Scallop Growth Research Articles

AMPK-mediated regulation of cardiac energy metabolism: Implications for thermotolerance in Argopecten irradians irradians

AMPK is a key regulator of metabolism in eukaryotes across various pathways related to energy regulation. Although extensive investigations of AMPK have been conducted in mammals and some model organisms, research on AMPK in scallops is comparatively limited. In this study, three AMPK family genes (AiAMPKα, AiAMPKβ and AiAMPKγ) in scallop Argopecten irradians irradians were identified through genome scanning. Structure prediction and phylogenetic analyses of AiAMPKs were performed to determine their structural features and evolutionary relationships. Spatiotemporal expression patterns of AiAMPKs at different developmental stages and in healthy adult tissues were analyzed to elucidate the function of AiAMPKs in bay scallops’ growth and development. The spatiotemporally specific expression of AiAMPKs implied their important roles in growth and development of bay scallops. Heat stress experiment was performed to determine the regulations of AiAMPKs in four kinds of thermosensitive tissues. Expression profiles revealed distinct molecular mechanisms of AiAMPKs in different tissues in response to heat stress: significant down-regulations in mobile hemocytes, but dominant up-regulations occurring in stationary gills, mantles and hearts. Functional verification including knock-down of AiAMPKα and inhibition of AiAMPK was separately conducted in the thermotolerant tissue heart at the post-transcription and translation levels. The thermotolerant index Arrhenius break temperature (ABT) showed a significant decrease and the rate-amplitude product (RAP) peaked earlier in the individuals after RNAi targeting AiAMPKα, displaying an earlier transition to anaerobic metabolism under heat stress, indicating an impairing ability of aerobic metabolism. After AiAMPK inhibition, widespread down-regulations of genes in key energy metabolism pathways, RNA polymerase II-mediated transcription, and aminoacyl-tRNA synthesis pathways were obviously observed, revealing the post-translational inhibition of AiAMPK hindered cardiac energy metabolism, basal transcription and translation. Overall, our findings provide evidences for exploring the molecular mechanisms of energy regulation in thermotolerant traits in bay scallops under ongoing global warming.

Trade-off between growth and reproduction in Argopecten purpuratus (L.) scallops exposed to medium-term hypoxia and acidification

Peruvian bays that are home to aquatic organisms of commercial interest are increasingly affected by hypoxia and low pH events. These stressors produce unfavorable conditions for the aquatic fauna, leading to mass mortality events. In this study, we evaluated the ecophysiological responses of the scallop Argopecten purpuratus exposed to moderate hypoxia (20% DO saturation) and low pH (OA, pH 7.4) using a 2 × 2 factorial design. We found that a 51-day exposure to low pH (OA treatment) had greater negative effects on A. purpuratus performances than hypoxia (lower survival and decreased clearance and calcification rates), but stimulated early gonad maturation. The survival rate was 1.3-fold higher under hypoxia than under acidic treatment. The interaction between hypoxia and low pH had an antagonistic effect on survival, since the combined treatment (HOA) resulted in lower scallop mortality than the single stress treatments. Calcification was negatively affected by all stress treatments, whereas hypoxia and OA both stimulated gametogenesis. OA treatment resulted in higher frequencies of previtellogenic and vitellogenic oocytes, greater gonad coverage area, and lower frequency of atretic oocytes, suggesting higher reproductive potential. HOA was positively related to oocyte development and high frequency of post-vitellogenic and atretic oocytes. These results suggest that, due to hypoxia and low pH, feeding is reduced and energy allocation prioritizes scallop gonad maturation. This trend would have negative effects on scallop growth and calcification, while increased reproduction under environmental stress could mitigate the effect on recruitment.

Offshore Wind Farms in South Korea: A Potential Site for Scallop Culture

Owing to the constant wind generated by the vast ocean, energy production from offshore wind farms (OWFs) plays an important role in the expansion of renewable energy. However, areas close to large wind farms are often left unutilized, and aquaculture farmers find it difficult to efficiently utilize these unoccupied spaces due to limited information showing the feasibility of utilization of OWFs as potential scallop culture sites. To analyze whether the two scallop species Zhikong scallop (Chlamys farreri) and bay scallop (Argopecten irradians) can be grown at OWFs of Gochang and Buan, Jeollabuk-do, Republic of Korea, the growth characteristics of the two scallop species were analyzed and compared with those grown at the Tongyeong Megacosm Test Station. The results clearly showed that the growth of scallops at the OWF was significantly lower with respect to the shell lengths, height, width, and weight, compared to those grown at the megacosm station. However, scallops grown at the OWF still showed consistent growth in parallel with those grown at the megacosm test station. Yet, there was a species-specific mortality rate between the two sites. In addition, our results suggest that temperature may be a key determinant of the growth of C. farreri and A. irradians. Overall, this study contributes to establishing a foundation for the stable and continuous farming of marine bivalves (e.g., clams, oysters, mussels, and scallops) in OWF areas.

Physiological responses of scallops and mussels to environmental variability: Implications for future shellfish aquaculture

Puget Sound (Washington, USA) is a large estuary, known for its profitable shellfish aquaculture industry. However, in the past decade, scientists have observed strong acidification, hypoxia, and temperature anomalies in Puget Sound. These co-occurring environmental stressors are a threat to marine ecosystems and shellfish aquaculture. Our research assesses how environmental variability in Puget Sound impacts two ecologically and economically important bivalves, the purple-hinge rock scallop (Crassodoma gigantea) and Mediterranean mussel (Mytilus galloprovincialis). Our study examines the effect of depth and seasonality on the physiology of these two important bivalves to gain insight into ideal grow-out conditions in an aquaculture setting, improving the yield and quality of this sustainable protein source. To do this, we used Hood Canal (located in Puget Sound) as a natural multiple-stressor laboratory, which allowed us to study acclimatization capacity of shellfish in their natural habitat and provide the aquaculture industry information about differences in growth rate, shell strength, and nutritional sources across depths and seasons. Bivalves were outplanted at two depths (5 and 30 m) and collected after 3.5 and 7.5 months. To maximize mussel and scallop growth potential in an aquaculture setting, our results suggest outplanting at 5 m depth, with more favorable oxygen and pH levels. Mussel shell integrity can be improved by placing out at 5 m, regardless of season, however, there were no notable differences in shell strength between depths in scallops. For both species, δ13C values were lowest at 5 m in the winter and δ15N was highest at 30 m regardless of season. Puget Sound's combination of naturally and anthropogenically acidified conditions is already proving to be a challenge for shellfish farmers. Our study provides crucial information to farmers to optimize aquaculture grow-out as we begin to navigate the impacts of climate change.

Effects of temperature, salinity, and food availability on shell growth rates of the Yesso scallop.

Shell growth rates in relationship to seasonal changes of environmental factors were studied in a wild population of the Yesso scallop Mizuhopecten yessoensis inhabiting Amur Bay (Peter the Great Bay, Sea of Japan, Russia). It was found that food availability is not a limiting factor for the scallop growth in the study area. A phytoplankton biomass of 3.5-6.0 g m-3 provided high scallop growth rates. The largest daily shell increments were observed with a phytoplankton biomass of about 6 g m-3. With a decrease in the phytoplankton biomass to <2 g m-3, as well as with an increase to >11 g m-3, the daily shell increments reduced. It appeared that the main exogenous factors causing the seasonal variations in the scallop growth rates are the water temperature, which was too high in July and August (>18°C) and too low in November-April (<4°C), and the water salinity, which was too low (<30‰) for this stenohaline species in summer. The relationship of the daily shell increment in Yesso scallop with the water temperature can be described by a dome-shaped curve. The largest increments were observed at 8-16°C. The dependence of the daily shell increments on the water salinity was also best described by a dome-shaped curve, showing the optimal range of 32.5-33.5‰. The revealed relationships, approximated by dome-shaped curves, evidently indicate that both insufficient and excessive effect of the factor negatively affects scallop growth. A suggestion was made to describe the result of the combined impact of several environmental factors on the daily shell increment as a multiplication of the functions of its dependence on each of the factors.

Seasonal growth, organ indices and food consumption of the Japanese scallop &lt;i&gt;Patinopecten&lt;/i&gt; &lt;i&gt;yessoensis&lt;/i&gt; (Jay, 1857) in relation to food availability in Tokoro seabed, Okhotsk Sea, North Japan

Seasonal growth, organ indices and food consumption of the Japanese scallop &lt;i&gt;Patinopecten&lt;/i&gt; &lt;i&gt;yessoensis&lt;/i&gt; (Jay, 1857) in relation to food availability in Tokoro seabed, Okhotsk Sea, North Japan

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.

Modeling Atlantic sea scallop (Placopecten magellanicus) scope for growth on the Northeast U.S. Shelf

AbstractAtlantic sea scallops support one of the most valuable fisheries in the eastern United States. The scallop population is susceptible to climate‐related environmental stress. Assessing and projecting climate impacts rely on the fundamental understanding of scallop ecophysiology, including the influences of temperature and food supply on its energy balance and growth potential. In this study, we developed a scope for growth (SFG) model driven by high‐resolution hydrodynamic and biological models to assess the spatial and seasonal variability of scallop energy dynamics. The overall SFG on the Northeast U.S. Shelf is higher in May–June and lower in January–February, with substantial spatial heterogeneity. In the Mid‐Atlantic Bight (MAB), negative SFG occurs from July to October due to strong thermal stress. Particulate organic matter in detrital form is an important food source for scallops, with higher/lower contribution in the cold/warm seasons, respectively. Warming and food deficiency induce a noticeable contraction of suitable scallop habitats in the MAB, while their impacts on Georges Bank are insignificant. Known seasonal spawning patterns and observed growth rates in these regions match the patterns of SFG generated by the model. The sensitivity of SFG to the variations in food and temperature increases with scallop size. Large scallops are more likely to experience low or negative SFGs than smaller ones, implying that the habitats shrink as scallops grow older/bigger. This study provides key information about scallop growth potential and biogeography from the perspective of energy balance, thus helping the development of adaptive fisheries management strategies.

Tight coupling between primary productivity, export production, and the growth of benthic scallops in the coastal region of the Okhotsk Sea along Hokkaido

AbstractScallop culture is conducted worldwide, nonfeeding and depending on the natural phytoplankton production for the diet. It is necessary for sustainable culture of this species to understand how the phytoplankton production and subsequent vertical transport to the bottom (export production) are regulated by environmental factors. A 3‐year time series monitoring of chlorophyll and temperature, as well as sinking particle flux, was conducted to elucidate the relationship between surface primary production, the subsequent export, and the growth of benthic cultured scallops in spring in the coastal region of the Okhotsk Sea along Hokkaido, Japan. Five times larger export fluxes were observed in 2013 than those in other years. Coscinodiscus spp., diameter &gt;200 μm, was the quantitatively dominant phytoplankton in 2013. This species contributed to the high export flux due to a higher settling velocity. The sudden drops in temperature by &gt;2°C were observed during the study period. These indicated that the supply of nutrients from Intermediate Cold Water (ICW), a cold and nutrients rich water mass, accelerated the primary productivity in this area. This intensity was strongest in 2013, contributing to the high export flux. The large export flux in 2013 provided a more sufficient food to the benthic cultured scallops, resulting in a two times higher growth of the scallops than in other years. This study demonstrated that the size of the dominant diatom species and the supply from ICW strongly influenced the export ratio and the growth of cultured scallops.

Factors Influencing the Interannual Variation in Biomass of Bottom-Cultured Yesso Scallop (Patinopecten yessoensis) in the Changhai Sea Area, China

Understanding how environmental factors impact the interannual variation in scallop growth and subsequently developing an easily obtained parameter to indicate this variation could provide a scientific basis for optimizing their aquaculture. In this study, we have set a growth scenario of uniformly sowed scallops of the same initial size in the Changhai sea area. The Yesso scallop culture ecosystem model was used to simulate the growth of bottom-cultured Yesso scallop each year from December 1, 2006 to November 30, 2017. The results show that the annual growth rate was higher in the northwest than in the southeast, and there were obvious high-value areas near the islands. The scallop biomass was significantly lower in 2009–2010 and reached its highest point in 2013–2014. Based on the match-mismatch conditions of bottom-water temperature, food availability, and the Yesso scallop growth process, three factors were determined: suitable growth days (SGD), restricted growth days (RGD), and food accumulation (FA). Subsequently, a multiple regression relationship was proposed with scallop biomass to explore the reasons affecting the interannual variations in scallop growth. We found that the anomaly of the contribution of SGD and FA for the scallop growth was small, and the interannual variation in scallop biomass was mainly regulated by RGD in winter. Our results indicated that the interannual variation in RGD in winter was closely related to the regional averaged air temperature in early winter. The air temperature in early winter is easily obtained in practice. Consequently, it could be used to predict the interannual growth of bottom-cultured scallops to improve aquaculture planning and management.

Growth and Survival Performance of Smooth Scallop (Flexopecten glaber Linnaeus, 1758) at Different Depths in the Aegean Sea

This study was conducted between July 2016 and 2017 to determine the growth and survival rates of the smooth scallop Flexopecten glaber spats in Urla Karantina Island. The sea water temperature was determined as 21.56±6.33°C, 21.1±6.40°C and 20.87±6.35°C at 2, 4 and 6 m depths, respectively. Salinity values varied between 36 and 38.19 PSU in the region. The highest chlorophyll-a value was determined as 8.95 µg l-1 in August at 2 m depth and 1.65 µg l-1 as the lowest at 4 m depth in January. Average values of total particulate matter amount were calculated as 4.41±1.86 mg l-1, 5.09±1.88 mg l-1 and 5.47±1.89 mg l-1 at 2, 4 and 6 m depth, respectively. Scallop spats with an average height of 8.26±1.55 mm were measured at the beginning of the study. The heights of the smooth scallop spats, which were placed at 2 m, 4 m and 6 m depths in the study area, were 42.6±1.11 mm, 41.53±12.85 mm and 41.57±1.64 mm and their weights were measured as 12.71±0.89 g, 12.85±0.53 g and 12.82±1.00 g, respectively. While the survival rate was 53% placed at 2 m depth in the study area, the lowest survival rate was found as 37% for the spats grown at 6m depth. The result showed that the mean values of height at the surface depth (2 m) were more significant than those at the other depths (4 m and 6 m). However, there were no statistically significant differences between the depths and specific growth rate (SGR) for height and weight (p&amp;gt;0.05). But SGRh and SGRw values at each depth showed statistically significant differences between months (p&amp;lt;0.05).

Growth of catarina scallop ( Argopecten ventricosus , Sowerby II, 1842) larvae from broodstock collected at different seasons

Aquaculture ResearchVolume 52, Issue 11 p. 5903-5907 SHORT COMMUNICATION Growth of catarina scallop (Argopecten ventricosus, Sowerby II, 1842) larvae from broodstock collected at different seasons José Manuel Mazón-Suástegui, orcid.org/0000-0003-4074-1180 Centro de Investigaciones Biológicas del Noroeste, La Paz, MéxicoSearch for more papers by this authorJesús Antonio López-Carvallo, Corresponding Author alopezcarvallo@gmail.com jcarvallo@pg.cibnor.mx orcid.org/0000-0002-7405-8665 Centro de Investigaciones Biológicas del Noroeste, La Paz, México Correspondence: Jesús Antonio López-Carvallo, Centro de Investigaciones Biológicas del Noroeste. Av. I.P.N. 195, Col. Playa Palo de Santa Rita Sur. C.P, La Paz, B.C.S 23096, México. Email: alopezcarvallo@gmail.com; jcarvallo@pg.cibnor.mxSearch for more papers by this authorDariel Tovar-Ramírez, orcid.org/0000-0003-1204-9576 Centro de Investigaciones Biológicas del Noroeste, La Paz, MéxicoSearch for more papers by this authorGuadalupe Fabiola Arcos-Ortega, Centro de Investigaciones Biológicas del Noroeste, La Paz, MéxicoSearch for more papers by this authorPedro E. Saucedo, orcid.org/0000-0002-2155-9677 Centro de Investigaciones Biológicas del Noroeste, La Paz, MéxicoSearch for more papers by this authorCésar Lodeiros, orcid.org/0000-0001-9598-2235 Universidad Técnica de Manabí, Bahía de Caráquez, Ecuador Instituto Oceanográfico de Venezuela, Universidad de Oriente, Cumaná, VenezuelaSearch for more papers by this authorLuis Freites, orcid.org/0000-0002-6432-7366 Instituto Oceanográfico de Venezuela, Universidad de Oriente, Cumaná, VenezuelaSearch for more papers by this author José Manuel Mazón-Suástegui, orcid.org/0000-0003-4074-1180 Centro de Investigaciones Biológicas del Noroeste, La Paz, MéxicoSearch for more papers by this authorJesús Antonio López-Carvallo, Corresponding Author alopezcarvallo@gmail.com jcarvallo@pg.cibnor.mx orcid.org/0000-0002-7405-8665 Centro de Investigaciones Biológicas del Noroeste, La Paz, México Correspondence: Jesús Antonio López-Carvallo, Centro de Investigaciones Biológicas del Noroeste. Av. I.P.N. 195, Col. Playa Palo de Santa Rita Sur. C.P, La Paz, B.C.S 23096, México. Email: alopezcarvallo@gmail.com; jcarvallo@pg.cibnor.mxSearch for more papers by this authorDariel Tovar-Ramírez, orcid.org/0000-0003-1204-9576 Centro de Investigaciones Biológicas del Noroeste, La Paz, MéxicoSearch for more papers by this authorGuadalupe Fabiola Arcos-Ortega, Centro de Investigaciones Biológicas del Noroeste, La Paz, MéxicoSearch for more papers by this authorPedro E. Saucedo, orcid.org/0000-0002-2155-9677 Centro de Investigaciones Biológicas del Noroeste, La Paz, MéxicoSearch for more papers by this authorCésar Lodeiros, orcid.org/0000-0001-9598-2235 Universidad Técnica de Manabí, Bahía de Caráquez, Ecuador Instituto Oceanográfico de Venezuela, Universidad de Oriente, Cumaná, VenezuelaSearch for more papers by this authorLuis Freites, orcid.org/0000-0002-6432-7366 Instituto Oceanográfico de Venezuela, Universidad de Oriente, Cumaná, VenezuelaSearch for more papers by this author First published: 19 June 2021 https://doi.org/10.1111/are.15412Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat Volume52, Issue11November 2021Pages 5903-5907 RelatedInformation

The coupled effects of stocking density and temperature on Sea Scallop (Placopecten magellanicus) growth in suspended culture

Despite the profitability of the wild Atlantic Sea Scallop, Placopecten magellanicus, fishery, the U.S. still imports more than 26,000 tonnes of various scallop products annually. Atlantic Sea Scallop (hereafter referred to as scallop) aquaculture is one method of mitigating this imbalance. We examined scallop growth at three sites across the mouth of Penobscot Bay, Maine to determine the coupled effects of lantern net stocking density and temperature on growth and mortality. Scallops were held in high and low (20 and 10 individuals tier−1, respectively) density treatments, and shell height measurements were recorded monthly for one year. We divided the growth rate analysis into three periods: winter - spring, summer, and fall. During summer across all sites, growth rates were 75 % higher in low-density nets than in high-density nets. We observed significant nonlinear relationships between shell height growth rate, temperature, and stocking density. Optimal growth occurred within a window of 10–15 °C. Above this threshold, there was a distinct negative relationship between temperature and growth. Our results highlight the importance of maintaining low densities within nets, particularly during periods of high temperature and growth. However, handling in summer and early fall may lead to mortality. Therefore, we recommend that growers stock nets at low densities in the spring, ensuring that they will not require thinning during peak temperatures. Similarly, finding sites that maximize time within a thermal envelope of 10–15 °C will be critical, which in the case of the Gulf of Maine will most likely warrant leasing sites at the mouths of estuaries and bays. These locations offer a combination of sufficient depth and space for sparsely stocked nets, adequate food levels, and optimal salinity and temperature.

Striae in the Antarctic scallop Adamussium colbecki provide environmental insights but not reliable age increments

Subannual growth increments in bivalves provide insight into past seasonal seawater conditions at high temporal resolution. The Antarctic scallop Adamussium colbecki (Smith 1902) accretes putatively fortnightly surficial growth lines (striae) and interstrial growth increments have the potential to archive sea ice variations. Cycles of paired groups of wide and narrow striae are sometimes used to determine ontogenetic age in these scallops, but previous quantitative work describing strial grouping and formation is limited to a few months of juvenile growth. Here, we analyze striae patterns in A. colbecki collected from two sites on western McMurdo Sound, Antarctica that differ by sea ice duration: Explorers Cove with multi-annual sea ice and Bay of Sails with annual sea ice. At both sites, visual analysis of striae groups and cycles (using the methods of previous authors) and wavelet analysis of interstrial increments suggest that striae groups are too variable to age A. colbecki. Only ~ 40% of striae groups and cycles conformed to expectations from annual cycles of fortnightly growth increments (~ 26 striae per cycle). Moreover, only one scallop from each study site displayed consistent periodicity at ~ 26 striae throughout juvenile growth in wavelet analysis. Though striae grouping was inconsistent, analysis of concurrent growth of juvenile scallops from Explorers Cove suggested strong environmental control on interstrial increment size and thus that strial increments are suitable for further analysis as sea ice proxies. Finally, the multi-annual sea ice site had smaller interstrial growth increments and less valve wear than the annual sea ice site, indicating overall slower growth and possibly lower metabolic activity.

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.

Estimation of Growth Parameters of the Black Scallop Mimachlamys Varia in the Gulf of Taranto (Ionian Sea, Southern Italy)

The present study examines the juvenile growth of nine cohorts of Mimachlamys varia in a coastal area of the Ionian Sea, from January 2014 to May 2015. The results showed that M. varia could reach commercial size in less than one year of cultivation, but significant differences in absolute growth rate (AGR) and specific growth rate (SGR) were found among cohorts (p &lt; 0.05). Relationships between scallop growth (size and weight) and environmental variables (water temperature, dissolved oxygen and chlorophyll concentration) were also identified. The length–weight relationship showed negative allometric growth and indicated high correlation with R2, ranging from 0.95 to 0.82. Von Bertalanffy growth parameters showed the highest values of L∞ in the cohorts collected in January, April and February (52.2, 51.2 and 50.3), respectively. The growth performance index (φ’) ranged between 2.52 (cohort collected in June) and 3.03 (cohort collected in August). The obtained data add basic knowledge to the growth performance of this species, making this a good opportunity to facilitate aquaculture diversification in this part of Mediterranean Sea.

Growth and longevity of the Antarctic scallopAdamussium colbeckiunder annual and multiannual sea ice

AbstractEcosystem engineers such as the Antarctic scallop (Adamussium colbecki) shape marine communities. Thus, changes to their lifespan and growth could have far-reaching effects on other organisms. Sea ice is critical to polar marine ecosystem function, attenuating light and thereby affecting nutrient availability. Sea ice could therefore impact longevity and growth in polar bivalves unless temperature is the overriding factor. Here, we compare the longevity and growth ofA. colbeckifrom two Antarctic sites: Explorers Cove and Bay of Sails, which differ by sea-ice cover, but share similar seawater temperatures, the coldest on Earth (-1.97°C). We hypothesize that scallops from the multiannual sea-ice site will have slower growth and greater longevity. We found maximum ages to be similar at both sites (18–19 years). Growth was slower, with higher inter-individual variability, under multiannual sea ice than under annual sea ice, which we attribute to patchier nutrient availability under multiannual sea ice. Contrary to expectations,A. colbeckigrowth, but not longevity, is affected by sea-ice duration when temperatures are comparable. Recent dramatic reductions in Antarctic sea ice and predicted temperature increases may irrevocably alter the life histories of this ecosystem engineer and other polar organisms.

Living in a growing host: growth pattern and dwelling formation of the scallop Pedum spondyloideum in massive Porites spp. corals

Pedum spondyloideum is a byssally attached scallop in the Indo-Pacific that lives in deep fan-shaped dwellings within live scleractinian and hydrozoan corals, with the ventral edges of the scallops’ valves protruding slightly from the dwellings. Juvenile scallops have rounded, oval shells and live in shallow depressions. Complete scallop dwellings are formed by the growth of the host and allometric growth of the scallop, and by chemical and physical interactions between the scallop and its host. Scallops were extracted intact from their dwellings within massive corals in the genus Porites in Thailand (7°36′32″ N, 98°21′55″ E; in May 2019) and Malaysia (2°45′17″ N, 104°13′30″ E; in November 2019) to examine the relationship between shell height (SH) and shell width (SW). The slope of the regression of SH on SW within the first 2 years of settlement was 0.79–0.9, indicating that SW increased slightly faster than SH during this period. As the scallop grew further, the slope of the SH on SW was 1.29–1.54, indicating that SH increased faster than SW. A histological study on scallop pallial tissue, including the tentacles, and SEM observations of the dwelling walls suggested that the scallop has secretions that damage coral tissue and widen the dwelling during growth. Thus, the distinctive fan-shaped dwellings of the adult scallops are caused by a combination of allometric scallop growth and erosion of the host tissue and dwelling walls.

Reducing stress by improving performance of hatchery-reared Catarina scallop (Argopecten ventricosus) spat with different genera of beneficial microorganisms: A biochemical and molecular analysis

This study investigated the probiotic effects of one lactobacillus, one marine yeast, mix of three bacilli and mix of all probiotic strains on the growth, survival, antioxidant response (superoxide dismutase = SOD, catalase = CAT, gluthatione peroxidase = GPX) and immune response (lysozyme = LYZ, heat shock protein =HSP70) of hatchery-reared Catarina scallop Argopecten ventricosus early spat. The spat was exposed every three days for 28 days to a single dose of 1 × 106 CFU mL–1 of one of five treatments used in triplicate: (1) Lactobacillus plantarum (C3); (2) Candida cretensis (S10); (3) Mix of Bacillus cereus, Bacillus flexus, and Bacillus firmus (BMix); (4) Mix of 1 + 2+3 (LLBMix); (5) Group of spat without probiotics as control. Survival was 100 % in all probiotic treatments and the control group. The spat treated with the yeast (S10) and lactobacillus (C3) significantly increased absolute growth and growth rate compared to the control. The antioxidant activity and gene expression was significantly lower in all spat treated with probiotics than in the control group, particularly with the BMix, LLBMix (SOD), C3 (CAT, GPX), and BMix (CAT) strains. The immune activity and gene expression was also significantly lower in spat treated with probiotics, particularly BMix, LLBMix (LYZ), C3, BMix, and S10 (HSP70) strains, compared to the control group. The use of a single dose of probiotic or mix of different strains reduced activation of antioxidant and immune response and improved overall performance of hatchery-reared A. ventricosus spat.

Molecular characterization of the myostatin gene and its regulation on muscle growth in Yesso scallop Patinopecten yessoensis

Myostatin (MSTN) belongs to the transforming growth factor β (TGF-β) family, which plays a critical role in negatively regulating muscle growth in vertebrates. However, little is known about its function in muscle growth of scallops that possess a large adductor muscle composed of striated and smooth muscle fibers. In this study, we first indentify and characterize the complete cDNA sequence of the myostatin gene from Yesso scallop P. yessoensis, an economically important species in Asian countries. The C-terminal mature TGF-β peptides are highly conserved in scallops, with sequence identity of >97% among these species. Gene expression at developmental stages revealed by whole-mount in situ hybridization indicates that myostatin is mainly expressed on the profusely ciliated rim of velum in veligers. The significant increase of muscle cellularity induced by RNA interference of myostatin can be explained as a result of a combination of hyperplasia and hypertrophy of MHC II striated myofibers, rather than myofiber growth of the paramyosin-rich smooth muscle. This is also evidenced by the quantification results of muscle gene expression, which indicate the significant increase of MHC expression after the inhibition of myostatin mRNA in the striated muscle, but not in the smooth muscle. For both of the striated and smooth muscles, however, no significant difference between the treatment and control groups is detected by real-time quantitative PCR analysis in other muscle genes. These findings suggest that the cellular targets of myostatin in scallop muscles are probably regulated by signaling directly to striated MHC. The new additional nuclei are potentially supplied by a population of satellite cells or muscle stem cell-like adult muscle precursors that may fuse with existing muscle fibers during muscle hypertrophy. These evidences found in this study highlight that myostatin may not only be involved in the development of larval musculature, but also play an important role in regulating scallop muscle growth.