Oyster Growth Research Articles

Predicting restoration and aquaculture potential of eastern oysters through an eco-physiological mechanistic model

A simple, non-negotiable truth of ensuring success in the restoration of ecological engineers (EE) and the functions they support is the need for the focal species to survive, grow and reproduce. Using mechanistic modeling, such as a dynamic energy budget (DEB), to map an EE's fundamental niche supports restoration and management predictive of EE resilience under current and future conditions. One EE, the eastern oyster, Crassostrea virginica, provides critical estuarine habitat and supports a valuable fishery across the northern Gulf of Mexico. Recent declines in oyster populations in this region from anthropogenic activities and extreme events have led to significant efforts to restore wild, self-sustaining broodstock reefs, and develop off-bottom aquaculture. To explore potential outcomes for oyster restoration and aquaculture development, we used an individual bioenergetic model based on DEB theory to derive an aquaculture index, based on survival and time to market size, and a restoration index, based on survival and reproductive output. The model was run across six major Texas and Louisiana estuaries under current (2014–2020) and future (2041–2050) projected environmental conditions. Aquaculture scores using daily averaged current conditions reproduce an observed gradient of oyster growth success increasing from the upper estuary to lower estuary (Texas) or offshore areas (Louisiana), with lower variation occurring in Texas estuaries. Restoration scores under daily averaged current conditions showed similar trends with more variability than the aquaculture index due to spawning potential, which is important for reef sustainability. In general, Louisiana estuaries showed higher growth rates and reproduction than Texas estuaries, but due to the higher variability and more frequent extremes in salinity and temperature, Louisiana estuaries were more likely to experience mortal conditions in any given year, as compared to Texas estuaries. Comparison between current and future conditions indicated that oyster aquaculture and restoration potential in presently occupied areas might decrease in the future; however, the spatial resolution of currently available climate model outputs within coastal and estuarine areas limits planning information. Addressing this gap represents a necessary improvement to better evaluate the physiological response of EE to future conditions, especially since most aquaculture and restoration developments are likely to occur close to the coastline. Finally, this work demonstrates the potential of mechanistic modeling to inform future planning under environmental conditions not currently within the realized niche of EE.

Synergy between Seasonality and Climatic Anomaly and their Effects on the Growth of Oysters Cultivated in the Amazon Coast

Synergy between Seasonality and Climatic Anomaly and their Effects on the Growth of Oysters Cultivated in the Amazon Coast

Effects of Rearing Structure on The Growth and Survival of Pearl Oysters (Pinctada maxima)

West Nusa Tenggara (NTB) is one of the provinces that cultivates many Pinctada maxima pearl oysters. Seed dispersal is a stage that can influence the growth and activity of pearl oysters because they will be moved from the hatchery to the sea. The use of appropriate containers in pearl oyster seed dispersal very necessary to prevent pearl oysters from being carried away by currents or attaching biofouling as a nuisance to biota. The aim of this research is to determine the effect of rearing containers on the growth and survival of pearl oysters (Pinctada maxima). This research used an experimental method using a completely randomized design (CRD) with 4 treatments and 3 replications. The treatments used are different types of keeping containers, namely using traditional containers, pocket baskets, waring baskets and lantern baskets. The results of the research showed that rearing pearl oyster spat (Pinctada maxima) for 60 days in Ekas Bay with the influence of different containers showed that the average absolute length growth obtained was 1.80-3.88 cm, the absolute weight ranged from 12.3 -31.10 g and survival rate 38.86 – 83.30%. The conclusion from this research is that using pocket baskets is better than other containers.

Comparison of live microalgae and Spray-dried algae powder effects on growth, digestive and antioxidant capacity of juvenile pearl oyster Pinctada maxima

The pearl production through the pearl oyster Pinctada maxima’s culture has developed slowly over the past decades due to over-fishing of wild populations and mass mortality at juvenile stages. Indoor farming is an alternative mode for P. maxima juvenile cultivation to improve survival rates. In pursuit of optimizing healthy management under the indoor farming mode, the objective of this investigation was to compare the growth performance, digestion, and antioxidant capacity of juveniles fed with different microalgae-based diets (live Isochrysis zhanjiangensis, Platymonas subcordiformis, Chaetoceros muelleri; and spray-dried I. zhanjiangensis, P. subcordiformis, C. muelleri powder). The juvenile survival rates fed with spray-dried microalgae powder (except C. muelleri powder) were not significantly different from those fed on live microalgae. However, the growth performance of juveniles fed with spray-dried microalgae powder could have been better than the live one. The digestive enzymatic activities were consistent with growth performance, and diets affected the antioxidant capacity. The spray-dried I. zhanjiangensis powder can serve as a substitute for live microalga in P. maxima juvenile indoor farming and is recommended under controlled conditions. The findings from this study would provide essential data to improve health management for P. maxima juveniles in indoor farming conditions.

No trade-off between growth and OsHV-1 tolerance in Pacific oysters (Crassostrea gigas) farmed on the West Coast, USA.

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.

The comparative growth and survival of juvnile tropical oyster (Magallana bilineata, Roding, 1798) using different intensive nursery systems

The comparative growth and survival of juvnile tropical oyster (Magallana bilineata, Roding, 1798) using different intensive nursery systems

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.

Effects of different aquaculture patterns on growth, survival and yield of diploid and triploid Portuguese oysters (Crassostrea angulata)

Bivalve molluscs are increasingly being promoted as an alternative to land-based meat production due to their high levels of high-quality protein and lipids. The Crassostrea angulata, also known as the Portuguese oyster, has been a globally productive and renowned oyster species. In this study, we evaluated the aquaculture performance of C. angulata over two consecutive culture periods (pre-harvest phase, post-harvest phase) at different stocking densities and water depths, and compared the survival, growth and yield of diploid and triploid oysters. The experiment spanned 13 months, beginning in June 2022 and ending in June 2023. The results indicated that both stocking density and water depth significantly affected the aquaculture performance of C. angulata and exhibited distinct patterns in the two culture phases. Overall, compared to diploid C. angulata, triploid oysters showed significant culture advantages in the pre-harvest period, the growth rates and total yield of which were much higher than those of diploids. In the pre-harvest phase, the depth of 1 m and low-density culture (5 substrates/rope) favored the survival and growth of triploid oysters, while diploid C. angulata presented higher growth rates at high-density cultivation (15 substrates/rope), and the total oyster yield under 5 m culture reached a minimum for both diploids and triploids. In the post-harvest phase, the survival rate was stabilized, water depths of 1–3 m were optimal, and diploid oysters grew better at low (50 ind/cage) and medium (100 ind/cage) densities, whereas triploids had a higher growth rate of shell height at medium and high (150 ind/cage) densities. The findings of this research provide theoretical guidelines for exploring efficient C. angulata cultivation methods in the future, which will be beneficial to its commercial production.

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.

Integrative proteome and metabolome analyses reveal molecular basis underlying growth and nutrient composition in the Pacific oyster, Crassostrea gigas

In order to comprehend the molecular basis of growth, nutrient composition, and color pigmentation in oysters, comparative proteome and metabolome analyses of two selectively bred oyster strains with contrasting growth rate and shell color were used in this study. A total of 289 proteins and 224 metabolites were identified differentially expressed between the two strains. We identified a series of specifically enriched functional clusters implicated in protein biosynthesis (RPL4, MRPS7, and CARS), fatty acid metabolism (ACSL5, PEX3, ACOXI, CPTIA, FABP6, and HSD17B12), energy metabolism (FH, PPP1R7, CLAM2, and RGN), cell proliferation (MYB, NFYC, DOHH, TOP2a, SMARCA5, and SMARCC2), material transport (ABCB1, ABCB8, VPS16, and VPS33a), and pigmentation (RDH7, RDH13, Retsat, COX15, and Cyp3a9). Integrated proteome and metabolome analyses indicate that fast-growing strain utilize energy-efficient mechanisms of ATP generation while promoting protein and polyunsaturated fatty acid synthesis, activating the cell cycle to increase cell proliferation and thus promoting their biomass increase. These results uncovered molecular mechanisms underlying growth regulation, nutrition quality, and pigmentation and provided candidate biomarkers for molecular breeding in oysters. SignificanceRapid growth has always been the primary breeding objective to increase the production profits of Pacific oyster (Crassostrea gigas), while favorable nutritional quality and beautiful color add commercial value. In recent years, proteomic and metabolomic techniques have been widely used in marine organisms, although these techniques are seldom utilized to study oyster growth and development. In this study, two C. gigas strains with contrasted phenotypes in growth and shell color provided an ideal model for unraveling the molecular basis of growth and nutrient composition through a comparison of the proteome and metabolome. Since proteins and metabolites are the critical undertakers and the end products of cellular regulatory processes, identifying the differentially expressed proteins and metabolites would allow for discovering biomarkers and pathways that were implicated in cell growth, proliferation, and other critical functions. This work provides valuable resources in assistance with molecular breeding of oyster strains with superior production traits of fast-growth and high-quality nutrient value.

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.

Integrated analysis of mRNAs and lncRNAs reveals candidate marker genes and potential hub lncRNAs associated with growth regulation of the Pacific Oyster, Crassostrea gigas

BackgroundThe Pacific oyster, Crassostrea gigas, is an economically important shellfish around the world. Great efforts have been made to improve its growth rate through genetic breeding. However, the candidate marker genes, pathways, and potential lncRNAs involved in oyster growth regulation remain largely unknown. To identify genes, lncRNAs, and pathways involved in growth regulation, C. gigas spat was cultured at a low temperature (15 ℃) to yield a growth-inhibited model, which was used to conduct comparative transcriptome analysis with spat cultured at normal temperature (25 ℃).ResultsIn total, 8627 differentially expressed genes (DEGs) and 1072 differentially expressed lncRNAs (DELs) were identified between the normal-growth oysters (cultured at 25 ℃, hereinafter referred to as NG) and slow-growth oysters (cultured at 15 ℃, hereinafter referred to as SG). Functional enrichment analysis showed that these DEGs were mostly enriched in the AMPK signaling pathway, MAPK signaling pathway, insulin signaling pathway, autophagy, apoptosis, calcium signaling pathway, and endocytosis process. LncRNAs analysis identified 265 cis-acting pairs and 618 trans-acting pairs that might participate in oyster growth regulation. The expression levels of LNC_001270, LNC_003322, LNC_011563, LNC_006260, and LNC_012905 were inducible to the culture temperature and food abundance. These lncRNAs were located at the antisense, upstream, or downstream of the SREBP1/p62, CDC42, CaM, FAS, and PIK3CA genes, respectively. Furthermore, the expression of the trans-acting lncRNAs, including XR_9000022.2, LNC_008019, LNC_015817, LNC_000838, LNC_00839, LNC_011859, LNC_007294, LNC_006429, XR_002198885.1, and XR_902224.2 was also significantly associated with the expression of genes enriched in AMPK signaling pathway, insulin signaling pathway, autophagy, apoptosis, calcium signaling pathway, and endocytosis process.ConclusionsIn this study, we identified the critical growth-related genes and lncRNAs that could be utilized as candidate markers to illustrate the molecular mechanisms underlying the growth regulation of Pacific oysters.

Submarine groundwater discharge interacts with creek geomorphology to affect eastern oyster Crassostrea virginica growth rates in a coastal Georgia creek.

Eastern oysters, Crassostrea virginica, are commercially important coastal species that provide many ecosystem services for coastal communities. Unfortunately, 85% of oyster reefs have been lost globally, prompting investments in restoration efforts to rebuild populations. Managers often consider several well-studied environmental and water quality parameters when making restoration site decisions. However, recent research suggests that submarine groundwater discharge (SGD) may play a role in driving the distribution of oysters in some estuaries. Specifically, SGD may result in localized areas of low dissolved oxygen and low pH that could inhibit oyster recruitment and survival. However, SGD may interact with other potential oyster stressors, including creek geomorphology. On point bars, sediment accumulation could alter growth rates of oysters and physiology, and it is possible that the two factors, SGD and creek geomorphology, could interact to impact oyster growth. We conducted a field experiment to examine the effects of SGD and creek geomorphology on oyster growth rates in a marsh-lined tidal creek in Georgia, USA. High and low SGD sites were paired within point bars and cut banks. Oysters were deployed in cages for 72 days and growth rates were determined. We found a significant interaction between SGD and creek geomorphology on oyster growth rates. Oysters grew at significantly faster rates at locations on accretionary point bars regardless of SGD flux, whereas, on erosional cut banks, high SGD flux significantly reduced oyster growth rate relative to low SGD flux. It appears that SGD may negatively influence oyster growth at specific creek locations, likely due to the presence of other stressors. Therefore, it is important to consider potential interacting and confounding stressors when managing oyster populations. As SGD is still a relatively understudied potential stressor for oysters, it is critical to continue to examine how groundwater might influence oysters in other locations and in combination with other stressors. Regardless, this study provides further evidence that SGD should be considered in future management efforts.

Pacific oysters do not compensate growth retardation following extreme acidification events.

Ocean acidification caused by anthropogenic carbon dioxide emissions alters the growth of marine calcifiers. Although the immediate effects of acidification from global ocean models have been well studied on calcifiers, their recovery capacity over a wide range of pH has never been evaluated. This aspect is crucial because acidification events that arise in coastal areas can far exceed global ocean predictions. However, such acidification events could occur transiently, allowing for recovery periods during which the effects on growth would be compensated, maintained or amplified. Here we evaluated the recovery capacity of a model calcifier, the Pacific oyster Crassostrea gigas. We exposed juveniles to 15 pH conditions between 6.4 and 7.8 for 14 days. Oyster growth was retarded below pH 7.1 while shells were corroded at pH 6.5. We then placed the oysters under ambient pH > 7.8 for 42 days. Growth retardation persisted at pH levels below pH 7.1 even after the stress was removed. However, despite persistent retardation, growth has resumed rapidly suggesting that the oysters can recover from extreme acidification. Yet we found that the differences in individual weight between pH conditions below 7.1 increased over time, and thus the growth retardation cannot be compensated and may affect the fitness of the bivalves.

THE EFFECT OF THE INTERVAL TIME IMMERSION IN THE NATURAL FEED TANK OF Chaetoceros simplex ON GROWTH AND SURVIVAL RATE OF PEARL OYSTER (Pinctada Maxima)

Pearl oysters are a fishery commodity with a high economic value because all parts of its body have a sale value. However, many problems of pearl oyster hatcheries are low survival rates and pearl oyster growth is not uniform. The research objective is to determine the effect of the interval time immersion in the natural feed tank in the feed concentrate of Chaetoceros simplex and to determiinterval time best immersion is duced the grey growth and survival rate of (Pinctada maxima). The method in this research is the experimental method and with a completely randomised design (CRD), with five treatments andthree3 replications. The A treatment) : control/without immersion, B (Interval time 24 hours immersion every one day, C (Interval time 48 hours immersion every two days, D (Interval time 72 hours): Immersion every three days and E treatment (Interval time 92 hours): immersion-furry for four days. The research result is interval time immersion spat of pearl oysters in the natural feed tank significantly affects the shell growth of the dorso ventral of pearl oyster Pinctada maxima (p<0,05). The highest growth was achieved in treatment B with an absolute growth value of 1.68 mm, a relative growth of 122,06% from the initial size, and a daily specific growth rate of 0,59% per day.

Energetic budget of diploid and triploid eastern oysters during a summer die-off.

Triploid oysters are widely used in off-bottom aquaculture of eastern oysters, Crassostrea virginica. However, farmers of the Gulf of Mexico (GoM) and Atlantic coast estuaries have observed unresolved, late-spring die-offs of triploid oysters, threatening the sustainability of triploid aquaculture. To investigate this, the physiological processes underlying oyster growth (e.g., feeding, respiration) and mortality of one-year-old diploid and triploid oysters were compared in early summer following an uptick in mortality. It was predicted that higher triploid mortality was the result of energetic imbalances (increased metabolic demands and decreased feeding behavior). Oyster clearance rates, percentage of time valves were open, absorption efficiency, oxygen consumption rates (basal and routine), ammonia excretion rate were measured in the laboratory and scope for growth was calculated. In addition, their condition index, gametogenic stage, Perkinsus marinus infection level, and mortality were measured. Mortality of triploids in the laboratory was greater than for diploids, mirroring mortality observed in a related field study. The physiological parameters measured, however, could not explain triploid mortality. Scope for growth, condition index, and clearance rates of triploids were greater than for diploids, suggesting sufficient energy reserves, while all other measurements where similar between the ploidies. It remains to be determined whether mortality could be caused from disruption of energy homeostasis at the cellular level.

Evaluating a short vs. long-term progeny test and investigating physiology associated with survival in extreme low salinity for the eastern oyster Crassostrea virginica

Low salinity negatively affects growth and survival in the eastern oyster, which decreases productivity of aquaculture operations along the mid-Atlantic and Gulf Coasts of the United States. With heavy rainfall events predicted to become more frequent, coastal aquaculture operations face increased risk of prolonged exposure to extreme low salinity conditions. While recent experimental work has determined that survival in extreme low salinity (< 3) is a moderately heritable trait in the eastern oyster, further experimental challenges were conducted to investigate the importance of challenge duration and temperature on the survival phenotype and estimation of its genetic parameters to hone the experimental challenge for potential incorporation into a breeding program. Growth (shell height) and algal removal were also assessed to investigate physiological phenotypes associated with differential survival in extreme low salinity. A subset of individuals from 51 half-sibling families were exposed to one of two experimental challenges: a short-term low salinity (2.5) challenge at constant temperature (27 °C) for 2 months, or a long-term low salinity (2.5) challenge where temperature was adjusted daily to match local ambient conditions for 6-months. Differential mortality was observed across families for both the short-term and long-term low salinity challenges, and narrow-sense heritability estimates were similar for both challenges (short-term h2 = 0.35, long-term h2 = 0.4). Strong phenotypic (rS = 0.89) and genetic (rG = 0.81) correlations for family mortality were found between challenges. Algal clearance metrics over a 24-h clearance experiment differed among families (p < 0.001), but were only weakly associated with family survival in the long-term low salinity exposure (range p = 0.08–0.23, R2 = 5–10%). Growth was negligible during the long-term challenge. However, after being returned to ambient salinities (13), there was no difference in growth rate, wet weight gain, or mortality between oysters from families with low or high survival in the long-term exposure (p > 0.05), indicating that low salinity tolerant oysters can recover following low salinity events. This work shows that a short-term (2 month) low salinity (2.5) challenge at a constant temperature captures the same patterns of family mortality as a 6-month, temperature fluctuating challenge. Additionally, measuring individual oyster clearance rate and the parameters derived from the algal removal curves provide additional insight into the physiological status of oysters under extreme low salinity stress.

Integrated multi-trophic aquaculture with sugar kelp and oysters in a shallow coastal salt pond and open estuary site.

Sustainable aquaculture includes the aquaculture of non-fed crops that provide ecosystem services including nutrient extraction and water quality improvement. While shellfish are the most farmed sustainable aquaculture crops in the USA, shellfish farmers in the northeastern US have an interest in diversifying their crops and incorporating seaweeds into their farms. In this study, we worked with oyster farmers to investigate the potential for farming sugar kelp, Saccharina latissima, across different environmental regimes in coastal Rhode Island USA. Kelp seed spools were outplanted at two time points in the fall/winter of 2017 and 2018 at four sites and cultivated until harvest the following spring. Kelp performance (length, width, yield), tissue content, and nutrient extraction were determined for each line in each year; oyster growth was also measured monthly for one year at each site. We found that kelp could successfully grow in both shallow coastal lagoons and estuarine sites, although the timing of planting and placement of sites was important. Lines that were planted earlier (as soon as water temperatures<15°C) grew longer and yielded more biomass at harvest; overall, kelp blade yield ranged from 0.36 ± 0.01 to 11.26 ± 2.18 kg/m long line. We report little variation in the tissue quality (C:N) of kelp among sites, but differences in biomass production led to differences in nutrient extraction, which ranged from 0.28 ± 0.04 to 16.35 ± 4.26 g nitrogen/m long line and 8.93 ± 0.35 to 286.30 ± 74.66 g carbon/m long line. We found extensive variability in kelp growth within and between lines and between years, suggesting that crop consistency is a challenge for kelp farmers in the region. Our results suggest that, as there is a lower barrier in terms of permitting (versus starting a new aquaculture farm), it may be a worthwhile investment to add sugar kelp to existing oyster farms, provided they have suitable conditions. At current market rates of US$0.88-$3.30 per kg, farmers in southern New England have the potential to earn US$2,229 per 60 m longline. While seaweed aquaculture is growing, considerable barriers still exist that prevent wide-scale kelp aquaculture adoption by existing aquafarmers.

Impact of Hydrodynamic and Suspended Sediment on Liyashan Oyster Reef

Based on the sensitivity of oysters to water environmental factors, a hydrodynamic model in Tongzhou Bay, southwest of China’s Yellow Sea, is set up to analyse the impact of the hydrodynamic and suspended sediment on the Liyashan Oyster Reef. The results show that the hydrodynamic characteristics of the waters near the oyster reef will not be significantly affected by the implementation of the project. The diffusion range of suspended sediment concentration greater than 10mg/L caused by channel dredging will not reach and affect oyster reef area, and the growth of oysters will not be significantly affected by Tongzhou Bay Channel Construction.

Predicting the Growth of Vibrio parahaemolyticus in Oysters under Varying Ambient Temperature

Temperature is a critical factor that influences the proliferation of pathogens in hosts. One example of this is the human pathogen Vibrio parahaemolyticus (V. parahaemolyticus) in oysters. Here, a continuous time model was developed for predicting the growth of Vibrio parahaemolyticus in oysters under varying ambient temperature. The model was fit and evaluated against data from previous experiments. Once evaluated, the V. parahaemolyticus dynamics in oysters were estimated at different post-harvest varying temperature scenarios affected by water and air temperature and different ice treatment timing. The model performed adequately under varying temperature, reflecting that (i) increasing temperature, particularly in hot summers, favors a rapid V. parahaemolyticus growth in oysters, resulting in a very high risk of gastroenteritis in humans after consumption of a serving of raw oysters, (ii) pathogen inactivation due to day/night oscillations and, more evidently, due to ice treatments, and (iii) ice treatment is much more effective, limiting the risk of illness when applied immediately onboard compared to dockside. The model resulted in being a promising tool for improving the understanding of the V. parahaemolyticus–oyster system and supporting studies on the public health impact of pathogenic V. parahaemolyticus associated with raw oyster consumption. Although robust validation of the model predictions is needed, the initial results and evaluation showed the potential of the model to be easily modified to match similar systems where the temperature is a critical factor shaping the proliferation of pathogens in hosts.