Argopecten Irradians Research Articles

Assessment of the Presence of Lipophilic Phycotoxins in Scallops (Argopecten purpuratus) Farmed along Peruvian Coastal Waters

Some harmful algal blooms produce lipophilic marine biotoxins (LMTs) such as okadaic acid (OA; and its analogs dinophysistoxins [DTXs]), yessotoxins (YTXs), pectenotoxins (PTXs), and azaspiracids (AZAs), all of which may accumulate in filter-feeding bivalve mollusks. European health regulations stipulate a limit of 160 μg/kg for OA or DTXs, PTXs, and AZAs and 3.75 mg/kg for YTXs. Argopecten purpuratus is a valuable commercial marine bivalve exploited in Peru. Despite its importance and the periodic reports of the presence of harmful algal blooms in Peruvian coastal waters, information regarding potential contamination of these scallops by LMTs is lacking. We evaluated LMTs in 115 samples of A. purpuratus collected between November 2013 and March 2015 from 18 production areas distributed along the Peruvian coast. The hepatopancreas, which accumulates most of the toxins in the scallop, was analyzed with liquid chromatography-tandem mass spectrometry to quantify OA in its free form, YTX, AZA-1, and PTX-2. Baseline separation was achieved in 19 min. Linearity (R2 > 0.997), precision (coefficient of variation < 15%), and limits of quantification (0.155 to 0.479 ng/mL) were satisfactory. YTX was found in 72 samples, and PTX-2 was found in 17 samples, but concentrations of both biotoxins were below the regulatory limits. Free OA and AZA-1 were not detected in the scallop samples. This atypical profile (i.e., presence of PTX-2 and absence of OA) may be linked to the presence of the dinoflagellate Dinophysis acuminata. The production of YTX could be associated with the phytoplankton Gonyaulax spinifera and Protoceratium reticulatum. This is the first systematic assessment of the four types of LMTs in shellfish from Peruvian coastal waters. The results suggest low prevalence of LMTs in Peruvian bay scallops but support continued surveillance and analysis of LMTs in Peru.

Acclimatization in the bay scallop Argopecten irradians along a eutrophication gradient: insights from heartbeat rate measurements during a simulated hypoxic event

ABSTRACT Coastal hypoxia can negatively impact shellfish, but it is unclear if exposure to intensifying diel-cycling hypoxia alters shellfish susceptibility to severe hypoxic events in late summer. In this study, bay scallops (Argopecten irradians) were acclimatized for 50 days at 5 sites along a eutrophication gradient, where scallops rarely, occasionally and frequently encountered hypoxic conditions. In a laboratory experiment, scallops were then exposed to a 24-h hypoxic event and heartbeat rates were recorded with non-invasive infrared sensors during the initial oxygen decline, during extended hypoxia, and for one hour after re-establishment of normoxia. Irrespective of acclimatization site, scallops sustained increased heartbeat rates during hypoxia, but cardiac responses were less pronounced in scallops that frequently encountered hypoxia during acclimatization. This study suggests that cardiac responses to changes in dissolved oxygen concentrations can be affected by exposure history, which may have important ramifications for scallop ecophysiology and resilience in dynamic coastal environments.

Bay Scallop Growth Rates as Measured by Citizen-Scientist Partners During Restoration Efforts in Florida

Local bay scallop Argopecten irradians populations are threatened or depleted in southwest Florida estuaries (Pinellas through Lee Counties) and in the Panhandle (Bay through Escambia Counties), and community-driven restoration efforts have been ongoing for many years. To obtain juvenile scallops for use in restoration, wild larvae (spat) were allowed to settle on suitable surfaces (settlement traps) at sites known to still have high larval supply. Traps used to harvest spat were constructed with enhanced surface area relative to routine monitoring traps. Enhanced traps resulted in 142 ± 317.1 (mean ± SD) spat per trap and a maximum of 2,321 spat on a single trap, whereas the routine traps resulted in 67 ± 146.7 spat per trap and a maximum of 726. Spat were harvested each winter (2008–2012) from either St. Andrew Bay or Tampa Bay and delivered to restoration sites where citizen-scientists or collaborators measured the growth (shell heights) and mortality (live count) of 25–50 scallops within 3–25 cages each month. Most cages were hung from their own dock or the dock of a partner organization. Scientists from the lead agency also measured growth of caged scallops. Thus, simultaneous sampling occurred across a large geographical range with varied organizations and skill levels. In the shortest trials, survival remained very high, and in most years involving prolonged efforts, some of the planted scallops survived long enough to reach a size where spawning likely occurred. A maximum survival period of 559 days and the greatest mean shell height (65.18 ± 2.48 mm) of caged scallops were observed in Sarasota Bay in 2012. The observed growth in restoration cages fit previously described patterns for Florida Bay scallops, reaching maximum sizes between 60 and 70 mm shell height in 1 y. Mean daily growth rates (mm/day ± SD) increased as latitude decreased: St. Andrew Bay, 0.15 ± 0.096 y; Tampa Bay, 0.21 ± 0.124; Sarasota Bay, 0.22 ± 0.134; Charlotte Harbor, 0.28 ± 0.112; and Pine Island Sound, 0.29 ± 0.086). Temperature, scallop shell height, and the number of days in captivity (a proxy for age) generally had only minor or no effect on growth rates. When combined, the process of collecting wild spat and growing those scallops in cages using volunteer networks offers the advantages of community engagement, relatively low costs, minimal technical skill requirements, and reduced threat of loss of genetic diversity.

Heavy metals pollution and health risk assessment in farmed scallops: Low level of Cd in coastal water could lead to high risk of seafood

Scallops are one of the most common bivalves, large-scale farmed in the coastal areas of China. Three species of scallops (Chlamys farreri, Argopecten irradians and Patinopecten yessoensis) from 10 samples sites along the Bohai Sea and the Yellow Sea were collected to investigate species-specific and tissues-specific bioaccumulation, spatial-temporal distribution and health risks for people. Cd must be paid attention since Cd concentrations in 96% of scallop samples exceeded standard with the highest Cd bioaccumulation potentials (BCF) >10,000 while those of the other metals were less than the corresponding limits except Zn with exceeding-limit percentage of 13%. The metal pollution index values showed that A. irradians could accumulate more metals than the other two species, and scallops in the Bohai Sea were polluted more seriously by heavy metals than in the Yellow Sea. The capacities of tissues in scallops to accumulate metals generally followed the order of digestive gland > gill > adductor muscle. However, Zn accumulated in gill was more than that in digestive gland and muscle. Adults and children would face the non-cancer risks because of the accumulation Cd in scallops based on health risk assessment. Cd was the major contributor of health risk to account for 85% of total hazard quotient and 48% of total cancer risk. Scallops could accumulate Cd rapidly from ambient environments to cause health risks according to the transplantation test. Moreover, the recommended maximum edible amounts of whole scallops were 127/63 g/week for adult/children on the basis of the provisional tolerance weekly intake. Humans are recommended to only consume adductor muscles for reducing health risks.

Acclimatization in the bay scallop Argopecten irradians along an eutrophication gradient: Insights from heartbeat rate measurements during a simulated hypoxic event

Acclimatization in the bay scallop Argopecten irradians along an eutrophication gradient: Insights from heartbeat rate measurements during a simulated hypoxic event

Successful restoration of seagrass beds

Ecosystem Recovery Since 1999, broadcasting more than 70 million seeds of the seagrass Zostera marina into coastal lagoons in Virginia has led to the reestablishment of more than 3600 hectares of previously lost seagrass beds. Orth et al. found that seagrass recovery led to rapid increases in the production and diversity of animals, increases in carbon and nitrogen sequestration, decreases in turbidity, and increases in previously depleted bay scallops. This is one of the larger success stories of ecosystem restoration and demonstrates that reversal of ecological collapse is possible when sustained initial efforts lead to positive feedbacks that support ecosystem recovery. Sci. Adv. 10.1126/sciadv.abc6434 (2020).

Differences in oxidative susceptibilities between glycerophosphocholine and glycerophosphoethanolamine in dried scallop (Argopecten irradians) adductor muscle during storage: an oxidation kinetic assessment.

Phospholipids, the main lipid component in marine shellfish, mainly comprise glycerophosphocholine (GPC) and glycerophosphoethanolamine (GPE). GPC and GPE in marine shellfish, especially scallop, carry n-3 long-chain polyunsaturated fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), although different types of glycerophospholipids (GP) have different health benefits on human health. Moreover, different GP subclasses such as GPC and GPE have different oxidative susceptibilities in complex food systems. The present study compared the oxidative susceptibilities of GPC and GPE in dried scallop during storage by high-performance liquid chromatography-tandem mass spectrometry and kinetic models, and also investigated the effects of natural phenolic antioxidant on their susceptibilities. The results showed that GPC and GPE molecular species (carrying EPA or DHA) contents in samples continuously reduced during storage at two different temperatures. The first-order kinetic model better reflected the changes of GPC and GPE molecular species (carrying EPA or DHA) in samples than the zero-order kinetic model during storage. According to the oxidation rate (k) obtained from first-order kinetic models, GPE possessed a greater oxidation rate than GPC during storage. Moreover, the results showed that antioxidants of bamboo leaves (AOB, polar polyphenolic antioxidants) significantly decreased the oxidation rates of GPC and GPE molecular species (carrying EPA or DHA) in samples during storage, and GPC could be more effectively protected by AOB compared to GPE. The present study provides a practical method for accurately evaluating the oxidative susceptibility of different phospholipid classes in complex food systems. © 2020 Society of Chemical Industry.

Effects of antioxidants of bamboo leaves (AOB) on the oxidative susceptibility of glycerophosphocholine and glycerophosphoethanolamine in dried scallop (Argopecten irradians) adductor muscle during storage

Phospholipids (PLs), the main lipid component in marine shellfish, consist mainly of glycerophosphocholine (GPC) and glycerophosphoethanolamine (GPE). This work compared the oxidative susceptibility of GPC and GPE in dried shellfish during storage and also investigated the effects of natural phenolic antioxidant on such oxidative susceptibility. The content of four representative polyunsaturated fatty acids (C18:3 n-3, C20:4 n-6, C20:5 n-3, and C22:6 n-3) esterified onto GPC or GPE in dried scallop adductor muscle during storage at two temperatures were matched with first-order kinetic models, in order to ascertain the oxidation reaction rate constant (k). The results showed that GPE possessed greater oxidation rate than GPC during storage, and GPC could be more effectively protected by the antioxidants of bamboo leaves (AOB, polar polyphenolic antioxidants) compared with GPE. This study provides a practical method for accurate evaluation of oxidative susceptibility of different PL classes in complex food systems.

A Global Overview of Restorative Shellfish Mariculture

Farming of marine organisms (mariculture) represented 36% of global aquaculture, with molluscs representing 58.8% in live weight. Mollusc populations in some locations are, however, threatened by degradation of the ecosystems and/or over-fishing. This threat is increasingly being addressed through Restorative Shellfish Mariculture (RSM), as opposed to mariculture alone. There is no general consensus in the literature on what can and cannot be considered RSM. While maximization of benefits other than provisioning services is often considered a prerequisite, in other cases the maximization of fisheries yields is prioritised. Here we define RSM as the farming of marine shellfish, implying some form of intervention during the species life cycle, in order to address negative socio-ecological issues arising from the unsustainable use of marine ecosystems, independent of the final ownership regime of the resource. Strategies for developing RSM were reviewed and classified along a gradient from the most conservation-oriented (e.g. habitat restoration, reintroduction of locally extinct endangered species), to the most fisheries-oriented (including some forms of fisheries enhancement), and classified as Non-hatchery Dependent or Hatchery Dependent strategies. We reviewed the targeted species and strategies implemented across 584 individual projects developed in the last decades in North America, Europe, Asia, Oceania and South America. We found that some 48 species, including 34 bivalves and 15 gastropods were targets of RSM in 34 countries. US projects accounted for ca. three quarters of the total (N=438), with Philippines, Japan and Australia also being home to a large number. More than 90% of the projects involved five species, namely the eastern oyster (Crassostrea virginica, N=379), the giant clam (Tridacna gigas, N=65), the Olympia oyster (Ostrea lurida, N=25), the bay scallop (Argopecten irradians, N=25) and the hard clam (Mercenaria mercenaria,N=15). Of the RSM projects, 51% used Non-hatchery dependent methods, mostly habitat restoration providing substrata for settlement, whilesome 49% involved hatcheries. Some three percent of the projects combined both methods. This review provides an overview of the breadth and depth and aims of RSM globally, develops a broad definition of the activity, and proposes a structure for classifying RSM.

Recreational Harvesting of the Florida Bay Scallop: Hernando County

A full-color map identifying access routes to the boat ramps and marinas in Hernando County, plus the latest information on scallops and scalloping, the recommended equipment you will want to bring, and a few tasty recipes for preparing Florida’s best summertime catch.

Effects of natural trypsin inhibitor from soybean on texture deterioration of the bay scallop (Argopecten irradians) during cold storage and its mechanism

SummaryIn this study, the inhibitory effects of natural trypsin inhibitor from soybean (SBTI) on texture deterioration of adductor muscle of scallop (AMS) during cold storage and its mechanism were revealed by determining the changes of structural proteins of AMS in situ and in vitro, respectively. Results indicated that the endogenous proteolysis resulted in the disintegration of connective tissue proteins, the degradation of myosin and actin, as well as the reduction of α‐helix, the increase of β‐sheet and amino acid side chains, and the exposure of tryptophan residues of isolated myofibrillar proteins (MPs). These changes in structural proteins contribute to the texture deterioration of AMS as reflected in a significant decrease in hardness, chewiness, adhesiveness and springiness, but a significant increase in cohesiveness. SBTI significantly inhibited the conformational changes of structural proteins caused by endogenous proteolysis, improved the MP gel‐forming ability and consequently retarded the texture deterioration of AMS.

Acclimatization in the bay scallop Argopecten irradians along a eutrophication gradient: Insights from heartbeat rate measurements during a simulated hypoxic event

Acclimatization in the bay scallop Argopecten irradians along a eutrophication gradient: Insights from heartbeat rate measurements during a simulated hypoxic event

Response to selection for growth in the second generation of two shell color lines of the bay scallop Argopecten irradians

The bay scallop Argopecten irradians is one of the most commercially important aquaculture species in China. A. irradians with two different shell color (red and black) from cultured stocks in China were used to establish two mass-selected strains (red shell line and black shell line) for fast growth, and a positive response to selection for fast growth was observed in the first generations. To determine whether continuous progress can be achieved by selection for growth, we evaluated response to selection for the second generations of the two shell color lines. At grow-out stage, a genetic gain of 13.23%–15.71%, selection response of 1.62–1.71 and realized heritability of 0.43–0.45 for shell length were observed in the selective breeding strains after two generations of selection. The current response to selection for growth obtained in the second-generation selection strains suggests that a large amount of genetic variance still remains in the selected strains and there is a potential for sustained genetic improvement in growth-related traits in these strains through selective breeding. The results obtained in this study provides important information for future breeding programs for A. irradians.

Selection of a carotenoid-rich scallop strain, QN Orange, from the inter-specific hybrids between the bay scallop and the Peruvian scallop

In our previous study, we reported the selection of ‘Bohai Red’, a new scallop strain with improved performance in growth from the hybrids between the bay scallop and the Peruvian scallop. In this study, we selected another new strain, the ‘QN Orange’ scallop, with orange adductor muscles, from the same hybrid cohort as the origin of ‘Bohai Red’. In brief, during the selection of the ‘Bohai Red’ strain, a small F1 cohort was produced through mass spawning of a large cohort of the bay scallop-Peruvian scallop hybrids and reproduced consecutively to obtain the F2-F3 cohorts with size-selected brood stocks. About 500 scallops with orange adductor muscles and shells were selected from the F3 selection cohort to form the base selection cohort (G0). The G1-G6 cohorts were reproduced with size-selected brood stocks with orange adductor muscles and orange shells from the G0-G5 cohorts, respectively. The results showed that the percentage of scallops with orange adductor muscles was 88.9% in G1, 92.3% in G2, 92.0% in G3, 94.9% in G4, 96.6% in G5 and 97.4% in G6, respectively. No significant difference in growth was found between the new selection cohort and the control ‘Bohai Red’ selection cohort, however, compared with the control bay scallop cohort, the average shell height, whole weight and adductor muscle weight of the new selection strain were 4.5%, 30.4% and 16.3% higher in G1, 4.1%, 40.6% and 65.2% higher in G2, 20.3%, 50.3% and 88.9% higher in G3, and 17.7%, 73.9% and 80.8% higher in G4, respectively. Thus, through continuous selection, we have obtained a new scallop strain with orange adductor muscle/orange shell and improved growth from the bay scallop-Peruvian scallop hybrids, which was named ‘QN Orange’ scallop.

Exposure of bay scallop Argopecten irradians to micro-polystyrene: Bioaccumulation and toxicity

Marine microplastic pollution poses a threat to aquatic organisms, including bivalves. In this study, we investigated the accumulation of microplastics and their elicited antioxidant stress response in the bay scallop Argopecten irradians. Scallops were exposed to 1 μm diameter micro-polystyrene (MP) beads at 10, 100, and 1000 beads/mL concentrations for a 7 day period. Bead presence in the digestive diverticula and defense responses in the digestive diverticula and hemolymph were measured at 1, 3, 5, and 7 days. The activity and expression of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) and H2O2 in the digestive diverticula and/or hemolymph of scallops increased with microplastic concentration and exposure duration. These results suggest that microplastics can accumulate in the digestive diverticula of A. irradians, and that exposure to microplastics induces oxidative stress in bivalves. It is likely that exposure to high concentrations of micro- or nano-sized plastic particles could potentially have adverse effects in bivalves.

Exposure to domoic acid causes oxidative stress in bay scallops Argopecten irradians

The neurotoxin domoic acid (DA) is produced by Pseudo-nitzschia spp. during harmful algal blooms and is linked to amnesic shellfish poisoning. This toxin is particularly problematic in the culture of bivalves for human consumption. In this study, we exposed bay scallops to 20, 40, and 60 ng/ml DA and examined toxin accumulation and stress response at 3, 6, 12, 24, 36, and 48 h of exposure. Oxidative stress was determined by measuring the levels of superoxide dismutase (SOD), catalase (CAT), heat shock protein 90 (HSP90), and metallothionein (MT) in the digestive diverticula and/or hemolymph and by determining H2O2 concentration in hemolymph. We also observed histological changes to gills following exposure to DA in order to determine changes in melanization. We found that scallops accumulated a maximum of 2.61 ng/ml DA in their digestive diverticula when exposed to 60 ng/ml. Stress indices rose under higher DA concentrations, and HSP levels increased under exposure to higher concentrations of DA. However, mRNA expression and activity of other stress parameters showed peaks at different times during exposure, with subsequent declines. Epithelial melanization of gills indicated a strong positive response to DA at 60 ng/ml for 48 h (P < 0.05). These results indicate that exposure to DA induces oxidative stress, disrupts metabolism, and has negative effects on the defense systems of bay scallops.

The effect of elevated pCO2 on cadmium resistance of a globally important diatom

Cadmium (Cd) pollution is a widespread threat to marine life, and ongoing ocean acidification (OA) is predicted to impact bio-toxicity of Cd compounds. However, the cascading effects of changed Cd toxicity to marine primary producers are not well characterized. Here, we studied the impact of OA on Cd toxicity responses in a globally important diatom Phaeodactylum tricornutum under both ambient and elevated pCO2 conditions. We found that increased pCO2 alleviated the impact of additive Cd toxicity on P. tricornutum not only under controlled indoor experiments but also in outdoor mesocosm experiments that reflect more natural growth conditions. Transcriptome analysis suggested that genes involved in Cd efflux and phytochelatin production were up-regulated and genes involved in Cd influx were down-regulated in long-term selected lineages under elevated pCO2. We further found a significant reduction of Cd transfer across trophic level, when the scallop Argopecten irradians was fed with Cd-exposed P. tricornutum previously cultured under elevated pCO2. Our results indicate that after long-term selection of P. tricornutum exposed to future OA conditions (i.e. elevated pCO2), the diatom alters its Cd detoxification strategy, which could have broader impacts on the bio-geochemical cycle of Cd in the marine ecosystem.

Action of endogenous proteases on texture deterioration of the bay scallop (Argopecten irradians) adductor muscle during cold storage and its mechanism

Texture deterioration occurs in adductor muscle of scallop (Argopecten irradians) (AMS) after 5 d of cold storage. Principal component analysis indicated the texture deterioration resulted in significant decrease of hardness, springiness, adhesiveness and chewiness, but significantly increased cohesiveness. Endogenous proteases degraded structural proteins, among which cysteine proteases were mainly responsible for myofibrillar proteins (MPs) degradation, while serine proteases degraded both MPs and connective tissue proteins. Pearson coefficient analysis showed that texture indicators significantly correlated with structural protein indicators in AMS. To be more specific, the hardness, springiness, adhesiveness and chewiness negatively correlated with myofibrillar fragmentation index, soluble hydroxyproline (Hyp) and soluble glycosaminoglycans, but positively correlated with solubility of MPs and water holding capacity. Meanwhile, the cohesiveness positively correlated with soluble Hyp. The Taylor diagram and Hierarchical cluster analysis confirmed that the inhibitors of cysteine and serine proteases could effectively retard textural deterioration of AMS during 5 d of cold storage.

Draft genomes of two Atlantic bay scallop subspecies Argopecten irradians irradians and A. i. concentricus

The two subspecies of Atlantic bay scallop (Argopecten irradians), A. i. irradians and A. i. concentricus, are economically important aquacultural species in northern and southern China. Here, we performed the whole-genome sequencing, assembly, and gene annotation and produced draft genomes for both subspecies. In total, 253.17 and 272.97 gigabases (Gb) of raw reads were generated from Illumina Hiseq and PacBio platforms for A. i. irradians and A. i. concentricus, respectively. Draft genomes of 835.7 Mb and 874.82 Mb were assembled for the two subspecies, accounting for 83.9% and 89.79% of the estimated sizes of their corresponding genomes, respectively. The contig N50 and scaffold N50 were 78.54 kb and 1.53 Mb for the A. i. irradians genome, and those for the A. i. concentricus genome were 63.73 kb and 1.25 Mb. Moreover, 26,777 and 25,979 protein-coding genes were predicted for A. i. irradians and A. i. concentricus, respectively. These valuable genome assemblies lay a solid foundation for future theoretical studies and provide guidance for practical scallop breeding.

High-resolution linkage and quantitative trait locus mapping using an interspecific cross between Argopecten irradians irradians (♀) and A. purpuratus (♂)

The bay scallop and Peruvian scallop are economically important species. Interspecific hybrids of these two scallops outperformed both of their parent species in multiple growth traits but exhibited decreased fertility, which provides good models for the study of heterosis and species divergence. Genetic mapping serves as a chromosomal-level framework to investigate the molecular mechanisms of hybridization and introgression. In this study, high-resolution linkage maps were constructed for the bay and Peruvian scallops with an interspecific hybrid family. The linkage map of the bay scallop covered over 98.9% of the whole genome with 2994 mapped markers and the average marker interval of 0.32 cM. For the Peruvian scallop, 1585 markers were mapped with the average maker interval of 0.51 cM, covering 97.7% of the genome. Both the two linkage maps have 16 linkage groups, corresponding to the haploid chromosome number of the two species. Approximately, 54.5% of markers exhibited significant deviation from the expected Mendelian ratio of segregation, lending insights into the intrinsic incompatibility between the two species. QTLs related to growth and shell coloration were detected, which could explain 13.1% and 74.9% of the phenotypic variance, respectively. This represents important information for further evaluation. These findings are an important addition to the genomic resources for scallop genetic studies, and are especially useful for investigations on genomic incompatibility for hybridization, genome evolution of closely related species, and genetic enhancement programs in aquaculture.