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In order to create new value in biomass production using sterile Ulva with high production efficiency, we selected sterile Ulva with high culture stability from the coast of Imari City in Japan and investigated the conditions for generating high concentrations of dissolved oxygen through photosynthesis using the sterile Ulva. In the cultivation of sterile Ulva, we investigated the conditions for generating high concentrations of dissolved oxygen (DO) by controlling conditions such as aeration, NO3‐N concentration, and population density. As a result, we found that under the cultivation control conditions we found, DO reached about 3.8 times the saturation concentration after 3 h. It was found that this high level of DO can be maintained if the supersaturated DO seawater obtained here is properly sealed. Seawater containing high levels of DO is essential for the cultivation of oysters and shellfish, which also prefer a growth temperature of 20°C−25°C. Therefore, from the perspective of creating new value in biomass production, we developed a new system for simultaneously cultivating sterile Ulva and cultivating oysters. [ABSTRACT FROM AUTHOR]

Marine molluscan cell lines, required for virus screening and cultivation, form essential tools for developing health management strategies for these animals in the blue economy. Moreover, they are also crucial to develop cultivated seafood. As there is no valid marine molluscan cell line, primary cell cultures are relied upon for all investigations. A sound protocol for generating primary cell cultures from molluscs is entailed, but existing protocols often involve heavy antibiotic usage and depuration that invariably affect gene expression and cell health. This work presents an easy‐to‐adopt, time‐saving protocol using non‐depurated mollusc Crassostrea madrasensis, which requires only initial antibiotic treatment and minimal exposure or no use of antibiotics in the cell culture medium. The important experimental considerations for arriving at this protocol have been elucidated. Accordingly, sodium hypochlorite and neomycin sulfate were chosen for disinfecting tissues. The study is the first to use shrimp cell culture medium (SCCM) as a cell culture medium for molluscan cell culture. Despite being osmoconformers, the oysters exhibited stable intracellular osmotic conditions and pH, which, when provided in vitro, promoted effective cardiomyocyte formation. The cell viability could be enhanced using 10% fetal bovine serum (FBS), but healthy cell culture could also be obtained using SCCM without FBS. The optimized culture conditions allowed for regular beating cardiomyocyte clusters that could be retained for a month. Limited cell proliferation, as shown by the BrdU assay, demands further interventions, such as possibly producing induced pluripotent stem cells. The optimized protocol and culture conditions also align with some requirements for producing cultivated meat from marine molluscs. [ABSTRACT FROM AUTHOR]

Native Olympia oysters (Ostrea lurida) occur in remnant natural populations throughout San Francisco Bay (SFB), California, United States, where managers have been working to restore oysters since 2002. Environmental conditions vary substantially along the estuarine gradient in the bay, such that oysters are exposed to different stressors in different locations and years. We monitored oysters that naturally recruited to experimental restoration substrates over 10 years at two sites on this gradient. We found that recruitment rates and adult densities varied over time and had different trajectories at the study locations. We found gradients in predation, space competition, and physical stressors between sites and along a tidal elevation span that corresponded with differences in adult densities. We documented mass mortality resulting from an extreme low‐salinity event at one site and subsequent recovery later that year. Our results, combined with data from natural populations at multiple sites, suggest that restoration outcomes within SFB could be improved by building and strengthening a connected portfolio of sites that are not simultaneously exposed to the same stressors. We recommend siting restoration projects across locations that represent a range of environmental conditions but that are sufficiently close for larval exchange. Unlike typical restoration approaches that use site selection to identify the best locations, the portfolio approach, just like the economic investment principle, would employ a diversity of environmental conditions. Because these environmental conditions can change over time, this approach can reap the greatest rewards over the long run precisely because of that diversity. [ABSTRACT FROM AUTHOR]

This study explored the potential of three local microalgal isolates as feed for oyster larvae in laboratory‐rearing experiments, towards the optimisation of seed production of Crassostrea tulipa to support its large‐scale farming along the West African coast. Three species of local microalgae—Rhodomonas sp., Nannochloropsis sp. and Pseudanabaena sp.—were isolated from waters off the coast of Ghana, West Africa, following a serial dilution technique. The growth performance of the isolates was assessed in the laboratory through daily estimation of cell density until the stationary phase was observed. Characterisation of the microalgal isolates was carried out by estimation of their biovolume, carbon content and energy content. Biovolumes of the microalgae were calculated from the estimated equivalent spherical diameters using proposed geometric shapes and formulae. Carbon weight and carbon energy content were subsequently calculated using derived conversions. The three microalgal isolates showed potential for large‐scale cultivation in the laboratory with marked differences in daily increases in cell densities. Nannochloropsis sp. and Rhodomonas sp. recorded the highest and the lowest peak densities of 2.4 × 105 and 1.5 × 105 cell mL−1, respectively, from an initial inoculating cell density of 1.05 × 105 cell mL−1. The estimated mean biovolumes of Rhodomonas sp., Nannochloropsis sp. and Pseudanabaena sp. were 238.9, 8.182 and 42.42 µm3, respectively, and the corresponding derived carbon energy contents were 1.7 × 10−6, 7.13 × 10−8 and 1.05 × 10−7 J, respectively. Results from a laboratory rearing experiment indicated that the individual microalgal isolates supported the growth and survival of oyster larvae at different scales, but a mixed diet of the three promoted superior growth and survival of C. tulipa larvae. The three local microalgal isolates‐ Rhodomonas sp., Nannochloropsis sp., and Pseudanabaena sp.‐ were well adapted to laboratory culture conditions, and the observed differences in growth and survival of the oyster larvae fed on these algal diets could be due to the differences in diet properties and biochemical compositions of the different species. A combination of the three algal diets, however, provided complementaery nutrients for the optimal growth and survival of C. tulipa larvae. The outcome of this study shows that local microalgal isolates have the potential to support hatchery rearing of C. tulipa, which is essential for the development of commercial mangrove oyster aquaculture in West Africa. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) pollution has wreaked havoc on biodiversity and food safety globally. The false ingestion of MPs causes harmful effects on organisms, resulting in a decline in biodiversity. The present review comprehended the current knowledge of MP contamination in Crustacea and Mollusca from 75 peer‐reviewed articles published in Asia between 2015 and 2023. A total of 79 species (27 Crustacea and 52 Mollusca) have been recorded to be contaminated with MPs. Out of the total 27 species of Crustacea, Metopograpsus quadridentatus (327.56 MPs/individual) and Balanus albicostatus (0.42 MPs/individual) showed the highest and lowest contamination, respectively. Out of the total 52 species of Mollusca, Dolabella auricularia (2325 MPs/individual) and Crassostrea gigas and Mytilus edulis (0.2 MPs/individual) showed the highest and lowest contamination, respectively. In terms of country‐wise MP contamination, China has the highest number of contaminated species in both phylums among Asia. Findings of pollution indices revealed a very high risk of MP contamination in all the countries. Fiber was reported predominantly in both groups. Blue and black‐colored MPs having <500 μm and <500 μm–1 mm size were found dominantly in Crustacea and Mollusca, respectively. Polypropylene was recorded as the dominant plastic polymer in both Crustacea and Mollusca. In essence, this review has provided a comprehensive insight into MP concentration in Crustacea and Mollusca of Asia, highlighting variations among species and geographic locations. This understanding is crucial for tackling urgent environmental challenges, safeguarding human health, and promoting global sustainability initiatives amid the escalating issue of plastic pollution. Practitioner Points: Microplastic pollution has created havoc on biodiversity and food safety.A total of 27 and 52 species of crustaceans and Mollusca have been recorded to be contaminated with MPs.Metopograpsus quadridentate and Dolabella auricularia have shown higher MPs contamination.Polypropylene was recorded as the dominant plastic polymer in both crustacean and Mollusca.Findings of pollution indices revealed a very high risk of MP contamination in all the countries. [ABSTRACT FROM AUTHOR]

Shell‐closing strength (SCS) is commonly used to assess oyster vigor and quality as an important physiological stress indicator of the oyster organism. In this study, a quality decision support system based on flexible wireless sensor network and web services was designed and developed to explore the application of SCS in the rapid assessment of vitality and quality. Based on physiological and environmental information collected by flexible wireless sensor networks, this study proposes a novel quantitative vitality assessment method to identify oyster life decline cycles and processes. Meanwhile, TVB‐N, TVC, and pH were selected as quality indicators, and a back‐propagation artificial neural network (BP‐ANN) was used to predict and evaluate oyster quality indicators. The results showed that the root mean square errors (RMSE) for TVB‐N, TVC, and pH were 0.4624, 0.8827, and 0.1941; the coefficients of determination (R2) were 0.8919, 0.8578, and 0.6249. Therefore, the rapid assessment of oyster vitality and quality based on a flexible wireless sensor network is a reliable and effective means. Practical applications: This study aims to explore the application of live oyster SCS for rapid quality evaluation. In this article, a quality decision support system based on a flexible wireless sensor network (WSN) and web services is developed to improve the quality and health of live oysters in the supply chain. The use of the multi‐sensor system enables the monitoring and collection of environmental and physiological signals of live oysters throughout the supply chain process. The evaluation of the quality of live oysters using physiological and environmental information collected by flexible wireless sensor networks is a reliable and efficient method. This will provide an effective and reliable quality evaluation and management for the oyster industry. [ABSTRACT FROM AUTHOR]

An important pathogen of concern for Pacific oyster growers in the USA is ostreid herpesvirus 1 (OsHV‐1). Currently, oyster stocks exist that are tolerant to OsHV‐1; however, it is uncertain if a trade‐off exists between their tolerance to OsHV‐1 and their growth in different environments. To investigate any potential trade‐offs, Pacific oyster families with varying levels of OsHV‐1 tolerance were grown in a bay where OsHV‐1 is endemic (Tomales Bay, CA) and in a bay where OsHV‐1 is absent (Willapa Bay, WA). In Tomales Bay, we found that oysters from OsHV‐1 tolerant families grew faster than oysters from OsHV‐1 susceptible families, while in Willapa Bay, no statistically significant difference in growth was found between oyster families with different levels of OsHV‐1 tolerance observed in Tomales Bay. These findings indicate that Pacific oysters bred to be tolerant to OsHV‐1 would not be expected to have a longer time‐to‐market regardless of the presence of OsHV‐1 in the growing environment. [ABSTRACT FROM AUTHOR]

Parallel diversification provides a proper framework for studying the role of natural selection in evolution. Yet, empirical studies from ecological 'non‐model' species of invertebrates are limited at the whole genome level. Here, we presented a chromosome‐scale genome assembly for Crassostrea angulata and investigated the parallel genomic evolution in oysters. Specifically, we used population genomics approaches to compare two southern–northern oyster species pairs (C. angulata–C. gigas and southern–northern C. ariakensis) along the coast of China. The estimated divergence time of C. angulata and C. gigas is earlier than that of southern and northern C. ariakensis, which aligns with the overall elevated genome‐wide divergence. However, the southern–northern C. ariakensis FST profile represented more extremely divergent "islands". Combined with recent reciprocal hybridization studies, we proposed that they are currently at an early stage of speciation. These two southern–northern oyster species pairs exhibited significant repeatability in patterns of genome‐wide differentiation, especially in genomic regions with extremely high and low divergence. This suggested that divergent and purifying selection has contributed to the genomic parallelism between southern and northern latitudes. Top differentiated genomic regions shared in these two oyster species pairs contained candidate genes enriched for functions in energy metabolism, especially adipogenesis, which are closely related to reproductive behaviours. These genes might be good candidates for further investigation in vivo. In conclusion, our results suggest that similar divergent selection and shared genomic features could predictably transform standing genetic variation within one species pair into differences in another. [ABSTRACT FROM AUTHOR]

Recently, three proton channels (HV) have been identified and characterized in Aplysia californica (AcHV1‐3). Focusing on AcHV1 and AcHV2, analysis of Transcriptome Shotgun Assembly and genomic databases of 91 molluscs identified HV homologous channels in other molluscs: channels homologous to AcHV1 and to AcHV2 were found in 90 species (56 full‐length sequences) and in 33 species (18 full‐length sequences), respectively. Here, we report the discovery of a fourth distinct proton channel family, HV4. This new family has high homology to AcHV1 and AcHV2 and was identified only in bivalvian molluscs (13 species, 12 full‐length sequences). Typically, these channels possess an extracellular S1–S2 loop of intermediate size (~ 20 amino acids) compared to the shorter loops of molluscan HV1 channels (~ 13 amino acids) and the much larger loops of molluscan HV2 channels (> 65 amino acids). The characteristic voltage‐sensor motif in S4 possesses only two arginine residues with the common third arginine being replaced by a lysine. Moreover, HV4 channels are much smaller with only around 200 amino acids in total length. The smallest functional channel found so far in nature (189 amino acids) is expressed in the pacific oyster Crassostrea gigas (CgHV4) and might be considered an archetypical minimal proton channel. Functional expression and electrophysiological characterization demonstrated that CgHV4 shares distinctive hallmarks of other investigated proton channels as high proton selectivity, slow activation, and pH‐ and voltage‐regulated gating. This work is the first description of a HV4 type channel, adding a new member to the recently expanded family of proton channels. [ABSTRACT FROM AUTHOR]

Crassostrea gigas oysters represent a significant global food source with 4.7 million tons harvested per year. In 2001, the bacterium Vibrio aestuarianus subsp. francensis emerged as a pathogen that causes adult oyster mortality in France and Ireland. Its impact on oyster aquaculture has increased in Europe since its re‐emergence in 2012. To better understand the evolutionary mechanisms leading to the emergence and persistence over time of this pathogen, we conducted a survey of mollusc diseases through national reference laboratories across Europe. We analysed 54 new genomes of Vibrio aestuarianus (Va) isolated from multiple environmental compartments since 2001, in areas with and without bivalve mortalities. We used a combination of comparative genomics and population genetics approaches and show that Va has a classical epidemic population structure from which the pathogenic Va francensis subspecies emerged and clonally expanded. Furthermore, we identified a specific cus‐cop‐containing island conferring copper resistance to Va francensis whose acquisition may have favoured the emergence of pathogenic lineages adapted and specialized to oysters. [ABSTRACT FROM AUTHOR]

Understanding the effects of environmental parameters on the reproductive cycle of shellfish is an essential tool for successful hatchery conditioning management and, consequently, for seed supply to the industry. For the tropical oyster, Crassostrea tulipa, little is known about the factors affecting the maturation process and reproduction, but there are indications that salinity may be of importance. Two experiments were carried out to evaluate the effects of salinity on the reproductive cycle of broodstock of C. tulipa. In the first experiment, oysters were reared in five salinities (40, 35, 30, 25, and 20) for 40 days and gonad histological samples were collected regularly. In a follow up experiment, oysters were reared in variable salinity conditions changing from 40 to 30 or from 20 to 30 over a period of 40 days. Salinity was found to affect the reproductive cycle of C. tulipa. Oysters kept in constant salinity of 30 showed a higher condition index compared to animals in other salinities, with most of the animals in the prespawning stage. Salinity variation was also shown to affect C. tulipa maturation. The prespawning stage was the most observed reproductive stage in low salinity, and high salinity induced a resting stage in the female animals. The results are considered the first step towards developing a protocol for the conditioning of C. tulipa in hatchery conditions. [ABSTRACT FROM AUTHOR]

This study was designed to examine the impacts of ark shell Scapharca subcrenata enhancement and suspended oyster Crassostrea sikamea farming on sediment properties and fauna communities in the benthic zone of Xiangshan Bay, China. Ark shell enhancement took place over 319 days, after which sediment samples were collected from each of the three treatment sites: the enhancement area, an oyster farm, and a control area. Sediments from the oyster farming area had significantly higher moisture and acid volatile sulfide content, and the highest Cu, Zn, Pb, and Cd concentrations in all three treatment areas. The ark shell enhancement area has the lowest total organic carbon. No significant difference was found between the mean grain size in each of the three areas. Benthic fauna communities in the ark shell enhancement area were similar to those in the control area. Among the 16 faunal taxa identified, Ruditapes philippinarum was the most abundant species, followed by Glycera onomichiensis and Musculus senhousia. Suspension feeders were not found in the sediment beneath the oyster rafts. Cluster analysis showed a distinct separation between the benthic fauna communities in the oyster farming area and the other two treatment areas. Ark shell enhancement was thus shown to have minimal impact on the benthic environment, while the raft-farmed oysters had significant effects on the sediment structure and the benthic fauna after more than ten years of farming. The differences between the impacts of ark shell enhancement and oyster farming could be attributed to the slowing of water flow caused by oyster rafts. [ABSTRACT FROM AUTHOR]

Comparing the responses of closely related species to environmental changes is an efficient method to explore adaptive divergence, for a better understanding of the adaptive evolution of marine species under rapidly changing climates. Oysters are keystone species thrive in intertidal and estuarine areas where frequent environmental disturbance occurs including fluctuant salinity. The evolutionary divergence of two sister species of sympatric estuarine oysters, Crassostrea hongkongensis and Crassostrea ariakensis, in response to euryhaline habitats on phenotypes and gene expression, and the relative contribution of species effect, environment effect, and their interaction to the divergence were explored. After a 2‐month outplanting at high‐ and low‐salinity locations in the same estuary, the high growth rate, percent survival, and high tolerance indicated by physiological parameters suggested that the fitness of C. ariakensis was higher under high‐salinity conditions and that of C. hongkongensis was higher under low‐salinity conditions. Moreover, a transcriptomic analysis showed the two species exhibited differentiated transcriptional expression in high‐ and low‐salinity habitats, largely caused by the species effect. Several of the important pathways enriched in divergent genes between species were also salinity‐responsive pathways. Specifically, the pyruvate and taurine metabolism pathway and several solute carriers may contribute to the hyperosmotic adaptation of C. ariakensis, and some solute carriers may contribute to the hypoosmotic adaptation of C. hongkongensis. Our findings provide insights into the phenotypic and molecular mechanisms underlying salinity adaptation in marine mollusks, which will facilitate the assessment of the adaptive capacity of marine species in the context of climate change and will also provide practical information for marine resource conservation and aquaculture. [ABSTRACT FROM AUTHOR]

The yield of squid has grown gradually; however, the lack of intensive processing has led to the slow development of the squid industry. In a previous study, some organic salts were found to improve the quality of squid surimi gel. Therefore, this research focused on the effects of sodium citrate (SC) and sodium tartrate (ST) on the quality of squid surimi gel. Physical measurements, such as gel texture, water‐holding capacity, and color of squid surimi gel, were conducted. The addition of 2.5% SC and ST significantly improved the gel strength by 40.7, 57.0, 22.9, and 58.1%, respectively, of gel strength compared with the addition of: 1.5 SC, 3.5 SC, 1.5 ST, and 3.5% ST alone. Rheological measurements revealed that the addition of 2.5% SC or ST shortened the gel degradation temperature range (i.e., 2.5% SC or ST: 40–53°C; other treatments: 40–60°C) of the squid paste during heating. Results of chemical force analysis showed that the addition of a high quantity of salt accelerated protein aggregation and reduced hydrophobic interactions and disulfide bond formation. Finally, an increase in the number of β‐sheets and a decrease in the bulk water content demonstrated that the addition of 2.5% organic salt could form squid gel with a better network structure. The findings provide a scientific basis for the development of high‐quality squid surimi gel. [ABSTRACT FROM AUTHOR]

Within estuarine and coastal ecosystems globally, extensive habitat degradation and loss threaten critical ecosystem functions and necessitate widescale restoration efforts. There is abundant evidence that ecological processes and species interactions can vary with habitat characteristics, which has important implications for the design and implementation of restoration efforts aimed at enhancing specific ecosystem functions and services. We conducted an experiment examining how habitat characteristics (presence; edge vs. interior) influence the communities of resident fish and mobile invertebrates on restored oyster (Crassostrea virginica) reefs. Similar to previous studies, we found that restored reefs altered community composition and augmented total abundance and biomass relative to unstructured sand habitat. Community composition and biomass also differed between the edge and interior of individual reefs as a result of species‐specific patterns over small spatial scales. These patterns were only weakly linked to oyster density, suggesting that other factors that vary between edge and interior (e.g. predator access or species interactions) are likely more important for community structure on oyster reefs. Fine‐scale information on resident species' use of oyster reefs will help facilitate restoration by allowing decision makers to optimize the amount of edge versus interior habitat. To improve the prediction of faunal use and benefits from habitat restoration, we recommend investigations into the mechanisms shaping edge and interior preferences on oyster reefs. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate the use of recirculation and settling chamber in synbiotic multi‐trophic culture of Crassostrea sp. with Litopenaeus vannamei. Four treatments were tested: MONO (shrimp monoculture); integrated multi‐trophic aquaculture (IMTA) (shrimp and oysters in the same tank); IMTA‐R (shrimp and oysters in adjacent tanks with recirculation) and IMTA‐RS (shrimp and oysters in adjacent tanks with recirculation using settling chamber). Shrimp post‐larvae (pL10) and oyster juveniles (3.12 cm) were stocked at a density of 3000 pL m−3 and 200 oysters m−2, respectively, for 42 days. The IMTA treatments showed lower values of settleable solids, when compared to monoculture. However, the excessive removal in the IMTA‐RS increased the levels of TAN (1.15 mg L−1) and nitrite‐N (3.47 mg L−1). The weight and yield of shrimp (1.59 g and 4.63 kg m−3) and the weight of oysters (18.05 g) was significantly higher in the IMTA. Regarding the planktonic community analysis, significant difference was observed on abundance in relation to time and among treatments, where the initial samples and IMTA treatments, with lower values, differed from the 21st and 42nd days and MONO respectively. The results indicate the benefits of the integrated multi‐trophic culture application with the two species in the same productive unit for better water quality and greater shrimp growth. [ABSTRACT FROM AUTHOR]

Summary: A novel natural zinc‐enriched polysaccharide: OZPs‐1 was isolated from oyster (Crassostrea hongkongensis), with 922.18 μg g−1 of zinc. The physicochemical properties and structural features of OZPs‐1 were systematically studied. The results showed OZPs‐1 was predominantly composed of glucose, with a molecular weight ranging from 4 to 2044 kDa. OZPs‐1 showed favourable thermal stability. NMR analysis showed that there was no sulphate substitution and C‐6 substitution in OZPs‐1, while C‐4 might be the binding site of zinc and polysaccharide. UV, FTIR and XRD spectra suggested ‐OH and ‐COOH group might be involved in the binding of zinc to polysaccharides in OZPs‐1 and there were no ZnO and sulphate substitutions in OZPs‐1. These conclusions indicated that zinc might bind with ‐OH and ‐COOH in C‐4 of polysaccharides and impart the stable structure and favourable physicochemical properties of OZPs‐1, which could facilitate the application of OZPs‐1 as natural organic zinc supplements. [ABSTRACT FROM AUTHOR]

Most studies using Integrated Multi‐Trophic Aquaculture (IMTA) systems in shrimp aquaculture have assessed the feasibility of culturing non‐native bivalve species. However, studies including native species are limited and could represent a better alternative since these organisms are adapted to local environmental conditions and do not represent a sanitary risk. Therefore, we assessed the growth performance of the native oyster Crassostrea corteziensis in IMTA system with a Mexican shrimp farm. The study included three grow‐out cycles (starting in October, November and December), three stocking densities (low, medium and high), and three positions of the Nestier®‐like tray (top, middle and bottom), in a drainage channel connected to a shrimp farm located in a mangrove zone. From all experimental conditions, the larger wet weight (WW) and shell length (SL) values were registered in October grow‐out cycle, associated to warmer temperatures, from oysters at medium stocking density and at the top position (WW: 110.1 ± 3.6 g; SL: 91.3 ± 1.5 mm). These results suggest that grow‐out cycle, stocking density and position of oysters in the Nestier®‐like trays highly influence the performance of the cultured oyster. Additionally, C. corteziensis growth can be improved by using IMTA systems consisting of shrimp farm effluents. [ABSTRACT FROM AUTHOR]

Summary: Vibrio parahaemolyticus infection in humans is associated with raw oyster consumption. Evaluation of V. parahaemolyticus presence in oysters is of most interest because of the economic and public health issues that it represents. To explore V. parahaemolyticus accumulation and depuration in adult Crassostrea gigas, we developed a GFP‐tagged V. parahaemolyticus strain (IFVp201‐gfp+), as well as a rapid and efficient quantification method in C. gigas oysters haemolymph by flow cytometry. Impact of the life history of C. gigas on accumulation and depuration of V. parahaemolyticus IFVp201 was subsequently investigated. We found that naive oysters, i.e. grown in controlled facilities with UV treated seawater, accumulated significantly more IFVp201 than environmental oysters, i.e. grown in intertidal environment. We hypothesized that environmental oysters could have been immune primed, thus could limit V. parahaemolyticus accumulation. Meanwhile, both naive and environmental oysters had similar depuration rates. [ABSTRACT FROM AUTHOR]

The Pacific cupped oyster Crassostreagigas is one of the most 'globalized' marine invertebrates and its production is predominant in many parts of the world including Europe. However, it is threatened by mortality events associated with pathogenic microorganisms such as the virus OsHV‐1 and the bacteria Vibrio aestuarianus. C. gigas is also a host for protozoan parasites including haplosporidians. In contrast with Haplosporidium nelsoni previously detected in Europe, H. costale was considered exotic although its presence in French oysters was suggested in the 1980s based on ultrastructural examination. Here, a combination of light and transmission electron microscopy, PCR and sequencing allowed characterizing the presence of the parasite in the context of low mortality events which occurred in 2019 in France. Histological observation revealed the presence of uninucleated, plasmodial and spore stages within the connective tissues of some oysters. Ultrastructural features were similar to H. costale ones in particular the presence of axe‐shaped haplosporosomes in spore cytoplasms. Three fragments of the genome including partial small subunit rRNA gene, the ITS‐1, 5.8S and ITS‐2 array and part of the actin gene were successfully sequenced and grouped with H. costale homologous sequences. This is the first time that the presence of H. costale was confirmed in C. gigas in France. Furthermore, a TaqMan real‐time PCR assay was developed and validated [DSe = 92.6% (78.2–99.8) and DSp = 95.5% (92.3–98.6)] to enable the rapid and specific detection of the parasite. The application of the PCR assay on archived samples revealed that the parasite has been present in French oyster populations at least since 2008. Considering the little information available on this parasite, the newly developed TaqMan assay will be very helpful to investigate the temporal and geographic distribution and the life cycle of the parasite in France and more generally in C. gigas geographic range. [ABSTRACT FROM AUTHOR]

Inducible prey defences occur when organisms undergo plastic changes in phenotype to reduce predation risk. When predation pressure varies persistently over space or time, such as when predator and prey co‐occur over only part of their biogeographic ranges, prey populations can become locally adapted in their inducible defences. In California estuaries, native Olympia oyster (Ostrea lurida) populations have evolved disparate phenotypic responses to an invasive predator, the Atlantic oyster drill (Urosalpinx cinerea). In this study, oysters from an estuary with drills, and oysters from an estuary without drills, were reared for two generations in a laboratory common garden, and subsequently exposed to cues from Atlantic drills. Comparative proteomics was then used to investigate molecular mechanisms underlying conserved and divergent aspects of their inducible defences. Both populations developed smaller, thicker, and harder shells after drill exposure, and these changes in shell phenotype were associated with upregulation of calcium transport proteins that could influence biomineralization. Inducible defences evolve in part because defended phenotypes incur fitness costs when predation risk is low. Immune proteins were downregulated by both oyster populations after exposure to drills, implying a trade‐off between biomineralization and immune function. Following drill exposure, oysters from the population that co‐occurs with drills grew smaller shells than oysters inhabiting the estuary not yet invaded by the predator. Variation in the response to drills between populations was associated with isoform‐specific protein expression. This trend suggests that a stronger inducible defence response evolved in oysters that co‐occur with drills through modification of an existing mechanism. [ABSTRACT FROM AUTHOR]

Animal biodiversity is greatly underestimated in nontemperate marine regions, especially for intertidal benthic organisms such as oysters. Recent surveys in the northern Arabian Gulf suggest the presence of numerous unidentified species, some of which form shallow reef ecosystems while others are cryptic and found under rocks. In this study, we focused on small oysters from Kuwait, which show typical characteristics in common with the genus Ostrea except for the presence of lophine chomata that would link it to the genera Lopha, Dendostrea, and Alectryonella. Phylogenetic analyses based on mitochondrial and nuclear markers unambiguously placed the Kuwait oyster within the Ostreinae as a sister to the Japanese species Ostrea futamiensis. The hypothesis that the Kuwait oyster represents a new species was assessed with phylogenetic and species delimitation methods combined with a morphological assessment. Results corroborated the Kuwait oysters as a new species herein described as Ostrea oleomargarita Oliver, Salvi, and Al-Kandari, sp. nov. The phylogeny of the Ostreinae shows extensive disagreement between morphology-based genera and phylogenetic clades. The genus Ostrea is polyphyletic, and the form and distribution of taxonomic characters such as chomata are not as definitive as suggested in previous studies. This study, along with other recent investigations, confirmed the Arabian Gulf as a key region for discovering marine animal diversity and suggested a possible biogeographic divide between the Eastern and Western Indo-Pacific. A pattern that has been documented in a growing number of taxa and that warrants further research attention. [ABSTRACT FROM AUTHOR]

BACKGROUND: Food allergy is a serious public nutritional health problem that has attracted extensive worldwide attention. Shellfish allergy is a long‐lasting disorder that has a lifelong impact on health. Sarcoplasmic calcium‐binding protein (SCP) plays a vital role in cell and muscle functions and has been identified as an allergen in oyster. RESULTS: In this study, recombinant SCP (rSCP) with a molecular mass of 21 kDa was produced and identified based on SCP amino acid sequencing of Pacific oyster (Crassostrea gigas), and was used as a follow‐up experimental material. Its physicochemical characterization showed that purified rSCP is highly stable to heat and acid‐alkali and trypsin digestion but less resistant to pepsin digestion. We established an animal sensitization model and rSCP displayed stronger Immunoglobulin E (IgE)‐binding activity with rat serum in the rSCP + cholera toxin (CT) group compared with the CT group and a control group. Five epitope peptides were identified as linear immunodominant epitopes by indirect competitive enzyme‐linked immunosorbent assay (icELISA) for the first time. We also found that conformational epitopes may play a major role in the immunoreactivity of SCP. CONCLUSION: These results are significant for understanding hypersensitization of humans to oyster and offer available preventive measures and treatment programs in further research. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

We cultivated the Pacific oyster (Crassostrea gigas) simultaneously in three types of cultivation device sets deployed in two sites: a sheltered site and a non‐sheltered site in the coast of the central area of Chile. Oysters were cultivated in polypropylene trays, nylon cones and lanterns suspended at 2, 5 and 8 m depth from long‐lines. Organism sampling was performed monthly from June, 2014 to May, 2015, measuring temperature, salinity and chlorophyll a. Growth was measured by shell length, wet meat weight and meat yield. At the end of cultivation, there were significant differences in the growth of oysters with higher growth in lanterns at 2 m at Punta Lobería (non‐sheltered site). Higher growth was also found at 2 m in Coliumo bay (sheltered site). Better growth seems associated with the stability of salinity and chlorophyll a. This is the first study that demonstrates the viability of oyster cultivation in non‐sheltered environments on the coast of central Chile. [ABSTRACT FROM AUTHOR]

Aim: Identifying niche shifts is key for forecasting future species distributions. Non‐indigenous species (NIS) are one of the greatest threats to biodiversity, and understanding how niche shifts affect the spread of NIS is fundamental. Here, we modelled the native and introduced niches, as well as the potential geographical extent of a widely distributed NIS, the Pacific oyster Magallana gigas. We then tested for niche shifts in environmental space and predicted spread under contemporary climate change (CCC) conditions. Location: Global. Methods: We used: (1) the two‐dimensional Centroid shift, Overlap, Unfilling and Expansion (COUE) framework and (2) the n‐dimensional hypervolume framework (NDH) to quantify the niches in both analogue and total environmental spaces. Niches were tested for equivalency by comparing the observed and randomized overlaps. Ensemble ecological niche models (ENMs) were then used to predict habitat suitability for the present‐day and two future CCC scenarios. Results: The NDH framework indicated that the introduced niche of M. gigas has shifted into new environmental conditions compared to the native niche. In contrast, COUE framework implied no niche shift, but the first two dimensions only accounted for a small proportion of the overall environmental variability. Ensemble ENMs revealed suitable areas where M. gigas has yet to be recorded and predicted both a poleward expansion and a tropical contraction of suitable habitat for M. gigas by 2100. Main conclusions: We found that M. gigas has rapidly shifted its niche in both analogue and non‐analogue environmental spaces since it was first recorded as introduced species over 50 years ago. Our results suggested that niche shifts facilitate both present‐day and future spread of NIS. Additionally, our study demonstrated the importance of modelling niche dynamics in multidimensional space for predicting range shifts of NIS under CCC. [ABSTRACT FROM AUTHOR]

A growing awareness of role that microbiota can play in mediating the effects of pathogens on hosts has given rise to the concept of the pathobiome. Recently, we demonstrated that the Pacific oyster mortality syndrome affecting Crassostrea gigas oysters is caused by infection with the Ostreid herpesvirus type 1 (OsHV‐1) followed by infection with multiple bacterial taxa.Here we extend the concept of this pathobiome beyond the host species and its bacterial microbiota by investigating how seaweed living in association with oysters influences their response to the disease. We hypothesized that by their mere presence in the environment, different species of seaweeds can positively or negatively influence the risk of disease in oysters by shaping their bacterial microbiota and their immune response. Although seaweed and oysters do not have direct ecological interactions, they are connected by seawater and likely share microbes.To test our hypothesis, oysters were acclimated with green, brown or red algae for 2 weeks and then challenged with OsHV‐1. We monitored host survival and pathogen proliferation and performed bacterial microbiota and transcriptome analyses.We found that seaweeds can alter the bacterial microbiota of the host and its response to the disease. More particularly, green algae belonging to the genus Ulva spp. induced bacterial microbiota dysbiosis in oyster and modification of its transcriptional immune response leading to increased susceptibility to the disease.This work provides a better understanding of a marine disease and highlights the importance of considering both macrobiotic and microbiotic interactions for conservation, management and exploitation of marine ecosystems and resources. [ABSTRACT FROM AUTHOR]

Crassostrea sikamea (C. sikamea) is used as an important edible and medicinal seafood in China. In the present study, an aqueous extract of C. sikamea (AECs) was prepared, and its immunomodulatory effects on rat splenocytes were studied. 3‐(4,5‐dimethylthiazol‐2‐yl)‐5‐(3‐carboxymethoxyphenyl)‐2‐(4‐sulfophenyl)‐2H‐tetrazolium (MTS) assay revealed that AECs was able to promote splenocyte proliferation. Moreover, flow cytometry revealed that AECs treatment markedly altered the populations of splenic lymphocyte subtypes. Data from real‐time quantitative PCR (RT‐qPCR) and enzyme‐linked immunosorbent assay (ELISA) showed that AECs promoted the mRNA expression and secretion of TNF‐α, IL‐2, IL‐6, IL‐12, and IFN‐γ. Mechanistically, p38 MAPK phosphorylation in splenocytes was significantly upregulated under AECs treatment and p38 MAPK inhibitor reversed the promoting effect of AECs on the expression of inflammatory cytokines. Collectively, our novel evidence suggests that AECs exhibits immunomodulatory activity in vitro, supporting the further application of C. sikamea as a potential functional food. [ABSTRACT FROM AUTHOR]

Pacific oysters (Crassostrea gigas) have been introduced worldwide for aquaculture, which can benefit food sovereignty and economic development; however, established non‐native populations may present risks for local organisms and habitats. We reviewed the documented introductions of C. gigas by country to evaluate factors related to introduction, establishment and production, and to determine impacts of feral populations. To date, C. gigas has been introduced in 64 countries and 10 territories, has been established in 32 and contributes to cupped oyster production in 36 (additionally, three native range countries). Oysters were more likely to be introduced and to establish in higher‐latitude countries, but the economic factor of per capita Gross Domestic Product per capita (GDPpc) served as a stronger explanatory variable than latitude for introduction. Earlier introduction and the use for extended periods in aquaculture, not just in trials, further increased establishment. Commercial production increased with coastline length and when established populations were present, but in contrast to establishment, declined at higher latitude. Effects of feral populations have been studied in 11 countries, spanning a range from negative to facilitative as expected for an ecosystem engineer, while reaching levels of concern warranting removal from coastlines in the UK, Norway, Sweden Australia and South Africa. The use of GDPpc in analyses revealed a widespread inequity in terms of low investment in Pacific oyster aquaculture in poorer countries, while richer countries were able to invest not only in aquaculture but also in studies of environmental impacts of feral oysters. [ABSTRACT FROM AUTHOR]

Human‐pathogenic marine bacteria in the genus Vibrio proliferate rapidly in shellfish tissues when exposed to warm ambient air conditions, such as during intertidal exposure. However, it remains unclear whether intertidal‐cultured shellfish are inherently associated with elevated Vibrio concentrations. Here we spatially matched eastern oysters (Crassostrea virginica) held in subtidal and intertidal aquaculture systems at six experimental oyster farms along the mid‐Atlantic coast and tested whether intertidal aquaculture elevates concentrations of V. parahaemolyticus, the predominant species associated with seafood‐related gastroenteritis, as well as concentrations of V. parahaemolyticus carrying the tdh and/or trh genes associated with pathogenicity in humans. Across the sites and over time, we found only slight evidence for increasing V. parahaemolyticus concentrations with exposure to ambient air at low tide; however, tdh/trh+ V. parahaemolyticus increased about 1.5‐fold. We also found that total V. parahaemolyticus concentrations and concentrations of tdh/trh+ V. parahaemolyticus did not differ between intertidal‐ and subtidal‐cultured oysters when submerged at high tides. Any changes to V. parahaemolyticus concentrations within oyster tissues, including concentrations of tdh/trh+ V. parahaemolyticus, therefore diminish with the incoming tide. Our results collectively support the existing time‐to‐cooling restrictions that are in place in many state Vibrio control plans, which involve minimizing the amount of time harvested shellfish can be held prior to cooling or refrigeration, but oppose more austere measures such as restricting or prohibiting intertidal harvest entirely. [ABSTRACT FROM AUTHOR]

Contaminant substances consist of chemical elements that present the potential to adversely impact the ecology of the environment, thus representing a threat to local fauna and flora. In this context, heavy metals are critical agents that, depending on the nature and level, are potentially toxic to living organisms. In order to evaluate the bioaccumulation of heavy metals in the Santos estuary and to determine the potential influence of salinity gradient on the heavy metal bioconcentration, the present study measured the concentrations of As, Cd, Pb, Cu, Cr, Fe, Ni, and Zn in two bivalve species (Crassostrea rhizophorae and Perna Perna) sampled at different sites of Santos Bay, in the southeastern region of Brazil. Throughout the study, the "sentinel species" used were effective in bioaccumulating contaminants. In oysters, based on the Brazilian legislation, critical limits were exceeded for As, Zn, Cu, and Cr. In the case of mussels, on the other hand, only for As, Zn, and Cr, the critical limits were overcome. In the present study, obtained data suggested salinity as a determinant parameter in As incorporation processes of bivalve mollusks. Practitioner Points: The present study presents important results for the development of environmental management policies in estuarine environments.The present study points out differences between different organisms as biomonitors, providing subsidies for the decision of an effective biomonitoring program.The present study discusses values of contaminants as a danger to public health in Santos Bay, which can be extrapolated to other similar environments around the world. [ABSTRACT FROM AUTHOR]

The Pacific oyster (Crassostrea gigas) and the Portuguese oyster (C. angulata) are important oyster species for commercial aquaculture. In this study, three stocking density regimes, including 20, 30 and 40 oysters/basket, were used to study the effects of stocking density on growth performance, survival rate and lipid nutritional quality of diploid and triploid C. gigas and C. angulata. The experiment lasted 163 days, from to 22 November 2011 to 3 April 2012. The main findings of this study are as follows: (1) C. gigas has growth advantage over C. angulata in Shantou waters; (2) geographic origin of the oysters has an impact on the overall performance of diploid and triploid oysters; (3) triploids are generally no growth and survival advantage over diploids in spring and summer; (4) oysters at low stocking density were generally outperformed those at high stocking density; (5) lipid composition of oysters is not affected by ploidy and stocking density; (6) in Shantou waters, C. angulata is more nutritious than C. gigas. This study compares the performance of C. gigas and C. angulata triploidy for the first time. The findings of this study can provide useful information to be applied in oysters aquaculture. [ABSTRACT FROM AUTHOR]

Growth and survival of the slipper oyster Crassostrea iredalei using traditional (tires and oyster shells) and new methods (pouches and trays) suspended from floating rafts were compared. After six months of grow‐out culture, mean shell length (mm SL) and body weight (g BW) of oysters were significantly highest in those reared in pouches (89.32 ± 0.41 mm SL, 87.70 ± 0.70 g BW), followed by those in trays (83.16 ± 0.31 mm SL, 87.06 ± 0.72 g BW), then those harvested from oyster shells (76.42 ± 0.88 mm SL, 67.35 ± 1.03 g BW), and lastly from tires (72.30 ± 1.21 mm SL, 55.07 ± 1.49 g BW). Growth rates both for length and weight were almost comparable between oysters reared in pouches (6.05 ± 1.28 mm mo−1, 10.98 ± 2.05 g mo−1) and trays (5.01 ± 1.46 mm mo−1, 10.77 ± 2.58 g mo−1). Although 60.7% of the oysters harvested from pouches (n = 1071) were classified as large (85–100 mm SL) and jumbo (100–120 mm SL) and only 39.5% of those from trays (n = 1048), their meat yield did not significantly differ (pouches = 22.60 ± 0.86%; trays = 24.76 ± 0.93%). Survival in pouches (95.2 ± 0.77%) and trays (93.15 ± 2.10%) was almost parallel at harvest. Growing oysters using the new methods produced single, larger, meatier oysters of almost the same size at a shorter culture duration. [ABSTRACT FROM AUTHOR]

Spat settlement (spat density, recruitment, and mortality) of edible oysters Crassostrea spp. was estimated for three sites (Nunia Chara [NC], Chowfoldandy [CD], and Sonadia Island [SI]) located along the Cox's Bazar coast of Bangladesh from February 2019 to January 2020 by deploying shellstrings. Field observations were made every 15 d to understand the monthly variation of oyster spat settlement more precisely. Environmental variables varied significantly with the study site × month interaction or across study sites and months. Gonadal maturation and spawning of oysters may depend on certain environmental conditions, which were greatly influenced by seasonality, especially the monsoon. Spat density, recruitment, and mortality rates were significantly different with the study site × month interaction. The NC site offered higher spat density and recruitment than CD and SI during most months; spat density was lower due to increased mortality during the monsoon (late May to mid‐October) at all sites. Spat density was positively related to salinity, pH, and total suspended solids but negatively related to temperature and high‐ and low‐tide water depths. Recruitment was positively related to salinity and negatively related to low‐tide water depth. Spat mortality was positively related to high‐tide water depth but negatively related to low‐tide water depth. Eight different groups of fouling organisms were observed during the study, which could affect spat settlement. Most interestingly, oyster drills at NC and SI and marine macrophytes and bushlike organisms at CD and SI could contribute to increased mortality during the monsoon. This study showed that none of the three sites would be potential locations for spat collection on shellstrings during the monsoon; however, if avoiding the monsoon, NC has a higher potentiality of allocation for spat collection both for commercial farming and oyster restoration efforts. [ABSTRACT FROM AUTHOR]

Infestations of commercially cultured eastern oysters (Crassostrea virginica) by shell‐boring spionid polychaetes are common in the northeastern United States. Historically, infestations were attributed to Polydora websteri, also known as mud‐blister worm. Among samples of shell‐boring worms sampled from eight oyster farms in northern New England (Maine, New Hampshire, and Massachusetts), we detected P. websteri, as well as worms that were morphologically distinct from P. websteri. Using a combination of light and scanning electron microscopy, along with analysis of molecular variation at the nuclear 18S rRNA and mitochondrial cytochrome c oxidase I (COI) genes, we determined that specimens related to two other species of Polydora, Polydora onagawaensis and Polydora cornuta, were inhabiting burrows within the shells of oysters. Polydora cornuta is not recognized as a shell‐boring species and likely invades existing burrows opportunistically. Our analysis of COI sequences identified three distinct genetic lineages among specimens morphologically identified as P. cornuta; one of these lineages is much more geographically widespread than previously had been reported. Polydora onagawaensis is considered a shell‐boring species, and our article constitutes the first time this species has been documented in the Northwest Atlantic. We also provide evidence for three divergent COI genetic lineages that occur sympatrically among the specimens provisionally identified as P. onagawaensis in the northeastern United States. [ABSTRACT FROM AUTHOR]

Summary: Evolution of virulence traits from adaptation to environmental niches other than the host is probably a common feature of marine microbial pathogens, whose knowledge might be crucial to understand their emergence and pathogenetic potential. Here, we report genome sequence analysis of a novel marine bacterial species, Vibrio bathopelagicus sp. nov., isolated from warm bathypelagic waters (3309 m depth) of the Mediterranean Sea. Interestingly, V. bathopelagicus sp. nov. is closely related to coastal Vibrio strains pathogenic to marine bivalves. V. bathopelagicus sp. nov. genome encodes genes involved in environmental adaptation to the deep‐sea but also in virulence, such as the R5.7 element, MARTX toxin cluster, Type VI secretion system and zinc‐metalloprotease, previously associated with Vibrio infections in farmed oysters. The results of functional in vitro assays on immunocytes (haemocytes) of the Mediterranean mussel Mytilus galloprovincialis and the Pacific oyster Crassostrea gigas, and of the early larval development assay in Mytilus support strong toxicity of V. bathopelagicus sp. nov. towards bivalves. V. bathopelagicus sp. nov., isolated from a remote Mediterranean bathypelagic site, is an example of a planktonic marine bacterium with genotypic and phenotypic traits associated with animal pathogenicity, which might have played an evolutionary role in the origin of coastal marine pathogens. [ABSTRACT FROM AUTHOR]

Oysters are widely distributed worldwide, but are mainly concentrated in tropics and subtropics. Total lipid (TL), fatty acid (FA) composition of TL and polar lipid (PoL) fractions, phospholipid (PL) class, and molecular species composition in soft tissues of Crassostrea lugubris were investigated for the first time from Vietnam. Phosphatidylglycolic acid (PGA) is the new phospholipid class first identified in marine species in general and Crassostrea lugubris in particular. Main eight classes of PL were determined in PoL fraction: diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylinositol (PI), phosphatidylserine (PS), ceramide aminoethylphosphonate (CAEP), CAEP with hydroxylated FAs (CAEP‐OH), and lysophosphatidylcholine. PE and PC accounted for approximately 63% of total known PL. Polyunsaturated FAs accounted for more than 30% of TL. Ninety molecular species of glycerophospholipids, including PGA, PE, PC, PS, PI, DPG, and PG, and sphingophosphonolipids (CAEP) were identified in PoL. Alkenyl‐acyl forms of glycerophospholipids were predominated in the molecular species of PGA, PE, and PS. PGA 38:1 (p18:0/20:1), PE 40:6 (p18:0/22:6 and p18:1/22:5), PC 30:0 (14:0/16:0), PS 38:1 (p18:0/20:1), PI 40:5 (20:1/20:4), PG 32:0 (16:0/16:0), DPG 88:24 (22:6/22:6/22:6/22:6), and CAEP 34:2 (d18:2/16:0) were major molecular species. [ABSTRACT FROM AUTHOR]

Indian Backwater oysters (Crassostrea madrasensis) are available en mass around Sri Lanka but nutritional value and seasonal changes have not been studied sufficiently. Proximate composition and percentage edibility (PE) for wild and cultured oysters in Kala Oya estuary and Puttalam lagoon were studied. Influence of environmental factors on proximate composition was also analysed for both cultured and wild oysters. The mean values ranged from 5.67 ± 0.15% to 8.08 ± 0.01% for protein, 1.02 ± 0.01% to 2.08 ± 0.26% for lipid, 1.39 ± 0.02% to 2.61 ± 0.09% for ash, 84.68 ± 0.28% to 89.72 ± 0.21% for moisture, 10.28 ± 0.21% to 15.32 ± 0.28% for dry weight and 1.37 ± 0.43% to 4.41 ± 0.47% for carbohydrate. A positive relationship with salinity was found for mean percentage of lipid (Adj‐R2 = 57.68%, p < 0.05), dry weight (Adj‐R2 = 61.58%, p < 0.001) and carbohydrate (Adj‐R2 = 40.71%, p < 0.001) while a negative relationship was found for moisture (Adj‐R2 = 61.58%, p < 0.001). PE varied from 6.10 ± 2.73% to 10.66 ± 6.70%, and a peak was observed from October to February for cultured oysters. The prominent peak of PE during October to February is suggestive of suitable harvesting period of cultured C. madrasensis. [ABSTRACT FROM AUTHOR]

The cultivated Eastern oyster (Crassostrea virginica) is sold in a niche market seeking rounder and thicker oysters. While most of the research conducted on optimal rearing densities focuses on survival and length growth, the present study looks at the oyster's shape. Three initial length classes were used for this study and reared in floating bags at different densities. The effects of the tested rearing densities were more pronounced on oyster shape than on length growth. In the smaller oysters, the three lower densities produced the rounder shape while thicker ones were obtained with the 500 densities. For the medium oysters, rounder and thicker shape was obtained with the two lower densities. The shape of the larger oysters was not influenced by the tested densities. This study showed that there was significant impact of rearing densities on smaller and medium oysters' growth and shape, while only length growth of larger ones was impacted by this factor. Based on these findings, oyster farmers should target rearing density of 500 oysters per bag for the 20–35 mm stage, 250 oysters for the 35–50 mm oysters and 200 oysters for the larger ones (50–65 mm). The latest recommendations are based on technical considerations. [ABSTRACT FROM AUTHOR]

In this study, the accumulation, depuration and methylation of mercury in Crassostrea gigas and Meretrix meretrix were analysed and evaluated using the two‐compartment kinetic model through exposure in mercury chloride (HgCl2) solution and depuration procedure in seawater. The results showed that the accumulation and depuration of mercury in organisms were related to the dissolved inorganic Hg(II) content with accumulation delay. It was suggested that the two organisms formed methylmercury (MeHg) when exposed to Hg(II) that is not only formed by anaerobic bacteria in marine sediments. The peak value of MeHg appeared in the depuration phase. The accumulation of C. gigas was stronger than that of M. meretrix, with a peak value of 37.86 ± 3.29 μg/g and 14.48 ± 0.29 μg/L respectively. Crassostrea gigas also had a stronger methylate ability. According to the reference dose for MeHg determined by the United States Environment Protection Agency along with model calculations, when the concentration of Hg in the water reaches 0.2 μg/L, the cultured M. meretrix would be safe for consumption, while cultured C. gigas should be depurated before marketing due to the higher content of MeHg (0.50 mg/kg). Therefore, the two‐compartment kinetic model could be used to monitor the Hg and MeHg content of bivalves when the concentration of Hg in seawater is known. [ABSTRACT FROM AUTHOR]

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Pacific oyster (Crassostrea gigas) farming has developed in recent years along the Italian coasts of the Adriatic sea. This is particularly true in sites located in the northern area and only recently becoming more common in the southern area, which is different particularly in regards to temperature and trophic conditions. There is a lack of studies on the status of the oysters farmed in this area; therefore, the present research aimed to monitor the health conditions of adult triploid oysters that were kept in offshore longline culture system over one year. Environmental parameters were daily estimated from satellite. Biometric, immunological and oxidative stress parameters were measured monthly, looking also for the presence of pathogens, such as OsHV‐1, Vibrio aestuarianus and Vibrio splendidus. During summer months, high temperatures and low food availability had a detrimental impact on the growth and immunological parameters which showed a progressive recovery during the autumn and winter months. Overall, no abnormal mortality was observed, and no histological alterations were evident. The presence of pathogens was negligible, and the oxidative stress parameters were poorly detected, except for the digestive glands during the autumn and winter seasons. On this basis, the data herein reported suggest that the area could be suitable for the development of triploid Pacific oyster farming, although animals would require a longer time to reach commercial size. [ABSTRACT FROM AUTHOR]

Aim: Understanding spatial patterns of the distribution of adult native oyster, Ostrea edulis, and the invasive Magallana (Crassostrea) gigas is important for management of these populations. The aim of this study was to use ensemble SDM's to (a) identify and predict conservation hotspots, (b) assess the current level of protection for O. edulis, and (c) quantify the amount of overlap between the two species where interactions with M. gigas are most likely. Location: Skagerrak, Sweden. Methods: We used data collected by video at depths from 0.5 to 10 m in 436 sites. Models of occurrence and densities >1 m−2 were fitted and assessed using ensemble methods ("biomod2" package). Models of high‐density hotspots were used to predict, map, and quantify areal extent of the species in order to assess the degree of overlap with protected areas and the potential for interactions between the two species. Results: Both species were widely distributed in the region. Observations of high‐density habitats, mainly occurring at depths of ≈3 and 0.5 m for O. edulis and M. gigas, respectively, were found in 4% and 2% of the sites. Models provided useful predictions for both species (AUC = 0.85–0.99; sensitivity = 0.74–1.0; specificity = 0.72–0.97). High‐density areas occupy roughly 15 km2 each with substantial overlap between species. 50% of these are protected only by fisheries regulations, 44% are found in Natura 2000 reserves and 6% of the predicted O. edulis enjoys protection in a national park. Main conclusions: Data collection by video in combination with SDM's provides a realistic approach for large‐scale quantification of spatial patterns of marine population and habitats. O. edulis and M. gigas are common in the area, but a large proportion of the most valuable O. edulis habitats are not found in protected areas. The overlap between species suggests that efforts to manage the invasive M. gigas need to be integrated with management actions to conserve the native O. edulis. [ABSTRACT FROM AUTHOR]

Water quality standards for cobalt (Co) have yet to be developed for the European Union or the United States. The primary objective of the present study was to produce a data set comprising marine Co toxicity data that could be used by both the European Union and the United States to determine a predicted‐no‐effect concentration and ambient water quality criteria, respectively. Ten marine species, ranging from algae to fish, were subjected to chronic Co toxicity tests that were designed to meet international water quality testing standards. Chronic 10% effect concentration values ranged from a low of 1.23 µg dissolved Co/L for red algae (Champia parvula) to a high of 31 800 µg dissolved Co/L for sheepshead minnow (Cyprinodon variegatus). The species sensitivity ranking for chronic marine Co exposure was as follows (from most to least sensitive): C. parvula > Neanthes arenaceodentata (polychaete) > Americamysis bahia (mysid shrimp) > Skeletonema costatum (marine diatom) > Dendraster excentricus (sand dollar) > Mytilus galloprovincialis (mussel) > Strongylocentrotus purpuratus (purple sea urchin) > Crassostrea gigas (oyster) > Dunaliella tertiolecta (marine flagellate) > C. variegatus. Chronic test results indicated that invertebrate and plant species were substantially more sensitive to Co exposure than fish. The chronic toxicity data were used to calculate a species sensitivity distribution, from which a hazardous concentration 5th percentile of 7.09 µg dissolved Co/L (95% CI 0.025–47.3 µg Co/L) was derived. Environ Toxicol Chem 2021;40:1405–1418. © 2021 SETAC [ABSTRACT FROM AUTHOR]

Sierra Leone constitutes the western boundary to the West Africa Upper Guinea Rainforest, one of 35 global biodiversity hotspots. The country is home to the third‐largest western chimpanzee (Pan troglodytes verus) population, a subspecies upgraded to Critically Endangered on the 2016 IUCN Red List. The main threats facing chimpanzees in Sierra Leone are habitat loss and increasing interactions with humans. The Mobonda Community Conservation Project (MCCP) is a component of Tacugama Chimpanzee Sanctuary's Community Outreach Program and Kids Environmental Education Program. The aim of MCCP is to promote community‐based forest management in combination with wildlife conservation through carefully designed programs that benefit communities, wildlife, and ecologically significant habitats. MCCP also aims to promote self‐sustained and integrated community landscape conservation, to facilitate policy discussions to strengthen wildlife laws, and to build the capacity of the Government to implement community‐based wildlife and forestry protection projects. Since Tacugama began collecting data in Moyamba District in June 2015, the project has evolved into an assembly of components. MCCP currently works with five communities, running programs including environmental education, ecological research, biomonitoring including wildlife law enforcement, habitat rehabilitation through reforestation of identified wildlife corridors, improved sustainable livelihoods, and ecotourism initiatives. These programs contributed to a reduction in the threats facing wildlife in the area; the project has seen stable chimpanzee numbers where decrements to chimpanzee populations continue to be experienced elsewhere. Other MCCP outcomes include boosted sustainable agricultural production and higher oyster yields while decreasing the negative impact on the mangrove ecosystem allowing it to recover and support an array of important fauna and flora. Highlights: The Mobonda Community Conservation Project aims to promote community‐based forest management in combination with wildlife conservation through programs that benefit communities, wildlife, and ecologically significant habitats.Main components of the project include environmental education and sensitization, wildlife and habitat assessments, biomonitoring, reforestation and sustainable and alternative livelihood support.Threats facing wildlife have reduced with stable chimpanzee populations recorded over 5 years. Other outcomes include higher oyster yields while decreasing the impact on mangroves allowing them to support other important fauna and flora. [ABSTRACT FROM AUTHOR]

Competition between organisms interfere in host and pathogen dynamics in ways that are difficult to predict. By one side, competitors can reduce the food supply and cause nutritional stress. Such stress could further modulate the susceptibility to infection by altering immune response or metabolic rate of the host. Alternatively, competitors may trap pathogens before they reach the focal host, and therefore reduce, enhance, or have no effect on infection according to the competitor's susceptibility to the infection. To better understand how competition influences host and pathogen interactions, we experimentally assessed the relative importance of competition for pathogens and resources on the severity of a viral disease infecting the Pacific oyster Crassostrea gigas. We designed an open‐flow system where food enriched seawater flowed to filter‐feeding competitors (or empty controls) before being delivered to recipient oysters. We tested a range of competing species that exhibit both low (ascidians, European oysters, mussels) and high (Pacific oysters) susceptibility to the virus. We assessed the physiological condition of the recipient oysters during acclimation, we added virus‐contaminated seawater upstream of the distribution system, and we monitored host and pathogen dynamics. We found that the presence of competitors, regardless of susceptibility to the virus, indirectly reduced the infection rate of hosts by decreasing their food ingestion and growth rates. Although competitors can reduce viral particles from the seawater, this had no effect on the host population. Our data suggest that the effect of competition for food overwhelmed that of competition for pathogens, thus emphasizing the importance of considering resource availability in host and pathogen dynamics. More particularly, resource availability can have positive effects at the individual level, fostering physiological condition and growth, but negative effects at the population level, increasing magnitude of epidemics. [ABSTRACT FROM AUTHOR]

The reproductive cycle of Crassostrea gasar oysters from a single origin (Federal University of Santa Catarina hatchery) was studied by culturing the species for 1 year in four distinct areas of Brazil; two of which were in tropical climates (02°44′S, 41°58′W; 02°47′S, 41°55′W) and two in temperate climates (26°28′S, 48°50′W; 27°35′S, 48°32′W). In each area, 20 individuals were collected each month for reproductive cycle analysis using standard histological techniques. Oysters cultivated in tropical climates demonstrated intermittent reproductive cycles, with individuals spawning throughout the year and rarely entering a resting stage. Oysters cultivated in temperate climates demonstrated spawning periods associated with increases in water temperatures, occurring in late spring and summer. Resting stages were clearly seen in samples from latitudes of 26 and 27 °S, with approximately 75% to 100% of the individuals in this stage between May and July. [ABSTRACT FROM AUTHOR]

Summary: Heat treatment is a convenient way to eliminate the effects of endogenous enzymes on the industrial production of stable products. This study describes the preparation of protein isolates from oysters (OPI and HOPI) and krill (KPI and HKPI) by isoelectric solubilisation/precipitation (ISP) with or without heat pretreatment and comparatively presents their characteristics. The results showed that the solubilities of HOPI (24.08 ± 1.94%) and HKPI (42.29 ± 0.78%) were higher than those of OPI (13.46 ± 0.78%) and KPI (21.71.46 ± 1.51%), and the free and total sulphhydryl (‐SH) content and surface hydrophobicity of HOPI and HKPI were higher than those of OPI and KPI, which are related to higher fat content of HOPI (10.37 ± 0.55%) and HKPI (34.89 ± 1.19%). SDS–PAGE and gel chromatography pattern results showed that macromolecular proteins were degraded by endogenous enzymes in OPI and KPI, while they remained unaffected in HOPI and HKPI. The FT‐IR spectra showed similar patterns between OPI and HOPI and between KPI and HKPI. While the essential amino acid content was similar for OPI and HOPI (47.06 ± 1.33% and 47.93 ± 1.02%), that of KPI and HKPI (50.89 ± 0.89% and 51.19 ± 1.11%, respectively) was not significantly different. [ABSTRACT FROM AUTHOR]

In his 1974 I BioScience i paper, Pomeroy applied these ideas exclusively to the ocean's food web, and directly considered implications for fisheries and management (Pomeroy 1974). In 1960, Larry, Janet, and their two children moved to the University of Georgia (UGA) main campus where Larry joined Odum as a faculty member in the Zoology department. In this instance, Pomeroy finagled his P-32 and, working with Bill Weibe and Michael Pilsen, demonstrated, for the first time, that the reef communities were not phosphorus-limited, "having evolved recycling loops to satisfy their (nutrient) requirements" (Pomeroy et al. 1974). By 1970, Pomeroy had framed many of the ideas that led to his famous paper in I BioScience i "The Ocean's Food Web, A Changing Paradigm" (Pomeroy 1974). [Extracted from the article]