Razor Clam Research Articles

Mollusc on the move; First record of the Newfoundland’s razor clam, Ensis terranovensis Vierna & Martínez-Lage, 2012 (Mollusca; Pharidae) outside its native range

Mollusc on the move; First record of the Newfoundland’s razor clam, Ensis terranovensis Vierna & Martínez-Lage, 2012 (Mollusca; Pharidae) outside its native range

Genome-wide characterization of the cytosolic sulfotransferase 1B member 1 (SULT1B1) family and its expression responses to sulfide stress in the razor clam Sinonovacula constricta

The razor clam (Sinonovacula constricta), a typical burrowing organism in the intertidal zones, is often exposed to sulfide environment and shows strong sulfide tolerance. Located downstream of the sulfur metabolism pathway, cytosolic sulfotransferase family 1B member 1 (SULT1B1) is a key enzyme catalysing the sulfonation reaction, and plays an important role in the biotransformation of endogenous substances such as thyroid hormones (THs). To investigate their roles in sulfide resistance, a systematic analysis of S. constricta SULT1B1s (ScSULT1B1s), including genomic distribution, phylogenetic relationships, gene structure, conserved motifs, and expression profiles under sulfide stress, was performed. A total of 10 ScSULT1B1 genes were found in the S. constricta genome. Sequence analysis showed that ScSULT1B1 gene family encoded 155–425 amino acids, containing four catalytic active sites (K, N, H, and S), one PAPS binding domain at the N-terminus, and one PAPS binding and dimerization domain at the C-terminus. The spatial–temporal expression patterns of ScSULT1B1s were further estimated by quantitative real-time PCR (qRT-PCR). Among them, partial ScSULT1B1s showed significantly high expression in the gill, hepatopancreas, and siphon. Furthermore, the response expression of certain ScSULT1B1s significantly fluctuated under sulfide stress. Together, our results suggest that ScSULT1B1s, by mediating the sulfonation reaction, may regulate THs levels to maintain basic metabolic and immune functions, making S. constricta highly sulfide tolerant.

Circadian clock genes Bmal1 and Period may regulate nocturnal spawning by controlling sex hormone secretion in razor clam Sinonovacula constricta

The circadian clock is an endogenous regulation mechanism that coordinates biological processes with daily changes, which are regulated by circadian clock genes. Bmal1 and Period are key circadian clock genes and their roles in reproductive development have been widely studied. The spawning time of Sinonovacula constricta is limited to the night even under external artificial stimulation, and it might be regulated by the internal circadian clock. In this study, the heart rate of S. constricta was higher between 20:00-04:00 at night and lower between 12:00-16:00 during the day, and the sex hormone contents were the highest at 00:00 and the lowest at 18:00 (P < 0.01). Therefore, these obvious changes in the circadian rhythm indicate that S. constricta is a nocturnal animal. The open reading frame (ORF) of Bmal1 comprises 1944 bp encoding 647 aa, while the ORF of Period comprises 3111 bp encoding 1036 aa. Bmal1 and Period were both expressed in four tissues, but they had opposite rhythmic expression patterns. Bmal1 expression was higher at 00:00-06:00 and lower at 12:00-18:00, and Period expression was opposite, thereby suggesting that Bmal1 and Period are involved in positive and negative pathways regulated by the circadian clock, respectively. Strong protein fluorescence signals of Bmal1 and Period proteins were observed in mature oocytes, spermatids, hepatocytes, and epithelial cells of siphons. After siRNA interference, the expression of both Bmal1 and Period significantly decreased (P < 0.01), and the sex hormone contents decreased significantly from 3 to 7 days in the siRNA treatment groups (P < 0.01). Therefore Bmal1 and Period may regulate nocturnal spawning by controlling sex hormone secretion. These findings provide a theoretical basis for understanding the molecular mechanism related to spawning, and may facilitate the artificial propagation of mollusks.

Light entrainment and molecular regulation of the circadian clock in razor clam Sinonovacula constricta

Sinonovacula constricta is an important bivalve with strong photosensitivity and a robust circadian rhythm. To elucidate the light entrainment of the molecular circadian clock in this species, this study identified the clock genes, characterized their tissue distribution, and investigated their transcriptional variations under different light regimes: LD (12 h light/12 h dark cycle), LL (continuous light), and DD (continuous dark). The results showed that the S. constricta clock system consists of seven genes [Circadian locomotor output cycles kaput (ScClock), Brain and muscle ARNT-like protein (ScBmal), Cryptochrome (ScCry1 and 2), Period (ScPer), and Timeless (ScTimeless1 and 2)] that are closely related to their orthologs in marine mollusks and contained corresponding conserved functional regions, indicating the conserved evolution of the circadian clock among organisms. These genes were expressed in all tissues, with high expression in the labial palps and hepatopancreas, suggesting a complex peripheral biological clock in S. constricta and the critical role of these two tissues in circadian functions. When exposed to different light regimes in labial palps, genes from the positive loop (ScClock and ScBmal) displayed a daily/circadian rhythm under both LD and DD and their acrophases were shifted by 5–7 h, whereas genes from the negative loop displayed daily rhythms (ScCry1 and ScPer) under LD and circadian rhythms (ScCry2 and ScTimeless2) under DD. However, only one gene (ScTimeless2) displayed a circadian rhythm under LL conditions. These results suggest that the S. constricta circadian system may be regulated by different clock genes to adapt to various light environments. Although similar phenomena were observed in the hepatopancreas, markedly different clock gene expression patterns occurred between the two tissues, indicating a tissue-specific regulated circadian system. Collectively, this study reveals how the circadian oscillators of S. constricta respond to light and may promote light environment optimization in the S. constricta farming industry.

Optimal Culture Capacity of White Shrimp (Litopenaeus vannamei) and Razor Clam (Sinonovacula constricta) in a New Series-Connection Culture Model

Optimal Culture Capacity of White Shrimp (Litopenaeus vannamei) and Razor Clam (Sinonovacula constricta) in a New Series-Connection Culture Model

Physiological response of the razor clam Sinonovacula constricta exposed to hyposalinity stress

The razor clam Sinonovacula constricta is an economically important bivalve species in China, which inhabits the mudflat of intertidal and estuaries areas and frequently suffers the low salinity stress due to heavy rain events. The present study investigated the effects of hyposalinity stress (salinity 10, 5, 3, and 1) on osmoregulation and haemolymph microbiota in S. constricta after 7 days of exposure. The results showed that the survival rate of razor clams was only significantly reduced in the 1 ppt group compared to the control group (salinity 20) (P < 0.05). Haemolymph osmolality in razor clams reduced significantly with decreasing salinities (P < 0.05). Taurine, arginine, alanine and ornithine were the dominant free amino acids (FAAs) with higher contents in the haemolymph. Exposure to low salinities altered the composition of haemolymph FAAs, with alanine being the highest in the control group and taurine being the highest in the low salinity (LS) groups. Hyposalinity stress caused an increase in Na+/K+-ATPase (NKA) activity in gills, and histological analysis revealed severe hyperplasia in gills and a significant reduction in the length of gill filaments (P < 0.05). The microbial community variation in the haemolymph assessed by 16S rRNA sequencing explains that bacterial communities was shifted under low salinity stress. At the genus level, the relative abundance of Marinobacterium, Marinomonas and Pseudomonas changed significantly under hyposalinity stress (P < 0.05). These findings give further insight into the physiological responses and potential adaptation strategies of razor clams to hyposalinity stress and provide information for the development of inland low salinity culture.

PDIA6 involves the thermal stress response of razor clam, Sinonovacula constricta

Protein disulfide isomerases A6 (PDIA6), an oxidoreductase and isomerase, catalyzes the oxidation reduction and isomerization of disulfide bonds, and serves as molecular chaperone to prevent the buildup of misfolded proteins under various environmental insults. However, the role of PDIA6 in mollusks remains largely obscure, although its multifunctional protein has been reported in other species under adverse conditions. To fill this gap, we identified PDIA6 from the razor clam Sinonovacula constricta (ScPDIA6) and investigated its expression patterns in response to thermal stress. Tissue distribution showed that the mRNA transcript of ScPDIA6 was ubiquitously expressed in nine tested tissues. Temporal expression profiles by qPCR revealed that ScPDIA6 in the gill and mantle was significantly increased by hyper-thermic treatment. Further, Western blot and immunofluorescence indicated that ScPDIA6 was significantly upregulated by thermal treatment at the protein level. Additionally, the survival test demonstrated that the viability of E. coli cells expressing recombinant ScPDIA6 protein increased at 42 °C compared with empty vector. Overall, these findings suggested that ScPDIA6 may play a pivotal role in counteracting thermal stress. This study will provide valuable reference data resource for understanding the potential role of PDIA6 in mollusks.

Assessing the carbon sink capacity of coastal mariculture shellfish resources in China from 1981–2020

The ocean has considerable potential to function as a carbon sink, absorbing anthropogenic CO2 and buffering the effects of climate change. How the culture of shellfish can be used to increase the ocean carbon sink warrants evaluation. We analyze the production and carbon sink capacity of six important mariculture shellfish species (oyster, ark clam, mussel, scallop, clam, and razor clam) in nine coastal provinces of China from 1981–2020 using quality assessment and logarithmic mean Divisia index (LMDI) decomposition methods. Over this time period both cultured shellfish production and its contribution to the carbon sink generally increase, averaging approximately 600,000 t annually over the last four decades. Both the annual production and carbon sink capacity of China’s mariculture shellfish industry vary geographically. The total annual tonnage (scale) of cultured shellfish, and to a lesser extent, coastal shellfish species composition (structure) influence carbon sink capacity, and affect China’s plans to achieve “dual carbon goals.” Combining historical analysis and the LMDI method, we propose a scheme that optimally and more sustainably manages China’s culture of shellfish.

The Mysterious Case of the Missing Razor Clams

Oceans are changing and these changes are affecting the animals that live there. Animals respond differently to changes in water temperature, food availability, and contaminants. Those responses can be seen in their genes. A technique called transcriptomics allows scientists to see the response of an animal’s genes to its environment. We used transcriptomics to compare two populations of Pacific razor clams in Alaska (United States): one that has lots of clams and one that used to have lots but does not anymore. We were surprised when we did not find any differences in their gene responses! So, we had to think about what else might be influencing the number of clams in these two populations. As we “dug” for answers, we found out that there are differences between the populations that do not influence their genes but may impact their numbers, such as being eaten by predators.

Subgrade soil stabilization using marine debris: A literature review

The use of different marine residues found in the great biodiversity of the Peruvian coast, such as crushed mollusk shells or fan shells, can be used as mechanical stabilizers for clay soils due to a change in granulometry. In this article, we reviewed 74 research studies indexed in different databases such as Scopus, Scielo, Ebsco, Proquest, Springer Link, and ScienceDirect, whose publication has not exceeded seven years, with the objective of carrying out a systematic review of the use, effect and influence of marine debris as soil stabilizers. For this purpose, the analyses of the mechanical and also physical properties of such mixtures in different marine debris were reviewed compared to the various types of stabilizers currently used. These evaluated results indicate, that the Pacific razor clam shell offers a lower bearing capacity compared to the fan shell when stabilizing clayey soil. However, the shredded output of both types of marine debris can meet the need for clay subgrade stabilization. Based on the review, it was determined that the addition of different types of shredded marine debris reduces water absorption by capillarity, increasing the resistance and bearing capacity of the soil.

Microplastics characteristics of lorjuk Solen sp. in east coastal waters of Surabaya

Microplastics (MPs) are plastic particles with sizes between <1 m to 5 mm. Microplastics are known to contaminate the environment and marine organisms. One type of marine organism that is often found on the east coast of the city of Surabaya is Lorjuk, namely bamboo shells or razor clams. Lorjuk is seafood and is known as a typical food of the city of Surabaya. This study aims to determine the potential for microplastic pollution in Lorjuk (Solen sp.) from 3 locations on the east coast of the city of Surabaya. Lorjuk observed were adult Lorjuk with a size of 5-6 cm. With the nature of Lorjuk as an infauna and filter feeder, microplastic observations were also carried out on sediment and water. The number, shape, color, size, and polymer type of microplastics were observed using an optical microscope and FTIR spectrophotometer. MPs were found in all samples of Lorjuk in the three locations, with an average number of 6-7 MPs/ind. The physical characteristics of microplastics indicate that fiber is the dominant form of microplastic (>90%) with the majority being blue. The MPs found in Lorjuk have an average size of 20-40 µm with low-density polyethylene (LDPE) polymer. The results of the Pearson correlation test showed that there was an effect of the relationship between the number of microplastics found in Lorjuk and microplastics in the environment around where Lorjuk lived (water column and sediment).

Economic impacts of harmful algal blooms on fishery-dependent communities

The recreational razor clam fishery is the largest recreational bivalve fishery in the Pacific Northwest and a major source of tourism-related income to small communities in the region. Delays and closures of recreational shellfisheries due to the increasing frequency of harmful algal blooms (HABs) threaten to have significant negative impacts on fishery dependent communities. Coupling previous recreational shellfishing expenditure estimates from the literature with a novel dataset of daily visits to local businesses, we estimate a range of economic impacts resulting from the cancellation of razor clam digs at Long Beach, WA, the most popular beach in the State for recreational clam diggers. Our results indicate that a full season closure can lead to lost sales revenues of $16,875 for gas stations, $117,600 for food stores, $217,800 for accommodations and $491,400 for food service places for a total lower bound economic impact of $843,675. We discuss the opportunity for early warning systems, like the Pacific Northwest HAB Bulletin, to guide policy and facilitate business decisions that hedge the risk of revenue losses associated with dig cancellations.

Back-calculation of soil parameters from displacement-controlled cavity expansion under geostatic stress by FEM and machine learning

Estimating soil properties from the mechanical reaction to a displacement is a common strategy, used not only in in situ soil characterization (e.g., pressuremeter and dilatometer tests) but also by biological organisms (e.g., roots, earthworms, razor clams), which sense stresses to explore the subsurface. Still, the absence of analytical solutions to predict the stress and deformation fields around cavities subject to geostatic stress, has prevented the development of characterization methods that resemble the strategies adopted by nature. We use the finite element method (FEM) to model the displacement-controlled expansion of cavities under a wide range of stress conditions and soil properties. The radial stress distribution at the cavity wall during expansion is extracted. Then, methods are proposed to prepare, transform and use such stress distributions to back-calculate the far field stresses and the mechanical parameters of the material around the cavity (Mohr-Coulomb friction angle phi , Young’s modulus E). Results show that: (i) The initial stress distribution around the cavity can be fitted to a sum of cosines to estimate the far field stresses; (ii) By encoding the stress distribution as intensity images, in addition to certain scalar parameters, convolutional neural networks can consistently and accurately back-calculate the friction angle and Young’s modulus of the soil.

Impact of ocean acidification on the physiology of digestive gland of razor clams Sinonovacula constricta

Ocean acidification (OA) can have widespread implications for marine bivalves. While our current understanding of OA effects on the physiological performance is increasing, very little is known about the physiology of digestive gland of marine bivalves in response to OA. Here, we examined how the digestive system of razor clams (Sinonovacula constricta) responded to OA. Following 35-day exposure to CO2-driven seawater acidification, no significant decreases in phenotypic traits, such as dry body weight gain, specific growth rate, condition index and survival rate, as well physiological functions, such as activities of antioxidant and digestive enzymes, were observed, demonstrating the resistance of razor clams under acidified conditions. Histological results showed that some direct damages on the structure of digestive gland was observed, including degradation of digestive tubular, atrophy of epithelial cells, loose cell arrangement, even diffuse. This study provides insights into the digestive performance of marine bivalves in a rapidly acidifying ocean.

Socioeconomic disruptions of harmful algal blooms in indigenous communities: The case of Quinault Indian nation

Harmful algal blooms (HABs) have been a pervasive challenge across coastal communities of the U.S. West Coast in recent years negatively affecting local economies and livelihoods. We focus on the effects of HABs to the Quinault Indian Nation (QIN) triggered by Pseudo-nitzschia that produce the toxin domoic acid (DA). This toxin accumulates in filter feeders and poses threats to human health via shellfish consumption. Consumption of razor clams with high levels of DA and Dungeness crab that prey on them can cause amnesic shellfish poisoning in humans and therefore requires closure of commercial, recreational and subsistence fisheries, postponing or limiting harvesting seasons. These disruptions result in significant losses in revenues along with negative effects to sociocultural dimensions of key importance to coastal communities. Livelihoods and wellbeing of tribal communities are affected disproportionately due to higher vulnerability and reliance on these marine resources for subsistence. We assess these effects at multiple levels for the QIN and discuss and reflect, through a tribal lens, upon advances and opportunities for impact mitigation and adaptation in the face of HABs, along with persisting challenges.

Effects of cooking methods on microplastics in dried shellfish.

Many studies have reported the occurrence of microplastics in live shellfish intended for human consumption. However, far fewer studies have been conducted on dried shellfish from supermarkets or fishery markets. In this study, the characteristics of microplastics in six kinds of dried shellfish products following different cooking treatments were investigated. Dietary exposure to microplastics in dried shellfish was estimated using the consumption rate of seafood among different age groups. Microplastics were detected in all the uncooked, dried shellfish products, ranging from 0.3 to 4.2 items/g. Fibres accounted for more than 80% of microplastics in razor clams, winkles, and scallops. The proportion of microplastics smaller than 1 mm in size ranged from 57.1% to 89.7% of the total microplastics found in dried shellfish. The polymer types included polyethylene terephthalate (PET), rayon, polyester, nylon, polypropylene (PP), cellophane (CP), and polyethylene (PE). Principal component analysis (PCA) showed that the sizes and shapes of microplastics in scallops were more susceptible to alteration by different cooking methods. Steaming and frying significantly reduced the abundance of microplastics in razor clams. In addition, significantly fewer microplastics were found in scallop products after boiling and steaming than were found in fried scallop products. The estimated dietary intake of microplastics for infants was the highest among the age groups considered (3.05 items/kg(bw)/day). Accordingly, frying was suggested for cooking mussels, boiling for clams and winkles, and steaming for scallops. Combining risks from ingesting plastics and plastic additives, steaming is suggested as the best method to cook shellfish.

Essential and Non-Essential Elements in Razor Clams (Solen marginatus, Pulteney, 1799) from the Domitio Littoral in Campania (Southwestern Tyrrhenian Sea, Italy).

The levels of essential (Cu, Cr, Co, Mn, Se, Zn) and non-essential (As, Be, Bi, Cd, Cs, Ga, Ni, Pb, Sr, Tl, U, V) trace elements were studied in razor clams (Solen marginatus) collected from the Tyrrhenian coast of Southern Italy at five selected sites along the Domitio littoral in the Campania region. The main objectives of this study were to assess the contamination status of these bivalve mollusks and to evaluate the risks to the environment and consumers due to metal contamination. The concentrations of 18 trace elements were determined after microwave-assisted mineralization and by inductively coupled plasma mass spectrometry (ICP-MS). Concentrations of the toxic elements Pb and Cd were below the maximum levels established by Commission Regulation (EC) 1881/2006, while higher average concentrations of arsenic were found at each of the five sites studied. Regarding the other trace elements, contamination levels followed the order: Zn > Sr > Mn > Cu > Se > Cr > V > Ni > Co > Ga > Cs > Be > U > Bi > Tl. No significant differences among the sites were found with regard to any of the trace elements analyzed, and element levels in razor clams did not reflect sediment contamination. The results demonstrated the substantial food safety of the razor clams in this area with respect to heavy metals but revealed a potential health risk due to arsenic contamination in all the areas sampled.

Modelling essential habitat for common scoter (Melanitta nigra) in a disturbed environment

The realised distribution of species in disturbed environments depends upon the degree to which their optimum habitat has been altered by impacts arising from human pressures. We investigated how pressures such as fishing activity, changes in prey availability and habitat quality affect the distribution of Common Scoter (CS) in the north Irish Sea. CS distribution data were obtained from aerial surveys in the winter of 2018–2019. We developed two generalised additive models using covariate information on depth, seabed shear stress, VMS activity of fishing vessels, AIS data of passenger and cargo vessels, portion of fine sand in the benthos, abundance of deep-burrowing bivalves and abundance of surficial bivalves. There was no clear evidence that the fishery, through either disturbance effects nor direct prey competition caused by extraction of razor clams, affected the distribution of CS in the area. However, indirect effects of the fishery, mediated through impacts on abundance and perhaps recruitment of bivalves on CS, could not be ruled out. The absence of a disturbance effect may be due to the small size of vessels in this fleet and their slow fishing speeds. The abundance of surficial bivalves, depth, the portion of fine sand and shear stress at the seabed in the sediments influenced CS distribution. This indicates that the distribution of CS in the area is driven by foraging conditions rather than the presence of fishing vessels.

Biological sensitivities to high-resolution climate change projections in the California current marine ecosystem.

The California Current Marine Ecosystem is a highly productive system that exhibits strong natural variability and vulnerability to anthropogenic climate trends. Relating projections of ocean change to biological sensitivities requires detailed synthesis of experimental results. Here, we combine measured biological sensitivities with high‐resolution climate projections of key variables (temperature, oxygen, and pCO2) to identify the direction, magnitude, and spatial distribution of organism‐scale vulnerabilities to multiple axes of projected ocean change. Among 12 selected species of cultural and economic importance, we find that all are sensitive to projected changes in ocean conditions through responses that affect individual performance or population processes. Response indices were largest in the northern region and inner shelf. While performance traits generally increased with projected changes, fitness traits generally decreased, indicating that concurrent stresses can lead to fitness loss. For two species, combining sensitivities to temperature and oxygen changes through the Metabolic Index shows how aerobic habitat availability could be compressed under future conditions. Our results suggest substantial and specific ecological susceptibility in the next 80 years, including potential regional loss of canopy‐forming kelp, changes in nearshore food webs caused by declining rates of survival among red urchins, Dungeness crab, and razor clams, and loss of aerobic habitat for anchovy and pink shrimp. We also highlight fillable gaps in knowledge, including specific physiological responses to stressors, variation in responses across life stages, and responses to multistressor combinations. These findings strengthen the case for filling information gaps with experiments focused on fitness‐related responses and those that can be used to parameterize integrative physiological models, and suggest that the CCME is susceptible to substantial changes to ecosystem structure and function within this century.

Spotlighting Women-Led Fisheries Livelihoods Toward Sustainable Coastal Governance: The Estuarine and Mangrove Ecosystem Shellfisheries of West Africa

The governance of coastal and marine resources remains a complex socio-ecological endeavor in many African countries, but women are leading the way and demonstrating a pathway for food fish security through rights-based co-management of shellfisheries in estuarine and mangrove ecosystems in West Africa. We report comprehensively, for the first time, the scale of estuarine and mangrove ecosystem-based shellfisheries across the West African coast (Senegal, Gambia, Guinea Bissau, Guinea, Sierra Leone, Liberia, Côte d’Ivoire, Ghana, Togo, Benin, and Nigeria), the gender dynamics, and implications for the sustainable management of this small-scale fishery. We find an extensive geographical coverage of active shellfisheries within these ecosystems with close to 571,000 household beneficiaries and over 50,000 harvesters, mainly women, being the primary resource users. An annual shellfish harvest of over 300,000 MT valued at USD 336 million is potentially undocumented across the region. Harvested shellfish species of economic importance comprised 18 species of mollusks, 11 species of crustaceans, and a few unidentified groups of gastropods, crustaceans, and cephalopods. The West African mangrove oyster, periwinkle, bloody cockle, whelk, and razor clam were, in that order, the most harvested estuarine shellfish. The bivalve and gastropod value chains are dominated by women harvesters at all nodes whereas women play significant roles in the processing and marketing of crustacean and cephalopod fisheries. Formal laws specific to the regulation of estuarine shellfisheries are generally nonexistent, however, the organized women shellfish harvester groups of the Tanbi wetlands (The Gambia) and Densu Delta (Ghana) have championed sustainable governance actions resulting in successful women resource user-led fisheries co-management. The elements of success and opportunities for scaling up these examples are discussed. The presence of such groups in several locations offers an entry point for replicating a similar co-management approach across the West African coast.