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Chetveryk, O. V., e N. A. Kravchuk. "The research of the oyster’s market condition: current state and future perspective development on the basis of marketing". Bioeconomics and Agrarian Business 11, n. 1 (29 maggio 2020): 98–110. http://dx.doi.org/10.31548/bioeconomy2020.01.098.
Testo completoAbstract (sommario):
The article conducts a marketing study of the oyster market in Ukraine and in the world. In the article was analyze the current state and prospects for future perspective development of the oyster market in Ukraine. The possibility of developing the market of oysters and enterprises of the oyster industry under the conditions of marketing use is considered. The results of the study showed that fisheries in Ukraine are a promising area of agro-industrial production, which provides the population with valuable food and promotes employment. The marketing research was based on the analysis of the supply of oysters in the world and Ukraine, the volume of demand in the domestic market of Ukraine, the characteristics of the main producers of oysters. The analysis suggests that the leading countries in oyster farming are China, Japan and the United States. A study of the dynamics of oyster production in the world showed their constant growth, and in 2018 received 4.7 million tons of oysters. The supply on the domestic market of oysters in Ukraine consists of imports and direct domestic production: 90% - import, 10% - domestic production. Ukraine's oyster imports fell from $ 9.5 million. to 5.98 million dollars, but still occupies the lion's share. The largest domestic producers of oysters are next companies: Silveo LLC (38%), Odyssey LLC (20%), Ocean LLC (13%), Triton-chernomor Company (11%). Despite imports and low domestic production, oyster consumption in Ukraine remains low at 0.9 kg per person per year. The consistently low demand for sea-food and oysters, in particular, is due to the steady deterioration of the economic situation and low purchasing power of the population. A prerequisite for the long-term and perspective development of the oyster market and oyster’s cultivation enterprises is the use of marketing. The most popular for oyster’s enterprises are traditional and cognitive marketing. The most popular instruments of cognitive marketing for the oyster enterprises are creating social videos about cinnamon of seafood, including oysters, organizing of the food festivals and food festivals of the sea-products, have been thoroughly disseminated, as well as take part in other trips, organizing tasting events at the festival and other.
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Lacoste, Arnaud, Fabienne Jalabert, Shelagh K. Malham, Anne Cueff e Serge A. Poulet. "Stress and Stress-Induced Neuroendocrine Changes Increase the Susceptibility of Juvenile Oysters (Crassostrea gigas) to Vibrio splendidus". Applied and Environmental Microbiology 67, n. 5 (1 maggio 2001): 2304–9. http://dx.doi.org/10.1128/aem.67.5.2304-2309.2001.
Testo completoAbstract (sommario):
ABSTRACT Oysters are permanently exposed to various microbes, and their defense system is continuously solicited to prevent accumulation of invading and pathogenic organisms. Therefore, impairment of the animal's defense system usually results in mass mortalities in cultured oyster stocks or increased bacterial loads in food products intended for human consumption. In the present study, experiments were conducted to examine the effects of stress on the juvenile oyster's resistance to the oyster pathogen Vibrio splendidus. Oysters (Crassostrea gigas) were challenged with a low dose of a pathogenic V. splendidus strain and subjected to a mechanical stress 3 days later. Both mortality andV. splendidus loads increased in stressed oysters, whereas they remained low in unstressed animals. Injection of noradrenaline or adrenocorticotropic hormone, two key components of the oyster neuroendocrine stress response system, also caused higher mortality and increased accumulation of V. splendidus in challenged oysters. These results suggest that the physiological changes imposed by stress, or stress hormones, influenced host-pathogen interactions in oysters and increased juvenile C. gigasvulnerability to Vibrio splendidus.
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Gilbert, Scott F. "Shells, Gills, and Gonads". Historical Studies in the Natural Sciences 53, n. 3 (1 giugno 2023): 221–41. http://dx.doi.org/10.1525/hsns.2023.53.3.221.
Testo completoAbstract (sommario):
The Atlantic oyster of Chesapeake Bay has been the focus of intense economic and ecological pressures. In the 1880s it was the main source for America’s favorite food, and the oyster was overharvested to the point of scarcity. Three scientific discoveries concerning the oyster’s material properties have been paving its way back from the brink of extinction. First, William Keith Brooks studied the embryology of this oyster and showed that its shell served as a necessary part of its life cycle. Second, Roger Newell demonstrated the prodigious water filtration properties of this oyster and linked these properties to its ability to clean the estuary. The discovery of the filtration properties of the oyster was an affordance that enabled the oyster to “partner” with governmental agencies and NGOs who were attempting to restore the bay’s clean water, fish, and birdlife. Third, Standish K. Allen, Ximing Guo, and their colleagues formulated a procedure that enabled the manipulation of oyster development to yield tasty, fast-growing, and disease-resistant triploid oysters. The disease-resistant oysters together with knowledge of the oyster’s life cycle enabled the proliferation of the oyster by conservation groups. The goal of Chesapeake Bay conservation changed from “Save the oyster” to “Plant more oysters; help save the bay.” This paper is part of a special issue entitled “Making Animal Materials in Time,” edited by Laurence Douny and Lisa Onaga.
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Cox, Clayton E., Anita C. Wright, Michael McClelland e Max Teplitski. "Influence of Salmonella enterica Serovar TyphimuriumssrBon Colonization of Eastern Oysters (Crassostrea virginica) as Revealed by a Promoter Probe Screen". Applied and Environmental Microbiology 82, n. 1 (23 ottobre 2015): 328–39. http://dx.doi.org/10.1128/aem.02870-15.
Testo completoAbstract (sommario):
ABSTRACTAlthoughSalmonellahas been isolated from 7.4 to 8.6% of domestic raw oysters, representing a significant risk for food-borne illness, little is known about the factors that influence their initial colonization bySalmonella. This study tested the hypothesis that specific regulatory changes enable a portion of the invadingSalmonellapopulation to colonize oysters. Anin vivopromoter probe library screen identified 19 unique regions as regulated during colonization. The mutants in the nearest corresponding downstream genes were tested for colonization defects in oysters. Only one mutation, inssrB, resulted in a significantly reduced ability to colonize oysters compared to that of wild-typeSalmonella. BecausessrBregulatesSalmonellapathogenicity island 2 (SPI-2)-dependent infections in vertebrate macrophages, the possibility thatssrBmediated colonization of oyster hemocytes in a similar manner was examined. However, no difference in hemocyte colonization was observed. The complementary hypothesis that signal exchange betweenSalmonellaand the oyster's native microbial community aids colonization was also tested. Signals that triggered responses in quorum sensing (QS) reporters were shown to be produced by oyster-associated bacteria and present in oyster tissue. However, no evidence for signal exchange was observedin vivo. ThesdiAreporter responded to salinity, suggesting that SdiA may also have a role in environmental sensing. Overall, this study suggests the initial colonization of live oysters bySalmonellais controlled by a limited number of regulators, includingssrB.
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Froelich, Brett A., e Rachel T. Noble. "Factors Affecting the Uptake and Retention of Vibrio vulnificus in Oysters". Applied and Environmental Microbiology 80, n. 24 (26 settembre 2014): 7454–59. http://dx.doi.org/10.1128/aem.02042-14.
Testo completoAbstract (sommario):
ABSTRACTVibrio vulnificus, a bacterium ubiquitous in oysters and coastal water, is capable of causing ailments ranging from gastroenteritis to grievous wound infections or septicemia. The uptake of these bacteria into oysters is often examinedin vitroby placing oysters in seawater amended withV. vulnificus. Multiple teams have obtained similar results in studies where laboratory-grown bacteria were observed to be rapidly taken up by oysters but quickly eliminated. This technique, along with suggested modifications, is reviewed here. In contrast, the natural microflora within oysters is notoriously difficult to eliminate via depuration. The reason for the transiency of exogenous bacteria is that those bacteria are competitively excluded by the oyster's preexisting microflora. Evidence of this phenomenon is shown usingin vitrooyster studies and a multiyearin situcase study. Depuration of the endogenous oyster bacteria occurs naturally and can also be artificially induced, but both of these events require extreme conditions, natural or otherwise, as explained here. Finally, the “viable but nonculturable” (VBNC) state ofVibriois discussed. This bacterial torpor can easily be confused with a reduction in bacterial abundance, as bacteria in this state fail to grow on culture media. Thus, oysters collected from colder months may appear to be relatively free ofVibriobut in reality harbor VBNC cells that respond to exogenous bacteria and prevent colonization of oyster matrices. Bacterial-uptake experiments combined with studies involving cell-free spent media are detailed that demonstrate this occurrence, which could explain why the microbial community in oysters does not always mirror that of the surrounding water.
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BRILLHART, CRYSTAL D., e LYNN A. JOENS. "Prevalence and Characterization of Salmonella Serovars Isolated from Oysters Served Raw in Restaurants". Journal of Food Protection 74, n. 6 (1 giugno 2011): 1025–29. http://dx.doi.org/10.4315/0362-028x.jfp-10-443.
Testo completoAbstract (sommario):
To determine if Salmonella-contaminated oysters are reaching consumer tables, a survey of raw oysters served in eight Tucson restaurants was performed from October 2007 to September 2008. Salmonella spp. were isolated during 7 of the 8 months surveyed and were present in 1.2% of 2,281 oysters tested. This observed prevalence is lower than that seen in a previous study in which U.S. market oysters were purchased from producers at bays where oysters are harvested. To test whether the process of refrigerating oysters in restaurants for several days reduces Salmonella levels, oysters were artificially infected with Salmonella and kept at 4°C for up to 13 days. Direct plate counts of oyster homogenate showed that Salmonella levels within oysters did not decrease during refrigeration. Six different serovars of Salmonella enterica were found in the restaurant oysters, indicating multiple incidences of Salmonella contamination of U.S. oyster stocks. Of the 28 contaminated oysters, 12 (43%) contained a strain of S. enterica serovar Newport that matched by pulsed-field gel electrophoresis a serovar Newport strain seen predominantly in the study of bay oysters performed in 2002. The repeated occurrence of this strain in oyster surveys is concerning, since the strain was resistant to seven antimicrobials tested and thus presents a possible health risk to consumers of raw oysters.
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Kecinski, Maik, Kent D. Messer, Lauren Knapp e Yosef Shirazi. "Consumer Preferences for Oyster Attributes: Field Experiments on Brand, Locality, and Growing Method". Agricultural and Resource Economics Review 46, n. 2 (18 luglio 2017): 315–37. http://dx.doi.org/10.1017/age.2017.21.
Testo completoAbstract (sommario):
Oyster aquaculture has experienced tremendous growth in the United States over the past decade, but little is known about consumer preferences for oysters. This study analyzed preferences for oysters with varied combinations of brands, production locations, and production methods (aquaculture vs. wild-caught) using dichotomous choice, revealed preference economic field experiments. Results suggest significant and distinct differences in behavior between first-time and regular oyster consumers. While infrequent oyster consumers were drawn to oysters labeled as wild-caught, experienced oyster consumers preferred oysters raised via aquaculture. These findings will be valuable for growers and policymakers who invest in aquaculture to improve surrounding ecosystems.
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Okronipa, Harriet, Alyssa Abreu, Katie Fiorella, Helena Bentil, Seth Adu-Afarwuah e Brietta Oaks. "Fishery Management Practices and Oyster Consumption Among Oyster-Harvesting Communities in Ghana". Current Developments in Nutrition 6, Supplement_1 (giugno 2022): 595. http://dx.doi.org/10.1093/cdn/nzac060.053.
Testo completoAbstract (sommario):
Abstract Objectives Sustainable management of fisheries is important for improving nutrition and food security. In 2017, an oyster harvesters’ association in Ghana began implementing a 5-month (Nov-Apr) closed season to improve oyster yields of the Densu estuary. It is unknown how much oysters contribute to the diet of women during the open season and whether there is a substantial reduction in oyster consumption during the closed season This study aimed to examine oyster consumption during the open and closed seasons and the perception of the closed season. Methods We recruited women (n = 137) residing in 4 major communities located near the Densu estuary in the Ga-South Municipality of Ghana. We collected data on oyster harvesting and consumption using a survey and a 30-day food frequency questionnaire during the closed (March 2020) and open (August 2020) seasons. The amount of oysters consumed was determined by converting reported portion sizes to grams using average wet weights of oysters purchased in the study area. We used McNemar's test for paired samples to compare differences in the proportion of women who consumed oysters, and Wilcoxon signed-rank test to compare differences in the amount of oysters consumed. Results A majority (63%) of the women were oyster harvesters. Significantly higher proportion of women consumed oysters in the 30 days preceding the interview during the open compared to the closed season (57% vs 13%, p < 0.0001). Among those who consumed oysters, the mean ± SD oysters (wet weight) consumed at a sitting was 218.4 ± 114.7 g, equivalent to 60 oysters, and did not differ between the open (211.6 ± 119.9 g) and closed ((242.8 ± 92.6 g) seasons (P = 0.73). The majority of women were aware of the closed season (87%) and viewed it positively (85%). Conclusions The majority of women in these communities consume oysters during the open season, and are in support of the closed season. Considering that a smaller percentage of women consumed oysters during the closed season, additional research is warranted to further examine the aggregate impacts of oyster management in Ghana on nutrition and household food insecurity, considering both consumption and income impacts. Funding Sources University of Rhode Island.
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Zhang, Ruihua, Xujun Chen, Zhengzhong Wan, Meng Wang e Xinqing Xiao. "Deep Learning-Based Oyster Packaging System". Applied Sciences 13, n. 24 (8 dicembre 2023): 13105. http://dx.doi.org/10.3390/app132413105.
Testo completoAbstract (sommario):
With the deepening understanding of the nutritional value of oysters by consumers, oysters as high-quality seafood are gradually entering the market. Raw edible oyster production lines mainly rely on manual sorting and packaging, which hinders the improvement of oyster packaging efficiency and quality, and it is easy to cause secondary oyster pollution and cross-contamination, which results in the waste of oysters. To enhance the production efficiency, technical level, and hygiene safety of the raw aquatic products production line, this study proposes and constructs a deep learning-based oyster packaging system. The system achieves intelligence and automation of the oyster packaging production line by integrating the deep learning algorithm, machine vision technology, and mechanical arm control technology. The oyster visual perception model is established by deep learning object detection techniques to realize fast and real-time detection of oysters. Using a simple online real-time tracking (SORT) algorithm, the grasping position of the oyster can be predicted, which enables dynamic grasping. Utilizing mechanical arm control technology, an automatic oyster packaging production line was designed and constructed to realize the automated grasping and packaging of raw edible oysters, which improves the efficiency and quality of oyster packaging. System tests showed that the absolute error in oyster pose estimation was less than 7 mm, which allowed the mechanical claw to consistently grasp and transport oysters. The static grasping and packing of a single oyster took about 7.8 s, and the success rate of grasping was 94.44%. The success rate of grasping under different transportation speeds was above 68%.
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LIU, CHENGCHU, RUIYING CHEN e YI-CHENG SU. "Bactericidal Effects of Wine on Vibrio parahaemolyticus in Oysters". Journal of Food Protection 69, n. 8 (1 agosto 2006): 1823–28. http://dx.doi.org/10.4315/0362-028x-69.8.1823.
Testo completoAbstract (sommario):
The bactericidal effects of wines on Vibrio parahaemolyticus in oysters were studied to evaluate potential inactivation of V. parahaemolyticus in contaminated oysters by wine consumption. Shucked whole oyster and oyster meat homogenate were inoculated with V. parahaemolyticus and mixed with red or white wine. Survivals of V. parahaemolyticus in inoculated oysters were determined at 7 and 25°C. Populations of V. parahaemolyticus in inoculated whole oysters (5.52 log most probable number [MPN] per g) decreased slightly to 4.90 log MPN/g (a 0.62-log reduction) after 24 h at 7°C but increased to 7.37 log MPN/g over the same period at 25°C. However, the populations in wine-treated whole oysters decreased by >1.7 and >1.9 log MPN/g after 24 h at 7 and 25°C, respectively. Both red and white wines were more effective in inactivating V. parahaemolyticus in oyster meat homogenate than in whole oyster. Populations of V. parahaemolyticus in oyster meat homogenate (7.8 × 103 MPN/g) decreased rapidly to nondetectable levels (<3 MPN/g) after 30 min of mixing with wine at 25°C (a 3.89-log MPN/g reduction). These results suggest that chewing oysters before swallowing when eating raw oysters may result in greater inactivation of V. parahaemolyticus if wine is consumed. More studies are needed to determine the bactericidal effects of wine on V. parahaemolyticus in the complicated stomach environment.
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Westphal, Gisela Geraldine Castilho, e Antonio Ostrensky. "Use of side-scan sonar for estimations of Crassostrea brasiliana (Lamarck, 1819) stocks in subtidal banks on the south coast of Brazil". Brazilian Journal of Oceanography 64, n. 1 (marzo 2016): 49–56. http://dx.doi.org/10.1590/s1679-87592016104506401.
Testo completoAbstract (sommario):
Abstract Uncontrolled extractivism has led to a worldwide reduction in oyster stocks. The use of new and more efficient management tools for impacted environments must increase. The application of such tools requires previous biological and environmental knowledge of the resident populations of these bivalve mollusks. Technical difficulties are usually associated with studies of submerged oyster banks, and these difficulties result in a considerable lack of biological data on the oysters that inhabit subtidal zones. This study aimed to survey Crassostrea brasiliana (also known as C. gasar) stocks in submerged banks and to evaluate a method with which to measure the extent of the banks and identify and quantify the oysters in the banks with the use of side-scan sonar. This study was conducted on 10 oysters banks located in the subtidal zone of Guaratuba Bay, on the south coast of Brazil. The prospection of all these banks was later validated by diving, and oyster samples (n = 20/bank) were collected for species identification with a molecular method. Only one bank contained oysters that were generically classified as Crassostrea sp.; those in the remaining banks being identified as C. brasiliana. The prospected banks contained oysters of various sizes (average 1.5 m, n = 1,107) that were heterogeneously scattered in the riverbeds. The total number of oysters in the 10 sampled banks was estimated to be 21,159.13 oysters or 1 oyster/4.5 m², which represents a low oyster density in the study site. The results validate the use of side-scan sonar as an efficient means with which to prospect for oysters in banks located within subtidal zones.
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Carroll, John M., Walker de la Torre e Jacque L. Kelly. "Submarine groundwater discharge interacts with creek geomorphology to affect eastern oyster Crassostrea virginica growth rates in a coastal Georgia creek". PeerJ 11 (4 agosto 2023): e15837. http://dx.doi.org/10.7717/peerj.15837.
Testo completoAbstract (sommario):
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.
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Brandão, Maria Aparecida da RessurreiÇão, Amanda Teixeira Sampaio Lopes, Maria Tereza da Silva Neta, Rhyan Barros Farias de Oliveira, Rachel Passos Rezende, George Rêgo Albuquerque, Verônica Dias Gonçalves, Dália dos Prazeres Rodrigues, Guisla Boehs e Bianca Mendes Maciel. "Microbiological Quality and Prevalence of β-Lactam Antibiotic Resistance Genes in Oysters (Crassostrea rhizophorae)". Journal of Food Protection 80, n. 3 (16 febbraio 2017): 488–96. http://dx.doi.org/10.4315/0362-028x.jfp-16-098.
Testo completoAbstract (sommario):
ABSTRACTThe microbiological quality of oysters reflects the microbiological quality of their habitats because they are filter feeders. The objective of this study was to assess the bacterial composition of the edible oyster Crassostrea rhizophorae in urban and preserved estuaries. Particularly, we assessed the presence of pathogenic bacteria, investigated antibiotic susceptibility in bacterial isolates, and quantified β-lactam antibiotic resistance genes (blaTEM, blaSHV, and blaKPC) via quantitative PCR of oyster DNA. Our results detected total coliforms, Escherichia coli, and enterobacteria in the oysters from urban estuaries, which is indicative of poor water quality. In addition, our detection of the eaeA and stxA2 virulence genes in 16.7% of E. coli isolates from oysters from this region suggests the presence of multiantibiotic-resistant enteropathogenic and enterohemorrhagic E. coli strains. During periods of low precipitation, increased contamination by E. coli (in winter) and Vibrio parahaemolyticus (in autumn) was observed. In contrast, cultivated oysters inhabiting monitored farms in preserved areas had low levels of bacterial contamination, emphasizing that oyster culture monitoring enhances food quality and makes oysters fit for human consumption. Distinct antibiotic resistance profiles were observed in bacteria isolated from oysters collected from different areas, including resistance to β-lactam antibiotics. The presence of the blaTEM gene in 91.3% of oyster samples indicated that microorganisms in estuarine water conferred the capability to produce β-lactamase. To our knowledge, this is the first study to directly quantify and detect β-lactam antibiotic resistance genes in oysters. We believe our study provides baseline data for bacterial dynamics in estuarine oysters; such knowledge contributes to developing risk assessments to determine the associated hazards and consequences of consuming oysters from aquatic environments containing pathogenic bacteria that may possess antibiotic resistance genes.
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Morgan, O. Ashton, Gregory S. Martin e William L. Huth. "Oyster Demand Adjustments to Counter-Information and Source Treatments in Response to Vibrio vulnificus". Journal of Agricultural and Applied Economics 41, n. 3 (dicembre 2009): 683–96. http://dx.doi.org/10.1017/s1074070800003151.
Testo completoAbstract (sommario):
A web-based contingent behavior analysis was developed to quantify the effect of both negative and positive information treatments and post harvest processes on demand for oysters. Results from a panel model indicate that consumers of raw and cooked oysters behave differently after news of an oyster-related human mortality. While cooked oyster consumers take precautionary measures against risk, raw oyster consumers exhibit optimistic bias and increase their consumption level. Further, by varying the source of a counter-information treatment, we find that source credibility impacts behavior. Oyster consumers, and in particular, raw oyster consumers, are most responsive to information provided by a not-for-profit, nongovernmental organization. Finally, post harvest processing of oysters has no impact on demand.
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Boullot, Floriane, Caroline Fabioux, Hélène Hégaret, Pierre Boudry, Philippe Soudant e Evelyne Benoit. "Electrophysiological Evaluation of Pacific Oyster (Crassostrea gigas) Sensitivity to Saxitoxin and Tetrodotoxin". Marine Drugs 19, n. 7 (30 giugno 2021): 380. http://dx.doi.org/10.3390/md19070380.
Testo completoAbstract (sommario):
Pacific oysters (Crassostrea gigas) may bio-accumulate high levels of paralytic shellfish toxins (PST) during harmful algal blooms of the genus Alexandrium. These blooms regularly occur in coastal waters, affecting oyster health and marketability. The aim of our study was to analyse the PST-sensitivity of nerves of Pacific oysters in relation with toxin bio-accumulation. The results show that C. gigas nerves have micromolar range of saxitoxin (STX) sensitivity, thus providing intermediate STX sensitivity compared to other bivalve species. However, theses nerves were much less sensitive to tetrodotoxin. The STX-sensitivity of compound nerve action potential (CNAP) recorded from oysters experimentally fed with Alexandrium minutum (toxic-alga-exposed oysters), or Tisochrysis lutea, a non-toxic microalga (control oysters), revealed that oysters could be separated into STX-resistant and STX-sensitive categories, regardless of the diet. Moreover, the percentage of toxin-sensitive nerves was lower, and the STX concentration necessary to inhibit 50% of CNAP higher, in recently toxic-alga-exposed oysters than in control bivalves. However, no obvious correlation was observed between nerve sensitivity to STX and the STX content in oyster digestive glands. None of the nerves isolated from wild and farmed oysters was detected to be sensitive to tetrodotoxin. In conclusion, this study highlights the good potential of cerebrovisceral nerves of Pacific oysters for electrophysiological and pharmacological studies. In addition, this study shows, for the first time, that C. gigas nerves have micromolar range of STX sensitivity. The STX sensitivity decreases, at least temporary, upon recent oyster exposure to dinoflagellates producing PST under natural, but not experimental environment.
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BIRKENHAUER, J. M., e J. D. OLIVER. "Effects of Refrigeration and Alcohol on the Load of Aeromonas hydrophila in Oysters". Journal of Food Protection 65, n. 3 (1 marzo 2002): 560–62. http://dx.doi.org/10.4315/0362-028x-65.3.560.
Testo completoAbstract (sommario):
Members of the bacterial genus Aeromonas are widely distributed throughout the environment and are readily cultured from a variety of foods. One member of this genus, Aeromonas hydrophila, has been reputed to be a significant cause of gastrointestinal disease. In this study, we examined the effects of refrigeration and alcohol on the level of A. hydrophila in oysters. Specifically, vodka was examined because it is used by the food service industry in preparation of Oysters Romanoff. One set of oysters was shucked on receipt, whereas others were refrigerated intact for 7 days at 5°C. The oysters were blended and the numbers of A. hydrophila present determined using starch ampicillin agar. Oysters were also shucked and placed on the half shell with 5 ml of vodka for 10 min. The oysters were then washed and presumptive A. hydrophila levels determined in both the washate and homogenate. On the day of purchase, the average number of presumptive A. hydrophila found was 7.6 × 104 CFU/g of oyster meat. After 7 days of refrigeration, the average number had increased to 3.2 × 105 CFU/g of oyster meat. In the oysters treated with vodka, the average number of A. hydrophila present internally was 9.9 × 104 with high numbers (103 to 104) isolated from the oyster surface. From these data, it is clear that refrigeration and alcohol treatment are not sufficient to reduce loads of A. hydrophila in or on oysters.
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Li, Yan, Jian G. Qin, Catherine A. Abbott, Xiaoxu Li e Kirsten Benkendorff. "Synergistic impacts of heat shock and spawning on the physiology and immune health ofCrassostrea gigas: an explanation for summer mortality in Pacific oysters". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 293, n. 6 (dicembre 2007): R2353—R2362. http://dx.doi.org/10.1152/ajpregu.00463.2007.
Testo completoAbstract (sommario):
Mass mortality is often observed in cultured oysters during the period following spawning in the summer season. To examine the underlying causes leading to this phenomenon, thermotolerance of the Pacific oyster Crassostrea gigas was assessed using pre- and postspawning oysters that were sequentially treated with sublethal (37°C) and lethal heat shocks (44°C). The effects were examined on a range of immune and metabolic parameters in addition to mortality rate. A preventative 37°C significantly reduced oyster mortality after exposure to a second heat shock of 44°C, but in postspawning oysters mortality remained at 80%, compared with < 10% in prespawning oysters. Levels of the 72 kDa and 69 kDa heat shock proteins were low in the gill tissue from postspawning oysters stimulated by heat shock, indicating spawning reduced heat shock protein synthesis. The postspawning oysters had depleted glycogen stores in the mantle tissue and reduced adenylate energy charge after heat shock, indicative of lower energy for metabolic activity. A cumulative effect of spawning and heat shock was observed on the immunocompetence of oysters, demonstrated by reduced hemocyte phagocytosis and hemolymph antimicrobial activity. These results support the hypothesis that the energy expended during reproduction compromises the thermotolerance and immune status of oysters, leaving them easily subject to mortality if heat stress occurs in postspawning stage. This study improves our understanding of oyster summer mortality and has implications for the long-term persistence of mollusks under the influence of global warming.
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Froelich, Brett A., Tiffany C. Williams, Rachel T. Noble e James D. Oliver. "Apparent Loss of Vibrio vulnificus from North Carolina Oysters Coincides with a Drought-Induced Increase in Salinity". Applied and Environmental Microbiology 78, n. 11 (23 marzo 2012): 3885–89. http://dx.doi.org/10.1128/aem.07855-11.
Testo completoAbstract (sommario):
ABSTRACTDespite years of successful isolation ofVibrio vulnificusfrom estuarine waters, beginning in 2007, it was extremely difficult to cultureV. vulnificusfrom either North Carolina estuarine water or oyster samples. After employing culture-based methods as well as PCR and quantitative PCR for the detection ofV. vulnificus, always with negative results, we concluded that this pathogen had become nearly undetectable in the North Carolina estuarine ecosystem. We ensured that the techniques were sound by seeding North Carolina oysters withV. vulnificusand performing the same tests as those previously conducted on unadulterated oysters.V. vulnificuswas readily detected in the seeded oysters using both classes of methods. Furthermore, oysters were obtained from the Gulf of Mexico, andV. vulnificuswas easily isolated, confirming that the methodology was sound but that the oysters and waters of North Carolina were lacking theV. vulnificuspopulation studied for decades. Strikingly, the apparent loss of detectableV. vulnificuscoincided with the most severe drought in the history of North Carolina. The drought continued until the end of 2009, with an elevated water column salinity being observed throughout this period and withV. vulnificusbeing nearly nonexistent. When salinities returned to normal after the drought abated in 2010, we were again able to routinely isolateV. vulnificusfrom the water column, although we were still unable to culture it from oysters. We suggest that the oysters were colonized with a more salt-tolerant bacterium during the drought, which displacedV. vulnificusand may be preventing recolonization.
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TAKAHASHI, MICHIKO, YUMIKO OKAKURA, HAJIME TAKAHASHI, HISAYA YAMANE, SATORU AKASHIGE, TAKASHI KUDA e BON KIMURA. "Evaluation of Inactivation of Murine Norovirus in Inoculated Shell Oysters by High Hydrostatic Pressure Treatment". Journal of Food Protection 82, n. 12 (19 novembre 2019): 2169–73. http://dx.doi.org/10.4315/0362-028x.jfp-19-186.
Testo completoAbstract (sommario):
ABSTRACT One of the major foods causing norovirus gastroenteritis is bivalve shellfish, such as oysters. Depuration and relaying methods have been used to control norovirus. However, these methods may be inadequate to control norovirus gastroenteritis. The present study aimed to investigate the effectiveness of high hydrostatic pressure (HHP) treatment in controlling norovirus in shelled oysters, by evaluating the inactivating effect of HHP on murine norovirus strain 1 (MNV-1) inoculated into a buffer, oyster homogenate, and shelled oysters. First, MNV-1 was inoculated (infectivity of 4.5 log PFU/mL) into the buffer and oyster homogenate, with a pH of 6.3 and salinity (NaCl) of 1.5%, mimicking the habitats of the Pacific oyster (Crassostrea gigas). HHP treatment at 100, 200, 275, and 300 MPa for 2 and 5 min was conducted at an initial temperature of 0 or 5°C. The infectivity of MNV-1 in both the buffer and the oyster homogenate was lower when the initial temperature was 0°C. In the buffer, the infectivity of MNV-1 decreased to 1.8 log PFU/mL after HHP treatment (200 MPa for 5 min at 0°C), and the inactivating effect was higher in the buffer than in the oyster homogenate. MNV-1 was inoculated into shelled oysters (4.8 log PFU per oyster), and HHP treatment was done at 275, 300, and 350 MPa for 5 min at the initial temperature of 0°C. The infectivity of MNV-1 decreased to 2.8 log PFU per oyster after HHP treatment at 275 MPa for 5 min. The results indicate that the inactivating effect of HHP treatment varies, depending on the medium surrounding the viral particles. Inactivation was best in buffer, followed by oyster homogenate and shelled oysters. The data could inform the development of methods to control norovirus in oysters. HIGHLIGHTS
20
Chen, Yen-Hua, Hui-Lin Feng, Yu-Cheng Lu e Sen-Shyong Jeng. "Oral Zinc-Rich Oyster Supplementation Corrects Anemia in Rats". Nutrients 15, n. 21 (4 novembre 2023): 4675. http://dx.doi.org/10.3390/nu15214675.
Testo completoAbstract (sommario):
This study investigates the impact of various zinc supplementation methods on anemia in rats induced by phenylhydrazine (PHZ) and in 5/6-nephrectomized anemic rats. We compare oral zinc sulfate (ZnSO4) supplementation, oyster Crassostrea gigas supplementation, and hard clam Meretrix lusoria supplementation on red blood cell (RBC) levels. Oral zinc-rich oyster supplementation (2.70 mg Zn (30 g oyster)/day/rat) effectively corrects anemia in both experimental groups. Rats orally fed oysters for four days exhibit similar effectiveness as those receiving a single ZnSO4 injection (0.95 mg Zn (4.18 mg ZnSO4⋅7H2O)/rat). In contrast, oral ZnSO4 supplementation (2.70 mg Zn (11.88 mg ZnSO4⋅7H2O)/day/rat) does not significantly increase RBC levels, suggesting better zinc absorption from oysters. A placebo group of anemic rats supplemented with hard clams, similar in composition to oysters but much lower in zinc, did not change RBC counts. This supports oysters’ high zinc content as the key to correcting anemia. Oysters also contain high iron levels, offering a potential solution for iron-deficiency anemia while supporting bone marrow erythropoiesis. In summary, oral oyster supplementation emerges as an effective strategy to correct anemia in rats with added zinc and iron support for erythropoiesis.
21
Liu, Pengfei, Luwei Zhang, You Li, Huanhuan Feng, Xiaoshuan Zhang e Mengjie Zhang. "rGO-PDMS Flexible Sensors Enabled Survival Decision System for Live Oysters". Sensors 23, n. 3 (23 gennaio 2023): 1308. http://dx.doi.org/10.3390/s23031308.
Testo completoAbstract (sommario):
The shell-closing strength (SCS) of oysters is the main parameter for physiological activities. The aim of this study was to evaluate the applicability of SCS as an indicator of live oyster health. This study developed a flexible pressure sensor system with polydimethylsiloxane (PDMS) as the substrate and reduced graphene oxide (rGO) as the sensitive layer to monitor SCS in live oysters (rGO-PDMS). In the experiment, oysters of superior, medium and inferior grades were selected as research objects, and the change characteristics of SCS were monitored at 4 °C and 25 °C. At the same time, the time series model was used to predict the survival rate of live oyster on the basis of changes in their SCS characteristics. The survival times of superior, medium and inferior oysters at 4 °C and 25 °C were 31/25/18 days and 12/10/7 days, respectively, and the best prediction accuracies for survival rate were 89.32%/82.17%/79.19%. The results indicate that SCS is a key physiological indicator of oyster survival. The dynamic monitoring of oyster vitality by means of flexible pressure sensors is an important means of improving oyster survival rate. Superior oysters have a higher survival rate in low-temperature environments, and our method can provide effective and reliable survival prediction and management for the oyster industry.
22
SUN, YI, e JAMES D. OLIVER. "Hot Sauce: No Elimination of Vibrio vulnificus in Oysters". Journal of Food Protection 58, n. 4 (1 aprile 1995): 441–42. http://dx.doi.org/10.4315/0362-028x-58.4.441.
Testo completoAbstract (sommario):
Either Tabasco® sauce or a horseradish-based seafood cocktail sauce was placed on freshly shucked oysters which were incubated for 10 min on the half shell. Oysters were then assayed for numbers of Vibrio vulnificus cells present on the surface and within the oyster tissue, and the results compared to control oysters to which no sauce was added. Results indicated that Tabasco® sauce, but not the cocktail sauce, was highly effective in reducing the number of V. vulnificus cells present on the oyster meat surface. However, little reduction in the numbers of V. vulnificus cells present within the oysters was observed with either sauce. Our results suggest that hot sauces are not capable of significantly reducing the overall numbers of V. vulnificus cells associated with oysters, and that persons who are at risk for infection with this bacterium should continue to avoid the consumption of raw seafood, especially raw oysters.
23
COOK, DAVID W., e R. D. ELLENDER. "Relaying to Decrease the Concentration of Oyster-Associated Pathogens". Journal of Food Protection 49, n. 3 (1 marzo 1986): 196–202. http://dx.doi.org/10.4315/0362-028x-49.3.196.
Testo completoAbstract (sommario):
Oysters experimentally contaminated with indicator bacteria, Salmonella and poliovirus were used in relaying studies designed to measure microbial elimination under a variety of environmental conditions. Two factors, level of microorganism in the oyster and temperature of the water, were important in determining the length of time necessary to purge the contaminating organisms. Oysters under physiological stress cleansed at a slower rate than did healthy oysters. Based on the expected level of pathogen contamination in naturally polluted oysters, healthy relaid oysters were capable of cleansing in a 7-d period provided the temperature was above 10°C. These results were verified by following the elimination of indicator bacteria and poliovirus in commercially relaid oysters. Fecal indicator bacteria and enteric pathogenic bacteria were eliminated at similar rates but fecal coliform levels did not correlate with virus elimination. Relaying waters may contain some indicator bacteria and this study suggested that fecal coliforms may not be useful as end-point indicators for this method of oyster purification.
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Heare, J. Emerson, Samuel J. White, Brent Vadopalas e Steven B. Roberts. "Differential response to stress inOstrea luridaas measured by gene expression". PeerJ 6 (15 gennaio 2018): e4261. http://dx.doi.org/10.7717/peerj.4261.
Testo completoAbstract (sommario):
Olympia oysters are the only oyster native to the west coast of North America. The population within Puget Sound, WA has been decreasing significantly since the early 1900’s. Current restoration efforts are focused on supplementing local populations with hatchery bred oysters. A recent study by Heare et al. (2017) has shown differences in stress response in oysters from different locations in Puget Sound however, nothing is known about the underlying mechanisms associated with these observed differences. In this study, expression of genes associated with growth, immune function, and gene regulatory activity in oysters from Oyster Bay, Dabob Bay, and Fidalgo Bay were characterized following temperature and mechanical stress. We found that heat stress and mechanical stress significantly changed expression in molecular regulatory activity and immune response, respectively. We also found that oysters from Oyster Bay had the most dramatic response to stress at the gene expression level. These data provide important baseline information on the physiological response ofOstrea lurida to stress and provide clues to underlying performance differences in the three populations examined.
25
Batchelor, Sarah, J. Scott Harrison, Stephen E. Greiman, Laura M. Treible e John M. Carroll. "Assessment of Infection Prevalence and Intensity of Disease-Causing Parasitic Protozoans Perkinsus marinus and Haplosporidium nelsoni in Georgia Oysters". Microorganisms 11, n. 7 (14 luglio 2023): 1808. http://dx.doi.org/10.3390/microorganisms11071808.
Testo completoAbstract (sommario):
Eastern oysters, Crassostrea virginica, are ecologically and economically important coastal species which provide a commercially valuable food product while also improving water quality through filtration, protecting shorelines, and providing habitat. The protozoan parasites Perkinsus marinus and Haplosporidium nesloni commonly infect oysters along the United States Atlantic and Gulf coasts and have been linked to poor oyster health and mass mortality events. In this study, wild oysters were collected from multiple reefs within four tidal creeks along the coast of Georgia to investigate P. marinus and H. nelsoni prevalence and intensity, their potential impact on oyster health, and identify possible drivers of the parasites. A second study occurred on four sites on Sapelo Island, Georgia, with continuous water quality monitoring data to further elucidate potential drivers. Oyster density and condition index, a proxy for health, were measured, and parasites were quantified using a TaqMan probe based quantitative real-time PCR within gill tissue. Real-time PCR showed that 86% of oysters tested were infected by one or both parasites in the coast-wide survey, and 93% of oysters from Sapelo Island were also infected by one or both parasites. Prevalence and infection intensity for both P. marinus and H. nelsoni varied across sites. Overall impacts on oysters were complex—intensity was not linked to oyster metrics in the coastwide study, but oyster condition was negatively correlated with P. marinus prevalence in the Sapelo Island study. Several relationships between both parasites and water quality parameters were identified, providing valuable information about potential drivers that should be investigated further.
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Ruesink, J. L., K. Houle, E. Beck, F. C. Boardman, A. Suhrbier e B. Hudson. "Intertidal Grow-Out Technique, Not Eelgrass (Zostera marina), Influences Performance of Pacific Oysters (Magallana gigas)". Aquaculture Research 2023 (16 novembre 2023): 1–13. http://dx.doi.org/10.1155/2023/6621043.
Testo completoAbstract (sommario):
Colocation of farmed shellfish in seagrass, although not permitted in some regions of the USA, has been proposed as a means to reach cobenefits of habitat and food production. Seagrass could benefit bivalves through protection from predation or abiotic stressors but conversely can reduce water flow and food delivery. At 10 farm sites in Washington state (USA), we tested the performance of Pacific oysters (Magallana (Crassostrea) gigas) grown in ground culture or off-bottom culture across a range of seagrass densities. Oysters averaged 32 m−2 and 30% shell cover on ground culture beds. Oysters in off-bottom culture showed a negative relationship between size and density across beds, consistent with growth and mortality through the crop cycle, and the largest oysters were at densities similar to ground culture. Within each farm site, ground and off-bottom beds were selected with each of three categories of seagrass (none, sparse, dense). Dense seagrass on aquaculture beds was half the density of nearby unfarmed seagrass beds. For outplanted oysters over 3–9 months, many aspects of oyster performance improved when oysters were elevated above the sediment. Relative to ground culture, off-bottom oysters had better survival (85% vs. 69%), 7% larger size, and 48% higher condition after 3 months in summer, and the survival advantages persisted over winter. Oyster survival on-bottom was especially impaired in finer sediment. No oyster performance differences were associated with seagrass, except for 9-month results, available for five of 10 farms. After 9 months at these five farms, oyster survival showed a small negative effect of dense seagrass, and shell size showed a small positive effect of sparse seagrass. Consequently, seagrass may not provide a boost to colocated intertidal shellfish, but we found little evidence of trade-offs in which maintaining seagrass would reduce yield of farmed oysters. Moving oysters out of the boundary layer and away from soft sediment improves both survival and tissue growth aspects of yield.
27
Song, Min Gyu, Ji Yoon Kim, Eun Bi Jeon, So Hee Kim, Min Soo Heu, Jung-Suck Lee, Jin-Soo Kim e Shin Young Park. "Antiviral Efficacy of Dielectric Barrier Discharge Plasma against Hepatitis A Virus in Fresh Oyster Using PMA/RT-qPCR". Applied Sciences 13, n. 6 (9 marzo 2023): 3513. http://dx.doi.org/10.3390/app13063513.
Testo completoAbstract (sommario):
The hepatitis A virus (HAV), which can be a threat to humans, can be found in oysters. Oysters need sterilization technology that does not cause quality changes because they are eaten raw. Therefore, in this study, antiviral effects and quality changes were conducted using dielectric barrier discharge plasma (DBDP). Total titers of non-PMA- and PMA-treated suspensions of HAV were reduced to 0.20–1.05 and 0.35–1.49 log10 copies/μL, respectively, after DBDP 10–60 min treatment. HAV titers on oysters were reduced to 0.20–1.11 and 0.33–1.33 log10 copies/μL, respectively, after identical an DBDP treatment of the non-PMA- and PMA-treated oysters. The HAV titers were revealed as 0.295 (=[0.25 for 30 min + 0.34 for 60 min]/2) and 0.22 (for 60 min) log10-reduction in PMA-treated suspensions and oysters, respectively, compared with the non-PMA-treated suspensions and oysters. The D1 of DBDP in PMA-treated suspensions and oysters were 39.99 and 46.73 min, respectively. There was no difference in the pH of oysters after DBDP treatment compared to the non-treated control. There were some changes in the hardness of the DBDP-treated oysters, which was due to oyster individual differences rather than the DBDP treatment. In conclusion, DBDP treatment did not affect oyster quality and PMA was able to distinguish HAV infectivity.
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Carmichael, Ruth H., William Walton e Heidi Clark. "Bivalve-enhanced nitrogen removal from coastal estuaries". Canadian Journal of Fisheries and Aquatic Sciences 69, n. 7 (luglio 2012): 1131–49. http://dx.doi.org/10.1139/f2012-057.
Testo completoAbstract (sommario):
Interest in use of bivalves to remediate estuarine eutrophication has increased in recent years. High variation among data sets, substantial focus on particle removal, and insufficient links to anthropogenic nitrogen (N) sources encouraged this empirical examination of N removal by bivalves from estuaries receiving different N loads. We determined the capacity of the oyster Crassostrea virginica to remove N by comparing N assimilated into tissues with anthropogenic N from land or available in phytoplankton. Oyster growth yielded 0.2–0.4 g N in tissues and depended on estuary-specific conditions. δ15N values confirmed that N in oyster tissues derived from local anthropogenic sources. At representative restoration and aquaculture conditions (≤400 oysters·m–2 at 0.5%–1.0% of estuary area), estimated N removal was ≤15% of land-derived loads and <1% of phytoplankton N. N removal via biogeochemical processes was negligible during grow-out, but became important after oysters attained harvestable size. This study explicitly demonstrates that oysters assimilated land-derived N, but suggests that bivalve bioremediation consider trade-offs between intensity of planting, ecological effects, and available space.
29
Lebata-Ramos, Ma Junemie Hazel, Ellen Flor Solis e Mark Jude Almeida. "Grow-out Culture of Oyster Magallana bilineata (Röding, 1798) Using Pouches: A Comparison of Growth and Survival in the River and Earthen Pond". Philippine Agricultural Scientist 106, n. 1 (1 marzo 2023): 55–65. http://dx.doi.org/10.62550/jz101022.
Testo completoAbstract (sommario):
Oysters are among the most in-demand aquaculture commodities in the Philippines and worldwide. With the decreasing culture area and the deteriorating water quality of oyster beds, there is a need to explore new culture sites and techniques to address the problems of dwindling stocks and the increasing demand for better quality oysters. This study compared the growth and survival of the oysters Magallana bilineata, the new accepted name of Crassostrea iredalei, cultured in an earthen pond and the river using pouches suspended from rafts. Mean growth rates of oysters in length and weight were significantly higher in those reared in the river (0.56 ± 0.02 cm mo-1; 10.27 ± 0.42 g mo-1) than those in the pond (0.41 ± 0.03 cm mo-1; 5.99 ± 0.22 g mo-1), but the meat yield of oysters reared in the river (25.96 ± 0.92%) was almost the same as in the pond (24.05 ± 1.41%). Likewise, the proximate composition was the same for oysters coming from the river and the pond, respectively, 58.04 ± 0.14% and 53.86 ± 0.38% crude protein, 7.00 ± 0.08% and 7.93 ± 0.38% crude fat, 24.68 ± 0.07% and 28.54 ± 0.74% nitrogen-free extract, and 10.27 ± 0.01% and 9.68 ± 0.01% ash. Oyster survival at harvest was significantly higher in the river (70.21 ± 2.84%) than in the pond (13.10 ± 1.57%). However, with some interventions, ponds may still be utilized for oyster culture despite the low survival results in this study. Extending oyster culture in these aquaculture facilities may serve as a basis for interventions to make the pond more habitable for oysters and may help boost production in the country.
30
Brumbaugh, R. D., L. A. Sorabella, C. Johnson e W. J. Goldsborough. "Small Scale Aquaculture as a Tool for Oyster Restoration in Chesapeake Bay". Marine Technology Society Journal 34, n. 1 (1 gennaio 2000): 79–86. http://dx.doi.org/10.4031/mtsj.34.1.9.
Testo completoAbstract (sommario):
Since the early 1990s, efforts to restore the Chesapeake Bay’s devastated oyster stocks have focused on the construction of small (∼2 ha.) intertidal shell reefs designed to mimic historic 3-dimensional reef habitat. The reefs are managed as oyster sanctuaries to allow adult oysters to accumulate, grow, and spawn over time. To enhance the effectiveness of this strategy, the Chesapeake Bay Foundation initiated a, program in 1997 to train students and volunteers to grow large numbers of hatchery-produced oysters for stocking sanctuary reefs in selected tributaries. In 1998, a significant increase in spat settlement was documented in the Lynnhaven River, a small tributary where volunteer-grown oysters were transplanted onto a sanctuary reef, providing further direction for restoration efforts. Since then, the program has expanded to include more than 500 citizens and 120 school classes on a Bay wide scale. This paper describes the strategy for restoring oysters in two small Virginia tributaries using volunteers, specifically middle and, high school students, to grow broods-tock (i.e., reproductively mature) oysters for transplanting onto state-managed sanctuary reefs using small-scale aquaculture techniques. To date, volunteers enlisted in a program dubbed the Chesapeake Bay Foundation “Oyster Corps” have grown and stocked more than 250,000 hatchery-produced oysters in Virginia’s portion of Chesapeake Bay. Small scale aquaculture techniques have provided a simple, yet effective, means of involving the public in a restoration effort designed to increase oysters by a factor of 10 by the year 2010.
31
Kamermans, Pauline, Ainhoa Blanco, Pim van Dalen, Marc Engelsma, Nienke Bakker, Pascalle Jacobs, Marco Dubbeldam, Inés M. Sambade, Manuel Vera e Paulino Martinez. "Bonamia-free flat oyster (Ostrea edulis L.) seed for restoration projects: non-destructive screening of broodstock, hatchery production and test for Bonamia-tolerance". Aquatic Living Resources 36 (2023): 11. http://dx.doi.org/10.1051/alr/2023005.
Testo completoAbstract (sommario):
Native (flat) oyster (Ostrea edulis) beds, once a major component of the North Sea, largely disappeared from the region in the late 19th century. Flat oyster restoration is taking place at a number of locations in the North Sea. When flat oyster beds are restored in areas where O. edulis is functionally extinct it is advised to treat these as disease-free areas. Adult oysters were collected in the Dutch Delta area which is infected with the pathogenic parasite Bonamia ostreae. The aim of this research was to obtain Bonamia-free seed from parents collected in a Bonamia-infected area. In addition, the oysters were analysed to identify candidate genomic regions related to bonamiosis tolerance and exposed to Bonamia in the field to assess survival compared to a naïve control group. With the aid of a non-destructive screening method, Bonamia-free broodstock were selected. These oysters produced Bonamia-free larvae and seed. For comparison, broodstock oysters were collected in the Dutch Wadden Sea, an area free of Bonamia. These oysters also produced Bonamia-free larvae and seed. To study if the Delta area oysters had developed a degree of resistance to the disease, while the naïve Wadden Sea oysters had not, seed of both groups was challenged in Lake Grevelingen where Bonamia occurs. Survival of the pre-selected Bonamia-free oysters was significantly higher than the naïve group. Samples of seed were analysed for association of candidate genetic markers related to bonamiosis tolerance. A higher percentage of individuals with tolerance-associated marker genotypes was found in the screened group compared to the naïve one. However, mortality of the naïve group could not be related to Bonamia presence. Further challenge tests are needed before firm conclusions regarding the genetic markers can be made. The results show that hatchery production of Bonamia-free and potentially Bonamia-tolerant flat oysters is possible.
32
COLE, MARY TOWNSEND, MARILYN B. KILGEN e CAMERON R. HACKNEY. "Evaluation of Methods for Extraction of Enteric Virus from Louisiana Oysters". Journal of Food Protection 49, n. 8 (1 agosto 1986): 592–95. http://dx.doi.org/10.4315/0362-028x-49.8.592.
Testo completoAbstract (sommario):
Six techniques were evaluated for recovery of poliovirus from Louisiana oysters. The methods were compared for percent recovery rates, toxicity, ease of extraction, bacterial contamination, and final volume of oyster concentrate. Oyster samples were contaminated with 30–40 plaque forming units of Poliovirus type 1 and processed by six variations of adsorption-elution-precipitation and elution-precipitation methods. The method developed by Ellender et al. (Natural enterovirus and fecal coliform contamination of gulf coast oysters. J. Food Prot. 43:105–110) was judged to be the preferred method for gulf coast oysters.
33
Markert, Alexandra. "How dense is dense? Toward a harmonized approach to characterizing reefs of non-native Pacific oysters – with consideration of native mussels". NeoBiota 57 (29 maggio 2020): 7–52. http://dx.doi.org/10.3897/neobiota.57.49196.
Testo completoAbstract (sommario):
Pacific oysters Crassostrea (Magallana) gigas have been successfully invading ecosystems worldwide. As an ecosystem engineer, they have the potential to substantially impact on other species and on functional processes of invaded ecosystems. Engineering strength depends on oyster density in space and time. Density has not yet been studied on the extent of reef structural dynamics. This study assessed abundance of naturalized Pacific oysters by shell length (SL) of live individuals and post-mortem shells at six sites over six consecutive years during post-establishment. Individual biomass, i.e. live wet mass (LWM), flesh mass (FM) and live shell mass (SM LIVE), were determined from a total of 1.935 live oysters in order to estimate areal biomass. The generic term density attribute was used for SL-related population categories and the biomass variables LWM, FM, SM LIVE and SM. As the oyster invasion modulated resident Mytilus edulis beds, the study was supplemented by contemporaneously assessed data of mussels and corresponding analyses. Interrelations of abundance and areal biomass revealed distinct linkages between specific density attributes. Most importantly, large individuals were identified as intrinsic drivers for the determination of areal biomass. Additionally, allometry of large oysters differed from small oysters by attenuated scaling relations. This effect was enhanced by oyster density as results showed that crowding forced large individuals into an increasing slender shape. The significant relationship between the density attributes large oyster and biomass enabled a classification of reef types by large oyster abundance. Reef type (simple or complex reef) and oyster size (small or large) were considered by implementing a novel concept of weighted twin functions (TF) for the relationship between SL and individual biomass. This study demonstrates that the interplay of scaling parameters (scalar, exponent) is highly sensitive to the estimation of individual biomass (shape) and that putative similar scaling parameters can exceedingly affect the estimation of areal biomass. For the first time, this study documents the crucial relevance of areal reference, i.e. cluster density (CD) or reef density (RD), when comparing density. RD considers reef areas devoid of oysters and results from CD reduced by reef coverage (RC) as the relative reef area occupied by oysters. A compilation of density attributes at simple and complex reefs shall serve as a density guide. Irrespective of areal reference, oyster structural density attributes were significantly higher at complex than at simple reefs. In contrast, areal reference was of vital importance when evaluating the impact of engineering strength at ecosystem-level. While mussel CD was similar at both reef types, RD at complex reefs supported significantly more large mussels and higher mussel biomass than at simple reefs. Although mussels dominated both reef types by abundance of large individuals, oysters were the keystone engineers by dominating biomass. The prominent status of large oysters for both allometric scaling and density, presumably characteristic for Pacific oyster populations worldwide, should be considered when conducting future investigations. The effort of monitoring will substantially be reduced as only large oysters have to be counted for an empirical characterization of Pacific oyster reefs. The large oyster concept is independent of sampling season, assessment method or ecosystem, and is also applicable to old data sets. Harmonization on the proposed density attributes with a clear specification of areal reference will allow trans-regional comparisons of Pacific oyster reefs and will facilitate evaluations of engineering strength, reef performance and invasional impacts at ecosystem-level.
34
Vanukon, Melody S. Vanukon, Jasha Dehm, Timothy Pickering, Moape Kania, Ciro Rico e Chinthaka Hewavitharane. "Growth rate of farmed Mangrove oysters (Magallana bilineata) at Laucala Bay, Suva, Fiji". Journal of Aquaculture Science 8, n. 2 (28 ottobre 2023): 74–82. http://dx.doi.org/10.20473/joas.v8i2.48697.
Testo completoAbstract (sommario):
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.
35
Ramadhaniaty, M., C. Octavina, FA Putri, S. Karina e Ichsan. "The density and distribution of Pacific Oyster (Crassostrea gigas) in Krueng Cut, Aceh Besar". IOP Conference Series: Earth and Environmental Science 869, n. 1 (1 novembre 2021): 012056. http://dx.doi.org/10.1088/1755-1315/869/1/012056.
Testo completoAbstract (sommario):
Abstract Crassostrea gigas is a Pacific oyster that has the largest size among the other oysters. This oyster is most often found because of its ability to adapt to a variety of environments. Krueng Cut is an estuary area that gets a lot of nutrient input from sea water because it is directly adjacent to the ocean. This condition makes this area has a high abundance of oysters with high fishing and antropogenic activities as well. The purpose of this study was to determine the density and distribution of the oyster population from 3 representative stations along the estuary area of Krueng Cut. The method used in this study is random sampling using a quadratic transect. The results show that the highest density is indicated by station 3 with 55.67 ind/m2 and the lowest density is indicated by station 1 is 40.33 ind/m2. These results indicate that the activities of residents, the entry of contaminants from antropogenic affect the density of oysters. The distribution of oysters from the three stations showed similarities, namely they tended to grouping. The aquatic environment at the three research stations still supports the growth of oysters. This study confirms that there has been a decline in the population, which is characterized by a decrease in the number of catches and a smaller size of oysters.
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SU, YI-CHENG, QIANRU YANG e CLAUDIA HÄSE. "Refrigerated Seawater Depuration for Reducing Vibrio parahaemolyticus Contamination in Pacific Oyster (Crassostrea gigas)". Journal of Food Protection 73, n. 6 (1 giugno 2010): 1111–15. http://dx.doi.org/10.4315/0362-028x-73.6.1111.
Testo completoAbstract (sommario):
The efficacy of refrigerated-seawater depuration for reducing Vibrio parahaemolyticus levels in Pacific oyster (Crassostrea gigas) was investigated. Raw Pacific oysters were inoculated with a mixed culture of five clinical strains of V. parahaemolyticus (105 to 106 most probable number [MPN] per g) and depurated with refrigerated seawater (5°C) in a laboratory-scale recirculation system equipped with a 15-W gamma UV sterilizer. Depuration with refrigerated seawater for 96 h reduced V. parahaemolyticus populations by >3.0 log MPN/g in oysters harvested in the winter. However, 144 h of depuration at 5°C was required to achieve a 3-log reduction in oysters harvested in the summer. Depuration with refrigerated seawater at 5°C for up to 144 h caused no significant fatality in the Pacific oyster and could be applied as a postharvest treatment to reduce V. parahaemolyticus contamination in Pacific oysters. Further studies are needed to validate the efficacy of the depuration process for reducing naturally accumulated V. parahaemolyticus in oysters.
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Richards, Gary P., Michael A. Watson, David S. Needleman, Karlee M. Church e Claudia C. Häse. "Mortalities of Eastern and Pacific Oyster Larvae Caused by the Pathogens Vibrio coralliilyticus and Vibrio tubiashii". Applied and Environmental Microbiology 81, n. 1 (24 ottobre 2014): 292–97. http://dx.doi.org/10.1128/aem.02930-14.
Testo completoAbstract (sommario):
ABSTRACTVibrio tubiashiiis reported to be a bacterial pathogen of larval Eastern oysters (Crassostrea virginica) and Pacific oysters (Crassostrea gigas) and has been associated with major hatchery crashes, causing shortages in seed oysters for commercial shellfish producers. Another bacterium,Vibrio coralliilyticus, a well-known coral pathogen, has recently been shown to elicit mortality in fish and shellfish. Several strains ofV. coralliilyticus, such as ATCC 19105 and Pacific isolates RE22 and RE98, were misidentified asV. tubiashiiuntil recently. We compared the mortalities caused by twoV. tubiashiiand fourV. coralliilyticusstrains in Eastern and Pacific oyster larvae. The 50% lethal dose (LD50) ofV. coralliilyticusin Eastern oysters (defined here as the dose required to kill 50% of the population in 6 days) ranged from 1.1 × 104to 3.0 × 104CFU/ml seawater; strains RE98 and RE22 were the most virulent. This study shows thatV. coralliilyticuscauses mortality in Eastern oyster larvae. Results for Pacific oysters were similar, with LD50s between 1.2 × 104and 4.0 × 104CFU/ml.Vibrio tubiashiiATCC 19106 and ATCC 19109 were highly infectious toward Eastern oyster larvae but were essentially nonpathogenic toward healthy Pacific oyster larvae at dosages of ≥1.1 × 104CFU/ml. These data, coupled with the fact that several isolates originally thought to beV. tubiashiiare actuallyV. coralliilyticus, suggest thatV. coralliilyticushas been a more significant pathogen for larval bivalve shellfish thanV. tubiashii, particularly on the U.S. West Coast, contributing to substantial hatchery-associated morbidity and mortality in recent years.
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Chau, Toby, Helen Lv Zhang, Yuyue Gui e Man Fai Lau. "AI-Powered Tracking for Sustainable Marine Ecosystem Resource Management Projects". International Journal of Information Technology Project Management 15, n. 1 (15 dicembre 2023): 1–13. http://dx.doi.org/10.4018/ijitpm.334716.
Testo completoAbstract (sommario):
Ecosystems are our planet's life-support systems that facilitate sustainable development. Within the marine ecosystem, oysters serve as a keystone species. Numerous oyster restoration projects have been launched with a crucial element involving precise assessment of oyster population sizes within specific reef areas. However, the current methods of tracking oyster populations are approximate and lack precision. To address this research gap, the authors developed an AI-empowered project for oyster detection. Specifically, they created a dataset of wild oysters, utilized Roboflow for image annotation, and employed image augmentation techniques to augment the training data. Then, they fine-tuned a YOLOv8 computer vision object detection model using their dataset. The results demonstrated a mean average precision (mAP) of 85.2 percent and an accuracy of 87.7 percent for oyster detection. This approach improved upon previous attempts to detect wild oysters, offering a more effective solution for population assessment, which is a fundamental step toward sustainable oyster restoration project management.
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Tamburini, Fano, Castaldelli e Turolla. "Life Cycle Assessment of Oyster Farming in the Po Delta, Northern Italy". Resources 8, n. 4 (30 ottobre 2019): 170. http://dx.doi.org/10.3390/resources8040170.
Testo completoAbstract (sommario):
Oysters represent an important portion of the world’s total aquaculture production. In recent years, in Italy, oyster farming has progressively increased its role in the economic growth of the aquaculture sector and still has great potential for growth. As in any other production, oyster farming generates environmental impacts over an oyster’s life cycle, due to material, energy, fuel, and water use. The aim of this work was to carry out a cradle-to-gate life cycle assessment (LCA) of 1 kg of fresh oysters of commercial size produced in the Po delta area, northern Italy. Two scenarios were considered. The current scenario provides for oyster seed purchasing from France and transport to Italy, whereas the alternative scenario includes in situ seed production in order to realize a complete local and traceable supply chain. Eco-indicator® 99-H and ReCiPe® midpoint (H) v.1.12 were used to perform the impact assessments. The overall impacts of the two scenarios were very similar and indicated that the main hotspots were the fattening and prefattening phases of farming, which were common in both scenarios. Focusing the analysis on the first stages, transport from France had a greater impact than did local seed production, emphasizing the importance of a short supply chain in aquaculture production.
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Cranfield, H. J., A. Dunn, I. J. Doonan e K. P. Michael. "Bonamia exitiosa epizootic in Ostrea chilensis from Foveaux Strait, southern New Zealand between 1986 and 1992". ICES Journal of Marine Science 62, n. 1 (1 gennaio 2005): 3–13. http://dx.doi.org/10.1016/j.icesjms.2004.06.021.
Testo completoAbstract (sommario):
Abstract Disease caused by the haplosporidian parasite, Bonamia exitiosa, swept through the dredge oyster (Ostrea chilensis) population of Foveaux Strait between 1986 and 1992, with consequent mortality reducing the population to 9% of the pre-disease level. Dead and dying oysters were first seen by fishers in far western Foveaux Strait in 1985 and more were found further east in 1986. Infection spread slowly through Foveaux Strait so the progress of the epizootic can be described from population surveys. A wave of infection radiated through the oyster population from the epicentre of infection in central western Foveaux Strait, and was followed by a wave of mortality. The epizootic ceased in oyster beds around the margins of oyster distribution in 1992. Infective particles released by diseased oysters spread through the water to infect other oysters directly. The epizootic broadly fitted a simple deterministic epizootic model and suggested that both diffusion and turbulent processes were important in transmission of infection. Bonamia exitiosa was also present in oysters at the end of an epizootic in 1964 and was probably the cause of that epizootic. Bonamiasis appears to be an endemic disease in Foveaux Strait. The high mortality in the 1986–1992 epizootic was like that caused by a newly introduced disease in an immunologically naïve population. We propose that other stressors have increased the susceptibility of oysters to this disease. Mechanical disturbance of oysters by increasingly intense dredging appears to be a major source of stress, as does the increasing scale of modification of benthic habitat by fishing. Recovery of the oyster population after the epizootic is closely linked to regeneration of habitat. The prognosis for the fishery could be improved by mitigating mechanical disturbance during dredging by use of lighter dredges and less damaging towing strategies, as well as pursuing rotational fishing strategies that allow benthic habitat to regenerate in undisturbed areas.
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Anh, Phan Thi Hoang, Ha Phuong Trang, Bui Dinh Thanh, Nguyen Thi Nu Trinh, Tran Dinh Thang, Doan Lan Phuong, Nguyen Ngoc Tuan e Tran Thi Huyen. "Antioxidant capacity and sequence of peptides derived from oysters and green mussels in Vietnam". International Food Research Journal 30, n. 3 (21 giugno 2023): 736–49. http://dx.doi.org/10.47836/ifrj.30.3.16.
Testo completoAbstract (sommario):
High-nutrition components and antioxidant compounds have been discovered in many marine organisms in recent years, especially oysters and mussels; but, the two bivalves have not been studied extensively in Vietnam. Therefore, both oysters and green mussels from Long Son, Vietnam were collected for investigation. Results showed that the total macronutrient contents in green mussels were greater than those of oysters, with glutamic acid being the most abundant amino acid in both oysters and green mussels at 1.35 and 1.25 g/100 g, respectively. Total relevant mineral content was 521,954 mg/100 g in oyster flesh, while that in green mussels was 496,847 mg/100 g. Specifically, the zinc content was 30.30 mg/100 g in oysters, 21.96 times more than that in green mussels (1.38 mg/100 g). Biological mixtures of peptides were obtained through enzymatic hydrolysis, and their calculated catalytic efficiencies in oysters and green mussels were 0.051 and 0.067 mg/mL/s, respectively. The antioxidant activity of these peptides was determined by IC50 values in DPPH, with 6.39 mg/mL for oysters, and 10.4 mg/mL for green mussels, and IC50 values in ABTS with 18.0 mg/mL for oysters, and 18.3 mg/mL for green mussels. The sequences of the four most abundant peptide fractions in oyster and green mussel hydrolysates were identified by LC-MS; the two fractions identified in oysters were Asn-Lys-Gln-Ala (F1) and Val-Val-Val-Asp-Val-Gly-Ile (F2), and those in green mussels were Gly-Arg-Thr-Tyr (F3), and Pro-Thr-Gln-Val-Lys-Leu (F4). Tyrosine, a powerful nucleophile, was found in F3. As a result, it is reasonable to believe that green mussels have stronger ABTS free radical scavenging activity than oysters. These results will provide a real insight for research on antioxidant processes involving biological peptides from oysters and green mussels in Vietnam.
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Love, Gabrielle, Shirley Baker e Edward V. Camp. "Oyster-Predator Dynamics and Climate Change". EDIS 2021, n. 1 (25 febbraio 2021): 5. http://dx.doi.org/10.32473/edis-fa228-2020.
Testo completoAbstract (sommario):
Oysters are one of the most important natural resources found in coastal and estuarine areas of Florida, but some Florida oyster populations appear to be declining. One possible driver of oyster population decline is increased mortality from oyster predators, including marine snails. But other environmental factors, such as changes in temperature or salinity, may also affect oysters. This 5-page fact sheet written by Gabrielle Love, Shirley Baker, and Edward V. Camp and published by the UF/IFAS School of Forest Resources and Conservation, Program in Fisheries and Aquatic Sciences describes how a changing climate may affect oysters directly but also indirectly by affecting their predators.https://edis.ifas.ufl.edu/fa228
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KAUFMAN, G. E., A. K. BEJ, J. BOWERS e A. DePAOLA. "Oyster-to-Oyster Variability in Levels of Vibrio parahaemolyticus". Journal of Food Protection 66, n. 1 (1 gennaio 2003): 125–29. http://dx.doi.org/10.4315/0362-028x-66.1.125.
Testo completoAbstract (sommario):
This study examined the variability in the levels of total and pathogenic Vibrio parahaemolyticus in individual oysters. Twenty oysters were collected on three occasions (in June, July, and September 2001) from a site near Mobile Bay, Ala. Ten of these oysters were tested immediately, and 10 were tested after 24 h of storage at 26°C. Levels of total and pathogenic V. parahaemolyticus were determined by alkaline phosphatase–labeled DNA probe procedures targeting the thermolabile hemolysin and thermostable direct hemolysin genes, respectively. Similar V. parahaemolyticus levels (200 to 2,000 CFU/g) were found in nearly 90% of the oysters (for all sampling occasions) prior to storage. The log-transformed densities (means ± standard deviations) of V. parahaemolyticus in oysters immediately after harvest were 2.90 ± 0.91, 2.88 ± 0.36, and 2.47 ± 0.26 log10 CFU/g for June, July, and September, respectively. After storage for 24 h at 26°C, the mean V. parahaemolyticus densities increased approximately 13- to 26-fold. Before storage, pathogenic V. parahaemolyticus was detected in 40% (10 to 20 CFU/g) of the oysters collected in June and July but was not detected in any oysters collected in September. After storage, pathogenic V. parahaemolyticus was detected in some oysters at levels of >100 CFU/g. These data should aid in the development of sampling protocols for oyster monitoring programs and in the determination of exposure distributions associated with raw oyster consumption.
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Nappier, Sharon P., Thaddeus K. Graczyk e Kellogg J. Schwab. "Bioaccumulation, Retention, and Depuration of Enteric Viruses by Crassostrea virginica and Crassostrea ariakensis Oysters". Applied and Environmental Microbiology 74, n. 22 (26 settembre 2008): 6825–31. http://dx.doi.org/10.1128/aem.01000-08.
Testo completoAbstract (sommario):
ABSTRACT Crassostrea ariakensis oysters are under review for introduction into the Chesapeake Bay. However, the human health implications of the introduction have not been fully addressed. This study evaluated rates of bioaccumulation, retention, and depuration of viruses by Crassostrea virginica and C. ariakensis when the two oyster species were maintained in separate tanks containing synthetic seawater of various salinities (8, 12, or 20 ppt). Oyster bioaccumulation tanks were seeded with 103 PFU/ml of hepatitis A virus (HAV), poliovirus, male-specific bacteriophage (MS2), and murine norovirus 1 (MNV-1) and 103 PCR units/ml of human norovirus (NoV). After 24 h, depuration commenced as oysters (n = 255) were placed in pathogen-free seawater under continuous filtration. Oysters (n = 6) were sampled weekly for 1 month from each tank. Viral RNA was recovered using a modified proteinase K, guanidine, and glassmilk method and analyzed by quantitative reverse transcription-PCR. The odds of C. ariakensis oysters harboring NoV, MNV-1, or HAV were statistically greater than the odds of C. virginica oysters harboring the same viruses (MNV-1 odds ratio [OR], 4.5; P = 0.01; NoV OR, 8.4; P < 0.001; HAV OR, 11.4; P < 0.001). Unlike C. virginica, C. ariakensis bioaccumulated and retained NoV, MNV-1, and HAV for 1 month at all salinities. Additionally, the odds of an oyster testing positive for NoV was 25.5 times greater (P < 0.001) when the oyster also tested positive for MNV-1. This research helps assess the threat of C. ariakensis as a vehicle for viral pathogens due to the consumption of raw oysters and validates the role for MNV-1 as a surrogate for NoV.
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Audemard, Corinne, Tal Ben-Horin, Howard I. Kator e Kimberly S. Reece. "Vibrio vulnificus and Vibrio parahaemolyticus in Oysters under Low Tidal Range Conditions: Is Seawater Analysis Useful for Risk Assessment?" Foods 11, n. 24 (16 dicembre 2022): 4065. http://dx.doi.org/10.3390/foods11244065.
Testo completoAbstract (sommario):
Human-pathogenic Vibrio bacteria are acquired by oysters through filtering seawater, however, the relationships between levels of these bacteria in measured in oysters and overlying waters are inconsistent across regions. The reasons for these discrepancies are unclear hindering our ability to assess if -or when- seawater samples can be used as a proxy for oysters to assess risk. We investigated whether concentrations of total and human pathogenic Vibrio vulnificus (vvhA and pilF genes) and Vibrio parahaemolyticus (tlh, tdh and trh genes) measured in seawater reflect concentrations of these bacteria in oysters (Crassostrea virginica) cultured within the US lower Chesapeake Bay region. We measured Vibrio spp. concentrations using an MPN-qPCR approach and analyzed the data using structural equation modeling (SEM). We found seawater concentrations of these bacteria to predictably respond to temperature and salinity over chlorophyll a, pheophytin or turbidity. We also inferred from the SEM results that Vibrio concentrations in seawater strongly predict their respective concentrations in oysters. We hypothesize that such seawater-oyster coupling can be observed in regions of low tidal range. Due to the ease of sampling and processing of seawater samples compared to oyster samples, we suggest that under low tidal range conditions, seawater samples can foster increased spatial and temporal coverage and complement data associated with oyster samples.
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Sakamaki, T., K. Hayashi, Y. Zheng, M. Fujibayashi e O. Nishimura. "Effects of oyster age on selective suspension-feeding and the chemical composition of biodeposits: insights from fatty acid analysis". Marine Ecology Progress Series 644 (25 giugno 2020): 75–89. http://dx.doi.org/10.3354/meps13359.
Testo completoAbstract (sommario):
The study objective was to clarify how the growth stages of the Pacific oyster Crassostrea gigas affect selective suspension-feeding of particulate organic matter (POM) and the composition of biodeposits. A day-long (22 h), continuous-flow mesocosm experiment was conducted with 3, 15, and 27 mo old oysters. The suspended particulate matter (PM), settled PM (mostly biodeposits in the oyster mesocosms), and oyster soft tissues were analysed to determine the content of fatty acids, organic carbon, and nitrogen, as well as the carbon and nitrogen stable isotope ratios to trace compositional changes in POM through oyster biodeposition. Regardless of oyster age, the stable isotope ratios of biodeposits were similar to those of the body tissues but not to those of the suspended PM, indicating that oysters selectively fed on assimilable fractions of POM. Compared with the suspended PM, a higher concentration of long-chain polyunsaturated fatty acids was found in the body tissues and, consequently, in the biodeposits; in contrast, the concentrations of shorter-chain fatty acids were generally lower in the biodeposits. Furthermore, the biodeposits produced by the older oysters had higher carbon, nitrogen, and fatty acid contents compared with the biodeposits produced by the 3 mo old oysters. The oxygen consumption rate of biodeposits was positively related to organic carbon content, but less so to fatty acid composition. Our findings demonstrate that older oysters not only produce larger amounts of biodeposits, but that these biodeposits have higher organic and fatty acid contents, potentially exhibiting greater effects on biogeochemical and ecological processes in nearby benthic habitats.
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Okon, Ekemini Moses, Harriet Nketiah Birikorang, Mohammad Bodrul Munir, Zulhisyam Abdul Kari, Guillermo Téllez-Isaías, Norhan E. Khalifa, Sameh A. Abdelnour et al. "A Global Analysis of Climate Change and the Impacts on Oyster Diseases". Sustainability 15, n. 17 (23 agosto 2023): 12775. http://dx.doi.org/10.3390/su151712775.
Testo completoAbstract (sommario):
Recently, global demand for seafood such oysters is increasing as consumers seek healthy and nutritive alternatives to a diet dominated by animal protein. This trend is attributed to the growing interest in sustainable seafood strategies and a surge in customer demand. Despite oysters being one of the most promising seafoods, the oyster industry faces various challenges, such as increased infectious diseases promoted by climate change, pollution, and environmental burdens. Hence, the industry’s current challenges must be addressed to ensure long-term viability. One of the current challenges in the production industry (in response to climate change) is mortality or poor product quality from microbial infection. This review reveals that climate change fosters pathogen development, significantly impacting disease spread, host susceptibility, and the survival rates of oysters. Rising temperatures, driven by climate, create favourable conditions for bacteria and viruses to multiply and spread quickly, making oysters more susceptible to diseases and ultimately adversely affecting the oyster industry. Climate-induced changes in oyster-associated microbes and pathogens, coupled with disruptions in biochemical pathways and physiological functions, can lead to increased disease outbreaks and reduced survival in the industry, impacting production and profitability. These adverse effects could result in decreased oyster supply, potentially affecting seafood markets and prices, and necessitate additional investments in disease management strategies. This review identifies and highlights how aquatic pathogens promoted by climate change will affect the oyster industry on a global scale. This review also presents an in-depth global assessment of climate change’s impacts on oysters relative to their disease exposure and pathogen spread and identifies possible future directions.
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COOK, DAVID W., e ANGELA D. RUPLE. "Cold Storage and Mild Heat Treatment as Processing Aids to Reduce the Numbers of Vibrio vulnificus in Raw Oysters". Journal of Food Protection 55, n. 12 (1 dicembre 1992): 985–89. http://dx.doi.org/10.4315/0362-028x-55.12.985.
Testo completoAbstract (sommario):
Pure cultures of Vibrio vulnificus held at temperatures of 4 and 0°C underwent a time-dependent decrease in number of recoverable cells. A similar pattern of decreasing numbers was observed with naturally occurring V. vulnificus in cold stored shellstock oysters and shucked oyster meats. The time required for the bacterium to reach undetectable levels (MPN <3/g) may exceed the usual storage life of 14 d for shucked oyster meats and 21 d for shellstock oysters. Freezing and storage of pure cultures of V. vulnificus at −20°C reduced the number of culturable cells more quickly than did holding the cultures at 0°C. However, the organism was cultured from oysters frozen at −20°C for 12 weeks. While cold storage reduced the numbers of V. vulnificus in oysters, such treatment cannot be relied upon to eliminate the organism. Exposure to temperatures above 45°C causes death of V. vulnificus. Decimal reduction times at 47°C for 52 strains averaged 78 s (SD ± 30 s), and D50 values for 18 of the hardiest strains averaged 39.8 s (SD ± 12.2 s). Heating oysters for 10 min in water at 50°C proved adequate to reduce V. vulnificus to a nondetectable level. This treatment does not impart a noticeable cooked appearance or taste to the oysters and may be employed as a strategy to improve the safety of raw oysters.
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Wakefield, Stephanie. "Making nature into infrastructure: The construction of oysters as a risk management solution in New York City". Environment and Planning E: Nature and Space 3, n. 3 (13 novembre 2019): 761–85. http://dx.doi.org/10.1177/2514848619887461.
Testo completoAbstract (sommario):
This paper investigates how nature is transformed into infrastructure through an examination of New York State’s Living Breakwaters project, a $60 million risk management experiment to grow oyster reefs in order to better govern storm surge, rising seas, and coastal flooding. While oysters’ infrastructural nature is portrayed by designers and planners as an inherent natural property which now simply needs harnessing, in reality making oysters into infrastructure requires extensive concrete work—by humans and oysters. Drawing on historical research, site observation, interviews, and media and design analysis, this article traces this work required to make oysters appear, and then function, as a risk management solution. In part one, I trace the narrative work involved in establishing the idea of oysters as infrastructure. In part two, I look at what it takes to build this idea in reality, to make oysters actually function within desired governmental parameters. Making oysters into infrastructure, I conclude, is a kind of biopolitics, both in the traditional sense of making certain forms of human life live, but also in which the goal is to make nature live in a particular way, albeit one imagined as natural to the oyster. While biopolitics forwards a dystopian view of human and nonhumans as vulnerable to threatening environmental processes and heavily secured, it may be undermined by the inability to make nature’s imagined “vitality” appear.
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Singh, Prashant, David Williams, Frank J. Velez e Ravinder Nagpal. "Comparison of the Gill Microbiome of Retail Oysters from Two Geographical Locations Exhibited Distinct Microbial Signatures: A Pilot Study for Potential Future Applications for Monitoring Authenticity of Their Origins". Applied Microbiology 3, n. 1 (23 dicembre 2022): 1–10. http://dx.doi.org/10.3390/applmicrobiol3010001.
Testo completoAbstract (sommario):
The oyster industry is a significant component of United States aquaculture and is vulnerable to various food frauds. In addition to species substitution, mislabeling of oyster geographical origin is performed for economic gains. The geographical origin misrepresentations are performed to claim a famed region of origin known for its unique flavor profile. DNA barcoding is the gold standard method for identifying seafood species but has limited resolution to the species level. This pilot study was conducted to characterize and compare the oyster gill microbiome as an alternative approach for tracking oysters’ origin. Commercially available raw east coast oysters (Crassostrea virginica) from two distinct geographical locations were purchased. Genomic DNA isolated from the gills was processed for microbiome analysis. The data revealed distinct microbiome signatures among the two sample sets. Oysters from Louisiana showed the presence of eighteen unique bacterial genera, whereas Maryland oysters showed a higher abundance of twelve genera. Findings from this study demonstrate the applicability of microbiome analysis as an emerging alternative approach for identifying geographical origin misrepresentations.