Mercenaria Mercenaria Research Articles

Biometry-dependent metal bioaccumulation in aquaculture shellfishes in southwest Taiwan and consumption risk

Shellfishes can easily accumulate metals via water and sediment and which may pose a human health risk by consumption. This study assessed the distribution of metals, including Cd, Cr, Cu, Pb, Ni, Zn, and Hg, in soft tissues of hard clam (Meretrix lusoria), surrounding water body, and sediment in the southwest coast of Taiwan. Hard clams contained the relatively higher concentration of the essential element, such as Zn, Cu, and Ni, and the metal concentration from high to low was Zn > Cu > Ni > Cd > Cr > Pb > Hg. However, the metal concentrations found in hard clam all were lower than the Sanitation Standard for Aquatic Animal of Taiwan. Results of bioaccumulation factors indicated that hard clam shows the ability of metal accumulation from water was higher than that from sediment. Moreover, the metal concentrations in hard clam were negatively correlated with body size except for Hg, which could be presented by the significant power function. Generally, hard clams from the aquaculture pond located on the southwest coast of Taiwan would not be harmful to adult consumers, except for people that consume shellfish more than 100 g. Besides strengthening the management of seafood safety and aquaculture, adjusting the eating and purchasing habits of the consumer could be a practical and feasible way for decreasing health risks. These results can assist the government in determining seafood safety and its implementation in Taiwan.

A lignin dissolution-precipitation strategy for porous biomass carbon materials derived from cherry stones with excellent capacitance

Abstract Bio-carbon derived from agricultural waste is promising as electrode material of supercapacitor. However, it is still challenging to obtain excellent capacitance from raw biomass with an inherently dense and hard structure. In this work, a facile and scalable route is developed to fabricate N-doped hierarchical porous bio-carbon from cherry stones (CSs). Through the pretreatment of lignin dissolution-reprecipitation, the dense CSs were successfully transformed into porous precursor. With the promotion of mass transfer inside the material, the as-obtained carbon can be well-manipulated by N-doping and molten salt activation. A hierarchical and porous structure was formed in the bio-carbon with a specific surface area of up to 1681 m2 g−1. The material possessed an excellent specific capacitance of 370.5 F g−1 in 6 M KOH at a current density of 0.5 A g−1 and a prominent rate performance with a capacitance remaining 225.1 F g−1 at 20.0 A g−1. After 5000 cycles, an initial capacitance of 99.1% was maintained. All the results ensured that the bio-carbon derived from CSs could serve as renewable, low-cost and high-performance electrode materials for supercapacitors, and the proposed pretreatment method could effectively enhance energy storage capability of biomass-derived activated carbon.

Fixed bed study of nitrate removal from water by protonated cross-linked chitosan supported by biomass-derived carbon particles

In this study, a green adsorbent was synthesized for the removal of nitrate ions from water. The adsorbent consisted of carbonaceous particles with high specific surface area (1,240 m2 g−1) and porosity derived from pyrolysis of cornelian cherry stone and modified by protonated cross-linked chitosan. The adsorbent was characterized using various techniques like SEM, FTIR, BJH and zeta potential measurements. Dynamic behavior of the adsorbent in the nitrate adsorption was studied in a packed bed system at various operating conditions and in the presence of other competing anions (PO43−, HCO3−, SO42−). Based on the error analysis, the optimum operating conditions were considered at flow rate of 3.8 mL min−1, bed depth of 10 cm and nitrate concentration of 75 mg L−1. The kinetics of the adsorption process was studied using Adams–Bohart and Thomas models and the qmax was calculated to be about 12.4 mg g−1 at neutral pH and room temperature. Furthermore, the relationship between the bed height and the breakthrough time was described by bed depth service time (BDST) model. The experimental results suggested that the adsorbent possessed significant ability in nitrate removal from water due to the desired chemistry of the biopolymer and the excellent textural properties of the carbon support.

Effects of hard clam (Mercenaria mercenaria) density and bottom shear stress on cohesive sediment erodibility and implications for benthic-pelagic coupling

The interacting effects of little neck hard clam (Mercenaria mercenaria) density and bottom shear stress on cohesive sediment erodibility were investigated. Short-term stepwise erosion experiments in 30 and 40 cm diameter Gust microcosms over a range of 0.0083 to 0.1932 Pa were performed using sequential 20-minute constant shear stress steps while sampling turbidity regularly. In addition, sediment erodibility was monitored in two one-month long ecosystem experiments with tidal resuspension and 0, 10, and 50 hard clams in 1 m3 shear turbulence resuspension mesocosms (STURM) with an initial stepwise erosion experiment (0.313 to 0.444 Pa). In short-term erosion experiments, a low density of hard clams did not significantly affect sediment erodibility, but a high density of hard clams destabilized muddy sediments through significantly decreased critical shear stresses and higher erosion rates, resulting in higher cumulative suspended mass (CSM). In long-term erosion experiments, the sediment stabilized over time between treatments and decreased to a CSM of approximately 60 g m–2 with different densities of hard clams. This was likely due to development of microphytobenthos, mediated by the filter-feeding clams, bottom shear stress and increased light. Bioturbation by a dense bed of hard clams in interaction with infrequent high bottom shear due to storms may increase CSM in the water column, with subsequent direct and indirect effects on the ecosystem. However, more controlled longer-term erosion studies to determine the interacting effects of long-term exposure to high bottom shear stress, benthos, and microphytobenthos on sediment erodibility and benthic-pelagic coupling are needed.

The turquoise killifish: a genetically tractable model for the study of aging

Lifespan is a remarkably diverse trait in nature, ranging from just hours in adult mayflies to hundreds of years in the Greenland shark and quahog clam. Great disparities in lifespan are often observed even among somewhat closely related species; for example, in the laboratory, wild-derived strains of the common house mouse have a maximum observed lifespan of approximately 6 years, while a similarly sized rodent, the naked mole rat, can live for over 30 years. Comparative biology of aging across the tree of life provides a tremendous opportunity for understanding the molecular and genetic basis underlying lifespan and aging. However, a lack of molecular and laboratory tools has limited the ability of researchers to take full advantage of the incredible diversity of aging phenotypes in nature. Recent developments in genomic technology have made it increasingly possible to study non-canonical model organisms for aging. One promising new genetic model organism amenable to a range of experimental interventions is the turquoise killifish (Nothobranchius furzeri). This fish species has a naturally short lifespan and undergoes a wide range of aging-related transformations. These fish have a fully sequenced genome and transcriptome, and killifish embryos are accessible to transgenesis and genome editing. Furthermore, different killifish species and populations show striking differences in lifespan, providing the opportunity for comparative analysis of aging. This Review introduces the natural life history of the turquoise killifish, its emerging applicability as an aging model system, the genetic tools that have been developed to study aging for this species and a summary of recent studies facilitated by these new tools.

Size-based physical properties of hard-shell clam (Mercenaria mercenaria) shell relevant to the design of mechanical processing equipment

The knowledge of physical properties of food products is of fundamental importance for efficient design, dimensioning, manufacturing and operation of different mechanical equipment used in the processing of these products. Clams of different sizes are utilized during processing, thus, all the sizes must be given adequate consideration for efficient processing. This study was conducted to investigate the size-based physical properties of hard-shell clam (Mercenaria mercenaria) shell relevant to the design of mechanical processing equipment. The sizes of the clam shells were identified and categorized as small, medium and large; and its effect on the physical properties were studied. The parameters investigated were length, width, thickness, arithmetic and geometric diameters, surface area, sphericity, aspect ratio, moisture content, bulk and true densities, porosity, clam shell weight, coefficient of static friction and angle of repose. Increase in the length and width of clam shells increased the arithmetic and geometric diameters, and the surface area, but decreased the sphericity and aspect ratio. Moisture content, bulk and true densities, porosity and clam shell weight increased with increase clam shell size. Coefficient of static friction of clam shell was highest on rubber surface and lowest on glass surface, and was positively correlated with size; while angle of repose decreased with size. There was an excellent agreement between the prediction of the normal distribution and the actual distribution of the clam shell sizes. All the parameters were significantly different with respect to clam shell size at p < 0.05, which makes a strong case for the consideration of clam shell size during processing.

Characteristics of a Novel Tyrosinase Gene Involved in the Formation of Shell Color in Hard Clam Meretrix meretrix

Hard clam (Meretrix meretrix) has a rich shell color variation among individuals from light yellow to bluish gray, brown red, and black, which may associating with melanin. Tyrosinase (Tyr) is a key rate-limiting enzyme for the biosynthesis of melanin, which affects the dark color of animal skin, hair, fur, scales and feathers. Here, we isolated and characterized the full-length cDNA sequence of M. meretrix tyrosinase gene (MmTyr) which encodes a protein with 689 amino acids. Sequence characteristics and phylogenetic analysis showed that there are a variety of Tyr genes in mollusks, which can be divided into different categories. The abundance of MmTyr transcript was detected in six tissues including mantle, adductor muscle, digestive gland, foot, gill and siphon of adult M. meretrix with qRT-PCR. The results showed a higher expression specifically in the mantle, digestive gland and siphon, which was consistent with the phenotypic color difference. In the embryos and larvae at different developmental stages, high expression was found in the trochophore larvae and juvenile clams. Among three M. meretrix strains with different shell colors, the expression level of MmTyr and total melanin content in the mantle edge both showed significant differences, suggesting that MmTyr is involved in the formation of shell color. The results obtained in this study will improve our understanding of molluscan tyrosinase gene function and molecular mechanism of shell color pattern determination.

Experimental acidification increases susceptibility of Mercenaria mercenaria to infection by Vibrio species

Ocean acidification alters seawater carbonate chemistry, which can have detrimental impacts for calcifying organisms such as bivalves. This study investigated the physiological cost of resilience to acidification in Mercenaria mercenaria, with a focus on overall immune performance following exposure to Vibrio spp. Larval and juvenile clams reared in seawater with high pCO2 (~1200 ppm) displayed an enhanced susceptibility to bacterial pathogens. Higher susceptibility to infection in clams grown under acidified conditions was derived from a lower immunity to infection more so than an increase in growth of bacteria under high pCO2. A reciprocal transplant of juvenile clams demonstrated the highest mortality amongst animals transplanted from low pCO2/high pH to high pCO2/low pH conditions and then exposed to bacterial pathogens. Collectively, these results suggest that increased pCO2 will result in immunocompromised larvae and juveniles, which could have complex and pernicious effects on hard clam populations.

Comparative evaluation of proximate compositions and taste attributes of three Asian hard clams (Meretrix meretrix) with different shell colors

ABSTRACT Meretrix meretrix with three shell colors (mottled shell, red shell, yellow shell) were analyzed for nutritive and taste attributes. Additionally, the influence of cooking on the taste active components was also evaluated. The three kinds of clams had higher crude protein contents. Alanine, glutamic acid, arginine, 5ʹ-adenosine monophosphate, Cl−, Na+, K+ and PO4 3- were the major taste compounds of Meretrix meretrix. In addition to PO4 3-, the contents of all major taste compounds decreased after cooking. Among raw samples, red shell clams had the highest value of equivalent umami concentration (EUC) and contents of Cl− and Na+, along with the lowest content of PO4 3-. In cooked samples, the value of EUC and the contents of Na+ and K+ in red shell clams were higher than those of yellow shell clams and lower than those of mottled shell clams. Furthermore, the contents of PO4 3- in red and yellow shell clams were higher than that in mottled shell clams. However, there were no significant differences in the amount of K+ among different raw samples and the amount of Cl− among different cooked samples.

Improving Model of Hard Clam (Meretrix lyrata) Seed Nursing in the Coastal Area - Case Study in Tra Vinh Province, Mekong River Delta, Vietnam

The model of clam seed nursery in the coastal area of Tra Vinh province was carried out from June 2019 to February 2020 in the coastal dune and tidal flat in Thanh Dat Cooperative. The clam seed source is the natural seed harvested in the coast of Tra Vinh province with the goal of exploiting and using local resources to provide clam seeds for the cooperative clam farming. The model consists of two phases: the first phase of nursing is in ponds on the coastal dune and the second phase of nursing is on the tidal flat in natural condition. It indicates that during the first phase, the input of model used 50 kg clam grade I (150,000 ind./ kg) was released into the nursing ponds, the nursing pond with oxygen supplementation is a good facility resulting high survival rate of 62.8% in comparison to 43.5% in case of pond without oxygen supplementation. In October 2019, total 285 kg of grade II clams (15,000 ind./ kg) was obtained and released on 6,000 m2 clam ground in Thanh Dat Cooperative. In February 2020, total 2.33 million clam individuals were harvested, it is about 3,880 kg clam seed with the size of 600 ind./ kg. The model of clam seed nursing in the tidal flat was completed with clam seed survival rate of 54.5%. All of clam seed is continued culturing to the commercial clam production on the same ground of Thanh Dat Cooperative.

Analysis of possibilities of using biomass from cherry and morello cherry stones for energy purposes

Growing demand for energy and care about natural environment is the motivation to find alternative sources of energy. One of them is biomass from cherry and morello cherry stones, which is food processing industry waste. Stones have fairly good physical properties regarding material for combustion. Cherry and morello cherry crop in Poland is at the level of 200 thousand tons yearly, and processing them generates a considerable amount of waste that consists of stones, which may be used for energy purposes. In the work, the initial water content (u), curves of combustion in different temperatures, percentage ash content, heat of combustion and percentage share of stone in the whole fruit were determined.

Carbon Mineralization Associated with Aquaculture of the Northern Quahog Mercenaria mercenaria

Molluscs mineralize carbon as calcium carbonate in shells within a protein matrix that is a small portion of the total shell mass. In parts of Florida, the northern quahog Mercenaria mercenaria is cultured in mesh bags in shallow coastal marine habitats. These habitats were selected by the State of Florida for their pre-existing lack of large molluscan populations, so most of the shell material harvested by aquaculture operations would not otherwise exist. The carbonate content of shell material was quantified by coulometry, and shell production was estimated per harvested clam, and per unit area per year. The majority of the shell material harvested (about 91%) was M. mercenaria, and the remainder came from other species of molluscs that grew in or on the mesh bags. Of the non-Mercenaria shell material, most (8.5% of total percentage) came from oysters (Crassostrea virginica and Ostrea stentina), and the rest from at least 37 other species of molluscs and other shelled taxa. Each harvested market-size clam represented approximately 2.93 g of mineralized carbon, including shell material that was not part of the marketed clams. Clam leases in full production produced about 1.0 × 103 g of mineralized carbon per square meter per year, including nonclam shell material, and the Florida northern quahog industry produced about 534 metric tons of mineralized carbon in 2008. This mineralization resulted in an estimated atmospheric efflux of 374 tons of metabolic-independent carbon in the form of carbon dioxide, from the Florida northern quahog industry in 2008.

Modelling crushing crab predation on bivalve prey using finite element analysis

ABSTRACT Amongst the many adaptive features of a bivalve shell, valve shape has been hypothesised to increase structural stability and to aid in withstanding crushing predation. Using Finite Element Analysis we modelled the crushing attack of a crab on a hard clam, soft clam, and blue mussel, assessing the effect of shell shape, size and thickness on their structural performance. Nanoindentation tests provide data on material properties. The hard clam is best suited to distribute applied loads evenly over a thick shell. Blue mussel shells work well when they are thin, and an increase in size is structurally disadvantageous. The soft clam accumulates the highest stresses; change in none of the tested variables improves its performance. The material properties and life habits of these taxa complement the structural responses of their shell shapes to crushing predation. Soft clams are poorly adapted to withstand crushing attacks, avoiding predators by living deeply burrowed in the substrate. Hard clams live shallower in the sediment, relying more on their thick valves to withstand attacks; these organisms are well adapted to disperse loads over a brittle shell. Epifaunal blue mussels absorb more energy than more brittle shells serving the organism well when small and thin.

Charcoal obtained from cherry stones in different carbonization atmospheres

The exploitation of using agro-industrial residues as the cherry stone to produce charcoal and activated carbon is very relevant nowadays due to the high demand of these materials and their environmental advantages.This work describes the methods to prepare charcoal from cherry stones (CS) using final heating temperature of 600 °C, with or without the application of an equal flow of nitrogen or air. The isothermal time has been of 2 h, an adequate time to study carbonisation by varying the atmosphere. The charcoal obtained has the appropriate characteristics as precursors of activated carbon. Of the three samples prepared in different atmospheres, *N, N∼ and AN, the third is an activated carbon.It is evidenced that the yield in material carbonaceous is somewhat lower when applying the nitrogen current and approximately 5 % less when applying the air current. For the different samples, in this work we have studied the effects of the atmosphere during the heat treatment of CS, the yield, the chemical composition and the structure, as well as the pore structure of the same.

Impacts of culture survival rate on culture cost and input factors: Case study of the hard clam (Meretrix meretrix) culture in Yunlin County, Taiwan

AbstractThis study applies a translog cost function model to analyze the culture costs and the use of input factors among three groups of hard clam farmer households in Yunlin County, Taiwan, with different survival rates (low‐intermediate, intermediate‐high, and high). The study found that farmer household production in the three observed groups all exhibited economies of scale and could significantly expand the scale of production to lower the average cost. For farmer households with high survival rates, production cost could be reduced by 2.16% by a 10% increase in output. Moreover, the study shows that the survival rate–cost interaction values of farmer households in the intermediate‐high and low‐intermediate survival rate clusters were negative. Therefore, any increase in the survival rate could help lower the culture cost of farmer households. For low‐intermediate farmers, the survival rate–cost interaction value was the most negative; any increase in the survival rate by 10% would decrease the cost per hectare by NT$23,424. For high survival‐rate households, seeding and capital were substitutes, and seeding and feed were complements. As such, farmers would reduce the use of seeding factors when increasing the use of capital and decreasing the use of feed.

Strong genetic differentiation of the clam Meretrix lamarckii in the China Sea revealed by mitochondrial DNA marker.

The hard clam Meretrix lamarckii is ecologically and economically important in the coastal regions of China. In this study, we evaluated the genetic diversity and population structure of six M. lamarckii populations in the East China Sea and the South China Sea using mitochondrial cytochrome c oxidase subunit 1 (COI) and cytochrome b (Cytb) genes. We obtained 582bp of partly sequences comprising 28 novel haplotypes of COI gene from 138 specimens and 1168bp of partly sequences comprising 22 novel haplotypes of Cytb gene from 125 specimens. The haplotype diversity of COI and Cytb genes ranged from 0.606 to 0.862 and 0.562 to 0.863, respectively. The nucleotide diversity ranged from 0.0015 to 0.0038 in COI gene and ranged from 0.0007 to 0.0032 in Cytb gene. Thus, there is moderate-level genetic diversity in M. lamarckii in the China Sea. The F-statistics showed that the Zhoushan (ZS) and Xiangshan (XS) populations were significantly (P < 0.01) differed from the populations of Wenzhou (WZ), Zhangpu (ZP), Shantou (ST), and Zhanjiang (ZJ) in both COI and Cytb genes. Both haplotypes network and plot of STRUCTURE analysis suggested obviously genetic divergence between East China Sea and South China Sea regions. Knowledge on genetic variation and population structure of M. lamarckii populations along the Southeast China Sea obtained from this study will support the aquaculture management and conservation of M. lamarckii in China.

Quantifying the impact of temperature variation on birnavirus transmission dynamics in hard clams Meretrix lusoria.

Susceptibility of hard clams Meretrix lusoria to birnavirus (BV) infections caused by temperature variations, from a mechanistic perspective, has rarely been explored. We used a deterministic susceptible-infectious-mortality (SIM) model to derive temperature-dependent key epidemiologic parameters based on data sets of viral infections in hard clams subjected to acute temperature changes. To parameterize seasonal pattern dependence, we estimated monthly based cumulative mortality and basic reproduction numbers (R0 ) between 1997 and 2017 by way of statistical analysis. Two alternative disease control models were also proposed to assess status of controlled temperature-mediated BV infection by using, respectively, control reproduction number (RC )-control line criterion and removal strategy-based control measure. We showed that based on RC -control strategy, when temperatures ranged from 15 to 26.8°C, proportion of susceptible hard clams removed should be at least 0.22%. Based on removal-control strategy, we found that by limiting pond water temperature to 25-30°C, together with increased removal rates and periods to remove hard clams, it is better to remove hard clams from June and August to reduce both mortality rate and spread of BV. Our results can be used to monitor BV transmission potential in hard clams that will contribute to government control strategy to eradicate future BV epidemics.

Sequence feature and expression profile of a tumor suppressor QM protein gene from hard clam Meretrix meretrix

The present study describes the molecular characterization and transcriptional features of a tumor suppressor QM protein gene, MmQM, in Meretrix meretrix. The full-length cDNA (819 bp) of MmQM consists of a 657 bp opening reading frame (ORF) encoding a 218 amino acid protein with a calculated molecular mass of 25.3 kDa and theoretical isoelectric point of 10.2. A ribosomal protein L10 signature, an SH3-binding motif, an antibiotic binding site, an amidation site and two protein kinase C phosphorylation sites were revealed from the MmQM sequence. Phylogenetic analysis showed that MmQM is clustered with previously identified mollusk QM proteins. MmQM mRNA transcripts were detectable in all of the examined tissues in a constitutive manner, and were significantly different from each other. After bacterial stimulation, the mRNA transcripts of MmQM in the hepatopancreas significantly increased. Hence, we conclude that MmQM could respond to pathogenic infections and it might play an important role in the innate immunity against microorganisms in the clam M. meretrix.

Bioaccumulation in Functionally Different Species: Ongoing Input of PCBs with Sediment Deposition to Activated Carbon Remediated Bed Sediments.

Activated carbon-amended bed sediments reduced total polychlorinated biphenyl (PCB) accumulation in 3 functionally different marine species, sandworms (Alitta virens), hard clams (Mercenaria mercenaria), and sheepshead minnows (Cyprinodon variegatus), during both clean and contaminated ongoing sediment inputs. Mesocosm experiments were conducted for 90 d to evaluate native, field-aged bed sediment PCBs, and ongoing input PCBs added 3 times a week. Simulated in situ remediation applied an activated carbon dose equal to the native organic carbon content that was premixed into the bed sediment for 1 mo. The highest bioaccumulation of native PCBs was in worms that remained in and directly ingested the sediment, whereas the highest bioaccumulation of the input PCBs was in fish that were exposed to the water column. When periodic PCB-contaminated sediment inputs were introduced to the water column, the activated carbon remedy had minimal effect on the input PCBs, whereas the native bed PCBs still dominated bioaccumulation in the control (no activated carbon). Therefore, remediation of only the local bedded sediment in environmental systems with ongoing contaminant inputs may have lower efficacy for fish and other pelagic and epibenthic organisms. While ongoing inputs continue to obscure remedial outcomes at contaminated sediment sites, the present study showed clear effectiveness of activated carbon amendment remediation on native PCBs despite these inputs but no remediation effectiveness for the input-associated PCBs (at least within the present study duration). Environ Toxicol Chem 2019;38:2326-2336. Published 2019 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Multi-trophic native and non-native prey naïveté shape marine invasion success

Invasive predators have caused rapid declines in many native prey species across the globe. Predator invasion success may be attributed to prey naïveté, or the absence of anti-predator behavior between native and non-native species. An understanding of the effects of naïveté at different timescales since introduction and across multiple trophic levels is lacking, however, particularly in marine systems. Given the central role of trophic interactions in invasion dynamics, this knowledge gap limits the ability to predict high impact predator invasions. Naïveté was examined across three trophic levels of marine invertebrates: a native basal prey (hard clam), two non-native intermediate predators (the recently-introduced Asian shore crab and the long-established European green crab), a native intermediate predator (juvenile blue crabs), and a native top predator (adult blue crab). We hypothesized that naïveté would be more pronounced in trophic interactions involving the recently-introduced non-native predator in comparison to the long-established non-native and native intermediate predators. We further hypothesized that the recently-introduced intermediate predator would both benefit from naïveté of the native basal prey and be hindered by higher mortality through its own naïveté to the native top predator. To test these hypotheses, three laboratory experiments and a field experiment were used. Consistent with our hypotheses, basal prey naïveté was most pronounced with the recently-introduced intermediate predator, and this increased the predator’s foraging success. This recently-introduced intermediate predator, however, exhibited an ineffective anti-predator response to the native top predator, and was also preyed upon more in the field than its long-established and native counterparts. Therefore, despite direct benefits from basal prey naïveté, the recently-introduced intermediate predator’s naïveté to its own predators may limit its invasion success. These results highlight the importance of a multi-trophic perspective on predator-prey dynamics to more fully understand the consequences of naïveté in invasion biology.