over 25 months, had little effect on observed variability indicating that any heatwave-induced effects may be masked by variability inherent to the population ecology and/or survey methodology. DiscussionThis analysis has highlighted the need for intertidal resource managers, and the greater research community, to consider alternative survey approaches designed to constrain variability in order to detect the effects of acute or extreme events. With the effects of climate change predicted to become more intense, targeted survey approaches may be needed to detect the effects and implications of such events and to continue effective management of intertidal bivalves in the Salish Sea and worldwide.

Phytoplankton subsidies from river inputs and wetland habitats can be important food sources for pelagic organisms in the Sacramento–San Joaquin Delta (Delta). However, while the Sacramento River is a key contributor of water to the Delta, providing 80% of the mean annual inflow, the river is only a minor source of phytoplankton to the system. The reason for low phytoplankton biomass in the Sacramento River is not well understood but appears to be associated with a 65-km stretch of the lower river where chlorophyll-a (Chl-a) concentrations can decline by as much as 90%. We conducted two surveys along the lower Sacramento River, in spring and fall of 2016, to investigate the relative contributions of different factors potentially driving this Chl-a decline. Our study evaluated the change in Chl-a concentrations as a result of dilution from tributaries, light availability, nutrient concentrations, nutrient uptake, phytoplankton productivity, zooplankton grazing, and clam grazing. Chl-a concentration decreased from 14 µg/L to 1.8 µg/L in the spring and from 4.0 µg/L to 1.2 µg/L in the fall. Dilutions from the Feather River and American River contributed 39% and 11% of Chl-a declines, respectively, during the spring. Average water depths roughly doubled downstream of the American River confluence, reducing water column light availability and lowering productivity. Zooplankton and clam grazing rates were generally low. Using a mass balance analysis, the measured variables explained 76% of the observed decline in Chl-a in the spring, suggesting additional losses from unidentified factors. We found that phytoplankton biomass is regulated by multiple potential factors in the lower Sacramento River, emphasizing the need for practitioners of restoration and management programs to evaluate multiple potential loss factors when attempting to enhance phytoplankton production in the Delta, or other large river systems.

This study examines the physiological response of the Atlantic surfclam (Spisula solidissima) to ocean acidification in warm summer temperatures. Working with ambient seawater, this experiment manipulated pH conditions while maintaining natural diel fluctuations and seasonal shifts in temperature. One-year-old surfclams were exposed to one of three pH conditions (ambient (control): 7.8 ± 0.07, medium: 7.51 ± 0.10, or low: 7.20 ± 0.10) in flow-through conditions for six weeks, and feeding and digestive physiology was measured after one day, two weeks, and six weeks. After six weeks of exposure to medium and low pH treatments, growth was not clearly affected, and, contrastingly, feeding and digestive physiology displayed variable responses to pH over time. Seemingly, low pH reduced feeding and absorption rates compared to both the medium treatment and ambient (control) condition; however, this response was clearer after two weeks compared to one day. At six weeks, suppressed physiological rates across both pH treatments and the ambient condition suggest thermal stress from high ambient water temperatures experienced the week prior (24–26 °C) dominated over any changes from low pH. Results from this study provide important information about reduced energy acquisition in surfclams in acidified environments and highlight the need for conducting multistressor experiments that consider the combined effects of temperature and pH stress. [ABSTRACT FROM AUTHOR]

In the last few decades, there has been a growing interest in understanding the behavior of personal care products (PCPs) in the aquatic environment. In this regard, the aim of this study is to estimate the accumulation and effects of four PCPs within the clam Ruditapes philippinarum. The PCPs selected were triclosan, OTNE, benzophenone-3, and octocrylene. A progressive uptake was observed and maximum concentrations in tissues were reached at the end of the exposure phase, up to levels of 0.68 µg g−1, 24 µg g−1, 0.81 µg g−1, and 1.52 µg g−1 for OTNE, BP-3, OC, and TCS, respectively. After the PCP post-exposure period, the removal percentages were higher than 65%. The estimated logarithm bioconcentration factor ranged from 3.34 to 2.93, in concordance with the lipophobicity of each substance. No lethal effects were found although significant changes were observed for ethoxyresorufin O-demethylase activity, glutathione S-transferase activity, lipid peroxidation, and DNA damage. [ABSTRACT FROM AUTHOR]

The spread of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli is a major public health issue. Bivalves are filter-feeder animals capable of bioaccumulating the microorganisms present in water. This physiological characteristic makes them both good indicators of environmental contamination and possible carriers of pathogenic bacteria, including those resistant to antimicrobials. The aim of this study was to investigate the occurrence of ESBL-producing E. coli in clams (n = 308) collected from harvesting areas of the Central Adriatic Sea between 2018 and 2019. ESBL-/class C β-lactamase (AmpC)- producing E. coli and Escherichia spp. were isolated by streaking over the surface of MacConkey agar plates supplemented with cefotaxime enriched broths of the initial shellfish suspension. E. coli and Escherichia spp. resistant to cefotaxime were screened for ESBL production by using the double disk synergy test. Susceptibility to different antimicrobials and confirmation of ESBL-production were determined by the minimum inhibitory concentration (MIC) test. Isolates were further characterized by whole genome sequencing (WGS) and bioinformatic analysis of genomes with different tools. Overall, ESBL-producing E. coli were isolated from 3% of the samples. Of 13 ESBL- and ESBL-/AmpC-producing Escherichia spp. (n = 11 E. coli, n = 1 E. marmotae, n = 1 E. ruysiae) isolates, 13 were resistant to ampicillin and cefotaxime, 9 to sulfamethoxazole, 6 to tetracycline and nalidixic acid, 4 to trimethoprim, and 3 to ceftazidime, cefoxitin, ciprofloxacin, and chloramphenicol. Moreover, the majority (8/11) of the ESBL-producing E. coli isolates were multidrug-resistant. WGS showed that the isolates predominantly carried the blaCTX-M-15 gene (3/11) and blaCTX-M-14 and blaCTX-M-1 (2/11 each). The AmpC β-lactamase CMY-2 was found in two isolates. Phylogroup A was the most prevalent (5/11), followed by phylogroups D (4/11), F (1/11), and B2 (1/11). Ten different sequence types (STs) were identified. Occurrence at sampling sites ranged between 0 and 27%. To identify associations between the occurrence of ESBL-producing E. coli and E. coli levels, samples were divided into two groups, with E. coli at >230 MPN/100g and E. coli at ≤230 MPN/100g. ESBL-producing E. coli isolates were significantly more commonly recovered in samples with higher E. coli levels (14%) than in those with lower levels of E. coli (2%). Moreover, the majority (3/4) of the potentially pathogenic strains were isolated in samples with higher E. coli levels. These findings provided evidence for the bacterial indicator of fecal contamination, E. coli, as an index organism for ESBL-producing E. coli isolates in bivalves. [ABSTRACT FROM AUTHOR]

The manila clam Ruditapes philippinarum has become an important bivalve species in worldwide aquaculture due to its delicious taste and high commercial value. With the rapid expansion of clam farming, there is an urgent need to obtain genetic improvement by selective breeding, such as family-based selection of improved varieties. In this study, 10 microsatellite loci were selected to establish four multiplex PCR groups using four different fluorescences (FAM, ROX, HEX, TAM). The accuracy of these loci was verified by the 100% success rate of parentage assignment in a full-sib family. Parentage assignment was carried out in the mixed-mating parents and their offspring with unknown pedigree information. The genotyping of ten microsatellite loci generated 90 alleles, having the observed heterozygosity (Ho) ranging from 0.333 to 0.729. The expected heterozygosity (He) varied from 0.358 to 0.794. The PIC ranged from 0.342 to 0.763, with a mean value of 0.620. The theoretical combined parentage exclusion (cEP) power for all ten microsatellites was 97% with known genotypes of one parent (P1) and 99% for given the genotypes of both parents (P2). The actual successful assignment rate reached 98% by using all four sets of multiplex microsatellites, serving as the effective method for parentage assignment in the clams. The development and application of multiplex microsatellite genotyping methods provide a cost-effective method for pedigree reconstruction, population genetics and selective breeding of the commercially important clams.

The spread of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli is a major public health issue. Bivalves are filter-feeder animals capable of bioaccumulating the microorganisms present in water. This physiological characteristic makes them both good indicators of environmental contamination and possible carriers of pathogenic bacteria, including those resistant to antimicrobials. The aim of this study was to investigate the occurrence of ESBL-producing E. coli in clams (n = 308) collected from harvesting areas of the Central Adriatic Sea between 2018 and 2019. ESBL- /class C β-lactamase (AmpC)- producing E. coli and Escherichia spp. were isolated by streaking over the surface of MacConkey agar plates supplemented with cefotaxime enriched broths of the initial shellfish suspension. E. coli and Escherichia spp. resistant to cefotaxime were screened for ESBL production by using the double disk synergy test. Susceptibility to different antimicrobials and confirmation of ESBL-production were determined by the minimum inhibitory concentration (MIC) test. Isolates were further characterized by whole genome sequencing (WGS) and bioinformatic analysis of genomes with different tools. Overall, ESBL-producing E. coli were isolated from 3% of the samples. Of 13 ESBL- and ESBL−/AmpC-producing Escherichia spp. (n = 11 E. coli, n = 1 E. marmotae, n = 1 E. ruysiae) isolates, 13 were resistant to ampicillin and cefotaxime, 9 to sulfamethoxazole, 6 to tetracycline and nalidixic acid, 4 to trimethoprim, and 3 to ceftazidime, cefoxitin, ciprofloxacin, and chloramphenicol. Moreover, the majority (8/11) of the ESBL-producing E. coli isolates were multidrug-resistant. WGS showed that the isolates predominantly carried the blaCTX-M-15 gene (3/11) and blaCTX-M-14 and blaCTX-M-1 (2/11 each). The AmpC β-lactamase CMY-2 was found in two isolates. Phylogroup A was the most prevalent (5/11), followed by phylogroups D (4/11), F (1/11), and B2 (1/11). Ten different sequence types (STs) were identified. Occurrence at sampling sites ranged between 0 and 27%. To identify associations between the occurrence of ESBL-producing E. coli and E. coli levels, samples were divided into two groups, with E. coli at >230 MPN/100 g and E. coli at ≤230 MPN/100 g. ESBL-producing E. coli isolates were significantly more commonly recovered in samples with higher E. coli levels (14%) than in those with lower levels of E. coli (2%). Moreover, the majority (3/4) of the potentially pathogenic strains were isolated in samples with higher E. coli levels. These findings provided evidence for the bacterial indicator of fecal contamination, E. coli, as an index organism for ESBL-producing E. coli isolates in bivalves.

Shallow coastal environments are becoming more susceptible to marine heatwaves, particularly in Atlantic Canada, which is experiencing higher rates of ocean warming compared with the global average. Understanding bivalves' tolerance to heatwaves in Atlantic Canada is especially important, given the magnitude of bivalve aquaculture in this region. In this study, the physiological state of four commercially important bivalve species—blue mussel (Mytilus edulis Linnaeus, 1758), eastern oyster (Crassostrea virginica (Gmelin, 1791)), soft shell clam (Mya arenaria Linnaeus, 1758), and hard clam (Mercenaria mercenaria (Linnaeus, 1758))—was observed during a naturally occurring heatwave in Prince Edward Island, Canada. The metabolism, feeding physiology, and scope for growth of each species were compared. Results from this study, and comparisons with the literature, show interspecific variability in the metabolic rate and feeding physiology between species, but generally oysters, soft shell clams, and hard clams were less impacted during the heatwave compared with the blue mussels. Additionally, only the scope for growth of mussels declined throughout this experiment, which may be explained by cumulative heat stress, as temperatures experienced during this heatwave exceeded the thermal tolerance limits of mussels. [ABSTRACT FROM AUTHOR]

Quantitative real-time PCR (qRT-PCR) has been widely used for gene expression analysis, and selection of reference genes is a key point to obtain accurate results. To find out optimal reference genes for qRT-PCR in Manila clam Ruditapes philippinarum in response to hypoxia, different tissues were used and compared to evaluate the stability of candidate reference genes under low oxygen stress (DO 0.5 mg L−1 and DO 2.0 mg L−1) and normal condition (DO 7.5 mg L−1). Seven candidate reference genes were selected to evaluate the stability of their expression levels. The reference genes were evaluated by Delta Ct, BestKeeper, NormFinder and geNorm, and then screened by RefFinder calculation. Under hypoxic stress of 0.5 mg L−1, the most suitable reference gene for gill and hepatopancreas was RPL31, and the optimal reference genes for axe foot and adductor muscle were TUB and HIS, respectively. For hypoxic stress of 2.0 mg L−1, the most stable reference gene for gill and hepatopancreas was RPL31, and the optimal reference genes for axe foot and adductor muscle were RPS23 and EF1A, respectively. At the normal condition, HIS and EF1A were identified as the optimal internal reference genes in gill and hepatopancreas respectively, and GFRP2 was the best internal reference gene for axe foot and adductor muscle. The present findings will provide important basis for the selection of reference genes for qRT-PCR analysis of gene expression level in bivalves under hypoxic stress, which might be helpful for the analysis of other molluscs too. [ABSTRACT FROM AUTHOR]

The present study was conducted to assess, for the first time, the effects of a 14 days experimental exposure to polyethylene (PE) based MPs (40–48 µm) on the clam Ruditapes decussatus. Clams were exposed to three different concentrations of MPs in controlled laboratory conditions: 10 µg/L (low), 100 µg/L (medium), and 1000 µg/L (high). The effects of MPs were assessed using a multi-marker approach, including the filtration rate, growth, and the integrity of immune cells (such as haemocyte numbers, viability, and lysosomal membrane destabilization). The results revealed that as the concentration of PE-MPs increased, the filtration rate decreased, indicating that PE-MPs hindered the clams' ability to filter water. Furthermore, there was a noticeable decrease in the overall weight of the clams, particularly in the group exposed to 1000 µg/L. This decrease could be attributed to the impairment of their nutrient filtration function. In terms of immune system biomarkers, exposure to PE-MPs led to immune system disruption, characterized by a significant increase in the number of haemocytic cells, especially in the group exposed to the high concentration. Additionally, there was a notable reduction in the viability of haemocytes, resulting in the destabilization of their lysosomal membranes, particularly in the groups exposed to medium and high PE-MPs concentrations. The findings of this study indicate that the sensitivity of hemolymph parameter changes and filtration rate in R. decussatus exposed to PE-MPs (100 and 1000 µg/L), surpasses that of growth performance and can serve as reliable indicators to assess habitat conditions and contaminant levels. [ABSTRACT FROM AUTHOR]

This study examines the physiological response of the Atlantic surfclam (Spisula solidissima) to ocean acidification in warm summer temperatures. Working with ambient seawater, this experiment manipulated pH conditions while maintaining natural diel fluctuations and seasonal shifts in temperature. One-year-old surfclams were exposed to one of three pH conditions (ambient (control): 7.8 ± 0.07, medium: 7.51 ± 0.10, or low: 7.20 ± 0.10) in flow-through conditions for six weeks, and feeding and digestive physiology was measured after one day, two weeks, and six weeks. After six weeks of exposure to medium and low pH treatments, growth was not clearly affected, and, contrastingly, feeding and digestive physiology displayed variable responses to pH over time. Seemingly, low pH reduced feeding and absorption rates compared to both the medium treatment and ambient (control) condition; however, this response was clearer after two weeks compared to one day. At six weeks, suppressed physiological rates across both pH treatments and the ambient condition suggest thermal stress from high ambient water temperatures experienced the week prior (24–26 °C) dominated over any changes from low pH. Results from this study provide important information about reduced energy acquisition in surfclams in acidified environments and highlight the need for conducting multistressor experiments that consider the combined effects of temperature and pH stress.

Freshwater clams or also known as pokes in tribal languange is clams to Sulawesi which posses high market value. However, their density and habitat preferences in Laeya River Estuary is currently unknown. This study aims to determine the density and habitat preferences of pokea clams in the Laeya River, Southeast Sulawesi. This research was conducted for 1 year from March 2016-February 2017. Pokea samples were taken every month in three stations using tangge (traditional fishing gear) with a total sample size of 2908 individuals. The density of pokea clam was analyzed using Mann Whitney test. Habitat preferences were analyzed by correspondence analysis using XLstat. The study showed that the density of pokea clams in 3 stations were similar. The clam density at stations I, II, and III were 85,47±66,44, 97,03± 81,70, and 59,84±82,31, respectively. The highest density was found during April-July 2016 with the peak density in May 2016 with a value of 268,78±29,23. The lowest density occurred during September 2016-February 2017. The lowest density was found in December 2016 with a value of 15,12±7,08. The density of pokea clams in the Laeya River was influenced by TDS. Pokea clams prefer habitats with deeper water and low brightness caused by organic matter and high TOM. [ABSTRACT FROM AUTHOR]

As population activity is increasing and the Kapuas River is still a means of transportation, causing Corbicula largillierti to accumulate heavy metals (Pb) and Coliform bacteria in their bodies. This makes it dangerous to be consumed by humans. Thus, this research has two main aims. First, to find out the concentration of Pb and Coliform inside C. largillierti that lives at Kapuas River, Pontianak and the river's water. Second, to analyze the health risk of consuming the clams. Furthermore, the Atomic Absorption Spectrophotometer (AAS) is used to analyze the Pb sample and the Most Probable Number (MPN) method is used to analyze the Coliform. The result of this research shows that concentrations of Pb and Coliform from the Kapuas River have exceeded the limits designated for aquatic biota based on the Decree of the State Minister for the Environment No. 51 of 2004. In addition, the health risk is measured using Estimated Daily Intake (EDI), Target Hazard Quotient (THQ), and Target Carcinogenic Risk (TR) with scores for each >10 times the RfD, >1, and 10-3. This result shows that based on the clam C. largillierti consumption for 70 years life span of 60 kg body weight, had a high and negative effect on health risk problems and had a cancer risk for consumers. However, the health risk problem might increase much worse due to the long and continual period of consumption exceeding the estimated daily intake. [ABSTRACT FROM AUTHOR]

High-resolution chronologies with the best time control are key for comparing palaeoenvironmental studies with independent high-precision historical, archaeological or climatic data. Precise chronologies are also essential for inter-site comparisons of palaeo records at decadal to centennial time scales. We present an updated sediment chronology from Burgäschisee, a small and well-studied lake in the Swiss lowlands. The new age-depth relationship was generated using a large number of new radiocarbon samples of terrestrial plant remains extracted from the Burgäschisee sediments and Bayesian age-depth modelling. The results reveal 2σ uncertainties of only ±19 years for the entire record covering the Early Bronze Age (3800 cal. BP) to the Early Middle Ages (1150 cal. BP). The differences between four age-depth modelling techniques (Bayesian and non-Bayesian) are minor (around 25 years) and remain stable with lower radiocarbon date availability. The maximum age offset between the preliminary previously published and the refined chronology from Burgäschisee is 225 years. Our results demonstrate the importance of a rigorous subsampling strategy that includes a careful selection of the best terrestrial plant material and avoiding radiocarbon calibration plateaus whenever possible. The new chronology from Burgäschisee now allows a more accurate site-to-site comparison with archaeological, historical and other palaeoecological evidence from the region. [ABSTRACT FROM AUTHOR]

Given the increased circulation time after fishing, a series of changes take place in live clams, leading to a deterioration in quality even after death. Thus, in this study, we aimed to explore the optimal mode of transportation of clams. The container for holding clams was reformed, and a water circulation temperature control system was established. The physiological responses of clams during anhydrous and watery transportation at two temperatures (4 and 15 °C) were investigated based on the aforementioned system. When comparing the transportation patterns after 3 d of transport, a higher survival rate was observed at 4°C (97%) than at 15 C (63%) in the anhydrous transportation groups and a lower survival rate was observed at 4°C (93%) than at 15°C (99%) in the watery transportation groups. In addition, the glycogen content, condition index (CI), and adenylate energy charge (A.E.C) value were higher at 4°C ((40.87 ± 0.99) mg g−1, 13.71% ± 0.50% and 57.45% ± 1.60%) than at 15°C ((30.54 ± 0.81) mg g−1, 9.09% ± 0.30% and 43.12% ± 1.65%) in the anhydrous transportation groups. In the watery transportation groups, a lower glycogen content, CI, and A.E.C. value were observed at 4°C ((33.78 ±0.84) mg g−1, 9.78% ± 0.50% and 64.65% ±1.25%) than at 15°C ((41.53 ± 0.93) mg g−1, 12.72% ± 0.83% and 71.58% ± 1.27%). Results from this study show that anhydrous transportation (4°C) is the optimal transport condition for clams to maintain a high quality and good physiological conditions. Thus, this study will be particularly useful for establishing shellfish transportation systems. [ABSTRACT FROM AUTHOR]

This study investigated the presence of microplastics in two common edible bivalves in Vietnam, the hard clam (Meretrix lyrata) and the undulate venus clam (Paratapes undulatus), from two estuaries in Da Nang city. Microplastics were detected in both species with relatively high concentrations—from 2.17 ± 0.43 to 2.38 ± 1.28 items g−1 in the undulate venus clams and from 4.71 ± 2.15 to 5.36 ± 2.69 items g−1 in the hard clams. Fibers were the most dominant form of microplastic in both clams, and a high proportion were fibers with sizes from 300 μm to 1500 μm. An estimation of microplastic intake in Vietnamese consumers' bodies from clam consumption was made, which showed an average ingestion of 2489 items person−1 year−1. Our study is also the first global record of microplastic distribution characteristics in the undulate venus clam Paratapes undulatus. [ABSTRACT FROM AUTHOR]

Phytoplankton subsidies from river inputs and wetland habitats can be important food sources for pelagic organisms in the Sacramento--San Joaquin Delta (Delta). However, while the Sacramento River is a key contributor of water to the Delta, providing 80% of the mean annual inflow, the river is only a minor source of phytoplankton to the system. The reason for low phytoplankton biomass in the Sacramento River is not well understood but appears to be associated with a 65-km stretch of the lower river where chlorophyll-a (Chl-a) concentrations can decline by as much as 90%. We conducted two surveys along the lower Sacramento River, in spring and fall of 2016, to investigate the relative contributions of different factors potentially driving this Chl-a decline. Our study evaluated the change in Chl-a concentrations as a result of dilution from tributaries, light availability, nutrient concentrations, nutrient uptake, phytoplankton productivity, zooplankton grazing, and clam grazing. Chl-a concentration decreased from 14 µg L-1 to 1.8 µg L-1 in the spring and from 4.0 µg L-1 to 1.2 µg L-1 in the fall. Dilutions from the Feather River and American River contributed 39% and 11% of Chl-a declines, respectively, during the spring. Average water depths roughly doubled downstream of the American River confluence, reducing water column light availability and lowering productivity. Zooplankton and clam grazing rates were generally low. Using a mass balance analysis, the measured variables explained 76% of the observed decline in Chl-a in the spring, suggesting additional losses from unidentified factors. We found that phytoplankton biomass is regulated by multiple potential factors in the lower Sacramento River, emphasizing the need for practitioners of restoration and management programs to evaluate multiple potential factors when attempting to enhance phytoplankton production in the Delta, or other large river systems. [ABSTRACT FROM AUTHOR]

Thyroid cancer is the most common endocrine cancer. Papillary thyroid cancer (PTC) is the most prevalent form of malignancy among all thyroid cancers arising from follicular cells. Fine needle aspiration cytology (FNAC) is a non-invasive method regarded as the most cost-effective and accurate diagnostic method of choice in diagnosing PTC. Identification of BRAF (V600E) mutation in thyroid neoplasia may be beneficial because it is specific for malignancy, implies a worse prognosis, and is the target for selective BRAF inhibitors. To the authors' best knowledge, this is the first automated precision oncology framework effectively predict BRAF (V600E) immunostaining result in thyroidectomy specimen directly from Papanicolaou-stained thyroid fine-needle aspiration cytology and ThinPrep cytological slides, which is helpful for novel targeted therapies and prognosis prediction. The proposed deep learning (DL) framework is evaluated on a dataset of 118 whole slide images. The results show that the proposed DL-based technique achieves an accuracy of 87%, a precision of 94%, a sensitivity of 91%, a specificity of 71% and a mean of sensitivity and specificity at 81% and outperformed three state-of-the-art deep learning approaches. This study demonstrates the feasibility of DL-based prediction of critical molecular features in cytological slides, which not only aid in accurate diagnosis but also provide useful information in guiding clinical decision-making in patients with thyroid cancer. With the accumulation of data and the continuous advancement of technology, the performance of DL systems is expected to be improved in the near future. Therefore, we expect that DL can provide a cost-effective and time-effective alternative tool for patients in the era of precision oncology. [ABSTRACT FROM AUTHOR]

The increasing concentration of CO2 in the atmosphere and resulting flux into the oceans will further exacerbate acidification already threatening coastal marine ecosystems. The subsequent alterations in carbonate chemistry can have deleterious impacts on many economically and ecologically important species including the northern quahog (Mercenaria mercenaria). The accelerated pace of these changes requires an understanding of how or if species and populations will be able to acclimate or adapt to such swift environmental alterations. Thus far, studies have primarily focused on the physiological effects of ocean acidification (OA) on M. mercenaria, including reductions in growth and survival. However, the molecular mechanisms of resilience to OA in this species remains unclear. Clam gametes were fertilized under normal pCO2 and reared under acidified (pH ~ 7.5, pCO2 ~ 1200 ppm) or control (pH ~ 7.9, pCO2 ~ 600 ppm) conditions before sampled at 2 days (larvae), 32 days (postsets), 5 and 10 months (juveniles) and submitted to RNA and DNA sequencing to evaluate alterations in gene expression and genetic variations. Results showed significant shift in gene expression profiles among clams reared in acidified conditions as compared to their respective controls. At 10 months of exposure, significant shifts in allele frequency of single nucleotide polymorphisms (SNPs) were identified. Both approaches highlighted genes coding for proteins related to shell formation, bicarbonate transport, cytoskeleton, immunity/stress, and metabolism, illustrating the role these pathways play in resilience to OA. [ABSTRACT FROM AUTHOR]

The liquid lead-lithium (Pb–17Li) blanket has many applications in fusion reactors due to its good tritium breeding performance, high heat transfer efficiency and safety. The compatibility of liquid Pb–17Li alloy with the structural material of blanket under magnetic field is one of the concerns. In this study, corrosion experiments China low activation martensitic (CLAM) steel and 316L steel were carried out in a forced convection Pb–17Li loop under 1.0 T magnetic field at 480 °C for 1000 h. The corrosion results on 316L steel showed the characteristic with a superficial porous layer resulted from selective leaching of high-soluble alloy elements and subsequent phase transformation from austenitic matrix to ferritic phase. Then the porous layers were eroded by high-velocity jet fluid. The main corrosion mechanism of CLAM steel was selective dissolution-base corrosion attack on the microstructure boundary regions and exclusively on high residual stress areas. CLAM steel performed a better corrosion resistance than that of 316L steel. The high Ni dissolution rate and the erosion of corroded layers are the main causes for the severe corrosion of 316L steel.

The Manila clam (Ruditapes philippinarum) is the second most exploited bivalve in the world but remains threatened by diseases and global changes. Their associated microbiota play a key role in their fitness and acclimation capacities. This study aimed at better understanding the behavior of clam digestive glands and extrapallial fluids microbiota at small, but contrasting spatial and temporal scales. Results showed that environmental variations impacted clam microbiota differently according to the considered tissue. Each clam tissue presented its own microbiota and showed different dynamics according to the intertidal position and sampling period. Extrapallial fluids microbiota was modified more rapidly than digestive glands microbiota, for clams placed on the upper and lower intertidal position, respectively. Clam tissues could be considered as different microhabitats for bacteria as they presented different responses to small-scale temporal and spatial variabilities in natural conditions. These differences underlined a more stringent environmental filter capacity of the digestive glands. [ABSTRACT FROM AUTHOR]

Although lacking an adaptive immune system and often living in habitats with dense and diverse bacterial populations, marine invertebrates thrive in the presence of potentially challenging microbial pathogens. However, the mechanisms underlying this resistance remain largely unexplored and promise to reveal novel strategies of microbial resistance. Here, we provide evidence that a mud-dwelling clam, Meretrix petechialis, synthesizes, stores, and secretes the antibiotic erythromycin. Liquid chromatography coupled with mass spectrometry, immunocytochemistry, fluorescence in situ hybridization, RNA interference, and enzyme-linked immunosorbent assay revealed that this potent macrolide antimicrobial, thought to be synthesized only by microorganisms, is produced by specific mucus-rich cells beneath the clam's mantle epithelium, which interfaces directly with the bacteria-rich environment. The antibacterial activity was confirmed by bacteriostatic assay. Genetic, ontogenetic, phylogenetic and genomic evidence, including genotypic segregation ratios in a family of full siblings, gene expression in clam larvae, phylogenetic tree, and synteny conservation in the related genome region further revealed that the genes responsible for erythromycin production are of animal origin. The detection of this antibiotic in another clam species showed that the production of this macrolide is not exclusive to M. petechialis and may be a common strategy among marine invertebrates. The finding of erythromycin production by a marine invertebrate offers a striking example of convergent evolution in secondary metabolite synthesis between the animal and bacterial domains. These findings open the possibility of engineering-animal tissues for the localized production of an antibacterial secondary metabolite. [ABSTRACT FROM AUTHOR]

Coalescent methods in population genetics aim to detect biodiversity patterns, evolutionary mechanisms, and signatures of historical changes in effective population sizes with respect to the species fidelity. Restriction site-associated DNA sequencing (RADseq) was used to evaluate the population dynamics of invertebrate species within the same localities. New sequencing technologies, such as the ones employed by population genetics, could be used to improve the management and sustainability of marine and aquaculture resources. Sea cucumbers (Holothuria tubolosa) showed genetic differentiation patterns favoring limited gene flow between studied areas. Similar results for clams (Venus verrucosa) suggest local adaptation and low-dispersal abilities for sessile organisms. On the contrary, cuttlefish (Sepia officinalis) exhibited a panmictic pattern, resulting in a single genetic stock in the area. The larvae settlement duration may be responsible for such interspecies variations. Interspecies demographic modeling revealed different environmental pressures of historical events' signatures with respect to the three invertebrates. Sea cucumbers favor a post-glacial bottleneck event followed by a more recent recovery, whereas cuttlefish favor an expansion before the late glacial maximum. Lastly, clams showed a constant effective population size in the area. The results of historical demographic changes in natural populations provide opportunities for critical evaluation and management in terms of the conservation of the species in the area. [ABSTRACT FROM AUTHOR]

Copper (Cu) is a ubiquitous trace element in the aquatic environment, and is usually found at low levels. Copper environmental concentrations can be altered as a result anthropogenic activities. Shellfish are useful bioindicators to ensure adequate environmental monitoring. Thus, the aim of the present study was as follows: (a) determine the LC50 of copper(I) chloride in grooved carpet shell (Ruditapes decussatus) collected in the Santa Gilla lagoon (Sardinia, Italy), and (b) analyze the antioxidant biomarkers in digestive gland and gills of same specimens exposed to different concentrations of the above-mentioned metal (0.045, 0.45, and 0.90 mg/L) for 96 h. A withdrawal period of 96 h was considered for the treated clam, carrying out the same biochemical analyses, superoxide dismutase (SOD), catalase (CAT), selenium-dependent glutathione peroxidase (Se-GPx), glutathione S-transferases (GSTs), and total glutathione (GSH+2GSSG) in the two tissues. Different time and dose responses of the antioxidant biomarkers were recorded in the digestive glands and gills. Oxidative stress biomarkers highlighted the ability of Cu to induce oxidative stress in R. decussatus. Clam, following the withdrawal period of 96 h, has not been able to achieve the control levels of all biochemical markers in the digestive gland and gills. R. decussatus can be a suitable model to assess the ecotoxicity of copper in aquatic ecosystems. These findings may advance knowledge on the role and the effects of copper on oxidative stress biomarkers in grooved carpet shell. The metal ecotoxicity response can be useful to perform accurate biomarker-based monitoring programs using this bivalve species. [ABSTRACT FROM AUTHOR]

This study explores a retrospective non-targeted analysis (NTA), based on Ultra High-Performance Liquid Chromatography coupled to High-Resolution Mass Spectrometry (UHPLC-HRMS), to assess hidden chemicals of emerging concern (CECs) in marine model organisms. Conventional ecotoxicological studies do not include evaluating the natural habitats of the collected organisms, missing the possibility of highlighting unexpected pollutants, and thus compromising the correctness and reliability of the experimental results. In this paper we reprocessed samples previously collected from the Venice Lagoon for ecotoxicological studies and used for targeted analysis of three bisphenols-related compounds (i.e. BPS, BPF and BPAF) on seawater and specimens of the clam Ruditapes philippinarum. Results from the validation were the following: accuracy, expressed as percentage recoveries (R%), in the range 80%

This work proposes the experimentation of an innovative hydraulic dredge for clam fishing (Chamelea gallina) in the Adriatic Sea (Italy). This innovative gear aimed at increasing the selectivity of the typical hydraulic dredge used currently, while at the same reducing the impact on benthos through the conception, installation, and experimentation of innovative technological solutions, consisting mainly of a vibrating bottom panel on the dredge and a “warning device” on the dredge mouth. Comparative experiments of the traditional vs. the modified gear, employing two boats fishing in parallel on the northern coast of Abruzzi (Adriatic Sea) and contrasting the catch with both paired comparisons and through modelling, showed that the innovative hydraulic dredge retains fewer undersize clams while yielding similar amounts of commercial product, moreover of higher quality; at the same time, it takes on board less discard, and catches significantly less vagile fauna. In short, the innovative gear is gaining five times over a list of six parameters considered as positive and/or advantageous for the clam fishery. The results allow proposals of potential improvements to clam-fishing instruments to make the selection processes more effective while promoting a lower impacting fishery, which is essential for clam management.

The navigation of a mobile robot is a very important issue, especially for an autonomous mobile robot. A robot autonomously can track the area by interpreting the arena, building an adequate map, and localizing itself to this map. This paper proposes a Hybrid filter for Concurrent Localization and Mapping (CLAM) in the navigation to rectify the faults, basically Unscented Fast Simultaneous Localization and Mapping (SLAM) (UFS). We also interrogate the effectiveness of the IF system to investigate nonlinear attributes. A probabilistic method has planned the solution to the CLAM issue, which is an essential requirement for the navigation of robots. The Hybrid filter CLAM contains an Intuitionistic Fuzzy Logic (IFL) and Unscented Kalman Filter (UKF). The IFL is first ordered by using a correctness function explained on score functions for the non-membership function (NMF) and membership function (MF) of the IFL. Then this ordering is utilized to develop a method for a sufficient decision on the CLAM issue. The proposed method has a few privileges in management robot navigation with nonlinear movements owing to the inference feature of the IFL, which also needs a fewer quantity of comparisons than the UFS and shows much better efficiency from the robustness, perspective assessment exactitude, and reliability than the UFS, also, for learning the measurement and control noise covariance matrices for increasing correctness and consistency are utilized IFL. The Hybrid filter CLAM proficiency compared with the UFS has a smaller quantity of computations and good efficiency for bigger areas as demonstrate in the results of simulation and experimental.

Salinity is an important environmental factor affecting the growth and survival of marine organisms. Marine shellfish possess the efficient osmoregulatory mechanism to cope with either hypo- or hyperosmotic stress. However, little is known about the molecular and metabolic adaptation involved in the osmotic regulation of these intertidal habitants. The Manila clam Ruditapes philippinarum is a worldwide cultured intertidal shellfish, which usually encounters a great risk of salinity stress in its coastal habitats. In the present study, the integrated analysis of transcriptomics and metabolomics was performed to investigate the transcriptional and metabolic profiles of the clams in response to abrupt salinity decrease. The comparative transcriptome analysis uncovers the changes of genes involved in ion channel activation, amino acid metabolism, and energy metabolism in the salinity-stressed condition. The metabolomics analysis reveals that the glucose-succinate pathway may play a critical role in energy metabolism during the osmotic stress. The multi-omics analysis reveals that neural adaptation to salinity stress may be potentially regulated by arachidonic acid metabolism and glutathione metabolism. The important metabolites (12-HPETE, PGEs, and spermine) may be served as the signaling molecules in response to acute salinity stress in the intertidal shellfish. These findings suggest that clams may get through the osmotic stress by ion channel activation, neural adaptation, and anaerobic metabolism to maintain their energy homeostasis for maximum survival. The present study provides great insights into the molecular and metabolic strategies of intertidal shellfish in response to salinity stress, and uncovers the new potential signaling metabolites to assess the health states of molluscs in aquaculture.

Objective. To determine the presence of Perkinsus sp. in the sand clam Chionista fluctifraga cultivated in an intertidal zone of the southeastern Gulf of California, using Ray's thioglycollate fluid medium staining (MFTR) and polymerase chain reaction (PCR). Material and Methods. The prevalence and parasite load of Perkinsus sp. were monthly obtained and correlated with environmental water conditions and clam biometric indicators (n=540), from May 2018 to September 2019. Results. Presumptive hypnospores of the protozoan were detected in eight months of culture. The prevalence fluctuated from 3.3% to 13.3%, while the average parasite load ranged from 2 to 1286 hypnospores/g of tissue. The intensity of infection varied from negative to light. The prevalence and parasite load were correlated with each other (r=0.61, p<0.05) but not with the environmental parameters, nor with the biometric indicators of the clam. The PCR test was negative for the MFTR positive cases. Conclusions. Presumptive hypnospores of Perkinsus sp. were detected in C. fluctifraga without clear indications of infection that compromised the clam health in culture. The constant monitoring of Perkinsus sp. in C. fluctifraga is highly recommended to establish possible infections. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) are widespread ocean pollutants and many studies have explored their effects. However, research on MPs combined impact with copper (Cu) on dimethylated sulfur compound production is limited. Dimethyl sulfide (DMS) is an important biogenic sulfur compound related to global temperatures. This study examined the ecotoxicological effects of polyamide 6 MPs and Cu on dimethylsulfoniopropionate (DMSP), DMS, and dimethyl sulfoxide (DMSO) production in Manila clams (Ruditapes philippinarum). Our findings showed that MPs and Cu increased oxidative stress, indicated by higher superoxide anion radical production and malondialdehyde levels while decreasing glutathione contents and increasing superoxide dismutase activities. Additionally, MPs and Cu exposure reduced DMS and dissolved DMSO (DMSO d ) concentrations due to decreased grazing. These results contribute to a better understanding of the ecotoxicological effects of MPs/Cu on bivalves and their roles in the organic sulfur cycle, suggesting a need for further research on long-term impacts on them., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Biomaterials such as seashells are intriguing due to their remarkable properties, including their hierarchical structure from the nanometer to the micro- or even macroscopic scale. Transferring this nanostructure to generate nanostructured polymers can improve their electrical conductivity. Here, we present the synthesis of polypyrrole using waste seashell powder as a template to prepare a polypyrrole/CaCO3 composite material. Various synthesis parameters were optimized to produce a composite material with an electrical conductivity of 2.1 × 10−4 ± 3.2 × 10−5 S/cm. This work presents the transformation of waste seashells into sustainable, electronically conductive materials and their application as an antistatic agent in polymers. The requirements of an antistatic material were met for a safety shoe sole. [ABSTRACT FROM AUTHOR]

Aquaculture is a rapidly expanding sector in which it is important to monitor the occurrence of multi-drug resistant (MDR) bacteria. The presence of extended-spectrum β-lactamase (ESBL-) or carbapenemase-producing Enterobacterales is a commonly used indicator of the resistance burden in a given sector. In this study, 641 pieces of farmed fish (sea bream and sea bass), as well as 1075 Mediterranean clams, were analyzed. All ESBL- and carbapenemase-producing Enterobacterales collected were whole-genome sequenced. The proportion of ESBL-producing Enterobacterales was 1.4% in fish and 1.6% in clams, carried by Escherichia coli (n = 23) and Klebsiella pneumoniae (n = 4). The ESBL phenotype was exclusively due to the presence of blaCTX-M genes, the most frequent one being blaCTX-M-15. The blaCTX-M-1 gene was also identified in six E. coli, among which four were carried by IncI1/pST3 plasmids, possibly betraying an animal origin. Carbapenemases were absent in fish but identified in two K. pneumoniae isolates from clams (blaNDM-1 and blaOXA-48). Several sequence types (STs) identified were associated with human MDR clones such as E. coli ST131 and ST617, or K. pneumoniae ST307 and ST147. Our results might indicate that bacteria from hospital or farm effluents can reach the open sea and contaminate seafood and fish that are living or raised nearby. Therefore, monitoring the quality of water discharged to the sea and the presence of MDR bacteria in seafood is mandatory to ensure the quality of fishery products. [ABSTRACT FROM AUTHOR]

As filter feeders, mollusks' growth is completely reliant on the natural environment. This leaves clam aquaculture, and more generally molluskan aquaculture, highly susceptible to environmental risks such as harmful algal blooms (HABs) and low salinity events. As marine environments change, whether due to climatic or nutrient related variations, there may be new risk combinations that farmers have yet to encounter. To analyze the financial effects of environmental risks on clam farmers in the Gulf of Mexico, we conducted a Monte–Carlo experiment, varying risk combinations and correlations among scenarios. Simultaneous stressors showed a significant impact on individual firms, decreasing average profit by 71% and internal rate of return (IRR) by 83% when compared to best case baseline scenarios without environmental risk, indicating a potential need for risk mitigation strategies. While our analysis focuses on Florida Gulf of Mexico clam farmers, the model presented is applicable to molluskan aquaculture globally. [ABSTRACT FROM AUTHOR]

Marine bivalves are valuable resources, however, some shellfish populations are endangered due to factors such as anthropogenic pressure, pathologies or lack of reproduction synchrony. Portuguese oyster (Crassostrea angulata) and striped venus clam (Chamelea gallina) have high socio-economic value and their endangered natural populations require rehabilitation. Cryopreservation is a valuable method for the preservation and management of genetic resources for aquaculture and restocking. Larvae cryopreservation is particularly valuable since diploid organisms are obtained upon thawing. The objective of this work was the establishment of C. angulata and C. gallina D-larvae cryopreservation through the selection of permeant cryoprotectant in the freezing solution, namely ethylene glycol (EG) and dimethyl sulfoxide (Me 2 SO). Cryoprotectants exposure showed that, in C. angulata, Me 2 SO promoted significantly higher incidence of abnormalities and enhanced glutathione reductase activity when compared to control (larvae without cryoprotectant exposure) or even to EG treatment. However, for both species, EG significantly reduced D-larvae average path velocity (VAP). In C. angulata post-thaw D-larvae, EG treatment promoted significantly lower motility and velocity when compared to control and Me 2 SO treatment. Superoxide dismutase (SOD) activity showed a reduction in C. angulata post-thaw D-larvae when compared to control, which was compensated by the enhancement of glutathione peroxidase (GPX) activity. In C. gallina post-thaw D-larvae, only motility, velocity and SOD activity were significantly lower than control. Therefore, the best treatment to cryopreserve C. angulata D-larvae was EG while for C. gallina Me 2 SO produced better results. This work established for the first time D-larvae cryopreservation protocols for C. angulata and C. gallina. [ABSTRACT FROM AUTHOR]

Clams are commercially important species and are a vital component of the offshore ecosystem. Investigations on microplastics (MPs) in clams have attracted public attention recently, for its ecological and food safety risks. However, knowledge gaps still exist regarding MPs in commercial clams from the intertidal zone of the South Yellow Sea (SYS), China, an important clam habitat. In this study, to investigate the distribution of MPs in clams of the SYS, four species of clams were collected from nine sites in different tide zones (high, middle, and low tides) in three coastal areas (Nantong, Yancheng and Lianyungang). The abundance and characteristics of MPs, including size, shape, color and composition, were determined using microscope and micro-Fourier transform infrared (FTIR) spectroscopy. Furthermore, to evaluate the MPs purification ability of clams, the abundance of MPs in various tissues was examined by microscopic observation after being purified in filtered seawater for 72 h. The results showed that there were significant differences in the abundance of MPs in clams from different regions, with the most serious pollution in the high-tide zone. Moreover, the lowest MPs abundance was found in Yancheng (5.07 ± 2.73 items/individual, 1.16 ± 0.78 items/g), while Lianyungang was found with the most abundant MPs (7.52 ± 2.68 items/individual, 3.94 ± 3.00 items/g). The size of MPs in Ruditapes philippinarum (1,329.99 μm) was significantly higher than in other species. The MPs in clams were characterized by fiber in shape, black-grey, blue-green and white-transparent in color and rayon in composition. Moreover, it was found that the MPs originally present in various tissues tended to migrate and accumulate into the mantle of the clam during depuration, and after 72 h of depuration, removing the mantle could reduce nearly half amount of microplastics in clams. Overall, our study revealed the microplastic distribution in commercial clams from the intertidal zone of the SYS and provided suggestions for the safety of aquatic production.

Ocean acidification has become increasingly severe in coastal areas. It poses emerging threats to coastal organisms and influences ecological functioning. Donax faba , a dominant clam in the intertidal zone of the Bay of Bengal, plays an important role in the coastal food web. This clam has been widely consumed by the local communities and also acts as a staple diet for shorebirds and crustaceans. In this paper, we investigated how acidified conditions will influence the physiology, biochemical constituents, and energetics of Donax faba. Upon incubation for 2 months in lowered pH 7.7 ± 0.05 and control 8.1 ± 0.05 conditions, we found a delayed growth in the acidified conditions followed by decrease in calcium ions in the clam shell. Although not significant, we found the digestive enzymes showed a downward trend. Total antioxidant was significantly increased in the acidified condition compared to the control. Though not significant, the expression level of MDA and antioxidant enzymes (SOD, CAT, GST, GPX, and APX) showed increasing trend in acidified samples. Among nutrients such as amino acids and fatty acids, there was no significant difference between treatments, however, showed a downward trend in the acidified conditions compared to control. Among the minerals, iron and zinc showed significant increase in the acidified conditions. The above results suggest that the clam growth, and physiological energetics may have deleterious effects if exposed for longer durations at lowered pH condition thereby affecting the organisms involved in the coastal food web. [Display omitted] • Daily growth rate & calcium concentration have significantly decreased in acidified condition. • Total antioxidants and antioxidant enzymes showed an upward tendency. • Nutrient composition in clams has altered in acidified condition compared to control. • Prolonged exposure to OA will cause deleterious effects on clams thereby upsetting the intertidal food chain. [ABSTRACT FROM AUTHOR]

This study investigated the presence of microplastics in two common edible bivalves in Vietnam, the hard clam (Meretrix lyrata) and the undulate venus clam (Paratapes undulatus), from two estuaries in Da Nang city. Microplastics were detected in both species with relatively high concentrations—from 2.17 ± 0.43 to 2.38 ± 1.28 items g−1 in the undulate venus clams and from 4.71 ± 2.15 to 5.36 ± 2.69 items g−1 in the hard clams. Fibers were the most dominant form of microplastic in both clams, and a high proportion were fibers with sizes from 300 μm to 1500 μm. An estimation of microplastic intake in Vietnamese consumers’ bodies from clam consumption was made, which showed an average ingestion of 2489 items person−1 year−1. Our study is also the first global record of microplastic distribution characteristics in the undulate venus clam Paratapes undulatus.

This work proposes the experimentation of an innovative hydraulic dredge for clam fishing (Chamelea gallina) in the Adriatic Sea (Italy). This innovative gear aimed at increasing the selectivity of the typical hydraulic dredge used currently, while at the same reducing the impact on benthos through the conception, installation, and experimentation of innovative technological solutions, consisting mainly of a vibrating bottom panel on the dredge and a "warning device" on the dredge mouth. Comparative experiments of the traditional vs. the modified gear, employing two boats fishing in parallel on the northern coast of Abruzzi (Adriatic Sea) and contrasting the catch with both paired comparisons and through modelling, showed that the innovative hydraulic dredge retains fewer undersize clams while yielding similar amounts of commercial product, moreover of higher quality; at the same time, it takes on board less discard, and catches significantly less vagile fauna. In short, the innovative gear is gaining five times over a list of six parameters considered as positive and/or advantageous for the clam fishery. The results allow proposals of potential improvements to clam-fishing instruments to make the selection processes more effective while promoting a lower impacting fishery, which is essential for clam management. [ABSTRACT FROM AUTHOR]

Clam Cyclina sinensis behaves a stronger ammonia nitrogen tolerance, whereas the molecular regulation mechanism remains unknown. In the present study, C. sinensis was exposed to ammonia nitrogen (32.90 mg/L) for 0 h (the control), 12 h (T1) and 24 h (T2). Integrated analysis of miRNA‐mRNA was conducted to reveal the regulatory roles of miRNAs in the metabolism of C. sinensis exposed to acute ammonia nitrogen. Numerous genes involved in detoxification and ammonia excretion expressed differently indicate that nitrogen assimilation and utilization is adjusted to accommodate ammonia exposure. The clam has to alter their glucose and lipid metabolism to meet energy requirements to adapt acute ammonia exposure in the environment. 12, 948 genes were identified as target genes of the differently expressed miRNAs. Most of mRNA–miRNA pairs were involved in metabolisms of carbohydrate, lipid and amino acid. miRNA‐mRNA integrated analysis revealed involvement of Purine metabolism, Wnt signalling pathway, Hippo signalling pathway, PI3K‐Akt signalling pathway in ammonia‐stress response of C. sinensis. Exposed to ammonia, clam may suffer hypoxia exposure. Overall, exposed to ammonia, clam has to alter their glucose and lipid metabolism to meet energy requirements. Numerous mRNA–miRNA pairs were involved in metabolisms of carbohydrate, lipid and amino acid and miRNA can regulate the metabolism of C. sinensis by regulating the expression of target genes during acute ammonia nitrogen stress. The net result is that nitrogen assimilation and utilization is adjusted to accommodate ammonia exposure. The current study is helpful for further investigation into the ammonia nitrogen response mechanisms in mollusks. [ABSTRACT FROM AUTHOR]

Reduced activation (with rapid activity decay) ferritic–martensitic steels are promising structural materials for fusion power engineering. This article discusses the capability of using them as a plasma-facing material in areas of relatively low energy load. Samples of Rusfer, Eurofer, CLAM, and F82H steels were irradiated with pulsed flows of deuterium plasma typical for peripheral plasma disruptions. Two variants of load were selected: 0.3 MJ/m2, 1 ms, i.e., the conditions under which the surfaces of these steels do not melt, and 0.6 MJ/m2, 1 ms, i.e., the conditions under which the surface layer melts. The samples were irradiated by 1–25 pulses during each load. The surface-layer modification was analyzed. It was established that if upon irradiation the surface layer of the samples melts, then already after one pulse the surface layer of Rusfer, CLAM, and F82H samples becomes wavy, and the surface of Eurofer steel remains flat until irradiation with 25 pulses with the following parameters: 0.6 MJ/m2, 1 ms. This can be related to the different compositions of the steels. The calculations demonstrate that the coefficient of surface tension in the molten layer of Eurofer steel is higher than that of Rusfer steel at the same temperature. Steel with a higher coefficient of surface tension keeps its shape better under the action of external forces. [ABSTRACT FROM AUTHOR]