Argopecten Irradians Research Articles

Coastal livelihood resilience to abrupt environmental change: the role of social capital in a Peruvian bay

Abrupt environmental change, such as sudden shifts in temperature or salinity, can severely alter the functioning of marine ecosystems and cause dramatic impacts on the associated social systems. Resource users, who rely on ecosystem services provided by the ocean, are particularly vulnerable to such drastic events. Functioning social relationships (social capital) have recently been suggested as a key driver for recovery after disaster. Here, we study how small-scale fishers who conduct sea-ranching of the Peruvian bay scallop Argopecten purpuratus in Northern Peru dealt with the literal wipe-out of their target resources caused by the Coastal El Niño (CEN) of 2017 that heavily impacted the entire region. Adopting an ego-network approach complemented by qualitative information from expert interviews, we investigated how resource users drew on their social networks to cope with the disaster. Results suggested a significant positive correlation between more desirable post-disaster trajectories and the number of helpful social links of scallop farmer associations. Disentangling the temporal aspect of this pattern, we found that social capital established before the disaster was driving this correlation. Importantly, both economic and non-economic links were contributing to the observed patterns. This study emphasizes the importance of social capital for dealing with the effects of disasters following natural events. Having extensive social networks increases the capacity to mobilize resources and information when needed and is associated with more efficient recovery after abrupt environmental change. Mechanisms to foster and enhance social capital are key for preventive management actions aiming to build resilience within vulnerable communities facing accelerating global change.

Transcriptome Analysis Reveals MAPK/AMPK as a Key Regulator of the Inflammatory Response in PST Detoxification in Mytilus galloprovincialis and Argopecten irradians.

Paralytic shellfish toxins (PSTs) are an increasingly important source of pollution. Bivalves, as the main transmission medium, accumulate and metabolize PSTs while protecting themselves from damage. At present, the resistance mechanism of bivalves to PSTs is unclear. In this study, Mytilus galloprovincialis and Argopecten irradians were used as experimental shellfish species for in situ monitoring. We compared the inflammatory-related gene responses of the two shellfish during PSTs exposure by using transcriptomes. The results showed that the accumulation and metabolism rate of PSTs in M. galloprovincialis was five-fold higher than that in A. irradians. The inflammatory balance mechanism of M. galloprovincialis involved the co-regulation of the MAPK-based and AMPK-based anti-inflammatory pathways. A. irradians bore a higher risk of death because it did not have the balance system, and the regulation of apoptosis-related pathways such as the PI3K-AKT signaling pathway were upregulated. Taken together, the regulation of the inflammatory balance coincides with the ability of bivalves to cope with PSTs. Inflammation is an important factor that affects the metabolic pattern of PSTs in bivalves. This study provides new evidence to support the studies on the resistance mechanism of bivalves to PSTs.

Bacterial exudates as growth‐promoting agents for the cultivation of commercially relevant marine microalgal strains

AbstractIn laboratory and industrial cultivation of marine microalgae, it is customary to enrich cultures with macronutrients (N, P), chelated trace metals, and vitamins at ~104× concentrations found in nature to obtain high culture densities. Other naturally occurring growth‐promoting compounds found in local seawater are not enriched and remain at environmental concentrations. Microalgae may thus be deprived of the mutualistic contributions of co‐occurring microorganisms with which they have evolved complex chemical relationships. In the present study, we assess the direct (mixed bacteria–microalgae cultivation) and indirect (exposure to exudates only, without physical contact) effects of 10 bacterial strains on the growth of five marine microalgal strains used as feeds in marine aquaculture hatcheries. Bacterial strains were selected based upon previously reported growth‐promoting characteristics in plants or microalgae, or known release of probiotics. Our experiments demonstrate superior stimulation of microalgal growth by bacterial exudates, and without the presence of the bacteria that produced these exudates. However, response to bacterial exudate enrichment was dependent upon the microalgae strain and bacterial pairing. Exudates fromBacillus,Mesorhizobium, andPhaeobacterstrains were most effective, with 22%–69% increases in microalgal specific growth rate. Such findings indicate that bacterial exudates accelerate rate‐limiting processes governing nutrient acquisition, assimilation, or anabolism, and possibly algal release of exopolymeric substances. Maximal cell density, however, remained constrained by macronutrient limitation. Scaled‐up trials in an oyster hatchery confirmed the practical benefit of bacterial exudate culture medium enrichment and demonstrated the suitability of exudate‐enriched microalgae to feed hatchery‐reared bay scallops. This work presents a promising strategy to improve microalgal culture media formulations using bacterial exudate components as growth promoters, and is the first such study to identify specific pairings with relevance for aquaculture production.

Potential Roles of PTEN on Longevity in Two Closely Related Argopecten Scallops With Distinct Lifespans.

Phosphatase and tensin homolog deleted on chromosome ten (PTEN) has been found to regulate longevity through the PI3K/Akt/FoxO pathway and maintenance of genome integrity in worms, flies, and mammals. However, limited information is available on the roles of PTEN in longevity of aquatic animals. Here we extended this paradigm using two closely related Argopecten scallops, Argopecten purpuratus, and Argopecten irradians, with significantly distinct life spans, which are commercially important bivalve species for fishery and aquaculture in China, United States, Peru, and Chile. The ORFs of the ApPTEN and AiPTEN were 1,476 and 1,473 bp, which encoded 491 and 490 amino acids, respectively. There were 48 synonymous and 16 non-synonymous SNPs and one InDel of three nucleotides between ApPTEN and AiPTEN, resulting in variations in 15 amino acids and lack of S453 in AiPTEN. Differences in conformation and posttranslational modification were predicted between ApPTEN and AiPTEN, which may indicate different activities of ApPTEN and AiPTEN. When the animals were subjected to nutrition restriction, the expression of both ApPTEN and AiPTEN was upregulated, with AiPTEN responded faster and more robust than ApPTEN. Ionizing radiation induced significantly elevated expression of ApPTNE but not AiPTEN in the adductor muscle, and the mortality rate of A. purpuratus was significantly lower than that of A. irradians, indicating that ApPTNE may play a protective role by maintaining the genome integrity. RNAi of ApPTNE significantly downregulated the expression of its downstream regulated genes known to favor longevity, such as FoxO, Mn-SOD, and CAT. These results indicated that PTEN may contribute to the longevity of A. purpuratus through regulation of nutrient availability and genomic stability, probably via PI3K/Akt/FoxO pathway. Our study may provide new evidence for understanding of the conservative functions of PTEN in regulation of lifespan in animals and human, and it may also benefit the selection of scallops strains with long lifespan and thus larger size.

Tissue-Specific and Time-Dependent Expressions of PC4s in Bay Scallop (Argopecten irradians irradians) Reveal Function Allocation in Thermal Response.

Transcriptional coactivator p15 (PC4) encodes a structurally conserved but functionally diverse protein that plays crucial roles in RNAP-II-mediated transcription, DNA replication and damage repair. Although structures and functions of PC4 have been reported in most vertebrates and some invertebrates, the PC4 genes were less systematically identified and characterized in the bay scallop Argopecten irradians irradians. In this study, five PC4 genes (AiPC4s) were successfully identified in bay scallops via whole-genome scanning through in silico analysis. Protein structure and phylogenetic analyses of AiPC4s were conducted to determine the identities and evolutionary relationships of these genes. Expression levels of AiPC4s were assessed in embryos/larvae at all developmental stages, in healthy adult tissues and in different tissues (mantles, gills, hemocytes and hearts) being processed under 32 °C stress with different time durations (0 h, 6 h, 12 h, 24 h, 3 d, 6 d and 10 d). Spatiotemporal expression profiles of AiPC4s suggested the functional roles of the genes in embryos/larvae at all developmental stages and in healthy adult tissues in bay scallop. Expression regulations (up- and down-) of AiPC4s under high-temperature stress displayed both tissue-specific and time-dependent patterns with function allocations, revealing that AiPC4s performed differentiated functions in response to thermal stress. This work provides clues of molecular function allocation of PC4 in scallops in response to thermal stress and helps in illustrating how marine bivalves resist elevated seawater temperature.

Effect of different sous-vide cooking conditions on textural properties, protein physiochemical properties and microstructure of scallop (Argopecten irradians) adductor muscle

Among 26 sous-vide cooking conditions of scallop adductor muscle (SAM), 65 °C-5.5 h, 70 °C-1.5 h and 100 °C-5 min were selected by the differential scanning calorimetry analysis. After sous-vide cooking, the shear force, hardness, springiness, cohesiveness, chewiness and recoverability of SAM increased significantly compared to fresh sample. The cooking also changed the secondary structures of the proteins in SAM with the rising β-sheet and descending α-helix, and the chemical interactions with the rising hydrophobic interactions and disulfide bonds but the descending ionic bonds and hydrogen bonds. These caused the longitudinal shrinkage and transverse aggregation of muscle fibers, and the aggregation and cross-linking between myofibrils which led to the squeeze of immobile water from myofibril network structure. This indicated that the denaturation, oxidation, aggregation and cross-linking of proteins caused by heat treatment changed the microstructure and water distribution, which contributed to the increased textural indicators of sous-vide cooked SAM.

Novel antioxidant peptides from protein hydrolysates of scallop (Argopecten irradians) mantle using enzymatic and microbial methods: Preparation, purification, identification and characterization

The aim of this study was to isolate, purify, identify, and characterize novel antioxidant peptides from protein hydrolysates of scallop (Argopecten irradians) mantle. Antioxidant peptides were obtained following protein hydrolysis, using a neutral protease, and microbial fermentation which was carried out by Bacillus licheniformis CICC 20033 under optimized conditions. Antioxidant peptides from the scallop mantle hydrolysates were then purified through fractionation using ultrafiltration membranes, and the fraction (<3 kDa) showed the highest oxygen radical absorbance capacity (ORAC) with the value of 0.362 μM trolox equivalent (TE)/mg. Subsequently, this fraction furtherly purified by Sephadex G-15 chromatography and reversed-phase high performance liquid chromatography (RP-HPLC) showed that the ORAC value was 2.96 ± 0.10 μM TE/mg. The ORAC value of fermented hydrolysates increased from 0.359 μM TE/mg to 0.425 μM TE/mg through 3 kDa ultrafiltration membrane. Five peptides from hydrolysates by enzyme treatment and twelve peptides from fermented scallop mantle hydrolysates were identified using LC-MS/MS. All selected sequences except Lys-Asp-Ala-Ala-Lys-Thr-Lys showed clear differences in scavenging activity for various radicals, which were dependent on the content and position of charged polar amino acids, aromatic amino acids and sulfur-containing amino acid in sequences.

Additive and epistatic effects influence spectral tuning in molluscan retinochrome opsin.

The relationship between genotype and phenotype is non-trivial because of the often complex molecular pathways that make it difficult to unambiguously relate phenotypes to specific genotypes. Photopigments, comprising an opsin apoprotein bound to a light-absorbing chromophore, present an opportunity to directly relate the amino acid sequence to an absorbance peak phenotype (λmax). We examined this relationship by conducting a series of site-directed mutagenesis experiments of retinochrome, a non-visual opsin, from two closely related species: the common bay scallop, Argopecten irradians, and the king scallop, Pecten maximus. Using protein folding models, we identified three amino acid sites of likely functional importance and expressed mutated retinochrome proteins in vitro. Our results show that the mutation of amino acids lining the opsin binding pocket is responsible for fine spectral tuning, or small changes in the λmax of these light-sensitive proteins. Mutations resulted in a blue or red shift as predicted, but with dissimilar magnitudes. Shifts ranged from a 16 nm blue shift to a 12 nm red shift from the wild-type λmax. These mutations do not show an additive effect, but rather suggest the presence of epistatic interactions. This work highlights the importance of binding pocket shape in the evolution of spectral tuning and builds on our ability to relate genotypic changes to phenotypes in an emerging model for opsin functional analysis.

Making connections: predatory behavior, prey availability and environment. Editorial comment on the highlight article “Predation on planted and wild bay scallops (Argopecten irradians irradians) by busyconine whelks: studies of behavior incorporating acoustic telemetry” by M. Sclafani et al. 2022

Making connections: predatory behavior, prey availability and environment. Editorial comment on the highlight article “Predation on planted and wild bay scallops (Argopecten irradians irradians) by busyconine whelks: studies of behavior incorporating acoustic telemetry” by M. Sclafani et al. 2022

Predation on planted and wild bay scallops (Argopecten irradians irradians) by busyconine whelks: studies of behavior incorporating acoustic telemetry

Quantifying predator–prey interactions and gaining insights into predator behavior are crucial for optimizing restoration strategies. However, such knowledge is often lacking for marine invertebrates. We examined potential impacts of predation by channeled Busycotypus canaliculatus and knobbed whelks Busycon carica on natural and planted populations of bay scallops in the Peconic Bays, New York, through laboratory and field investigations. In lab experiments, mean predation rates exhibited by small channeled whelks were low: 0.06 and 0.005 scallops d−1 for adult and juvenile scallops, respectively. Predation rates of small knobbed whelks on juvenile scallops were 22 × higher. Eighty-six percent (86%) of scallops consumed by channeled whelks had undamaged shells, while 73% eaten by knobbed whelks had notched ventral margins. In field plots where scallop densities were manipulated via removals/plantings, whelks consumed ~ 2% of ~ 19,100 planted juveniles, whereas crabs and presumably finfish consumed > 40% overall. Acoustic telemetry revealed that tagged channeled whelks moved shorter distances and spent more time in plots planted with scallops versus those without scallops. Whelks spent more time in low versus high-density plots, but consumed far more scallops in the latter. In trials without scallops, whelk movement rates were 5 × higher, presumably due to increased exploratory behavior. Overall, whelks were most active during crepuscular hours and during periods of increasing wind speeds. Our results, combined with population abundance data, suggest that whelks (especially B. carica) are drawn to planted bay scallop aggregations, but probably contribute to relatively low overall mortality in the context of restoration efforts.

Toxicity response to benzo[α]pyrene exposure: Modulation of immune parameters of the bay scallop, Argopectenirradians

Bay scallops were exposed to four BaP concentrations (0.5, 1.0, 10 and 50 μg/L) for 72 h to elucidate their immune response. Immune parameters were evaluated by measuring nitric oxide (NO) levels in hemolymph. Additionally, we measured peptidoglycan recognition proteins (PGRP), fibrinogen-domain-containing protein (FReDC1), metallothionein (MT), and heat shock protein (HSP) 70 mRNA expression in digestive diverticula. NO as well as FReDC1 and MT expression in each BaP group increased significantly over time except for the BaP 0.5 group. The PGRP and HSP70 mRNA expression in the BaP 50 group increased in the range 6–24 h and then decreased. In situ hybridization also confirmed that there was higher MT mRNA expression in the BaP 50 group than in the control group at 72 h. Our results suggest that higher levels of BaP dampened scallop immune responses, while simultaneously reducing their ability to cope with oxidative stress and DNA damage. BaP exposure can be considered a potential immune inducer in bay scallop.

Transcriptomic analyses of hermaphroditic gonads at different stages revealing candidate genes for sex differentiation and gonad growth/maturation in QN Orange scallops

Argopecten scallops are hermaphroditic bivalves and commercially important in aquaculture. Up to now, the molecular mechanism of sex differentiation and gonad growth/maturation in hermaphroditic animals is still largely unknown. In this study, we analyzed the transcriptome of the gonads at different stages of the QN Orange scallop, a new scallop strain selected from the hybrids between the bay scallop and the Peruvian scallop. Among sex differentiation-related genes, 5 transcription factors (TFs) (1 SOX, 2 FOXL and 2 GATA) and 2 TGF-βs (2 BMP) were mainly expressed in the male part and 2 TFs (1 FOXL and 1GATA) and 2 TGF-βs (2 BMP) were mainly expressed in the female part of the gonads. Among gonad growth/maturation related genes, 1 TF (GATA) might be only involved in male gonad growth/maturation, 8 TFs (1 SOX, 1 WNT, 2 FOXL and 4 GATA) and 3 TGF-βs (1 GDF and 2 BMP) only participated in ovarian growth/maturation, 3TFs (1 SOX, 1 DMRT and 1 FOXL) and 2 TGF-βs (1 GDF and 1 BMP) might be involved in both male and female gonad growth/maturation. Based on the results of transcriptome and qRT-PCR, 11 genes were screened to be involved in sex differentiation and 16 genes might be involved in gonad growth/maturation. The results of this study may provide new insights into the understanding of the mechanisms of sex differentiation and gonad growth/maturation in hermaphroditic scallops.

Dynamics of phytoplankton community in scallop farming waters of the Bohai Sea and North Yellow Sea in China

BackgroundAs the major suppliers of food for higher consumers, phytoplankton are closely related to the yield, nutritional ingredients and even toxin contents of mariculture animals, potentially influencing the human health when they are consumed. With the increase of shellfish culture density, phytoplankton in the coastal waters have been excessively consumed in recent years, and the nutrients they depend on are becoming more and more limited, which severely restrict the shellfish mariculture and threaten the coastal ecosystems.ResultsIn the present study, nutrient concentrations, phytoplankton assemblages and scallop growth status were investigated in the main bay scallop farming waters of the Bohai Sea (Qinhuangdao site) and North Yellow Sea (Zhuanghe site) in 2018. Both phosphate and silicate limitations were observed at the two sites, with the major determinant of phytoplankton assemblages being silicate in Qinhuangdao and phosphate in Zhuanghe, respectively. The phytoplankton assemblages at the two sites displayed different community structures and succession patterns. The phytoplankton community was dominated by dinoflagellates and diatoms in Qinhuangdao, while dinoflagellates were the most abundant group in Zhuanghe, which accounted for 41.9% of the total phytoplankton abundance. The dominant genera of diatoms in Qinhuangdao were Skeletonema, Thalassiosira and Leptocylindrus, while those in Zhuanghe were Thalassiosira and Cyclotella. Greater biomass and more appropriate structure of phytoplankton contributed to higher growth rate and glycogen content of cultured bay scallops.ConclusionsOur study characterized the relationship between nutrient concentration, phytoplankton community and scallop mariculture in the main bay scallop farming waters in northern China. The results suggest that, as nutrient limitation intensified, dinoflagellates are becoming the dominant phytoplankton species in the scallop farming waters of the Bohai Sea and the North Yellow Sea, which is harmful to the coastal mariculture.

Globular C1q domain-containing protein from Pinctada fucata martensii participates in the immune defense process

The globular C1q domain-containing (C1qDC) protein can recognize a variety of ligands, such as pathogen-associated molecular patterns, and plays an important role in the innate immune response. Our previous studies showed that a novel globular C1q domain-containing protein (PmC1qDC-1) is involved in the damage repair process of pearl oyster shells. However, the function of PmC1qDC-1 in pearl oyster innate immunity remains unknown. In the present study, the high-level structural analysis showed that PmC1qDC-1 was a spherical structure composed of 10 strands and was similar to the AiC1qDC-2 of bay scallop (Argopecten irradians). In situ hybridization indicated that PmC1qDC-1 had strong fluorescence signal in gills. Furthermore, the mRNA expression of PmC1qDC-1 was highly induced at 6–48 h in gill after lipopolysaccharide, peptidoglycan and polyinosinic–polycytidylic acid stimulation. Additionally, we obtained the recombinant protein of PmC1qDC-1 (rPmC1qDC-1) and found that rPmC1qDC-1 had antibacterial activity against Gram-negative (i.e., Pseudomonas aeruginosa, Vibrio parahaemolyticus, Escherichia coli, and Aeromonas hydrophila) and Gram-positive (i.e., Staphylococcus aureus and Bacillus subtilis) bacteria. These results indicated that PmC1qDC-1 might play an important role in the immune response against bacteria and viruses. This study provides clues for further studying the immune defense of Pinctada fucata martensii against pathogens and exploring the evolution of the classic pathway of complement system.

Metabolomic and Transcriptomic Responses of Argopecten irradians concentricus to Thermal Stresses

The bay scallop southern subspecies, Argopecten irradians concentricus, which is widely cultured in southern China waters, is a eurythermal animal that is more adaptive to high-temperature waters but less tolerant to low-temperature waters. Despite that temperature is one of the most dominant environmental factors affecting dramatically its growth, survival, and hence production, the mechanism underlying the responses to thermal stress has not been explored in this animal. In this study, transcriptomic and metabolomic analyses were carried out in the adductor muscles of the bay scallop southern subspecies exposed to low and high thermal stresses. Transcriptomic analyses revealed that differentially expressed genes (DEGs) were enriched in the calcium ion, kinase activity, phosphatase activity, and lipid-related pathways in the group exposed to thermal stress, while most DEGs were enriched in the RNA processing pathways in the group exposed to low-temperature thermal stress. A large number of differentially expressed transcription factors involved in oxidation-reduction process, membrane-related pathways, transmembrane signaling receptor activity, and transduction-related pathways were induced by exposure to thermal stress. Results from metabolomic analyses showed that the retinol metabolism, inositol phosphate metabolism, and phosphatidylinositol pathways may be involved in the responses to high thermal stress, while more signaling pathways were enriched in the group exposed to low thermal stress. Integrated analyses of the transcriptomic and metabolomic data indicated that the degradation of valine, leucine, and isoleucine and the tricarboxylic acid cycle may be the major events induced by low and high thermal stress, and the retinol pathway may play critical roles in the responses of the scallops to high thermal stress. It seems that the bay scallop southern species have evolved distinct pathways in dealing with low and high thermal stress. Our results may provide useful information for marker-assisted selection of high-resistant strains in this scallop.

Different tea polyphenol treatments on lipid oxidation of scallop ( Argopecten irradians ) adductor muscle during hot air drying

This study investigated the effects of different tea polyphenol (TP) treatments (control, unmarinated, and marinated) on scallop adductor muscle lipid oxidation during hot air drying. Results showed that the marinated sample had the lowest peroxide value, thiobarbituric acid reactive substances, polyunsaturated fatty acids loss, free radical level, and lipoxygenase activity during drying, indicating that the marination process maximized the antioxidant effects of TP. These results were achieved by the distributing of TP on lipid oxidation site, effectively intercepting free radical chain reaction and inhibiting lipoxygenase activity. The significant loss of total phenolic content in the marinated sample confirmed this result. The control, unmarinated, and marinated sample lost 26.52%, 9.99%, and 6.46% of eicosapentaenoic acid and docosahexaenoic acid during drying, respectively, indicating that the marination more efficiently maintained its high nutritive value in terms of lipid. This study provided a more effective way of using TP to control lipid oxidation in seafood during drying. Novelty impact statement Marinated with TP improved its antioxidant effect during scallop drying. More than 26% of EPA + DHA lost in scallop adductor muscle, while less than 7% of EPA + DHA lost in marinated scallop adductor muscle during drying. Marinated with TP maintained the higher nutritive value of scallop during drying.

Materialities, discourses and governance: scallop culture in Sechura, Peru

ABSTRACT This paper looks at the institutional emergence, particularly space rights, within the culture of the Peruvian bay scallop (Argopecten purpuratus) in Sechura Bay. The institutional system developed within a period of 20 years from an open-access, gold rush scenario to a rather structured, formal activity – however, still relies on a lot of informality. This work uses the matrix provided by the material dependency framework presented in this special issue distinguishing between nature, human and hybrid-made materialities that influence the emergence of institutional structures, on the one axis and path-, inter- and goal dependencies on the other axis. In this work, we argue that existing natural (high environmental risks associated with scallop culture in this setting), hybrid (need to process quickly) and human-made (export-oriented production) materialities have shaped different path dependencies in institutional development in favour of larger firms who gradually took over the control of scallop production from small-scale producers, who in turn became piece wage labourers. Yet, the realities of both actors are necessarily intertwined, with informal loop holes being intentionally left open, shaping different institutional solutions over time. Applying the material dependency framework shows how materialities and goal dependencies are intertwined in this particular case of scallop bottom aquaculture.

Molecular characterization and SNPs association with growth‐related traits of myosin heavy chains from the pearl oyster Pinctada fucata martensii

Myosin heavy chains (MYHs) are important proteins in muscle growth and contraction, which may potentially enhance shellfish growth. In this study, the MYH gene from Pinctada fucata martensii (PmMYH) was studied. Sequence analysis revealed that it has an open reading frame of 5823 bp that encode 1940 polypeptide residues. Analysis of PmMYH showed four conserved domains, namely Myosin_N, MYSc, IQ and Myosin_tail_1. Blast analysis confirmed that PmMYH has a high identity with MYH protein sequences from Crassostrea virginica (87.25%), C. gigas (86.15%), Biomphalaria glabrata (78.8%), Pecten maximus (77.15%), Mizuhopecten yessoensis (75.78%) and Argopecten irradians (77.30%). Expression pattern analysis of PmMYH demonstrated that it is widely expressed in tissues and developmental stages, especially in the adductor muscles and late development stage. Furthermore, PmMYH also expressed significantly higher in individuals selected for fast growth compared with those selected for slow growth, thereby suggesting its role on growth-related traits. Ninety-five single nucleotide polymorphisms (SNPs) were identified in the exon region of PmMYH, and 18 of which were significantly associated with growth (p < 0.05). Of the 18 SNPs, 2 were also verified in two independent populations. Therefore, PmMYH and its SNPs could be used as for the gene-assisted selection of P. f. martensii.

Effects of salinity changes on the osmoregulatory and stress responses in the bay scallop Argopecten irradians

Effects of salinity changes on the osmoregulatory and stress responses in the bay scallop Argopecten irradians

Comparison of Visual Surveys Versus Dredging for Monitoring Bay Scallops (Argopecten irradians) in Seagrass Beds

Bay scallops (Argopecten irradians), once a profitable fishery species in North Carolina, have declined in population size following harmful algal blooms in the late 1980s. To prepare for future scallop restoration efforts, appropriate survey methods should be identified to evaluate the status of the population with respect to managing harvest. The North Carolina Division of Marine Fisheries monitors bay scallop populations in seagrass beds using a scallop dredge, though it is still unclear what the current natural densities of bay scallops are. In this study, visual surveys in three time treatments (5, 10, and 20 min) were compared with dredging in terms of quantifying scallop density and the catch per unit effort (CPUE) in seagrass beds in Core Sound, North Carolina. There was no significant difference in scallop density and the CPUE among visual survey time treatments. Scallop densities observed during visual surveys were three times higher than densities using a scallop dredge; however, the CPUE was five times higher using a scallop dredge compared with visual surveys. If visual surveys indicate the true natural density of bay scallops in this study system, then the dredge sampling efficiency for evaluating bay scallop density was 33%. Dredging for bay scallops can uproot seagrass and displace juvenile bay scallops. Visual surveys provide a low-impact method for identifying the distribution and abundance of bay scallops in seagrass bed habitats.