Oyster Culture Research Articles

The Probiotic Bacillus hwajinpoensis Colonizes the Digestive System of Crassostrea gigas Larvae and Protects Them from Vibrio alginolyticus Infection.

The Pacific oyster Crassostrea gigas is one of the most important cultured marine species around the world. Production of Pacific oysters in China has depended primarily on hatchery produced seeds since 2016, with the successful introduction and development of triploid oysters. However, the seed supply of Pacific oysters is threatened by recurring mass mortality events in recent years. Vibriosis is the most commonly encountered disease associated with intensive oyster culture in hatcheries and nurseries. Vibrio alginolyticus and Bacillus hwajinpoensis were the two strains with pathogenic and probiotic effects, respectively, identified during the Pacific oyster larvae production. To monitor their colonization process in Pacific oyster larvae, green fluorescent protein (GFP) and red fluorescent protein (RFP) were labeled to the pathogenic V. alginolyticus and the probiotic B. hwajinpoensis stain, respectively. The pathogenic and probiotic effects of the two strains during the colonization process were then assessed. Stabile expression of GFP and RFP were observed in corresponding stains, and the capabilities of growth, biofilm formation and in vitro adhesion of GFP- and RFP- tagged stains were not significantly different from those of the wild-type strains. Usage of probiotics of 105 CFU/mL significantly inhibited the growth of pathogenic V. alginolyticus and reduced the mortality of D-sharped larvae. Both the pathogenic and probiotic strains employed a similar route to enter and colonize the oyster larvae, which indicates that competing with pathogens for binding and spreading sites were one of the mechanisms of B. hwajinpoensis to provide the probiotic effects to oyster larvae. In summary, employment of fluorescence-tagged pathogenic and probiotic strains simultaneously provides us with an excellent bioassay model to investigate the potential mechanisms of probiotics.

Circular utilization of discarded oyster farming bamboo scaffolding in pulp and papermaking

Oyster Farming is one of important fisheries and aquaculture industries in Taiwan. Each year, approximately 4000–5000 tons of discarded bamboo scaffolding (BS) used in oyster farming, are generated, so the treatment and utilization of BS should be taken seriously. This study evaluates the suitability of BS for pulp and papermaking by assessing the chemical compositions, microstructural, and fiber morphology. The pulping properties is investigated by soda pulping. The chemical composition of BS shows the potential for application in pulping. The BS microstructure shows that can enhance pulping reactions, while the fiber morphology indicates the possibility of producing high-strength paper. Through the pulping experiment, it demonstrated that BS is suitable for pulping with lower NaOH dosage and longer digestion time. The condition at 170 °C with 14% NaOH dosage for 90 min digestion has the highest yield. After refining the highest pulping yield BS pulp, it can improve the handsheet strength and bulk of the OCC-BS mixed pulp, which can achieve the strength property required for industrial paper. In summary, BS exhibits the potential for pulping application and produces a better paper strength than OCC pulp, exhibiting the feasibility of enhancing the circular utilization value of BS in Taiwan.

OYSTER BIO DEPOSITION ENHANCED THE FUNCTIONAL POTENTIAL OF LABILE AND RECALCITRANT CARBON IN SHENZHEN BAY’S SEDIMENTS

Oysters are typical aquatic animals with their special biological property of filter feeding in the water column. However, the biodeposition of oysters may change the sediment chemistry and also may affect the biogeochemical processes. We conducted research work to determine the effect of Oyster Biodeposition (OBD) on the sediments microbes, and their metabolic abilities on carbon at the site rich with oyster culture area of Shenzhen Bay China. After biochemical and Geochip5 analysis, we found that the genes coding the metabolic enzymes pullulanase, glucoamylase, exoglucanase, cellobiase, xylanase, etc. were highly abundant in oyster farming place compared to reference place. Meanwhile, the functional genes cda (6%), pectinase (5%), and xyla (5%) were greatly abundant at the surface oyster area and they were showing significantly higher ( P= <0.05) normalized gene intensities compared to bottom sediment site. These genes were mostly involved in the degradation of labile and recalcitrant forms of carbon. These detected genes were mainly involved in the carbon degradation process and they were showing more tendency towards the degradation of labile carbon. Small abundance of enzymes such as glyoxal oxidase and phenol oxidase were also found which were involved in the degradation of recalcitrant carbon. Taken together, our results indicated that the OBD enhanced the degrading capacity of both labile and recalcitrant forms of carbon, it has a positive stimulating effect on sediment carbon metabolism.

Seasonal Feeding Behavior of Aquaculture Eastern Oysters (Crassostrea virginica) in the Mid-Atlantic

The Eastern Oyster (Crassostrea virginica) is a commercially important aquaculture species and food resource along the Atlantic and Gulf coasts of the USA. In addition to its economic value, oyster aquaculture provides ecological value such as water quality improvement. Oyster filtration is highly variable as filtration behavior is influenced by environmental conditions, oyster size, and oyster energetic demands. However, average rates generated in laboratory experiments are often used to estimate the ecological impact of oyster filtration, and there is a need for field-based, farm-specific estimates of filtration that account for this variation. In this study, field experiments were conducted between September 2020 and September 2021 to estimate seasonal oyster filtration physiology at oyster farms in three different bays in the Mid-Atlantic (Barnegat Bay and Delaware Bay in New Jersey and Rehoboth Bay in Delaware). The physiological activity of oysters at each farm varied such that oysters at Barnegat Bay were the most active and oysters at Rehoboth Bay were the least active. Seasonal physiological trends were observed such that filtration behavior generally increased in warmer months. An increase in physiological activity across all farms was associated with an increase in salinity and temperature, but physiological activity at each farm was associated with a different suite of environmental variables including total particulate matter and the organic content of seston. This study provides a robust dataset which can be incorporated into models estimating ecological filtration rates in the Mid-Atlantic and adds to the growing body of evidence supporting bivalve aquaculture as a nutrient reduction strategy.

Relative importance of phenotypic plasticity and carryover effects in response to small salinity shifts during oyster aquaculture production

Variability of water conditions in coastal environments could affect oyster aquaculture production through three main environmental-tolerance mechanisms: phenotypic plasticity, within-generation carryover effects, and selective mortality. Aquaculture production of eastern oyster, Crassostrea virginica, larvae occurs on weekly timescales in Virginia, with variations in salinity experienced by subsequent larval cohorts. The present study examined the relative importance of within-generation carryover effects – phenotypic changes during a previous life stage that impact a later stage – and phenotypic plasticity in shaping the performance of juvenile oysters after an experience of small differences in salinity (< 2 salinity units) during the larval stage. Genetic diversity was also assessed to rule out large shifts in allele frequencies, or loss of diversity, that would suggest observed effects were the result of selective mortality rather than carryover effects or phenotypic plasticity. Larval oysters were reared through settlement and metamorphosis under two salinities (thirteen and fifteen) that represent small differences between consecutive spawns in a hatchery. Juveniles were then raised in situ in two Virginia tributaries of the lower Chesapeake Bay, the York and Rappahannock rivers. Oyster production occurs within these two tributaries under distinct salinity conditions, with the Rappahannock tending to be of lower salinity. Metrics of survival, growth, oxidative stress, and condition index were compared to assess phenotypic plasticity and within-generation carryover effects. Juvenile oyster survival and physiology correlated with in situ environmental conditions rather than previous larval salinity experience. Specifically, juvenile oysters raised in the Rappahannock River had greater survival (13%), shell length (14%), condition index (38%), and dry tissue weight (78%) than those raised in the York River, regardless of larval salinity. Rappahannock River oysters also had 20% lower total antioxidant capacity than York River oysters. Genetic diversity remained high with no large shifts in allelic frequencies that would suggest non-random loss of alleles attributable to selection. Our results suggest that small salinity differences experienced in shellfish hatcheries 48 h after fertilization likely do not impact juvenile oyster performance during grow-out; rather, phenotypic plasticity likely underpins juvenile oyster performance during the transition from hatchery to farms. The importance of phenotypic plasticity presents another reason why farm site selection is critical to the performance and success of aquaculture product. Future studies are needed to further identify whether larval responses to salinity conditions are dependent on additional environmentally relevant conditions like temperature or the timing of exposure post-fertilization to better understand the relative importance of phenotypic plasticity, within-generation carryover effects, and selective mortality within oyster aquaculture.

Comparative Description and Analysis of Oyster Aquaculture in Selected Atlantic Regions: Production, Market Dynamics, and Consumption Patterns

In the face of an increasing world population and a subsequent need for an increase in sustainable and healthy food production, low trophic species, such as oysters, emerge as a promising alternative. However, regional variations in oyster production techniques, market dynamics, and consumption patterns create challenges for both the global and local industry’s growth. In this study, a descriptive qualitative analysis of oyster markets across seven Atlantic regions was carried out. The Pacific oyster (Crassostrea gigas) was found to be farmed in most Atlantic regions except the US but is classified as invasive in Sweden and potentially invasive in South Africa. Other farmed and/or harvested species include native species (C. gasar and C. rhizophorae) in Brazil, the American cupped oyster (C. virginica) in the US, and the European flat oyster (Ostrea edulis) in France, Sweden, and the US. In Irish farms, Pacific oysters are primarily for export to European markets. The marine aquaculture sectors of Sweden, South Africa, and Namibia, as well as Brazil’s farming for C. gasar, were found to be underdeveloped. This study also observed a variation in licensing, property rights, and regulatory frameworks. Financial challenges for small businesses, ecological implications of seed production techniques, biosecurity risks, and public health considerations are emphasized as critical areas for attention. This study offers valuable insights into the selected markets and can serve as a useful resource for policymakers, aquaculture practitioners, and stakeholders in optimizing global shellfish industry strategies.

Hydrodynamic coefficients of mussel dropper lines derived from large-scale experiments and structural dynamics

The expansion of marine aquaculture production is driven by a high market demand for marine proteins and a stagnation of wild catch of fish. Bivalve farming, i.e., the cultivation of oysters, mussels and scallops, is an important part of the ongoing market dynamics and production expansion. As marine spatial planning is considering various use purposes, available space for near-shore aquaculture is already becoming scarce; this has fueled research and development initiatives to enable production installations further offshore. The highly energetic conditions at more exposed offshore marine sites lead to increased loads on aquaculture systems and their components and it is still not sufficiently understood how the load transfer from oceanic environmental conditions onto shellfish-encrusted surfaces attached to elastic ropes may be appropriately quantified. This study data gathered large-scale data sets in a wave tank facility, which are used to validate a novel, numerical model, building on the dynamics of rope structures which allows for the determination of the hydrodynamic loads transferred to the dropper lines. The forces and hydrodynamic parameters are measured and numerically analyzed. Based on the results, drag and inertia coefficients are determined. A drag coefficient of CD=1.1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$C_\ extrm{D} = 1.1$$\\end{document} and an inertia coefficient of CM=1.7\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$C_\ extrm{M} = 1.7$$\\end{document} are recommended to model shellfish-encrusted dropper lines exposed to oscillatory flows with KC =\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$=$$\\end{document} 40–90. The numerical model for the determination of wave-induced forces on mussel dropper lines is developed and validated using the experimental data. It employs a modified Morison equation, which takes into account the displacement of the mussel dropper line. The influence of varying aquaculture-related parameters is discussed by applying the numerical model. Based on the gathered insights, recommendations can be given from an engineering point of view concerning the optimal placement of mussel aquaculture within the water column.

Assessing impacts of coastal warming, acidification, and deoxygenation on Pacific oyster (Crassostrea gigas) farming: a case study in the Hinase area, Okayama Prefecture, and Shizugawa Bay, Miyagi Prefecture, Japan

Abstract. Coastal warming, acidification, and deoxygenation are progressing primarily due to the increase in anthropogenic CO2. Coastal acidification has been reported to have effects that are anticipated to become more severe as acidification progresses, including inhibiting the formation of shells of calcifying organisms such as shellfish, which include Pacific oysters (Crassostrea gigas), one of the most important aquaculture resources in Japan. Moreover, there is concern regarding the combined impacts of coastal warming, acidification, and deoxygenation on Pacific oysters. However, spatiotemporal variations in acidification and deoxygenation indicators such as pH, the aragonite saturation state (Ωarag), and dissolved oxygen have not been observed and projected in oceanic Pacific oyster farms in Japan. To assess the present impacts and project future impacts of coastal warming, acidification, and deoxygenation on Pacific oysters, we performed continuous in situ monitoring, numerical modeling, and microscopic examination of Pacific oyster larvae in the Hinase area of Okayama Prefecture and Shizugawa Bay in Miyagi Prefecture, Japan, both of which are famous for their Pacific oyster farms. Our monitoring results first found Ωarag values lower than the critical level of acidification for Pacific oyster larvae in Hinase, although no impact of acidification on larvae was identified by microscopic examination. Our modeling results suggest that Pacific oyster larvae are anticipated to be affected more seriously by the combined impacts of coastal warming and acidification, with lower pH and Ωarag values and a prolonged spawning period, which may shorten the oyster shipping period and lower the quality of oysters.

Aquaculture in Algeria: Current Status, Analysis, and Considerations for Commercial Development

Aquaculture in Algeria has developed significantly since the 1920s, primarily focusing on oyster and mussel farming. Establishing the Ministry of Fisheries and Marine Resources (MPRH) in 1999 marked a crucial milestone for the industry. Despite challenges in data collection, Algerian aquaculture production reached only 4,779.29 tonnes in 2021, showing a mere 0.2% of African production and 0.0044% of world aquaculture production. More than half of production comes from marine fish cultured in private-sector sea cages. However, shrimp production is almost null. The taxonomic composition of Algerian aquaculture is diverse, with marine and freshwater fish species playing prominent roles. Despite these challenges, the aquaculture field in Algeria has demonstrated an impressive annual growth rate of 12.49% and receives continuous government support. Nevertheless, limited infrastructure, a shortage of expertise, and the need for further research pose significant obstacles. Efforts are underway to integrate aquaculture with agriculture in Saharan zones, further facilitated by governmental support. Overcoming challenges and promoting sustainability through strengthening research capacities, fostering collaboration, and providing financial support is crucial for the advancement of industry. By addressing challenges and embracing sustainability, the aquaculture sector in Algeria can unlock its full potential, ensuring food security, economic growth, and environmental sustainability.

Features of the reproductive biology of representatives of the genus Haslea Simonsen (Bacillariophyta), allowing the use of classical breeding methods

The application of the classical selection of diatoms on the example of the genus Haslea is considered. The ability of some representatives of this genus to synthesize marennine and marennine-like pigments is interesting to researchers and owners of oyster farms because these unique pigments can colorise the tissues of mollusks in a greenish color and improve their organoleptic properties. It has been shown that marennine has antibacterial, antiviral, antioxidant and other biological activities. It is assumed that the efficiency of marennine biosynthesis can be increased by obtaining highly productive strains by selection, which was not previously carried out in diatoms. The assessment of the possibility and prospects of applying the methods of classical breeding in relation to representatives of the genus Haslea is given. It is shown that significant success has been achieved to date in the study of the life cycle, crossing systems and other features of the reproductive biology of representatives of the genus Haslea, which allows them to carry out classical selection by selection, hybridization and obtaining descendants of the next generation.

Risky Business: Can Oyster Farmers Defend Themselves against Foodborne Illness–Related Demand Shocks?

Risky Business: Can Oyster Farmers Defend Themselves against Foodborne Illness–Related Demand Shocks?

Genetic improvement of oysters: Current status, challenges, and prospects

AbstractOysters are one of the most commercially important shellfish species and have been cultured for thousands of years. Oyster aquaculture supports the major aquaculture industries in many countries. Over the last few decades, the oyster breeding and aquaculture industries have developed rapidly to meet the continually growing demand. Many researchers have made significant efforts toward the genetic improvement of commercially important traits in oysters. Some strains with fast‐growing, disease‐resistant, and stable shell‐colours have been developed through selective breeding. Some hybrid varieties have been developed by crossing different geographical populations or cultivated strains. Several hybrids exhibit considerable genetic variation and improved productive performance. Additionally, polyploid induction technologies have been applied in the oyster aquaculture industry, which provides a useful tool for performance improvement and genetic containment of cultured stocks. At present, the development of molecular breeding also provides a great opportunity for oyster genetic improvement. These advances in oyster breeding have improved the quality of oysters, brought great economic benefits, and been conducive to the sustainability of oyster production. Nonetheless, there are still some limitations and obstacles in oyster breeding, such as infectious diseases, summer mortality, conservation of germplasm resources, environmental contamination, and climate change. The present review provides an overview of the current status, challenges, and prospects in oyster breeding.

Optimization of plastic polymers for shellfish aquaculture infrastructures: in situ antifouling performance assessment

Biofouling poses a significant challenge to bivalve aquaculture affecting both the target culture and/or the immersed infrastructure. In suspended bivalve cultures (e.g., oysters and scallops), biofouling accumulation leads to additional labor demands and increased costs for the maintenance of underwater structures. Given that the inherent properties of materials used in farming infrastructure influence the formation of fouling communities, evaluating how these materials perform under diverse environmental conditions can help the industry select the most effective materials for preventing or minimizing biofouling growth. This study evaluates the impact of aquaculture material and environmental conditions on biofouling, focusing on two commonly used plastic polymers in marine aquaculture: polyamide (PA) and high-density polyethylene (PE). Both untreated and color-additive treated polymers were tested for their response to fouling development. Performance was gauged by total fouling wet weight and the extent of fouling-induced mesh occlusion. Experimental panels were deployed for 4 months (from May to September 2021) in estuarine (oyster farm) and marine (port) environments on the northern coast of Portugal. The marine sites exhibited greater fouling species diversity, while higher biofouling loads were found in the subtidal estuarine area. Within 3 months, complete mesh occlusion occurred mainly due to colonial hydroids (Obelia dichotoma) in the subtidal site. In contrast, panels deployed in the intertidal estuarine area had lower fouling biomass and mesh occlusion. Notably, significant differences between polymer types and treatments were only evident in the estuarine intertidal area, with long air exposure during low tide. White panels outperformed orange ones in fouling biomass, and PA panels outperformed PE panels in mesh occlusion. These differences were attributed to the settlement and growth of the acorn barnacle Austrominius modestus, known to favor dark-colored and less hydrophilic surfaces. Considering that oyster production in intertidal areas is one of the most important aquaculture industries globally, these findings offer valuable insights into material selection and characteristics that can mitigate fouling loads and their associated impacts. These results could also be relevant for other forms of bivalve aquaculture where infrastructure-related biofouling presents a challenge.

Growth rate of farmed Mangrove oysters (Magallana bilineata) at Laucala Bay, Suva, Fiji

The cultivation of oysters has a significant historical background in the South Pacific region. The cultivation of pearls has been a significant source of livelihood for numerous island nations. Despite the significant cultural, dietary, and subsistence value of bivalve molluscs among Pacific Islanders, there has been limited advancement in the aquaculture of edible oysters in To enable a comprehensive assessment of the viability of cultivating edible oysters in Fiji, an estimation was conducted pertaining to the growth rate of mangrove oysters Magallana bilineata. A total of 105 oyster spat were cultured in Laucala Bay, Suva, Fiji, over the course of one year, from January 25th, 2021 to January 26th, 2022. The investigation documented exponential growth in oysters, with measurements of 87.3 ± 1.0 mm in length, 67.4 ± 0.7 mm in width, 49.8 ± 0.6 mm in depth, and 104.90 ± 22.6 g in weight. The findings of the study indicated the occurrence of positive isometric growth in relations to weight, length, width, and depth. The observed survival rate was 94%. The growth rates observed in oyster farming in Fiji exhibit similarities to those documented in other geographical locations, thereby providing a favourable indication for the progress of oyster aquaculture in the region.

Comparative Transcriptome and WGCNA Analysis Reveal Molecular Responses to Salinity Change in Larvae of the Iwagaki Oyster Crassostrea Nippona.

The Iwagaki oyster Crassostrea nippona is an important aquaculture species with significant potential for large-scale oyster farming. It is susceptible to the fluctuated salinity in the coastal area. In this study, we compared the transcriptome of Crassostrea nippona larvae under variant conditions with low-salinity stress (28, 20, 15, 10, and 5 practical salinity units (psu)) for 24h. KEGG enrichment analysis of differentially expressed genes (DEGs) from pairwise comparisons identified several free amino acid metabolism pathway (taurine and hypotaurine, arginine and proline, glycine, and beta-alanine) contributing to the salinity change adaptation and activated "lysosome" and "apoptosis" pathway in response to the low-salinity stress (10 and 5 psu). Trend analysis revealed sustained upregulation of transmembrane transport-related genes (such as SLC family) and downregulation of ribosomal protein synthesis genes faced with decreasing salinities. In addition, 9 biomarkers in response to low-salinity stress were identified through weighted gene co-expression network analysis (WGCNA) and validated by qRT-PCR. Our transcriptome analysis provides a comprehensive view of the molecular mechanisms and regulatory networks underlying the adaptive responses of oyster larvae to hypo-salinity conditions. These findings contribute to our understanding of the complex biological processes involved in oyster resilience and adaptation to changing environmental conditions.

Evaluating the influence of cage motion on the growth and shell characteristics of oysters (Crassostrea virginica) among several gear types

An influx of new oyster culture gear provides growers with an expanded ability to grow oysters throughout the water column. Each gear type is exposed to a different regime of physical forces, which is thought to affect oyster production differently; however, there is a poor understanding of the physical conditions inside cages and how they influence the production rate and quality of oysters. A greater understanding of the fundamental relationships between cage motion, oyster growth, and shell shape could help to improve the efficiency of off-bottom oyster production. Such understanding is critical for tailoring gear selection and tuning gear performance to suit grower needs. To address this void, cage motion, internal oyster movement, and oyster growth among three common cultivation methods (Virginia-style bottom cages, Seapa® long-line baskets, and floating cages) were monitored over a single growing season to clarify the role of the physical environment on oyster performance (shell and tissue growth). The averages and variance in motion among each cultivation method were noticeably different, which resulted in significant differences in the growth rate and quality of oysters they produced. Movement of the floating cages and long-line baskets could largely be explained by wind waves generated from a single direction in the field (r2 = 0.49, r2 = 0.36, respectively), while bottom cage movement was far less affected by wind waves. The changes in physical conditions inside each cultivation method demonstrated a trade-off between shell growth rate (a metric of time to market) and shell and meat quality (representative of crop value). These results can help inform growers wishing to strategically adopt cultivation methods that are most aligned with their production goals.

Market opportunities for Florida farmed oysters

The oyster aquaculture industry has grown quickly in recent years. New farming techniques target specific attributes that increase oysters' value and allow them to be sold in the high-value, half-shell market. A lack of economic data makes it difficult for growers to determine which specific attributes increase oyster value, however. This publication summarizes findings from a recent study that examined restaurant menus to obtain economic data on raw, half-shell oysters. Major findings indicate that brand is an oyster attribute that provides value, and that marketing oysters with information on two or more attributes can also result in higher prices. Additionally, locally sourced oysters are often sold at cheaper prices, providing an opportunity for growers from outside regions to enter new markets. The findings will be useful to Florida oyster growers as attempts to expand Florida’s oyster aquaculture industry continue.

Nursery upweller type has minimal impact on subsequent grow-out of Eastern oysters (Crassostrea virginica)

Demand for oysters in the premium half-shell market drives the need for research to optimize and improve oyster aquaculture production methods. After setting, oysters are typically maintained in nursery upwellers that provide nutrients and oxygen while removing waste. They remain in the nursery until they are large enough to be deployed in aquaculture gear. Land-based upweller systems include silo and bottle upwellers, with bottles requiring less space and maintenance. However, it is unknown if upweller type influences oyster growth, shape, or survival after field deployment. This study reared Eastern oysters, Crassostrea virginica, to 2 mm in silo or bottle upwellers and deployed them to floating bags for a six-week grow-out period. Oysters were sampled initially, then size graded, counted, and redeployed every two weeks. Changes in growth parameters, quality ratios, survival, and hinge backbend deformity prevalence were determined after six weeks. Initially, silo-reared oysters were larger than those reared in bottles, likely due to the need for flow rate optimization and/or the tumbling action that breaks the fragile growing edge of the shell. Despite these initial differences, there were minimal size differences between upweller types after six weeks of growth in the field. There were no significant differences in survival, hinge backbend abnormality prevalence, or size class distribution between upweller types. These results indicate that upweller choice has minimal impact on the grow-out phase of oyster production and both systems are acceptable for Eastern oyster production in the northern Gulf of Mexico.

Tools to Enumerate and Predict Distribution Patterns of Environmental Vibrio vulnificus and Vibrio parahaemolyticus.

Vibrio vulnificus (Vv) and Vibrio parahaemolyticus (Vp) are water- and foodborne bacteria that can cause several distinct human diseases, collectively called vibriosis. The success of oyster aquaculture is negatively impacted by high Vibrio abundances. Myriad environmental factors affect the distribution of pathogenic Vibrio, including temperature, salinity, eutrophication, extreme weather events, and plankton loads, including harmful algal blooms. In this paper, we synthesize the current understanding of ecological drivers of Vv and Vp and provide a summary of various tools used to enumerate Vv and Vp in a variety of environments and environmental samples. We also highlight the limitations and benefits of each of the measurement tools and propose example alternative tools for more specific enumeration of pathogenic Vv and Vp. Improvement of molecular methods can tighten better predictive models that are potentially important for mitigation in more controlled environments such as aquaculture.

Abundance and distribution of non-indigenous Calyptraeidae gastropods along north and central Atlantic shores of Portugal

Two non-indigenous species of slipper limpets (Gastropoda: Calyptraeidae) have been recorded in NW Europe: Crepidula fornicata and Crepipatella dilatata. Although the former is widespread distributed in European Atlantic, records on Portuguese coasts are scarce. Regarding C. dilatata, it has been only reported in the southern Galician Rías (NW Spain). In this study, C. dilatata is reported for first time on Portugal and the distribution of these two species were studied in the North and Centre of Portugal. Moreover, abundance, distribution and structure of C. dilatata populations were compared between two intertidal habitats. Abundance and structure of C. dilatata populations showed no significant differences between habitats, suggesting that the species is well established in both. Regarding size-frequencies, bigger individuals were more frequent in soft bottoms. The recent development of oyster aquaculture in Portugal and the variety of substrates in which these NIS have been found could facilitate future introductions in nearby locations.