Effect of ocean acidification on growth, calcification, and gene expression in the pearl oyster, Pinctada fucata.

PubMed

Liu, Wenguang; Yu, Zonghe; Huang, Xiande; Shi, Yu; Lin, Jianshi; Zhang, Hua; Yi, Xuejie; He, Maoxian

2017-09-01

In this study, shell growth, shell microstructure, and expression levels of shell matrix protein genes (aspein, n16, and nacrein) that play a key role in the CaCO 3 crystal polymorphism (calcite and aragonite) of the shell were investigated in the pearl oyster Pinctada fucata at pH 8.10, 7.70, and 7.40. We found that the shell length and total weight index did not vary significantly between oysters reared at pH 8.10 and 7.70, but was significantly lower at pH 7.40. Calcium content and shell hardness were not significantly different between pH 8.10 and 7.70, but were significantly different at pH 7.40. At pH 7.40, the shell exhibited a poorly organized nacreous microstructure, and showed an apparent loss of structural integrity in the nacreous layer. The prismatic layer appeared morphologically dissimilar from the samples at pH 8.10 and 7.70. The internal layer was corroded and had dissolved. At pH 7.40, the expression levels of nacrein, aspein, and n16 decreased on day 1, and remained low between days 2 and 42. The expression levels of these genes were significantly lower at pH 7.40 than at pH 8.10 and 7.70 during days 2-42. These results suggest that ocean acidification will have a limited impact on shell growth, calcification, and associated gene expression levels at a pH of 7.70, which is projected to be reached by the end of the century. The negative effects were found on calcification and gene expression occurred at the lowest experimental pH (7.40). Copyright © 2017 Elsevier Ltd. All rights reserved.

Denitrification potential of the eastern oyster microbiome using a 16S rRNA gene based metabolic inference approach

PubMed Central

Bowman, Jeff S.; Piehler, Michael

2017-01-01

The eastern oyster (Crassostrea virginica) is a foundation species providing significant ecosystem services. However, the roles of oyster microbiomes have not been integrated into any of the services, particularly nitrogen removal through denitrification. We investigated the composition and denitrification potential of oyster microbiomes with an approach that combined 16S rRNA gene analysis, metabolic inference, qPCR of the nitrous oxide reductase gene (nosZ), and N2 flux measurements. Microbiomes of the oyster digestive gland, the oyster shell, and sediments adjacent to the oyster reef were examined based on next generation sequencing (NGS) of 16S rRNA gene amplicons. Denitrification potentials of the microbiomes were determined by metabolic inferences using a customized denitrification gene and genome database with the paprica (PAthway PRediction by phylogenetIC plAcement) bioinformatics pipeline. Denitrification genes examined included nitrite reductase (nirS and nirK) and nitrous oxide reductase (nosZ), which was further subdivided by genotype into clade I (nosZI) or clade II (nosZII). Continuous flow through experiments measuring N2 fluxes were conducted with the oysters, shells, and sediments to compare denitrification activities. Paprica properly classified the composition of microbiomes, showing similar classification results from Silva, Greengenes and RDP databases. Microbiomes of the oyster digestive glands and shells were quite different from each other and from the sediments. The relative abundance of denitrifying bacteria inferred by paprica was higher in oysters and shells than in sediments suggesting that oysters act as hotspots for denitrification in the marine environment. Similarly, the inferred nosZI gene abundances were also higher in the oyster and shell microbiomes than in the sediment microbiome. Gene abundances for nosZI were verified with qPCR of nosZI genes, which showed a significant positive correlation (F1,7 = 14.7, p = 6.0x10-3, R2 = 0.68). N2 flux rates were significantly higher in the oyster (364.4 ± 23.5 μmol N-N2 m-2 h-1) and oyster shell (355.3 ± 6.4 μmol N-N2 m-2 h-1) compared to the sediment (270.5 ± 20.1 μmol N-N2 m-2 h-1). Thus, bacteria carrying nosZI genes were found to be an important denitrifier, facilitating nitrogen removal in oyster reefs. In addition, this is the first study to validate the use of 16S gene based metabolic inference as a method for determining microbiome function, such as denitrification, by comparing inference results with qPCR gene quantification and rate measurements. PMID:28934286

Denitrification potential of the eastern oyster microbiome using a 16S rRNA gene based metabolic inference approach.

PubMed

Arfken, Ann; Song, Bongkeun; Bowman, Jeff S; Piehler, Michael

2017-01-01

The eastern oyster (Crassostrea virginica) is a foundation species providing significant ecosystem services. However, the roles of oyster microbiomes have not been integrated into any of the services, particularly nitrogen removal through denitrification. We investigated the composition and denitrification potential of oyster microbiomes with an approach that combined 16S rRNA gene analysis, metabolic inference, qPCR of the nitrous oxide reductase gene (nosZ), and N2 flux measurements. Microbiomes of the oyster digestive gland, the oyster shell, and sediments adjacent to the oyster reef were examined based on next generation sequencing (NGS) of 16S rRNA gene amplicons. Denitrification potentials of the microbiomes were determined by metabolic inferences using a customized denitrification gene and genome database with the paprica (PAthway PRediction by phylogenetIC plAcement) bioinformatics pipeline. Denitrification genes examined included nitrite reductase (nirS and nirK) and nitrous oxide reductase (nosZ), which was further subdivided by genotype into clade I (nosZI) or clade II (nosZII). Continuous flow through experiments measuring N2 fluxes were conducted with the oysters, shells, and sediments to compare denitrification activities. Paprica properly classified the composition of microbiomes, showing similar classification results from Silva, Greengenes and RDP databases. Microbiomes of the oyster digestive glands and shells were quite different from each other and from the sediments. The relative abundance of denitrifying bacteria inferred by paprica was higher in oysters and shells than in sediments suggesting that oysters act as hotspots for denitrification in the marine environment. Similarly, the inferred nosZI gene abundances were also higher in the oyster and shell microbiomes than in the sediment microbiome. Gene abundances for nosZI were verified with qPCR of nosZI genes, which showed a significant positive correlation (F1,7 = 14.7, p = 6.0x10-3, R2 = 0.68). N2 flux rates were significantly higher in the oyster (364.4 ± 23.5 μmol N-N2 m-2 h-1) and oyster shell (355.3 ± 6.4 μmol N-N2 m-2 h-1) compared to the sediment (270.5 ± 20.1 μmol N-N2 m-2 h-1). Thus, bacteria carrying nosZI genes were found to be an important denitrifier, facilitating nitrogen removal in oyster reefs. In addition, this is the first study to validate the use of 16S gene based metabolic inference as a method for determining microbiome function, such as denitrification, by comparing inference results with qPCR gene quantification and rate measurements.

Inducible defenses in Olympia oysters in response to an invasive predator.

PubMed

Bible, Jillian M; Griffith, Kaylee R; Sanford, Eric

2017-03-01

The prey naiveté hypothesis suggests that native prey may be vulnerable to introduced predators because they have not evolved appropriate defenses. However, recent evidence suggests that native prey sometimes exhibit induced defenses to introduced predators, as a result of rapid evolution or other processes. We examined whether Olympia oysters (Ostrea lurida) display inducible defenses in the presence of an invasive predator, the Atlantic oyster drill (Urosalpinx cinerea), and whether these responses vary among oyster populations from estuaries with and without this predator. We spawned oysters from six populations distributed among three estuaries in northern California, USA, and raised their offspring through two generations under common conditions to minimize effects of environmental history. We exposed second-generation oysters to cue treatments: drills eating oysters, drills eating barnacles, or control seawater. Oysters from all populations grew smaller shells when exposed to drill cues, and grew thicker and harder shells when those drills were eating oysters. Oysters exposed to drills eating other oysters were subsequently preyed upon at a slower rate. Although all oyster populations exhibited inducible defenses, oysters from the estuary with the greatest exposure to drills grew the smallest shells suggesting that oyster populations have evolved adaptive differences in the strength of their responses to predators. Our findings add to a growing body of literature that suggests that marine prey may be less likely to exhibit naiveté in the face of invasive predators than prey in communities that are more isolated from native predators, such as many freshwater and terrestrial island ecosystems.

Biometric, microstructural, and high-resolution trace element studies in Crassostrea gigas of Cantabria (Bay of Biscay, Spain): Anthropogenic and seasonal influences

NASA Astrophysics Data System (ADS)

Higuera-Ruiz, R.; Elorza, J.

2009-04-01

Living Crassostrea gigas oysters of different ages and sizes were collected in three estuaries of Cantabria (Bay of Biscay, Spain): San Vicente de la Barquera Estuary, Santander Bay, and Marismas de Santoña Estuary. The main objective was to determine different shell responses to variable environmental parameters. A shell morphological study, based on three biometric indices, indicates that oysters of Santander Bay have two significant shell anomalies: abnormal thickening of the right valve and loss of vital cavity volume. These shell abnormalities are related with the presence in these waters of the chemical tributyltin. In the other two estuaries, the oysters show no detectable anomalies. Four shell microstructures have been distinguished: Regular Simple Prismatic, Regular Foliated, cone-Complex Cross Foliated, and Chalk. In Santander Bay oysters, the Chalk forms a "root-type" framework, whereas in the other two estuaries it forms a more compact microstructure. It is proposed that exposure to tributyltin has produced this modification. High-spatial-resolution geochemical transects have been carried out on the Regular Foliated microstructure in the umbo region in order to evaluate the distribution of Mg, Sr, and Na. The elements analysed exhibit clear cyclic variations in San Vicente de la Barquera Estuary and Marismas de Santoña Estuary oysters, related with seasonal periods, and characterised by broad maxima during months in which the waters are warmer and have higher salinity. These patterns are buffered in Santander Bay oysters. Our results demonstrate that biometric, microstructural, and high-resolution trace element studies in oyster shells can provide information about contaminants and seasonal variations in the estuarine environment.

Inhibition of 4NQO-Induced Oral Carcinogenesis by Dietary Oyster Shell Calcium

PubMed Central

Chen, Ying; Jiang, Yi; Liao, Liyan; Zhu, Xiaoxin; Tang, Shengan; Yang, Qing; Sun, Lihua; Li, Yujie; Gao, Shuangrong; Xie, Zhongjian

2015-01-01

Oyster has gained much attention recently for its anticancer activity but it is unclear whether calcium, the major antitumor ingredient in oyster shell, is responsible for the anticarcinogenic role of the oyster. To address this issue, C57BL/6 mice were fed with the carcinogen 4-nitroquinoline-1-oxide (4NQO, 50 µg/mL) and normal diet or a diet containing oyster powder, oyster calcium, or calcium depleted oyster powder. The tongue tissue specimens isolated from these mice were histologically evaluated for hyperplasia, dysplasia, and papillary lesions, and then analyzed for proliferation and differentiation markers by immunohistochemistry. The results showed that mice on the diet containing oyster calcium significantly reduced rates of tumors in the tongue and proliferation and enhanced differentiation in the oral epithelium compared with the diet containing calcium depleted oyster powder. These results suggest that calcium in oyster plays a critical role in suppressing formation of oral squamous cell carcinoma and proliferation and promoting differentiation of the oral epithelium. PMID:26293805

Adsorption of cadmium on cerium oxide nanoparticles and oyster shells

NASA Astrophysics Data System (ADS)

Ji, Yongbo; Liu, Zhuomiao; Dang, Yonghui; Xu, Lina; Ning, Fangyuan; Xue, Yinhao; Wei, Yongpeng; Dai, Yanhui

2018-03-01

This study investigated the adsorption of cadmium (Cd(II)) by cerium oxide nanoparticles (CeO2 NPs) and oyster shells in seawater. The results showed that the addition of Cd(II) significantly inhibited the agglomeration of CeO2 NPs both in DI water and seawater, increased the positive charges of CeO2 NPs in DI water and neutralized the negative charges of CeO2 NPs in seawater. Additionally, CeO2 NPs could adsorb Cd and the bioavailability of Cd was reduced in the presence of oyster shells. This study demonstrated that the adsorption of metals on shells should not be neglected for the accumulation of metals by shellfish.

Does restoring oyster reefs restore oyster health?

USDA-ARS?s Scientific Manuscript database

American colonists found native oyster reefs so plentiful that oysters, with tobacco and spirits, completed the triumvirate of necessities, and their discarded shells paved the earliest colonial streets from New England down to the Gulf Coast. Industrialization and dredging, however, had devastating...

Post-mortem ecosystem engineering by oysters creates habitat for a rare marsh plant.

PubMed

Guo, Hongyu; Pennings, Steven C

2012-11-01

Oysters are ecosystem engineers in marine ecosystems, but the functions of oyster shell deposits in intertidal salt marshes are not well understood. The annual plant Suaeda linearis is associated with oyster shell deposits in Georgia salt marshes. We hypothesized that oyster shell deposits promoted the distribution of Suaeda linearis by engineering soil conditions unfavorable to dominant salt marsh plants of the region (the shrub Borrichia frutescens, the rush Juncus roemerianus, and the grass Spartina alterniflora). We tested this hypothesis using common garden pot experiments and field transplant experiments. Suaeda linearis thrived in Borrichia frutescens stands in the absence of neighbors, but was suppressed by Borrichia frutescens in the with-neighbor treatment, suggesting that Suaeda linearis was excluded from Borrichia frutescens stands by interspecific competition. Suaeda linearis plants all died in Juncus roemerianus and Spartina alterniflora stands, regardless of neighbor treatments, indicating that Suaeda linearis is excluded from these habitats by physical stress (likely water-logging). In contrast, Borrichia frutescens, Juncus roemerianus, and Spartina alterniflora all performed poorly in Suaeda linearis stands regardless of neighbor treatments, probably due to physical stresses such as low soil water content and low organic matter content. Thus, oyster shell deposits play an important ecosystem engineering role in influencing salt marsh plant communities by providing a unique niche for Suaeda linearis, which otherwise would be rare or absent in salt marshes in the southeastern US. Since the success of Suaeda linearis is linked to the success of oysters, efforts to protect and restore oyster reefs may also benefit salt marsh plant communities.

Oyster Shell Recycling and Bone Waste Treatment Using Plasma Pyrolysis

NASA Astrophysics Data System (ADS)

Jae, Ou Chae; Knak, S. P.; Knak, A. N.; Koo, H. J.; Ravi, V.

2006-11-01

Investigations on the recycling of oyster shells and bone waste treatment using the plasma pyrolysis technique are presented in this paper. A arc based plasma torch operated at 25 kW was employed for the experiments. Fresh oyster shells were recycled using the plasma torch to convert them to a useful product such as CaO. Bone waste was treated to remove the infectious organic part and to vitrify the inorganic part. The time required for treatment in both cases was significantly short. Significant reduction in the weight of the samples was observed in both cases.

CO₂ uptake performance and life cycle assessment of CaO-based sorbents prepared from waste oyster shells blended with PMMA nanosphere scaffolds.

PubMed

Wang, Tsinghai; Xiao, Da-Cheng; Huang, Chih-Hung; Hsieh, Yi-Kong; Tan, Chung-Sung; Wang, Chu-Fang

2014-04-15

In this paper, we demonstrate a means of simultaneously solving two serious environmental issues by reutilization of calcinated mixture of pulverized waste oyster shells blending with poly(methyl methacrylate) (PMMA) nanospheres to prepare CaO-based sorbents for CO2 capture. After 10 cycles of isothermal carbonation/calcination at 750°C, the greatest CO2 uptake (0.19 g CO2/g sorbent) was that for the sorbent featuring 70 wt% of PMMA, which was almost three times higher than that (0.07 g CO2/g sorbent) of untreated waste oyster shell. The greater CO2 uptake was likely a result of particle size reduction and afterwards surface basicity enhancement and an increase in the volume of mesopores and macropores. Following simplified life cycle assessment, whose all input values were collected from our experimental results, suggested that a significant CO2 emission reduction along with lesser human health and ecosystems impacts would be achieved immediately once waste is reutilized. Most importantly, the CO2 uptake efficiency must be greater than 20% or sorbents prepared from limestone mining would eventually produce a net positive CO2 emission. Copyright © 2014 Elsevier B.V. All rights reserved.

SETTLEMENT AND SURVIVAL OF THE OYSTER CRASSOSTREA VIRGINICA ON CREATED OYSTER REEF HABITATS IN CHESAPEAKE BAY

EPA Science Inventory

Efforts to restore the Eastern oyster (Crassostrea virginica) reef habitats in Chesapeake Bay typically begin with the placement of hard substrata to form three-dimensional mounds on the seabed to serve as a base for oyster recruitment and growth. A shortage of oyster shell for ...

Temporal and local variations in biochemical composition of Crassostrea gigas shells

NASA Astrophysics Data System (ADS)

Almeida, Maria J.; Machado, Jorge; Moura, Gabriela; Azevedo, Manuela; Coimbra, João

1998-12-01

The objective of this work was to find relations between organic and inorganic shell components. Crassostrea gigas shells were analysed from live specimens collected at five different stations: the Lima estuary (1), the Ria de Aveiro (2, 3), and the Mondego estuary (4, 5), Portugal. About 30% of the oysters, from stations 1, 2 and 3 had shell-thickness-index values ≤10, indicating a severe thickening. Oysters from the Mondego estuary contained mud blisters due to Polydora infestations. Oysters from station 3 had thicker shells and showed a higher Pb content in shell and tissues than oysters from the other stations. Amino-acid composition changed mainly according to the modified protein (jelly-like substance) probably produced by the presence of TBT (tributyltin) in the water; in particular, we observed an increase in glutamic acid and threonine and a decrease in major amino acids such as aspartic acid, serine and glycine. Elemental shell composition was mainly associated with environmental conditions: shells from stations in open areas had higher Li, Cd, Cr and Ca and lower Mn levels than those from semi-enclosed areas (fish farms). Discriminant analyses against the three kinds of shell observed (normal, thick and infested), using chemical elements and amino acids as discriminant variables, showed the infested group to have the biggest differences. There was no correlation between amino-acid and chemical-element patterns in shell composition. Observed changes in amino-acid pattern, probably due to TBT, did not imply a simultaneous change of elemental composition.

Comparative Transcriptome Analysis of the Pacific Oyster Crassostrea gigas Characterized by Shell Colors: Identification of Genetic Bases Potentially Involved in Pigmentation

PubMed Central

Feng, Dandan; Li, Qi; Yu, Hong; Zhao, Xuelin; Kong, Lingfeng

2015-01-01

Background Shell color polymorphisms of Mollusca have contributed to development of evolutionary biology and population genetics, while the genetic bases and molecular mechanisms underlying shell pigmentation are poorly understood. The Pacific oyster (Crassostrea gigas) is one of the most important farmed oysters worldwide. Through successive family selection, four shell color variants (white, golden, black and partially pigmented) of C. gigas have been developed. To elucidate the genetic mechanisms of shell coloration in C. gigas and facilitate the selection of elite oyster lines with desired coloration patterns, differentially expressed genes (DEGs) were identified among the four shell color variants by RNA-seq. Results Digital gene expression generated over fifteen million reads per sample, producing expression data for 28,027 genes. A total number of 2,645 DEGs were identified from pair-wise comparisons, of which 432, 91, 43 and 39 genes specially were up-regulated in white, black, golden and partially pigmented shell of C. gigas, respectively. Three genes of Abca1, Abca3 and Abcb1 which belong to the ATP-binding cassette (ABC) transporters super-families were significantly associated with white shell formation. A tyrosinase transcript (CGI_10008737) represented consistent up-regulated pattern with golden coloration. We proposed that white shell variant of C. gigas could employ “endocytosis” to down-regulate notch level and to prevent shell pigmentation. Conclusion This study discovered some potential shell coloration genes and related molecular mechanisms by the RNA-seq, which would provide foundational information to further study on shell coloration and assist in selective breeding in C. gigas. PMID:26693729

Preliminary Evaluation of Microbial Communities Isolated from the Calcifying Fluid of Oysters

NASA Astrophysics Data System (ADS)

Banker, R.

2016-02-01

The process of biomineralization is defined as the selective uptake of elements that are incorporated into a defined mineral structure under strict biological control. For bivalve molluscs, such as clams, oysters, and mussels, the mantle is the primary organ in control of shell deposition. Alternatively, remote calcification takes place when carbonate-precipitating microbes (e.g. sulfate reducers) colonize a shell-secreting organism and enhance the ability of the host to build shell material. The oyster syndrome is a term that describes bivalves that possess an unusual shell morphology characterized by exceptionally thick valves containing numerous chambers filled with chalky calcite. Although remote calcification via microbial metabolism has been proposed as a mechanism of chalky deposit formation in oysters, this hypothesis has not yet been rigorously investigated. Here I present data on the microbial communities found in the calcifying fluid of two oyster species; Crassostrea gigas and Ostrea lurida are examples of oysters that do and do not exhibit the oyster syndrome, respectively. Comparison of the microbiomes of these two morphological end members may provide insight into the role of microbes in the formation of chalky deposits. Results indicate that the microbial community in the surrounding water is the dominant source for bacterial taxa found in the calcifying fluid of both oyster species. Also, it appears as though C. gigas maintains a microbial community that is more similar to its ambient environment than O. lurida. These results demonstrate that the ambient aquatic environment has a guiding influence on the microbiome found in the calcifying fluid of bivalve molluscs. However, the magnitude of this effect varies among organisms, even those that are closely related.

Restoration of oyster reefs in an estuarine lake: population dynamics and shell accretion

USGS Publications Warehouse

Casas, Sandra M.; La Peyre, Jerome F.; La Peyre, Megan K.

2015-01-01

Restoration activities inherently depend on understanding the spatial and temporal variation in basic demographic rates of the species of interest. For species that modify and maintain their own habitat such as the eastern oyster Crassostrea virginica, understanding demographic rates and their impacts on population and habitat success are crucial to ensuring restoration success. We measured oyster recruitment, density, size distribution, biomass, mortality and Perkinsus marinus infection intensity quarterly for 3 yr on shallow intertidal reefs created with shell cultch in March 2009. All reefs were located within Sister Lake, LA. Reefs were placed in pairs at 3 different locations within the lake; pairs were placed in low and medium energy sites within each location. Restored reefs placed within close proximity (<8 km) experienced very different development trajectories; there was high inter-site and inter-annual variation in recruitment and mortality of oysters, with only slight variation in growth curves. Despite this high variation in population dynamics, all reefs supported dense oyster populations (728 ± 102 ind. m-2) and high live oyster biomass (>14.6 kg m-2) at the end of 3 yr. Shell accretion, on average, exceeded estimated rates required to keep pace with local subsidence and shell loss. Variation in recruitment, growth and survival drives local site-specific population success, which highlights the need to understand local water quality, hydrodynamics, and metapopulation dynamics when planning restoration.

Photosynthetic epibionts and endobionts of Pacific oyster shells from oyster reefs in rocky versus mudflat shores.

PubMed

Barillé, Laurent; Le Bris, Anthony; Méléder, Vona; Launeau, Patrick; Robin, Marc; Louvrou, Ioanna; Ribeiro, Lourenço

2017-01-01

The Pacific oyster, Crassostrea gigas (Thunberg), is the main bivalve species cultivated in the world. With global warming enabling its reproduction and larval survival at higher latitudes, this species is now recognized as invasive and creates wild oyster reefs globally. In this study, the spatial distribution of photosynthetic assemblages colonizing the shells of wild C. gigas was investigated on both a large scale (two contrasting types of reefs found in mudflats and rocky areas) and a small scale (within individual shells) using a hyperspectral imager. The microspatial distribution of all phototrophs was obtained by mapping the Normalized Difference Vegetation Index (NDVI). Second derivative (δδ) analyses of hyperspectral images at 462, 524, 571 and 647 nm were subsequently applied to map diatoms, cyanobacteria, rhodophytes and chlorophytes, respectively. A concomitant pigment analysis was carried out by high performance liquid chromatography and completed by taxonomic observations. This study showed that there was high microalgal diversity associated with wild oyster shells and that there were differences in the structure of the phototropic assemblages depending on the type of reef. Namely, vertically-growing oysters in mudflat areas had a higher biomass of epizoic diatoms (hyperspectral proxy at δδ462 nm) and were mainly colonized by species of the genera Navicula, Nitzschia and Hippodonta, which are epipelic or motile epipsammic. The assemblages on the horizontal oysters contained more tychoplanktonic diatoms (e.g. Thalassiosira pseudonana, T. proschkinae and Plagiogrammopsis vanheurckii). Three species of boring cyanobacteria were observed for both types of reef: Mastigocoleus testarum, Leptolyngbya terrebrans, and Hyella caespistosa, but the second derivative analysis at 524 nm showed a significantly higher biomass for the horizontally-growing oysters. There was no biomass difference for the boring chlorophyte assemblages (δδ647 nm), with two species: Eugomontia testarum and Ostreobium quekettii observed for both types of reef. This study shows that oyster shells are an idiosyncratic but ubiquitous habitat for phototrophic assemblages. The contribution of these assemblages in terms of biomass and production to the functioning of coastal areas, and particularly to shellfish ecosystems, remains to be evaluated.

Photosynthetic epibionts and endobionts of Pacific oyster shells from oyster reefs in rocky versus mudflat shores

PubMed Central

Le Bris, Anthony; Méléder, Vona; Launeau, Patrick; Robin, Marc; Louvrou, Ioanna; Ribeiro, Lourenço

2017-01-01

The Pacific oyster, Crassostrea gigas (Thunberg), is the main bivalve species cultivated in the world. With global warming enabling its reproduction and larval survival at higher latitudes, this species is now recognized as invasive and creates wild oyster reefs globally. In this study, the spatial distribution of photosynthetic assemblages colonizing the shells of wild C. gigas was investigated on both a large scale (two contrasting types of reefs found in mudflats and rocky areas) and a small scale (within individual shells) using a hyperspectral imager. The microspatial distribution of all phototrophs was obtained by mapping the Normalized Difference Vegetation Index (NDVI). Second derivative (δδ) analyses of hyperspectral images at 462, 524, 571 and 647 nm were subsequently applied to map diatoms, cyanobacteria, rhodophytes and chlorophytes, respectively. A concomitant pigment analysis was carried out by high performance liquid chromatography and completed by taxonomic observations. This study showed that there was high microalgal diversity associated with wild oyster shells and that there were differences in the structure of the phototropic assemblages depending on the type of reef. Namely, vertically-growing oysters in mudflat areas had a higher biomass of epizoic diatoms (hyperspectral proxy at δδ462 nm) and were mainly colonized by species of the genera Navicula, Nitzschia and Hippodonta, which are epipelic or motile epipsammic. The assemblages on the horizontal oysters contained more tychoplanktonic diatoms (e.g. Thalassiosira pseudonana, T. proschkinae and Plagiogrammopsis vanheurckii). Three species of boring cyanobacteria were observed for both types of reef: Mastigocoleus testarum, Leptolyngbya terrebrans, and Hyella caespistosa, but the second derivative analysis at 524 nm showed a significantly higher biomass for the horizontally-growing oysters. There was no biomass difference for the boring chlorophyte assemblages (δδ647 nm), with two species: Eugomontia testarum and Ostreobium quekettii observed for both types of reef. This study shows that oyster shells are an idiosyncratic but ubiquitous habitat for phototrophic assemblages. The contribution of these assemblages in terms of biomass and production to the functioning of coastal areas, and particularly to shellfish ecosystems, remains to be evaluated. PMID:28934317

RELATIONSHIP OF AMEBOCYTES AND TERRESTRIAL ELEMENTS TO ADULT SHELL DEPOSITION IN EASTERN OYSTERS

EPA Science Inventory

Fisher, William S. Submitted. Relationship of Amebocytes and Terrestrial Elements to Adult Shell Deposition in Eastern Oysters. J. Shellfish Res. 30 p. (ERL,GB 1197).

Freshwater runoff contains terrestrial elements from geological deposits that may be vital to eastern oys...

Production of Biodiesel from Chlorella sp. Enriched with Oyster Shell Extracts

PubMed Central

Choi, Woon Yong; Kang, Do Hyung; Lee, Hyeon Yong

2014-01-01

This study investigated the cultivation of the marine microalga Chlorella sp. without supplying an inorganic carbon source, but instead with enriching the media with extracts of oyster shells pretreated by a high-pressure homogenization process. The pretreated oyster shells were extracted by a weak acid, acetic acid, that typically has harmful effects on cell growth and also poses environmental issues. The concentration of the residual dissolved carbon dioxide in the medium was sufficient to maintain cell growth at 32 ppm and pH 6.5 by only adding 5% (v/v) of oyster shell extracts. Under this condition, the maximum cell density observed was 2.74 g dry wt./L after 27 days of cultivation. The total lipid content was also measured as 18.1 (%, w/w), and this value was lower than the 23.6 (%, w/w) observed under nitrogen deficient conditions or autotrophic conditions. The fatty acid compositions of the lipids were also measured as 10.9% of C16:1 and 16.4% of C18:1 for the major fatty acids, which indicates that the biodiesel from this culture process should be a suitable biofuel. These results suggest that oyster shells, environmental waste from the food industry, can be used as a nutrient and carbon source with seawater, and this reused material should be important for easily scaling up the process for an outdoor culture system. PMID:24696841

Production of biodiesel from Chlorella sp. enriched with oyster shell extracts.

PubMed

Choi, Cheol Soon; Choi, Woon Yong; Kang, Do Hyung; Lee, Hyeon Yong

2014-01-01

This study investigated the cultivation of the marine microalga Chlorella sp. without supplying an inorganic carbon source, but instead with enriching the media with extracts of oyster shells pretreated by a high-pressure homogenization process. The pretreated oyster shells were extracted by a weak acid, acetic acid, that typically has harmful effects on cell growth and also poses environmental issues. The concentration of the residual dissolved carbon dioxide in the medium was sufficient to maintain cell growth at 32 ppm and pH 6.5 by only adding 5% (v/v) of oyster shell extracts. Under this condition, the maximum cell density observed was 2.74 g dry wt./L after 27 days of cultivation. The total lipid content was also measured as 18.1 (%, w/w), and this value was lower than the 23.6 (%, w/w) observed under nitrogen deficient conditions or autotrophic conditions. The fatty acid compositions of the lipids were also measured as 10.9% of C16:1 and 16.4% of C18:1 for the major fatty acids, which indicates that the biodiesel from this culture process should be a suitable biofuel. These results suggest that oyster shells, environmental waste from the food industry, can be used as a nutrient and carbon source with seawater, and this reused material should be important for easily scaling up the process for an outdoor culture system.

Impact of pCO2 on the energy, reproduction and growth of the shell of the pearl oyster Pinctada margaritifera

NASA Astrophysics Data System (ADS)

Le Moullac, G.; Soyez, C.; Vidal-Dupiol, J.; Belliard, C.; Fievet, J.; Sham-Koua, M.; Lo-Yat, A.; Saulnier, D.; Gaertner-Mazouni, N.; Gueguen, Y.

2016-12-01

The possible consequences of acidification on pearl farming are disruption of oyster metabolism and change in growth. In the laboratory, we studied the impact of pCO2 (3540, 1338 and 541 μatm) on the physiology of pearl oysters exposed for 100 days. This experiment was repeated after an interval of one year. Several physiological compartments were examined in pearl oysters: the scope for growth by measuring ingestion, assimilation and oxygen consumption, gametogenesis by means of histological observations, shell growth by measurement and observation by optical and electronic microscopy, and at molecular level by measuring the expression of nine genes of mantle cells implied in the biomineralisation process. Results from both experiments showed that high pCO2 had no effect on scope for growth and gametogenesis. High pCO2 (3540 μatm) significantly slowed down the shell deposit rate at the ventral side and SEM observations of the inside of the shell found signs of chemical dissolution. Of the nine examined genes high pCO2significantly decreased the expression level of one gene (Pmarg-PUSP 6). This study showed that shell growth of the pearl oyster would be slowed down without threatening the species since the management of energy and reproduction functions appeared to be preserved. Further investigations should be conducted on the response of offspring to acidification.

Amorphous calcium carbonate: A precursor phase for aragonite in shell disease of the pearl oyster.

PubMed

Huang, Jingliang; Liu, Chuang; Xie, Liping; Zhang, Rongqing

2018-02-26

Amorphous calcium carbonate (ACC) has long been shown to act as an important constituent or precursor phase for crystalline material in mollusks. However, the presence and the role of ACC in bivalve shell formation are not fully studied. In this study, we found that brown deposits containing heterogeneous calcium carbonates were precipitated when a shell disease occurred in the pearl oyster Pinctada fucata. Calcein-staining of the brown deposits indicated that numerous amorphous calcium deposits were present, which was further confirmed by Fourier-transform infrared spectroscopy (FTIR), Raman spectrum and X-ray difraction (XRD) analyses. So we speculate that ACC plays an important role in rapid calcium carbonate precipitation during shell repair process in diseased oysters. Copyright © 2018 Elsevier Inc. All rights reserved.

Genomics on the Half Shell: So, What do Oysters Have to do with Energy? (2010 JGI User Meeting)

ScienceCinema

Hedgecock, Dennis

2018-04-26

Dennis Hedgecock from the University of Southern California answers the question, "Genomics on the Half Shell: So, What Do Oysters Have to Do with Energy?" on March 24, 2010 at the 5th Annual DOE JGI User Meeting.

Effects of pre- or post-processing storage conditions on high-hydrostatic pressure inactivation of Vibrio parahaemolyticus and V. vulnificus in oysters.

PubMed

Ye, Mu; Huang, Yaoxin; Gurtler, Joshua B; Niemira, Brendan A; Sites, Joseph E; Chen, Haiqiang

2013-05-15

The effects of storage conditions on subsequent high-hydrostatic pressure (HHP) inactivation of Vibrio parahaemolyticus and Vibrio vulnificus in oysters were investigated. Live oysters were inoculated with V. parahaemolyticus or V. vulnificus to ca. 7-8 log MPN/g by feeding and stored at varying conditions (i.e., 21 or 35 °C for 5h, 4 or 10 °C for 1 and 2 days and -18 °C for 2 weeks). Oyster meats were then treated at 225-300 MPa for 2 min at 4, 21 or 35 °C. HHP at 300 MPa for 2 min achieved a >5-log MPN/g reduction of V. parahaemolyticus, completely inactivating V. vulnificus (negative by enrichment) in oysters. Treatment temperatures of 4, 21 and 35 °C did not significantly affect pressure inactivation of V. parahaemolyticus or V. vulnificus (P>0.05). Cold storage at -18, 4 and 10 °C, prior to HHP, decreased V. parahaemolyticus or V. vulnificus populations by 1.5-3.0 log MPN/g, but did not increase their sensitivity to subsequent HHP treatments. The effects of cold storage after HHP on inactivation of V. parahaemolyticus in oysters were also determined. Oysters were inoculated with V. parahaemolyticus and stored at 21 °C for 5h or 4 °C for 1 day. Oyster meats were then treated at 250-300 MPa for 2 min at 21 or 35 °C and stored for 15 days in ice or in a freezer. V. parahaemolyticus populations in HHP-treated oysters gradually decreased during post-HHP ice or frozen storage. A validation study using whole-shell oysters was conducted to determine whether the presence of oyster shells influenced HHP inactivation of V. parahaemolyticus. No appreciable differences in inactivation between shucked oyster meat and whole-shell oysters were observed. HPP at 300 MPa for 2 min at 21 °C, followed by 5-day ice storage or 7-day frozen storage, and HPP at 250 MPa for 2 min at 21 °C, followed by 10-day ice or 7-day frozen storage, completely inactivated V. parahaemolyticus in whole-shell oysters (>7 log reductions). The combination of HHP at a relatively low pressure (e.g., 250 MPa) followed by short-term frozen storage (7 days) could potentially be applied by the shellfish industry as a post-harvest process to eliminate V. parahaemolyticus in oysters. Copyright © 2013 Elsevier B.V. All rights reserved.

From middens to modern estuaries, oyster shells sequester source-specific nitrogen

NASA Astrophysics Data System (ADS)

Darrow, Elizabeth S.; Carmichael, Ruth H.; Andrus, C. Fred T.; Jackson, H. Edwin

2017-04-01

Oysters (Crassostrea virginica) were an important food resource for native peoples of the northern Gulf of Mexico, who deposited waste shells in middens. Nitrogen (N) stable isotopes (δ15N) in bivalve shells have been used as modern proxies for estuarine N sources because they approximate δ15N in suspended particulate matter. We tested the use of midden shell δ15N as a proxy for ancient estuarine N sources. We hypothesized that isotopic signatures in ancient shells from coastal Mississippi would differ from modern shells due to increased anthropogenic N sources, such as wastewater, through time. We decalcified shells using an acidification technique previously developed for modern bivalves, but modified to determine δ15N, δ13C, %N, and % organic C of these low-N, high-C specimens. The modified method resulted in the greatest percentage of usable data from midden shells. Our results showed that oyster shell δ15N did not significantly differ between ancient (500-2100 years old) and modern oysters from the same locations where the sites had undergone relatively little land-use change. δ15N values in modern shells, however, were positively correlated with water column nitrate concentrations associated with urbanization. When N content and total shell mass were combined, we estimated that middens sequestered 410-39,000 kg of relic N, buried at a rate of up to 5 kg N m-2 yr-1. This study provides a relatively simple technique to assess baseline conditions in ecosystems over long time scales by demonstrating that midden shells can be an indicator of pre-historic N source to estuaries and are a potentially significant but previously uncharacterized estuarine N sink.

Extreme ocean acidification reduces the susceptibility of eastern oyster shells to a polydorid parasite.

PubMed

Clements, J C; Bourque, D; McLaughlin, J; Stephenson, M; Comeau, L A

2017-11-01

Ocean acidification poses a threat to marine organisms. While the physiological and behavioural effects of ocean acidification have received much attention, the effects of acidification on the susceptibility of farmed shellfish to parasitic infections are poorly understood. Here we describe the effects of moderate (pH 7.5) and extreme (pH 7.0) ocean acidification on the susceptibility of Crassostrea virginica shells to infection by a parasitic polydorid, Polydora websteri. Under laboratory conditions, shells were exposed to three pH treatments (7.0, 7.5 and 8.0) for 3- and 5-week periods. Treated shells were subsequently transferred to an oyster aquaculture site (which had recently reported an outbreak of P. websteri) for 50 days to test for effects of pH and exposure time on P. websteri recruitment to oyster shells. Results indicated that pH and exposure time did not affect the length, width or weight of the shells. Interestingly, P. websteri counts were significantly lower under extreme (pH 7.0; ~50% reduction), but not moderate (pH 7.5; ~20% reduction) acidification levels; exposure time had no effect. This study suggests that extreme levels - but not current and projected near-future levels - of acidification (∆pH ~1 unit) can reduce the susceptibility of eastern oyster shells to P. websteri infections. © 2017 John Wiley & Sons Ltd.

The Mendelian inheritance of rare flesh and shell colour variants in the black-lipped pearl oyster (Pinctada margaritifera).

PubMed

Ky, Chin-Long; Nakasai, Seiji; Pommier, Steve; Sham Koua, Manaarii; Devaux, Dominique

2016-10-01

Pinctada margaritifera is French Polynesia's most economically important aquaculture species. This pearl oyster has the specific ability to produce cultured pearls with a very wide range of colours, depending on the colour phenotypes of donor oysters used. Its aquaculture is still based on natural spat collection from wild stocks. We investigated three rare colour variants of P. margaritifera - orange flesh, and red and white shell colour phenotypes - in comparison with the wild-type black flesh and shell commonly found in this species. The study aimed to assess the geographic distribution and genetic basis of these colour variants. Colour frequencies were evaluated during transfer and graft processes of pearl oyster seed captured at collector stations. Among the collection locations studied, Mangareva Island showed the highest rate of the orange flesh phenotype, whereas Takaroa and Takume atolls had relatively high rates of red and white shell phenotypes respectively. Broodstocks were made of these rare colour variants, and crosses were performed to produce first- and second-generation progenies to investigate segregation. The results were consistent with Mendelian ratios and suggest a distinct model with no co-dominance: (i) a two-allele model for flesh trait, whereby the orange allele is recessive to the black fleshed type, and (ii) a three-allele model for shell trait, whereby the black wild-type allele is dominant to the red coloration, which is dominant to the white shell. Furthermore, the proposed model provides the basis for producing selected donor pearl oyster lines through hatchery propagation. © 2016 Stichting International Foundation for Animal Genetics.

Abundance of non-native crabs in intertidal habitats of New England with natural and artificial structure

PubMed Central

Lovely, Christina M.; Judge, Michael L.

2015-01-01

Marine habitats containing complex physical structure (e.g., crevices) can provide shelter from predation for benthic invertebrates. To examine effects of natural and artificial structure on the abundance of intertidal juvenile crabs, 2 experiments were conducted in Kingston Bay, Massachusetts, USA, from July to September, 2012. In the first experiment, structure was manipulated in a two-factor design that was placed in the high intertidal for 3 one-week periods to test for both substrate type (sand vs. rock) and the presence or absence of artificial structure (mesh grow-out bags used in aquaculture, ∼0.5 m2 with 62 mm2 mesh openings). The Asian shore crab, Hemigrapsus sanguineus, and small individuals of the green crab, Carcinus maenas, were observed only in the treatments of rocks and mesh bag plus rocks. Most green crabs were small (<6 mm in carapace width) whereas H. sanguineus occurred in a wide range of sizes. In the second experiment, 3 levels of oyster-shell treatments were established using grow-out bags placed on a muddy sand substrate in the low intertidal zone: mesh grow-out bags without shells, grow-out bags with oyster shells, and grow-out bags containing live oysters. Replicate bags were deployed weekly for 7 weeks in a randomized complete block design. All crabs collected in the bags were juvenile C. maenas (1–15 mm carapace width), and numbers of crabs differed 6-fold among treatments, with most crabs present in bags with live oysters (29.5 ± 10.6 m−2 [mean ± S.D.]) and fewest in bags without shells (4.9 ± 3.7 m−2). Both C. maenas and H. sanguineus occurred in habitats with natural structure (cobble rocks). The attraction of juvenile C. maenas to artificial structure consisting of plastic mesh bags containing both oyster shells and living oysters could potentially impact oyster aquaculture operations. PMID:26401456

Abundance of non-native crabs in intertidal habitats of New England with natural and artificial structure.

PubMed

Lovely, Christina M; O'Connor, Nancy J; Judge, Michael L

2015-01-01

Marine habitats containing complex physical structure (e.g., crevices) can provide shelter from predation for benthic invertebrates. To examine effects of natural and artificial structure on the abundance of intertidal juvenile crabs, 2 experiments were conducted in Kingston Bay, Massachusetts, USA, from July to September, 2012. In the first experiment, structure was manipulated in a two-factor design that was placed in the high intertidal for 3 one-week periods to test for both substrate type (sand vs. rock) and the presence or absence of artificial structure (mesh grow-out bags used in aquaculture, ∼0.5 m(2) with 62 mm(2) mesh openings). The Asian shore crab, Hemigrapsus sanguineus, and small individuals of the green crab, Carcinus maenas, were observed only in the treatments of rocks and mesh bag plus rocks. Most green crabs were small (<6 mm in carapace width) whereas H. sanguineus occurred in a wide range of sizes. In the second experiment, 3 levels of oyster-shell treatments were established using grow-out bags placed on a muddy sand substrate in the low intertidal zone: mesh grow-out bags without shells, grow-out bags with oyster shells, and grow-out bags containing live oysters. Replicate bags were deployed weekly for 7 weeks in a randomized complete block design. All crabs collected in the bags were juvenile C. maenas (1-15 mm carapace width), and numbers of crabs differed 6-fold among treatments, with most crabs present in bags with live oysters (29.5 ± 10.6 m(-2) [mean ± S.D.]) and fewest in bags without shells (4.9 ± 3.7 m(-2)). Both C. maenas and H. sanguineus occurred in habitats with natural structure (cobble rocks). The attraction of juvenile C. maenas to artificial structure consisting of plastic mesh bags containing both oyster shells and living oysters could potentially impact oyster aquaculture operations.

Oxygen Isotope Records in Modern Oyster Shells from Chi Ku, Tainan and Their Implication of Seasonality

NASA Astrophysics Data System (ADS)

Chen, Y. C.; Mii, H. S.; Li, K. T.

2015-12-01

To exam whether oxygen isotope records of Crassostrea gigasoysters can be used as proxies of environment, 133 cultivated oysters and 21 water samples were collected from Chi Ku area, Tainan City, southern Taiwan in December of 2012, and from March, 2013 to July, 2014. Instrumental air and water temperatures and precipitation records were obtained from a nearest Central Weather Bureau (CWB) station roughly 16 km north of Chi Ku. The oxygen and carbon isotope values of the ligamental area of the modern oyster shells are from -6.92‰ to -0.08‰ (-3.05 ± 1.17‰, N = 2280; 1σ; VPDB) and from -5.57‰ to 0.63‰ (-1.88 ± 0.81‰), respectively. Oxygen isotope values of the water samples are mainly between -0.28‰ and 0.74‰ (0.18 ± 0.29‰, N = 20; 1σ; VSMOW). However, water oxygen isotope value of -2.75‰ was observed for the water sample collected immediately after a typhoon heavy rainfall. Seasonal temperature fluctuation pattern of estimated oxygen isotope temperatures from modern shells is similar to that of CWB instrumental records. However, the oxygen isotope temperatures are respectively about 3 °C and 10°C higher than those of instrumental records for winter and summer. Higher estimated oxygen isotope temperatures are most likely caused by underestimated fraction of freshwater. We analyzed 5 archaeological oyster shells of Siraya culture (500~250B.P.) collected from Wu Chien Tuso North (WCTN) archaeological site of Tainan branch of Southern Taiwan Science Park to infer the harvest season of mollusks. Oxygen isotope values of the ligamental area of the archaeological oyster shells are between -5.98‰ and -1.26‰ (-3.34 ± 1.37‰, N = 60; 1σ), and carbon isotope values are between -3.21‰ and 0.60‰ (-2.04‰ ± 0.55‰). The oxygen isotope records of archaeological oyster shells also showed clear seasonality. Most of the oysters were collected in autumn and winter. Oxygen isotope values of archaeological oyster shells was 1‰ greater than that of present for summer whereas was 1.2‰ less than that of present for wintwr. Assuming the temperature of 500-300 B.P. in Tainan was similar to that of present, it may indicate that the precipitation was weaker in summer but heavier in winter in southern Taiwan 500-300 B.P.

Remediation of muddy tidal flat sediments using hot air-dried crushed oyster shells.

PubMed

Yamamoto, Tamiji; Kondo, Shunsuke; Kim, Kyung-Hoi; Asaoka, Satoshi; Yamamoto, Hironori; Tokuoka, Makoto; Hibino, Tadashi

2012-11-01

In order to prove that hot air-dried crushed oyster shells (HACOS) are effective in reducing hydrogen sulfide in muddy tidal flat sediments and increasing the biomass, field experiments were carried out. The concentration of hydrogen sulfide in the interstitial water, which was 16 mg SL(-1) before the application of HACOS, decreased sharply and maintained almost zero in the experimental sites (HACOS application sites) for one year, whereas it was remained at ca. 5 mg SL(-1) in the control sites. The number of macrobenthos individuals increased to 2-4.5 times higher than that in the control site. Using a simple numerical model, the effective periods for suppression of hydrogen sulfide were estimated to be 3.2-7.6 and 6.4-15.2 years for the experimental sites with 4 and 8 tons per 10 × 10 × 0.2m area, respectively. From these results, it is concluded that HACOS is an effective material to remediate muddy tidal flats. Copyright © 2012 Elsevier Ltd. All rights reserved.

Are oysters being bored to death? Influence of Cliona celata on Crassostrea virginica condition, growth and survival.

PubMed

Carroll, John M; O'Shaughnessy, Kathryn A; Diedrich, Grant A; Finelli, Christopher M

2015-11-17

The boring sponge Cliona celata is a nuisance species that can have deleterious effects on eastern oyster Crassostrea virginica growth, condition, and survival. Surprisingly, however, these effects have not been well documented and when examined, results have been equi-vocal. In this study, we provide a direct comparison of growth, condition, and survival of sponge-colonized and uncolonized oysters in southeast North Carolina in 2 separate experiments. In the first experiment, sponge-colonized oysters exhibited significantly slower growth rates, reduced condition, and lower survival relative to uncolonized oysters, although results may have been confounded by oyster source. In the second experiment, using smaller oysters from the same source population, growth rate was again significantly reduced in colonized oysters relative to uncolonized oysters, however neither condition nor survival differed. In field surveys of the same population, colonized individuals across a range of sizes demonstrated significantly reduced condition. Further, condition index was negatively correlated with sponge biomass, which was positively correlated with oyster size, suggesting that the impact of the sponge changes with ontogeny. By investigating clearance rates, tissue isotopic and nutrient content, as well as caloric value, this study provides further evidence that sponge presence causes the oysters to divert energy into costly shell maintenance and repair at the expense of shell and somatic growth. Thus, although variable, our results demonstrate negative impacts of sponge infestation on oyster demographics, particularly as oysters grow larger.

Populations of Pacific oysters Crassostrea gigas respond variably to elevated CO2 and predation by Morula marginalba.

PubMed

Wright, John M; Parker, Laura M; O'Connor, Wayne A; Williams, Mark; Kube, Peter; Ross, Pauline M

2014-06-01

Ocean acidification is anticipated to decrease calcification and increase dissolution of shelled molluscs. Molluscs with thinner and weaker shells may be more susceptible to predation, but not all studies have measured negative responses of molluscs to elevated pCO2. Recent studies measuring the response of molluscs have found greater variability at the population level than first expected. Here we investigate the impact of acidification on the predatory whelk Morula marginalba and genetically distinct subpopulations of the Pacific oyster Crassostrea gigas. Whelks and eight family lines of C. gigas were separately exposed to ambient (385 ppm) and elevated (1000 ppm) pCO2 for 6 weeks. Following this period, individuals of M. marginalba were transferred into tanks with oysters at ambient and elevated pCO2 for 17 days. The increase in shell height of the oysters was on average 63% less at elevated compared to ambient pCO2. There were differences in shell compression strength, thickness, and mass among family lines of C. gigas, with sometimes an interaction between pCO2 and family line. Against expectations, this study found increased shell strength in the prey and reduced shell strength in the predator at elevated compared to ambient pCO2. After 10 days, the whelks consumed significantly more oysters regardless of whether C. gigas had been exposed to ambient or elevated CO2, but this was not dependent on the family line and the effect was not significant after 17 days. Our study found an increase in predation after exposure of the predator to predicted near-future levels of estuarine pCO2. © 2014 Marine Biological Laboratory.

A microbial spoilage profile of half shell Pacific oysters (Crassostrea gigas) and Sydney rock oysters (Saccostrea glomerata).

PubMed

Madigan, Thomas L; Bott, Nathan J; Torok, Valeria A; Percy, Nigel J; Carragher, John F; de Barros Lopes, Miguel A; Kiermeier, Andreas

2014-04-01

This study aimed to assess bacterial spoilage of half shell Pacific and Sydney rock oysters during storage using microbial culture and 16S rRNA pyrosequencing. Odour and pH of oyster meats were also investigated. Estimation of microbiological counts by microbial culture highlighted growth of psychrotrophic bacteria. During storage, odour scores (a score describing deterioration of fresh odours where a score of 1 is fresh and 4 is completely spoiled) increased from 1.0 to 3.0 for Pacific oysters and from 1.3 to 3.4 for Sydney rock oysters. pH results obtained for both species fluctuated during storage (range 6.28-6.73) with an overall increase at end of storage. Pyrosequencing revealed that the majority of bacteria at Day 0 represented taxa from amongst the Proteobacteria, Tenericutes and Spirochaetes that have not been cultured and systematically described. During storage, Proteobacteria became abundant with Pseudoalteromonas and Vibrio found to be dominant in both oyster species at Day 7. Analysis of the pyrosequencing data showed significant differences in bacterial profiles between oyster species and storage time (both P = 0.001). As oysters spoiled, bacterial profiles between oyster species became more similar indicating a common spoilage profile. Data presented here provides detailed insight into the changing bacterial profile of shucked oysters during storage and has identified two genera, Pseudoalteromonas and Vibrio, as being important in spoilage of shucked oysters. Copyright © 2013 Elsevier Ltd. All rights reserved.

Automatic determination of 3D orientations of fossilized oyster shells from a densely packed Miocene shell bed

NASA Astrophysics Data System (ADS)

Puttonen, Ana; Harzhauser, Mathias; Puttonen, Eetu; Mandic, Oleg; Székely, Balázs; Molnár, Gábor; Pfeifer, Norbert

2018-02-01

Shell beds represent a useful source of information on various physical processes that cause the depositional condition. We present an automated method to calculate the 3D orientations of a large number of elongate and platy objects (fossilized oyster shells) on a sedimentary bedding plane, developed to support the interpretation of possible depositional patterns, imbrications, or impact of local faults. The study focusses on more than 1900 fossil oyster shells exposed in a densely packed Miocene shell bed. 3D data were acquired by terrestrial laser scanning on an area of 459 m2 with a resolution of 1 mm. Bivalve shells were manually defined as 3D-point clouds of a digital surface model and stored in an ArcGIS database. An individual shell coordinate system (ISCS) was virtually embedded into each shell and its orientation was determined relative to the coordinate system of the entire, tectonically tilted shell bed. Orientation is described by the rotation angles roll, pitch, and yaw in a Cartesian coordinate system. This method allows an efficient measurement and analysis of the orientation of thousands of specimens and is a major advantage compared to the traditional 2D approach, which measures only the azimuth (yaw) angles. The resulting data can variously be utilized for taphonomic analyses and the reconstruction of prevailing hydrodynamic regimes and depositional environments. For the first time, the influence of possible post-sedimentary vertical displacements can be quantified with high accuracy. Here, the effect of nearby fault lines—present in the reef—was tested on strongly tilted oyster shells, but it was found out that the fault lines did not have a statistically significant effect on the large tilt angles. Aside from the high reproducibility, a further advantage of the method is its non-destructive nature, which is especially suitable for geoparks and protected sites such as the studied shell bed.

Demography of the ecosystem engineer Crassostrea gigas, related to vertical reef accretion and reef persistence

NASA Astrophysics Data System (ADS)

Walles, Brenda; Mann, Roger; Ysebaert, Tom; Troost, Karin; Herman, Peter M. J.; Smaal, Aad C.

2015-03-01

Marine species characterized as structure building, autogenic ecosystem engineers are recognized worldwide as potential tools for coastal adaptation efforts in the face of sea level rise. Successful employment of ecosystem engineers in coastal protection largely depends on long-term persistence of their structure, which is in turn dependent on the population dynamics of the individual species. Oysters, such as the Pacific oyster (Crassostrea gigas), are recognized as ecosystem engineers with potential for use in coastal protection. Persistence of oyster reefs is strongly determined by recruitment and shell production (growth), processes facilitated by gregarious settlement on extant shell substrate. Although the Pacific oyster has been introduced world-wide, and has formed dense reefs in the receiving coastal waters, the population biology of live oysters and the quantitative mechanisms maintaining these reefs has rarely been studied, hence the aim of the present work. This study had two objectives: (1) to describe the demographics of extant C. gigas reefs, and (2) to estimate vertical reef accretion rates and carbonate production in these oyster reefs. Three long-living oyster reefs (>30 years old), which have not been exploited since their first occurrence, were examined in the Oosterschelde estuary in the Netherlands. A positive reef accretion rate (7.0-16.9 mm year-1 shell material) was observed, consistent with self-maintenance and persistent structure. We provide a framework to predict reef accretion and population persistence under varying recruitment, growth and mortality scenarios.

Long-term experimental in situ farming of Crambe crambe (Demospongiae: Poecilosclerida).

PubMed

Padiglia, Andrea; Ledda, Fabio D; Padedda, Bachisio M; Pronzato, Roberto; Manconi, Renata

2018-01-01

The marine sponge Crambe crambe was chosen as an experimental model of sustainable shallow-water mariculture in the Sardinian Sea (Western Mediterranean) to provide biomass with high potential in applied research. Explants were cultured in four long-term experiments (19 and 31 months at ca. 2.5 m depth), to determine the suitability of new culture techniques by testing substrata and seeding time (season), and monitoring survival and growth. Explants were excised and grown in an experimental plant close to the wild donor sponge population. Percentage growth rate (GR%) was measured in terms of surface cover area, and explant survival was monitored in situ by means of a digital photo camera. Explant survival was high throughout the trial, ranging from 78.57% to 92.85% on travertine tiles and from 50% to 71.42% on oyster shells. A few instances of sponge regression were observed. Explant cover area correlated positively with season on two substrata, i.e., tiles and shells. The surface cover area and GR% of explants were measured in the starting phase and monitored up to the end of the trial. High GR% values were observed both on tiles (>21%) and on oyster shells (>15%). The data on the behaviour and life-style of cultured fragments, together with an increase >2,400% in cover area, demonstrate that in situ aquaculture is a viable and sustainable method for the shallow-water biomass supply of Crambe crambe .

Long-term experimental in situ farming of Crambe crambe (Demospongiae: Poecilosclerida)

PubMed Central

Padiglia, Andrea; Ledda, Fabio D.; Padedda, Bachisio M.; Pronzato, Roberto

2018-01-01

Background The marine sponge Crambe crambe was chosen as an experimental model of sustainable shallow-water mariculture in the Sardinian Sea (Western Mediterranean) to provide biomass with high potential in applied research. Methods Explants were cultured in four long-term experiments (19 and 31 months at ca. 2.5 m depth), to determine the suitability of new culture techniques by testing substrata and seeding time (season), and monitoring survival and growth. Explants were excised and grown in an experimental plant close to the wild donor sponge population. Percentage growth rate (GR%) was measured in terms of surface cover area, and explant survival was monitored in situ by means of a digital photo camera. Results Explant survival was high throughout the trial, ranging from 78.57% to 92.85% on travertine tiles and from 50% to 71.42% on oyster shells. A few instances of sponge regression were observed. Explant cover area correlated positively with season on two substrata, i.e., tiles and shells. The surface cover area and GR% of explants were measured in the starting phase and monitored up to the end of the trial. High GR% values were observed both on tiles (>21%) and on oyster shells (>15%). Discussion The data on the behaviour and life-style of cultured fragments, together with an increase >2,400% in cover area, demonstrate that in situ aquaculture is a viable and sustainable method for the shallow-water biomass supply of Crambe crambe. PMID:29915695

Shell Games. VORTEX: Virginia's Oyster Reef Teaching EXperience.

ERIC Educational Resources Information Center

Harding, Juliana M.; Mann, Roger; Clark, Vicki P.

This document introduces Virginia's Oyster Reef Teaching EXperience (VORTEX), which is an interdisciplinary program focusing on the importance of oyster reef communities in the Chesapeake Bay ecosystem. The VORTEX program uses field and laboratory experiences supported by multimedia instruction. This document presents an overview on the biology of…

Refining the tethering of American oysters (Crassostrea virginica) to measure the effects of two environmental stressors.

PubMed

Poirier, Luke A; Gilbert, Shane T C; St-Hilaire, Sophie; Davidson, Jeff; Cox, Ruth; Quijón, Pedro A

2018-02-01

Tethering assays, or the physical restraint of test organisms, has been used in the past to measure selected organisms' response to stressors while removing the observer from the experimental setting. Although informative for monitoring and hypothesis testing, these assays often used microfilaments that have been found to be too invasive or prone to biases given their effects on test organisms' behavior. Here, we describe a new variation of tethering using American oysters (Crassostrea virginica) and illustrate its use in the study of their mortality rates as a result of two stressors: siltation and predation by a non-indigenous species. Our protocol identified a resistant (non-toxic) glue that could be used to attach oysters to stone slabs, thus partially mimicking the natural cementation of the shell to natural substrates. This variation of tethering was harmless and maintained oysters' body position and natural ability to filter feed. Using tethered oysters in separate two-week field cage experiments, we also show how siltation and predation by a non-indigenous species (the European green crab, Carcinus maenas), caused a gradual, easily measurable increase in oyster mortality rates. We argue that this variation of tethering is a cost-effective and advantageous way to monitor or test the effects of these and other stressors on oysters and similar species. Copyright © 2017 Elsevier Ltd. All rights reserved.

Rapid age determination of oysters using LA-ICP-MS line scans of shell Mg/Ca ratios

NASA Astrophysics Data System (ADS)

Gillikin, D. P.; Durham, S. R.; Goodwin, D. H.

2016-02-01

Magnesium to calcium (Mg/Ca) ratios exhibit a strong temperature dependence in foraminifera and corals, but not in bivalve mollusks. Various studies have reported Mg/Ca-temperature relationships with R2 values ranging from 0.3 to 0.8 and significantly different relationships for bivalves growing at different salinities. However, this poor temperature correlation does not render Mg/Ca data useless. A weak temperature dependence would allow time (seasons and years) to be determined along the growth axis of shells. This would provide information about age, growth rate and also allow other proxies to be aligned with time. Typically, oxygen isotopes (δ18O) are used to age shells without clear periodic growth lines, which is time consuming and expensive. Line scans using laser ablation systems can cover several centimeters of shell in a few minutes. We test this method on the resilifer of two oyster species (Crassostrea gigas and C. virginica) using a 193 nm Laser-Ablation-ICP-MS. Living oysters were collected from San Francisco Bay, North Carolina, South Carolina, and the Gulf of Mexico; fossil shells (Pleistocene) were also collected in South Carolina. Shells were sampled for δ18O values and Mg/Ca ratios. We use annual cycles in δ18O values to confidently determine age, then apply the Mg/Ca technique. Shells of both species exhibit annual cyclicity in Mg/Ca ratios using spot and line scan laser sampling, which matche the seasonal cyclicity determined using δ18O values. Results show a good correlation between ages determined using the different methods. We conclude that LA-ICP-MS line scans offer a rapid and inexpensive technique for determining age, growth rate, and timing of shell growth in oyster reslifers.

Effects of pCO2 stress on gene expression and biomineralization of developing larvae of the Pacific oyster Crassostrea gigas.

NASA Astrophysics Data System (ADS)

De Wit, P.; Durland, E.; Ventura, A.; Waldbusser, G. G.; Langdon, C. J.

2016-02-01

The high larval mortalities in oyster hatcheries on the US west coast have gotten large media coverage in the past few years, and the link has been made between occurrences of coastal upwelling of deep water with low carbonate ion availability and abnormal shell formation in hatchery larvae. However, the mechanism by which this happens is still not well understood. In the Pacific oyster, numerous genes are known to be involved in biomineralization but little is known about the timing of gene expression in relation to formation of the initial larval shell. In order to study this process, we scanned all expressed larval genes using an RNA-Seq approach over the time interval of initial shell formation in both control and pCO2-stressed conditions. Scanning the expression data for patterns matching observed shell formation rates (see Fig 1), we identified a number of genes potentially involved in shell nucleation, most of which are involved in transmembrane transport or protein binding. In addition, we also identified a set of co-expressed genes likely to be involved in the cellular early shell formation machinery. This study is the first to investigate the genes involved in the initial larval shell formation in the Pacific oyster. We discover a set of 149 genes that are likely involved in this process from a combination of CPL microscopy and RNA-Seq, most of which are involved in ion transport or protein binding. These are the two main processes involved in shell formation. Additionally, we observe an increase in the relative content of wax esters in control larvae after 18 hours, something not seen in the treatment larvae. The reason for this is not quite clear at this point, but it could be speculated that stressed larvae develop slower, thus consuming lipids at a slower rate. Thus, follow-up experiments that study the long-term effects of changed carbonate chemistry on the genetics of Pacific oysters will be critical for future aquaculture efforts.

High pressure treatment changes spoilage characteristics and shelf life of Pacific oysters ( Crassostrea gigas) during refrigerated storage

NASA Astrophysics Data System (ADS)

Cao, Rong; Zhao, Ling; Liu, Qi

2017-04-01

The effects of high pressure (HP) treatment on spoilage characteristic and shelf life extension of Pacific oysters ( Crassostrea gigas) during refrigerated storage were studied. Results showed that HP treatment of 275 MPa for 3 min or 300 MPa for 2 min could achieve 100% full release of oyster adductor muscle, pressures higher than 350 MPa caused excessive release as the shells of oysters were broken, thus use of higher pressures should be cautious in oyster processing industry because of its adverse impact on the appearance of shells. HP treatment (300 MPa, 2 min) was proper for the shucking of Pacific oyster ( Crassostrea gigas) in China. This treatment caused no organoleptic disadvantage. Moreover, HP treatment resulted in obvious differences in biochemical spoilage indicators (pH, TVB-N and TBARS) changes and volatile compounds profile determined by electronic nose during storage. HP treatment (300 MPa, 2 min) also led to a reduction of aerobic bacterial count (APC) by 1.27 log cycles. Furthermore, the APC values of oysters treated by HP were always lower than those of the control samples during storage. Based on the organoleptic, biochemical and microbiological indicators, shelf life of 6-8 d for control and 12 d for HP-treated oysters could be expected. HP treatment showed great potential in oyster processing and preservation.

Quantifying early 17th century changes in Chesapeake Bay estuarine carbon dynamics from James River, VA oyster geochemistry

NASA Astrophysics Data System (ADS)

Grimm, B. L.; Spero, H. J.; Harding, J. M.

2012-12-01

The first successful European colonization of North America occurred in 1607 following the arrival of English settlers at Jamestown, Virginia. Within a few decades, land use changes and clear-cutting farming practices dramatically altered the terrestrial landscape and removed the overlying canopy and stabilizing root network of the previously-dominant hardwood forests. The Eastern oyster, Crassostrea virginica, has inhabited the Chesapeake Bay since the end of the last deglaciation. During the start of the Jamestown Colony, an extensive drought (1606-1612) shifted James River salinity zones upriver, expanding the available oyster habitat to the vicinity of Jamestown. This allowed the colonists to collect and eat oysters from areas near the colony down to the river's entry into the bay, and later discard the shells in wells and trash pits that have recently been excavated. The oysters' calcium carbonate shells discovered in these deposits act as multi-year stationary recorders preserving the local environmental chemistry throughout their life until collection. Here we present δ13C, δ18O, and radiocarbon data from historical oyster shell hinge transects that encompass the time period between ~1609 and the early 1700s. Samples include shells from the 1609 Jamestown freshwater well and five additional sites, as well as modern shells collected in 2006. Because shell δ13C and radiocarbon (14C) reflect James River δ13CDIC, it is possible to document carbon source changes during this period of land use change. Our preliminary data suggest a decrease in ambient δ13CDIC of approximately 2‰ between just prior to 1609 conditions and the modern estuary. This is most likely due to an increase in isotopically light organic carbon loading into the river as water moves more rapidly through the terrestrial system. Radiocarbon reservoir ages will also be presented to better constrain carbon flow through the system during this period of disturbance. δ18O measurements from the same shells provide seasonal signals and also show an offset from modern that is consistent with drought conditions during the early 17th century. These high fidelity records allow for a direct, high-resolution comparison of the residence time of carbon in the environment immediately prior to European colonization and during the first century of land use change in mid-Atlantic North America.

Climatic fluctuations and seasonality during the Late Jurassic (Oxfordian-Early Kimmeridgian) inferred from δ18O of Paris Basin oyster shells

NASA Astrophysics Data System (ADS)

Brigaud, Benjamin; Pucéat, Emmanuelle; Pellenard, Pierre; Vincent, Benoît; Joachimski, Michael M.

2008-08-01

Oxygen isotope data from biostratigraphically well-dated oyster shells from the Late Jurassic of the eastern Paris Basin are used to reconstruct the thermal evolution of western Tethyan surface waters during the Early Oxfordian-Early Kimmeridgian interval. Seventy eight oyster shells were carefully screened for potential diagenetic alteration using cathodoluminescence microscopy. Isotope analyses were performed on non-luminescent parts of shells (n = 264). Intra-shell δ18O variability was estimated by microsampling along a transect perpendicular to the growth lines of the largest oyster shell. The sinusoidal distribution of the δ18O values along this transect and the dependence of the amplitude of variations with bathymetry suggest that intra-shell variability reflects seasonal variations of temperature and/or salinity. Average amplitudes of about 5 °C in shallow water environments and of about 2-3 °C in deeper offshore environments are calculated. These amplitudes reflect minimum seasonal temperature variation. Our new data allow to constrain existing paleotemperature trends established from fish tooth and belemnite δ18O data and are in better agreement with paleontological data. More specifically, a warming trend of about 3 °C is reconstructed for oceanic surface waters during the Early to Middle Oxfordian transition, with maximum temperatures reaching 24 °C in the transversarium Zone (late Middle Oxfordian). From the transversarium Zone to the bimmamatum Zone, a cooling of about 7 °C is indicated, whereas from the bimmamatum Zone, temperatures increased again by about 7 °C to reach 24 °C in average during the cymodoce Zone (Early Kimmeridgian).

On the Half Shell: An Introduction to Oysters and Their Unique Structures and Function

ERIC Educational Resources Information Center

Frederick, J. Adam; Haines, Sarah; Romano, Christina; Takacs, Jacqueline

2017-01-01

The eastern oyster, "Crassostrea virginica," is an ecologically and economically important species in Chesapeake Bay. Oysters are ecologically unique in the Chesapeake Bay because they build a structure known as a bar or reef by attaching to one another over a 45 long period of time. They have been coined the "Ecological Engineers…

The sense of hearing in the Pacific oyster, Magallana gigas

PubMed Central

Charifi, Mohcine; Sow, Mohamedou; Ciret, Pierre; Benomar, Soumaya

2017-01-01

There is an increasing concern that anthropogenic noise could have a significant impact on the marine environment, but there is still insufficient data for most invertebrates. What do they perceive? We investigated this question in oysters Magallana gigas (Crassostrea gigas) using pure tone exposures, accelerometer fixed on the oyster shell and hydrophone in the water column. Groups of 16 oysters were exposed to quantifiable waterborne sinusoidal sounds in the range of 10 Hz to 20 kHz at various acoustic energies. The experiment was conducted in running seawater using an experimental flume equipped with suspended loudspeakers. The sensitivity of the oysters was measured by recording their valve movements by high-frequency noninvasive valvometry. The tests were 3 min tone exposures including a 70 sec fade-in period. Three endpoints were analysed: the ratio of responding individuals in the group, the resulting changes of valve opening amplitude and the response latency. At high enough acoustic energy, oysters transiently closed their valves in response to frequencies in the range of 10 to <1000 Hz, with maximum sensitivity from 10 to 200 Hz. The minimum acoustic energy required to elicit a response was 0.02 m∙s-2 at 122 dBrms re 1 μPa for frequencies ranging from 10 to 80 Hz. As a partial valve closure cannot be differentiated from a nociceptive response, it is very likely that oysters detect sounds at lower acoustic energy. The mechanism involved in sound detection and the ecological consequences are discussed. PMID:29069092

The sense of hearing in the Pacific oyster, Magallana gigas.

PubMed

Charifi, Mohcine; Sow, Mohamedou; Ciret, Pierre; Benomar, Soumaya; Massabuau, Jean-Charles

2017-01-01

There is an increasing concern that anthropogenic noise could have a significant impact on the marine environment, but there is still insufficient data for most invertebrates. What do they perceive? We investigated this question in oysters Magallana gigas (Crassostrea gigas) using pure tone exposures, accelerometer fixed on the oyster shell and hydrophone in the water column. Groups of 16 oysters were exposed to quantifiable waterborne sinusoidal sounds in the range of 10 Hz to 20 kHz at various acoustic energies. The experiment was conducted in running seawater using an experimental flume equipped with suspended loudspeakers. The sensitivity of the oysters was measured by recording their valve movements by high-frequency noninvasive valvometry. The tests were 3 min tone exposures including a 70 sec fade-in period. Three endpoints were analysed: the ratio of responding individuals in the group, the resulting changes of valve opening amplitude and the response latency. At high enough acoustic energy, oysters transiently closed their valves in response to frequencies in the range of 10 to <1000 Hz, with maximum sensitivity from 10 to 200 Hz. The minimum acoustic energy required to elicit a response was 0.02 m∙s-2 at 122 dBrms re 1 μPa for frequencies ranging from 10 to 80 Hz. As a partial valve closure cannot be differentiated from a nociceptive response, it is very likely that oysters detect sounds at lower acoustic energy. The mechanism involved in sound detection and the ecological consequences are discussed.

Deeply hidden inside introduced biogenic structures - Pacific oyster reefs reduce detrimental barnacle overgrowth on native blue mussels

NASA Astrophysics Data System (ADS)

Buschbaum, Christian; Cornelius, Annika; Goedknegt, M. Anouk

2016-11-01

In sedimentary coastal ecosystems shells of epibenthic organisms such as blue mussels (Mytilus edulis) provide the only major attachment surface for barnacle epibionts, which may cause detrimental effects on their mussel basibionts by e.g. reducing growth rate. In the European Wadden Sea, beds of native blue mussels have been invaded by Pacific oysters Crassostrea gigas, which transformed these beds into mixed reefs of oysters with mussels. In this study, we determined the spatial distribution of M. edulis and their barnacle epibionts (Semibalanus balanoides) within the reef matrix. Mean mussel density near the bottom was about twice as high compared to the mussel density near the top of an oyster reef, whereas barnacles on mussels showed a reversed pattern. Barnacle dry weight per mussel was on average 14 times higher near the top than at the bottom. This pattern was confirmed by experimentally placing clean M. edulis at the top and on the bottom of oyster reefs at two sites in the Wadden Sea (island of Texel, The Netherlands; island of Sylt, Germany). After an experimental period of five weeks (April and May 2015, the main settlement period of S. balanoides), the number of barnacles per mussel was at both sites significantly higher on mussels near the top compared to near the bottom. We conclude that the oyster reef matrix offers a refuge for M. edulis: inside reefs they are not only better protected against predators but also against detrimental barnacle overgrowth. This study shows that alien species can cause beneficial effects for native organisms and should not be generally considered as a risk for the recipient marine ecosystems.

Shellfish Face Uncertain Future in High CO2 World: Influence of Acidification on Oyster Larvae Calcification and Growth in Estuaries

PubMed Central

Miller, A. Whitman; Reynolds, Amanda C.; Sobrino, Cristina; Riedel, Gerhardt F.

2009-01-01

Background Human activities have increased atmospheric concentrations of carbon dioxide by 36% during the past 200 years. One third of all anthropogenic CO2 has been absorbed by the oceans, reducing pH by about 0.1 of a unit and significantly altering their carbonate chemistry. There is widespread concern that these changes are altering marine habitats severely, but little or no attention has been given to the biota of estuarine and coastal settings, ecosystems that are less pH buffered because of naturally reduced alkalinity. Methodology/Principal Findings To address CO2-induced changes to estuarine calcification, veliger larvae of two oyster species, the Eastern oyster (Crassostrea virginica), and the Suminoe oyster (Crassostrea ariakensis) were grown in estuarine water under four pCO2 regimes, 280, 380, 560 and 800 µatm, to simulate atmospheric conditions in the pre-industrial era, present, and projected future concentrations in 50 and 100 years respectively. CO2 manipulations were made using an automated negative feedback control system that allowed continuous and precise control over the pCO2 in experimental aquaria. Larval growth was measured using image analysis, and calcification was measured by chemical analysis of calcium in their shells. C. virginica experienced a 16% decrease in shell area and a 42% reduction in calcium content when pre-industrial and end of 21st century pCO2 treatments were compared. C. ariakensis showed no change to either growth or calcification. Both species demonstrated net calcification and growth, even when aragonite was undersaturated, a result that runs counter to previous expectations for invertebrate larvae that produce aragonite shells. Conclusions and Significance Our results suggest that temperate estuarine and coastal ecosystems are vulnerable to the expected changes in water chemistry due to elevated atmospheric CO2 and that biological responses to acidification, especially calcifying biota, will be species-specific and therefore much more variable and complex than reported previously. PMID:19478855

A developmental and energetic basis linking larval oyster shell formation to acidification sensitivity

NASA Astrophysics Data System (ADS)

Waldbusser, George G.; Brunner, Elizabeth L.; Haley, Brian A.; Hales, Burke; Langdon, Christopher J.; Prahl, Frederick G.

2013-05-01

Acidified waters are impacting commercial oyster production in the U.S. Pacific Northwest, and favorable carbonate chemistry conditions are predicted to become less frequent. Within 48 h of fertilization, unshelled Pacific oyster (Crassostrea gigas) larvae precipitate roughly 90% of their body weight as calcium carbonate. We measured stable carbon isotopes in larval shell and tissue and in algal food and seawater dissolved inorganic carbon in a longitudinal study of larval development and growth. Using these data and measured biochemical composition of larvae, we show that sensitivity of initial shell formation to ocean acidification results from diminished ability to isolate calcifying fluid from surrounding seawater, a limited energy budget and a strong kinetic demand for calcium carbonate precipitation. Our results highlight an important link between organism physiology and mineral kinetics in larval bivalves and suggest the consideration of mineral kinetics may improve understanding winners and losers in a high CO2 world.

Nutrient bioassimilation capacity of aquacultured oysters: quantification of an ecosystem service.

PubMed

Higgins, Colleen B; Stephenson, Kurt; Brown, Bonnie L

2011-01-01

Like many coastal zones and estuaries, the Chesapeake Bay has been severely degraded by cultural eutrophication. Rising implementation costs and difficulty achieving nutrient reduction goals associated with point and nonpoint sources suggests that approaches supplemental to source reductions may prove useful in the future. Enhanced oyster aquaculture has been suggested as one potential policy initiative to help rid the Bay waters of excess nutrients via harvest of bioassimilated nutrients. To assess this potential, total nitrogen (TN), total phosphorous (TP), and total carbon (TC) content were measured in oyster tissue and shell at two floating-raft cultivation sites in the Chesapeake Bay. Models were developed based on the common market measurement of total length (TL) for aquacultured oysters, which was strongly correlated to the TN (R2 = 0.76), TP (R2 = 0.78), and TC (R2 = 0.76) content per oyster tissue and shell. These models provide resource managers with a tool to quantify net nutrient removal. Based on model estimates, 10(6) harvest-sized oysters (76 mm TL) remove 132 kg TN, 19 kg TP, and 3823 kg TC. In terms of nutrients removed per unit area, oyster harvest is an effective means of nutrient removal compared with other nonpoint source reduction strategies. At a density of 286 oysters m(-2), assuming no mortality, harvest size nutrient removal rates can be as high as 378 kg TN ha(-1), 54 kg TP ha(-1), and 10,934 kg TC ha(-1) for 76-mm oysters. Removing 1 t N from the Bay would require harvesting 7.7 million 76-mm TL cultivated oysters.

Stabilization of As-, Pb-, and Cu-contaminated soil using calcined oyster shells and steel slag.

PubMed

Moon, Deok Hyun; Wazne, Mahmoud; Cheong, Kyung Hoon; Chang, Yoon-Young; Baek, Kitae; Ok, Yong Sik; Park, Jeong-Hun

2015-07-01

In this study, As-, Pb-, and Cu-contaminated soil was stabilized using calcined oyster shells (COS) and steel slag (SS). The As-contaminated soil was obtained from a timber mill site where chromate copper arsenate (CCA) was used as a preservative. On the other hand, Pb- and Cu-contaminated soil was obtained from a firing range. These two soils were thoroughly mixed to represent As-, Pb-, and Cu-contaminated soil. Calcined oyster shells were obtained by treating waste oyster shells at a high temperature using the calcination process. The effectiveness of stabilization was evaluated by 1-N HCl extraction for As and 0.1-N HCl extraction for Pb and Cu. The treatment results showed that As, Pb, and Cu leachability were significantly reduced upon the combination treatment of COS and SS. The sole treatment of SS (10 wt%) did not show effective stabilization. However, the combination treatment of COS and SS showed a significant reduction in As, Pb, and Cu leachability. The best stabilization results were obtained from the combination treatment of 15 wt% COS and 10 wt% SS. The SEM-EDX results suggested that the effective stabilization of As was most probably achieved by the formation of Ca-As and Fe-As precipitates. In the case of Pb and Cu, stabilization was most probably associated with the formation of pozzolanic reaction products such as CSHs and CAHs.

A preliminary study for identification of candidate AFLP markers under artificial selection for shell color in pearl oyster Pinctada fucata.

PubMed

Zou, Keshu; Zhang, Dianchang; Guo, Huayang; Zhu, Caiyan; Li, Min; Jiang, Shigui

2014-05-25

Pearl oyster Pinctada fucata is widely cultured to produce seawater pearl in South China, and the quality of pearl is significantly affected by its shell color. Thus the Pearl Oyster Selective Breeding Program (POSBP) was carried out for the shell color and growth traits. The black (B), gold (G), red (R) and white (W) shell strains with fast growth trait were achieved after five successive generation selection. In this study, AFLP technique was used to scan genome of four strains with different shell colors to identify the candidate markers under artificial selection. Eight AFLP primer combinations were screened and yielded 688 loci, 676 (98.26%) of which were polymorphic. In black, gold, red and white strains, the percentage of polymorphic loci was 90.41%, 87.79%, 93.60% and 93.31%, respectively, Nei's gene diversity was 0.3225, 0.2829, 0.3221 and 0.3292, Shannon's information index was 0.4801, 0.4271, 0.4825 and 0.4923, and the value of FST was 0.1805. These results suggested that the four different shell color strains had high genetic diversity and great genetic differentiation among strains, which had been subjected to the continuous selective pressures during the artificial selective breeding. Furthermore, six outlier loci were considered as the candidate markers under artificial selection for shell color. This study provides a molecular evidence for the inheritance of shell color of P. fucata. Copyright © 2014 Elsevier B.V. All rights reserved.

Impacts of biochar and oyster shells waste on the immobilization of arsenic in highly contaminated soils.

PubMed

Chen, Yongshan; Xu, Jinghua; Lv, Zhengyong; Xie, Ruijia; Huang, Liumei; Jiang, Jinping

2018-07-01

Soil contamination is a serious problem with deleterious impacts on global sustainability. Readily available, economic, and highly effective technologies are therefore urgently needed for the rehabilitation of contaminated sites. In this study, two readily available materials prepared from bio-wastes, namely biochar and oyster shell waste, were evaluated as soil amendments to immobilize arsenic in a highly As-contaminated soil (up to 15,000 mgAs/kg). Both biochar and oyster shell waste can effectively reduce arsenic leachability in acid soils. After application of the amendments (2-4% addition, w/w), the exchangeable arsenic fraction decreased from 105.8 to 54.0 mg/kg. The application of 2%biochar +2% oyster shell waste most effectively reduced As levels in the column leaching test by reducing the arsenic concentration in the porewater by 62.3% compared with the treatment without amendments. Biochar and oyster shell waste also reduced soluble As(III) from 374.9 ± 18.8 μg/L to 185.9 ± 16.8 μg/L and As(V) from 119.8 ± 13.0 μg/L to 56.4 ± 2.6 μg/L at a pH value of 4-5. The treatment using 4% (w/w) amendments did not result in sufficient As immobilization in highly contaminated soils; high soluble arsenic concentrations (upto193.0 μg/L)were found in the soil leachate, particularly in the form of As(III), indicating a significant potential to pollute shallow groundwater aquifers. This study provides valuable insights into the use of cost-effective and readily available materials for soil remediation and investigates the mechanisms underlying arsenic immobilization in acidic soils. Copyright © 2018 Elsevier Ltd. All rights reserved.

Sclerochronology of Holocene oyster shells (Crassostrea gigas) from the West Coast of Bohai Sea, China

NASA Astrophysics Data System (ADS)

Fan, C.; Koeniger, P.; Wang, H.; Frechen, M.

2009-04-01

Sclerochronology, the study of periodic increments in skeletal organisms, can decipher the life history and environmental records preserved in fossil shells. Although there have been a number of studies that apply isotopic analyses to shells in open ocean and fresh water, investigations for brackish environments are rare. One of the common inhabitants in estuaries is the Crassostrea oyster. Kirby et al. (1998) demonstrated a close correspondence between the ligamental increments of convex and concave bands and yearly ^18O cycles; Andrus and Crowe (2000) found a close correspondence between translucent growth bands on the cross-section of the hinge and yearly ^18O cycles. They conclude that the morphological features on hinge and growth bands on the cross-section are formed annually and can be used to determine accurately age and growth rate in this species. However, Surge et al. (2001) could not find that these morphologic features have seasonal significance in the C. virginica shells. Therefore, these concave ridges are not reliable independent proxies of seasonality. These studies were carried out with C. virginica shells; none was studied with nature C. gigas, which was widely distributed along the Pacific coastal area. C. gigas has been introduced from its native home to all over the world, ranging from North America to Australia and Europe; it has become an important commercial harvest in many of these places. Buried Holocene oyster shells of C. gigas were sampled from a huge buried oyster reef on the West of Bohai Sea, China. One of these shells was selected for high resolution micro-sampling and stable isotope analyses testing the assumption that C. gigas ligamental increments are annual in nature. We analyzed 236 consecutive samples from the shell to show that morphologic features both on hinge and cross-section are annual by comparing them to the ^18O profiles. We tested the assumption that the morphologic features of C.gigas are delineated by convex tops and concave bottoms on hinge and corresponding translucent growth bands on cross-section. The shell has 13.5 ligamental increments, based on 13.5 convex bands and 13 concave bottoms on hinge. Convex tops correspond to ^18O minima (summers), whereas concave bottoms correspond to ^18O maxima, which were formed during the low temperature of winter in the study area. We demonstrate that the ligamental increments of convex tops, concave bottoms and translucent growth bands in the studied C. gigas shell are suitable indicators of annual growth increments. The life spans, growth rates, and the timing of death can be determined from the ligament increments and isotope profiles of buried oyster shells.

D Central Line Extraction of Fossil Oyster Shells

NASA Astrophysics Data System (ADS)

Djuricic, A.; Puttonen, E.; Harzhauser, M.; Mandic, O.; Székely, B.; Pfeifer, N.

2016-06-01

Photogrammetry provides a powerful tool to digitally document protected, inaccessible, and rare fossils. This saves manpower in relation to current documentation practice and makes the fragile specimens more available for paleontological analysis and public education. In this study, high resolution orthophoto (0.5 mm) and digital surface models (1 mm) are used to define fossil boundaries that are then used as an input to automatically extract fossil length information via central lines. In general, central lines are widely used in geosciences as they ease observation, monitoring and evaluation of object dimensions. Here, the 3D central lines are used in a novel paleontological context to study fossilized oyster shells with photogrammetric and LiDAR-obtained 3D point cloud data. 3D central lines of 1121 Crassostrea gryphoides oysters of various shapes and sizes were computed in the study. Central line calculation included: i) Delaunay triangulation between the fossil shell boundary points and formation of the Voronoi diagram; ii) extraction of Voronoi vertices and construction of a connected graph tree from them; iii) reduction of the graph to the longest possible central line via Dijkstra's algorithm; iv) extension of longest central line to the shell boundary and smoothing by an adjustment of cubic spline curve; and v) integration of the central line into the corresponding 3D point cloud. The resulting longest path estimate for the 3D central line is a size parameter that can be applied in oyster shell age determination both in paleontological and biological applications. Our investigation evaluates ability and performance of the central line method to measure shell sizes accurately by comparing automatically extracted central lines with manually collected reference data used in paleontological analysis. Our results show that the automatically obtained central line length overestimated the manually collected reference by 1.5% in the test set, which is deemed sufficient for the selected paleontological application, namely shell age determination.

Growth history of cultured pearl oysters based on stable oxygen isotope analysis

NASA Astrophysics Data System (ADS)

Nakashima, R.; Furuta, N.; Suzuki, A.; Kawahata, H.; Shikazono, N.

2007-12-01

We investigated the oxygen isotopic ratio in shells of the pearl oyster Pinctada martensii cultivated in embayments in Mie Prefecture, central Japan, to evaluate the biomineralization of shell structures of the species and its pearls in response to environmental change. Microsamples for oxygen isotope analysis were collected from the surfaces of shells (outer, middle, and inner shell layers) and pearls. Water temperature variations were estimated from the oxygen isotope values of the carbonate. Oxygen isotope profiles of the prismatic calcite of the outer shell layer reflected seasonal variations of water temperature, whereas those of nacreous aragonites of the middle and inner shell layers and pearls recorded temperatures from April to November, June to September, and July to September, respectively. Lower temperatures in autumn and winter might slow the growth of nacreous aragonites. The oxygen isotope values are controlled by both variations of water temperature and shell structures; the prismatic calcite of this species is useful for reconstructing seasonal changes of calcification temperature.

In situ distribution and characterization of the organic content of the oyster shell Crassostrea gigas (Mollusca, Bivalvia).

PubMed

Dauphin, Yannicke; Ball, Alexander D; Castillo-Michel, Hiram; Chevallard, Corinne; Cuif, Jean-Pierre; Farre, Bastien; Pouvreau, Stéphane; Salomé, Murielle

2013-01-01

Cultivation of commercial oysters is now facing the possible influence of global change in sea water composition, commonly referred to as "ocean acidification". In order to test the potential consequence of the predicted environmental changes, a cultivation experiment was carried out. The left and right valves of the oyster shell Crassostrea gigas differ in their structure; moreover, lenses of non compact layers are irregular. The shell layers of juvenile C. gigas are studied using a variety of highly spatially resolved techniques to establish their composition and structure. Our results confirm the presence of three different calcitic structural types. The role of the lenses of chalky layers is not yet deciplered. Despite a common mineralogy, the elemental composition of the layers differs. The sulphur aminoacids and sulphated polysaccharide contents of the intracrystalline and intercrystalline matrices differ, as well as those of the structural types. The possible different sensitivity of these structures to environmental changes is still unknown. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effects of an artificial oyster shell reef on macrobenthic communities in Rongcheng Bay, East China

NASA Astrophysics Data System (ADS)

Xu, Qinzeng; Zhang, Libin; Zhang, Tao; Zhou, Yi; Xia, Sudong; Liu, Hui; Yang, Hongsheng

2014-01-01

An artificial oyster shell reef was deployed in Rongcheng Bay, East China. However, the effects of this reef on the surrounding macrobenthic communities were unknown. We compared sedimentary factors, macrobenthic biomass, abundance, and community composition and ecological indicators between the reef and non-reef areas over a one year period. The mean values for chlorophyll a (Chl a), total organic matter (TOM), total organic carbon (TOC), and total nitrogen (TN) content in surface sediments in the reef area were slightly higher than those in the non-reef area. The Chl a levels differed significantly between the two areas, but the TOM, TOC, and TN were not significantly different. The abundance of crustaceans was significantly different between the two areas, but the abundance and biomass of polychaetes, echinoderms, mollusk did not differ significantly. The permutational multivariate analysis of variance (PERMANOVA) revealed that the macrobenthic community differed significantly through time and analysis of similarity multivariate analyses (ANOSIM) revealed that the macrobenthic community differed significantly in some months. The ecological indicators revealed that the environmental quality of the reef area was slightly better than that of the non-reef area. Overall, our results suggest that the artificial oyster shell reef may change the macrobenthic community and the quality of the environment. Despite the lack of an effect in the short term, long-term monitoring is still needed to evaluate the effects of artificial oyster shell reefs on macrobenthic communities.

Bivalve-specific gene expansion in the pearl oyster genome: implications of adaptation to a sessile lifestyle.

PubMed

Takeuchi, Takeshi; Koyanagi, Ryo; Gyoja, Fuki; Kanda, Miyuki; Hisata, Kanako; Fujie, Manabu; Goto, Hiroki; Yamasaki, Shinichi; Nagai, Kiyohito; Morino, Yoshiaki; Miyamoto, Hiroshi; Endo, Kazuyoshi; Endo, Hirotoshi; Nagasawa, Hiromichi; Kinoshita, Shigeharu; Asakawa, Shuichi; Watabe, Shugo; Satoh, Noriyuki; Kawashima, Takeshi

2016-01-01

Bivalve molluscs have flourished in marine environments, and many species constitute important aquatic resources. Recently, whole genome sequences from two bivalves, the pearl oyster, Pinctada fucata, and the Pacific oyster, Crassostrea gigas, have been decoded, making it possible to compare genomic sequences among molluscs, and to explore general and lineage-specific genetic features and trends in bivalves. In order to improve the quality of sequence data for these purposes, we have updated the entire P. fucata genome assembly. We present a new genome assembly of the pearl oyster, Pinctada fucata (version 2.0). To update the assembly, we conducted additional sequencing, obtaining accumulated sequence data amounting to 193× the P. fucata genome. Sequence redundancy in contigs that was caused by heterozygosity was removed in silico, which significantly improved subsequent scaffolding. Gene model version 2.0 was generated with the aid of manual gene annotations supplied by the P. fucata research community. Comparison of mollusc and other bilaterian genomes shows that gene arrangements of Hox, ParaHox, and Wnt clusters in the P. fucata genome are similar to those of other molluscs. Like the Pacific oyster, P. fucata possesses many genes involved in environmental responses and in immune defense. Phylogenetic analyses of heat shock protein70 and C1q domain-containing protein families indicate that extensive expansion of genes occurred independently in each lineage. Several gene duplication events prior to the split between the pearl oyster and the Pacific oyster are also evident. In addition, a number of tandem duplications of genes that encode shell matrix proteins are also well characterized in the P. fucata genome. Both the Pinctada and Crassostrea lineages have expanded specific gene families in a lineage-specific manner. Frequent duplication of genes responsible for shell formation in the P. fucata genome explains the diversity of mollusc shell structures. These duplications reveal dynamic genome evolution to forge the complex physiology that enables bivalves to employ a sessile lifestyle in the intertidal zone.

Half-Truths on the Half Shell.

ERIC Educational Resources Information Center

White, Randy Wayne

1993-01-01

Recounts the author's experiences investigating the oyster fisheries off the panhandle of Florida. Describes the life of an oyster fisherman whose business has declined because of media claims of fishery contamination, and discusses those claims with an environmental administrator, a university professor, and a biologist. (MDH)

Adult Pacific Oyster (Crassostrea gigas) May Have Light Sensitivity

PubMed Central

Yang, Yanjian; Li, Zhuang; Guo, Ting; Li, Yongchuan; Wang, Xiaotong

2015-01-01

Light-sensitivity is an important aspect of mollusk survival as it plays a vital role in reproduction and predator avoidance. In the Pacific oyster Crassostrea gigas light sensitivity has been demonstrated in the larval stage but has not yet been conclusively demonstrated in adult oysters. In this paper we describe an experiment which was undertaken to determine if adult Pacific oysters were sensitive to light. One LED flashlight was used to shine light onto adult oysters while they were filtering seawater through their shell openings. We found that the degree of opening increased gradually during the light period but rapidly decreased when the flashlight was turned off in the treated group but not in the control group. These results suggest that adult Pacific oyster may be sensitive to light. PMID:26474058

Growth response, nutrient and mineral retention, bone mineralisation and walking ability of broiler chickens fed with dietary inclusion of various unconventional mineral sources.

PubMed

Oso, A O; Idowu, A A; Niameh, O T

2011-08-01

Growth response, nutrient and mineral retention, bone mineral content and walking ability of broiler chicken fed dietary inclusion of various unconventional calcium sources were studied using 160-day-old broilers. Four isonitrogenous, isocaloric diets balanced for Ca and P were formulated such that oyster shell, snail shell, wood ash and limestone were used as main non-phytate (Ca from other sources apart from plant) calcium sources. Each dietary treatment consisted of 40 birds replicated four times with 10 birds per replicate. A single diet was fed to the broilers throughout the duration of the study which lasted for 8 weeks. Broilers fed diet containing oyster shell as calcium sources recorded the highest (p < 0.05) feed intake of 5863.30 g, while those fed diet containing limestone consumed the least intake (p < 0.05) of 5432.56 g. Occurrence of lameness and evidences of gaits were highest (p < 0.05) for broilers fed diet containing wood ash. Lowest (p < 0.05) Ca and ash retention were recorded for broiler fed diet containing wood ash as Ca sources. Similar tibia ash values were recorded for broilers fed oyster shell, snail shell and limestone. Wood ash inclusion resulted in a low Ca availability hence its inclusion in feeds for broilers should be discouraged. © 2011 Blackwell Verlag GmbH.

Mechanisms to Explain the Elemental Composition of the Initial Aragonite Shell of Larval Oysters

NASA Astrophysics Data System (ADS)

Haley, Brian A.; Hales, Burke; Brunner, Elizabeth L.; Kovalchik, Kevin; Waldbusser, George G.

2018-04-01

Calcifying organisms face increasing stress from the changing carbonate chemistry of an acidifying ocean, particularly bivalve larvae that live in upwelling regions of the world, such as the coastal and estuarine waters of Oregon (USA). Arguably the first and most significant developmental hurdle faced by larval oysters is formation of their initial prodissoconch I (PDI) shell, upon which further ontological development depends. We measured the minor metal compositions (Sr/Ca, Mg/Ca) of this aragonitic PDI shell and of post-PDI larval Crassostrea gigas shell, as well as the water they were reared in, over ˜20 days for a May and an August cohort in 2011, during which time there was no period of carbonate under-saturation. After testing various methods, we successfully isolated the shell from organic tissue using a 5% active chlorine bleach solution. Elemental compositions (Sr, Mg, C, N) of the shells post-treatment showed that shell Sr/Ca ranged from 1.55 to 1.82 mmol/mol; Mg/Ca from 0.60 to 1.11 mmol/mol, similar to the few comparable published data for larval oyster aragonite compositions. We compare these data in light of possible biomineralization mechanisms: an amorphous calcium carbonate (ACC) path, an intercellular path, and a direct-from-seawater path to shell formation via biologically induced inorganic precipitation of aragonite. The last option provides a mechanistic explanation for: (1) the accelerated precipitation rates of biogenic calcification in the absence of a calcifying fluid; (2) consistently elevated precipitation rates at varying ambient-water saturation states; and (3) the high Ca-selectivity of the early larval calcification despite rapid precipitation rates.

Effect of acclimatization on hemocyte functional characteristics of the Pacific oyster (Crassostrea gigas) and carpet shell clam (Ruditapes decussatus).

PubMed

Hurtado, Miguel Ángel; da Silva, Patricia Mirella; Le Goïc, Nelly; Palacios, Elena; Soudant, Philippe

2011-12-01

Most experimental procedures on molluscs are done after acclimatization of wild animals to lab conditions. Similarly, short-term acclimation is often unavoidable in a field survey when biological analysis cannot be done within the day of sample collection. However, acclimatization can affect the general physiological condition and particularly the immune cell responses of molluscs. Our aim was to study the changes in the hemocyte characteristics of the Pacific oyster Crassostrea gigas and the carpet shell clam Ruditapes decussatus acclimated 1 or 2 days under emersed conditions at 14 ± 1 °C and for 1, 2, 7, or 10 days to flowing seawater conditions (submerged) at 9 ± 1 °C, when compared to hemolymph withdrawn from organisms sampled in the field and immediately analyzed in the laboratory (unacclimated). The hemocyte characteristics assessed by flow cytometry were the total (THC) and differential hemocyte count, percentage of dead cells, phagocytosis, and reactive oxygen species (ROS) production. Dead hemocytes were lower in oysters acclimated both in emersed and submerged conditions (1%-5%) compared to those sampled in the field (7%). Compared to oysters, the percentage of dead hemocytes was lower in clams (0.4% vs. 1.1%) and showed a tendency to decrease during acclimatization in both emersed and submerged conditions. In comparison to organisms not acclimated, the phagocytosis of hemocytes decreased in both oysters and clams acclimated under submerged conditions, but was similar in those acclimated in emersed conditions. The ROS production remained stable in both oysters and clams acclimated in emersed conditions, whereas in submerged conditions ROS production did not change in both the hyalinocytes and granulocytes of oysters, but increased in clams. In oysters, the THC decreased when they were acclimated 1 and 2 days in submerged conditions and was mainly caused by a decrease in granulocytes, but the decrease in THC in oysters acclimated 2 days in emersed conditions was caused by a decrease in hyalinocytes and small agranular cells. In clams, the THC was significantly lower in comparison to those not acclimated, regardless of the conditions of the acclimatization. These findings demonstrate that hemocyte characteristics were differentially affected in both species by the tested conditions of acclimatization. The phagocytosis and ROS production in clams and phagocytosis in oysters were not different in those acclimated for 1 day under both conditions, i.e. emersed and submerged, and those sampled in the field (unacclimated). The THC was significantly affected by acclimatization conditions, so the differences between clams and oysters should be considered in studies where important concentrations of hemocytes are required. The difference in the immune response between both species could be related to their habitat (epifaunal vs. infaunal) and their ability of resilience to manipulation and adaptation to captivity. Our results suggest that functional characteristics of hemocytes should be analyzed in both oysters and clams during the first 1 or 2 days, preferably acclimated under emersed rather than submerged conditions. Copyright © 2011. Published by Elsevier Ltd.

Semi-automated fault system extraction and displacement analysis of an excavated oyster reef using high-resolution laser scanned data

NASA Astrophysics Data System (ADS)

Molnár, Gábor; Székely, Balázs; Harzhauser, Mathias; Djuricic, Ana; Mandic, Oleg; Dorninger, Peter; Nothegger, Clemens; Exner, Ulrike; Pfeifer, Norbert

2015-04-01

In this contribution we present a semi-automated method for reconstructing the brittle deformation field of an excavated Miocene oyster reef, in Stetten, Korneuburg Basin, Lower Austria. Oyster shells up to 80 cm in size were scattered in a shallow estuarine bay forming a continuous and almost isochronous layer as a consequence of a catastrophic event in the Miocene. This shell bed was preserved by burial of several hundred meters of sandy to silty sediments. Later the layers were tilted westward, uplifted and erosion almost exhumed them. An excavation revealed a 27 by 17 meters area of the oyster covered layer. During the tectonic processes the sediment volume suffered brittle deformation. Faults mostly with some centimeter normal component and NW-SE striking affected the oyster covered volume, dissecting many shells and the surrounding matrix as well. Faults and displacements due to them can be traced along the site typically at several meters long, and as fossil oysters are broken and parts are displaced due to the faulting, along some faults it is possible to follow these displacements in 3D. In order to quantify these varying displacements and to map the undulating fault traces high-resolution scanning of the excavated and cleaned surface of the oyster bed has been carried out using a terrestrial laser scanner. The resulting point clouds have been co-georeferenced at mm accuracy and a 1mm resolution 3D point cloud of the surface has been created. As the faults are well-represented in the point cloud, this enables us to measure the dislocations of the dissected shell parts along the fault lines. We used a semi-automatic method to quantify these dislocations. First we manually digitized the fault lines in 2D as an initial model. In the next step we estimated the vertical (i.e. perpendicular to the layer) component of the dislocation along these fault lines comparing the elevations on two sides of the faults with moving averaging windows. To estimate the strike-slip dislocation component, the surface points of the dissected shells on both sides of the fault planes were compared and displacement vectors were derived. The exact orientation of the fault planes cannot be accurately extracted automatically, so the distinction between normal and reverse fault is difficult. This makes the third component of the dislocation to be estimated inaccurately. These derived dislocation values are regarded as components of the dislocation vectors and were transformed back to the real world spatial coordinate system. Interpolating these dislocation vectors along fault lines we calculated and visualized the deformation field along the whole surface of the oyster reef. Although this deformation field is only a 2D section of the real 3D deformation field, its elaboration reveals the spatial variability of the deformation according to sediment inhomogeneity. The project is supported by the Austrian Science Fund (FWF P 25883-N29).

Characterization of adhesive from oysters: A structural and compositional study

NASA Astrophysics Data System (ADS)

Alberts, Erik

The inability for man-made adhesives to set in wet or humid environments is an ongoing challenging the design of biomedical and marine adhesive materials. However, we see that nature has already overcome this challenge. Mussels, barnacles, oysters and sandcastle worms all have unique mechanisms by which they attach themselves to surfaces. By understanding what evolution has already spent millions of years perfecting, we can design novel adhesive materials inspired by nature's elegant designs. The well-studied mussel is currently the standard for design of marine inspired biomimetic polymers. In the work presented here, we aim to provide new insights into the adhesive produced by the eastern oyster, Crassostrea virginica. Unlike the mussel, which produces thread-like plaques comprised of DOPA containing-protein, the oyster secretes an organic-inorganic hybrid adhesive as it settles and grows onto a surface. This form of adhesion renders the oyster to be permanently fixed in place. Over time, hundreds of thousands of oyster grow and agglomerate to form extensive reef structures. These reefs are not only essential to survival of the oyster, but are also vital to intertidal ecosystems. While the shell of the oyster has been extensively studied, curiously, only a few conflicting insights have been made into the nature of the adhesive and contact zone between shell and substrate, and even lesfs information has been ascertained on organic and inorganic composition. In this work, we provide microscopy and histochemical studies to characterize the structure and composition of the adhesive, using oyster in the adult and juvenile stages of life. Preliminary work on extracting and characterizing organic components through collaborative help with solid-state NMR (SSNMR) and proteomics are also detailed here. We aim to provide a full, comprehensive characterization of oyster adhesive so that in the future, we may apply what we learn to the design of new materials.

Cretaceous honeycomb oysters (Pycnodonte vesicularis) as palaeoseasonality records: A multi-proxy study

NASA Astrophysics Data System (ADS)

de Winter, Niels J.; Vellekoop, Johan; Vorsselmans, Robin; Golreihan, Asefeh; Petersen, Sierra V.; Meyer, Kyle W.; Speijer, Robert P.; Claeys, Philippe

2017-04-01

Pycnodonte or "honeycomb-oysters" (Bivalvia: Gryphaeidea) is an extinct genus of calcite-producing bivalves which is found in abundance in Cretaceous to Pleistocene fossil beds worldwide. As such, Pycnodonte shells could be ideal tracers of palaeoclimate through time, with the capability to reconstruct sea water conditions and palaeotemperatures in a range of palaeoenvironmental settings. Only few studies have attempted to reconstruct palaeoclimate based on Pycnodonte shells and with variable degrees of success (e.g. Videt, 2003; Huyge et al., 2015). Our study investigates the shell growth, structure and chemical characteristics of Maastrichtian Pycnodonte vesicularis from Bajada de Jaguel in Argentina and aims to rigorously test the application of multiple palaeoenvironmental proxies on the shells of several Maastrichtian Pycnodonte oysters for palaeoclimate reconstruction. The preservation state of four calcite shells was assessed by fluorescence microscopy, cathodoluminescence and micro X-Ray Fluorescence (XRF) mapping. Their shell structure was investigated using a combination of XRF mapping, high-resolution color scanning and microCT scanning. Long integration time point-by-point XRF line scanning yielded high-resolution trace element profiles through the hinge of all shells. Microdrilled samples from the same locations on the shell were analyzed for trace element composition by ICP-MS and for stable carbon and oxygen isotopes by IRMS. Preservation of the calcite microstructure was found to be of sufficient quality to allow discussion of original shell porosity, annual growth increments and pristine chemical signatures of the bivalves. The combination of fluorescence and cathodoluminescence microscopy with XRF mapping and microCT scanning sheds light on the characteristic internal "honeycomb" structure of these extinct bivalves and allows comparison with that of the related extant Neopycnodonte bivalves (Wisshak et al., 2009). Furthermore, high resolution trace element and stable isotope records allow discussion of the degree to which Pycnodonte shells record their palaeoenvironment and can be used to reconstruct past sea water conditions. Preliminary results indicate that stable isotope and trace element ratios in Pynodonte shells record different seasonally changing sea water conditions in the Maastrichtian and reconstructed temperatures are consistent with results from clumped isotope analysis on the same shells and TEX86 analysis on the surrounding rocks. This multi-proxy study sheds light on the shell structure of Pycnodonte oysters, their chemical signature and growth pattern and investigates the expression of palaeoenvironmental proxies in the pristine shell calcite of these bivalves. This investigation shows the potential of using fossil Pycnodonte bivalves as a new archive for palaeoclimate reconstruction on a seasonal scale over a wide range of palaeolatitudes from the Cretaceous until the Pleistocene. References Huyghe et al. (2015) J. Geol Soc 172.5: 576-587. Videt (2003) Diss. Université Rennes 1. Wisshak, et al. (2009) Deep-Sea Res Pt I 56.3: 374-407.

A Preliminary Study on the Pattern, the Physiological Bases and the Molecular Mechanism of the Adductor Muscle Scar Pigmentation in Pacific Oyster Crassostrea gigas

PubMed Central

Yu, Wenchao; He, Cheng; Cai, Zhongqiang; Xu, Fei; Wei, Lei; Chen, Jun; Jiang, Qiuyun; Wei, Na; Li, Zhuang; Guo, Wen; Wang, Xiaotong

2017-01-01

The melanin pigmentation of the adductor muscle scar and the outer surface of the shell are among attractive features and their pigmentation patterns and mechanism still remains unknown in the Pacific oyster Crassostrea gigas. To study these pigmentation patterns, the colors of the adductor muscle scar vs. the outer surface of the shell on the same side were compared. No relevance was found between the colors of the adductor muscle scars and the corresponding outer surface of the shells, suggesting that their pigmentation processes were independent. Interestingly, a relationship between the color of the adductor muscle scars and the dried soft-body weight of Pacific oysters was found, which could be explained by the high hydroxyl free radical scavenging capacity of the muscle attached to the black adductor muscle scar. After the transcriptomes of pigmented and unpigmented adductor muscles and mantles were studied by RNAseq and compared, it was found that the retinol metabolism pathway were likely to be involved in melanin deposition on the adductor muscle scar and the outer surface of the shell, and that the different members of the tyrosinase or Cytochrome P450 gene families could play a role in the independent pigmentation of different organs. PMID:28955252

Culture and Sustainability: Lessons from the Oyster and Other Metaphors

ERIC Educational Resources Information Center

Galloway, Vicki

2015-01-01

Consider the oyster. Like all good metaphors, it has done some morphing since the days of Shakespeare's "Merry Wives of Windsor." Newer bands of shell material have repainted the mollusk metaphor, transforming it from ostracism, opportunism, and exploitation to openness, opportunity and exploration, and thus an apt symbol for the…

PARASITIC AND SYMBIOTIC FAUNA IN OYSTERS (CRASSOSTREA VIRGINICA) AND MUD CRABS (PANOPEUS SPP.) FROM THE CALOOSAHATCHEE ESTUARY, FLORIDA, USA.

EPA Science Inventory

Volety, Aswani K., S. Greg Tolley and James T. Winstead. 2002. Parasitic and Symbiotic Fauna in Oysters (Crassostrea virginica) and Mud Crabs (Panopeus spp.) from the Caloosahatchee Estuary, Florida, USA (Abstract). Presented at the 4th International Conference on Molluscan Shell...

Exploring relationships of calcification rate with respiration rate and predator cue presence in juvenile Crassostrea virginica

NASA Astrophysics Data System (ADS)

McCutcheon, M.; Hu, X.

2016-02-01

The eastern oyster (Crassostrea virginica) is a biologically and economically important calcifier that has been experiencing a global population decline due to multiple stressors. The process of biomineralization is essential in the growth and predator defense of oysters. Several studies investigating morphological and mechanical shell properties have noted a phenotypic plasticity in response to predator presence. We present the first study that attempts to detect an alteration in the calcification rate of juvenile C. virginica as well as measure respiration rates in the presence and absence of predator exudates. An alkalinity anomaly technique was used to quantify calcification and respiration rates of oysters exposed to blue crab or mud crab cues or a no cue control condition. No significant differences in calcification rate were detected between predator and control treatments. However, the linear relationship between calcification and respiration rates differed between treatments. This changing relationship is not fully understood and warrants further investigation. In addition, this study also revealed our experimental oysters maintained calcification rates comparable to literature values while respiration rates were an order of magnitude lower than previously reported levels. Future direction for this research involves inclusion of acidification treatments. Any environmental factors (including predator presence) that may on their own or in conjunction with estuarine acidification alter calcification (or respiration) rates will impact the local to regional carbon cycle as well as oyster fitness and consequent future population dynamics.

Effects of the red tide dinoflagellate, Karenia brevis, on early development of the eastern oyster Crassostrea virginica and northern quahog Mercenaria mercenaria.

PubMed

Rolton, Anne; Vignier, Julien; Soudant, Philippe; Shumway, Sandra E; Bricelj, V Monica; Volety, Aswani K

2014-10-01

The brevetoxin-producing dinoflagellate, Karenia brevis, adversely affects many shellfish species including the commercially and ecologically important bivalve molluscs, the northern quahog (=hard clam) Mercenaria mercenaria and eastern oyster Crassostrea virginica, in the Gulf of Mexico, USA. This study assessed the effects of exposure of these bivalves to K. brevis during their early development. In separate experiments, embryos of 2-4 cell stage of M. mercenaria and C. virginica were exposed to both whole and lysed K. brevis cells isolated from Manasota Key, Florida. Low bloom concentrations of 500 to 3000 cells mL(-1) were simulated for 96 h. Shell length, percent abnormality (and normality), and percent mortality of resulting larvae were measured. Percentages were recorded after 6, 24, and 96 h of exposure; larval shell length was measured at 24 and 96 h. For both quahogs and oysters, the effects of exposing embryos to K. brevis on all larval responses were generally dose- and time-dependent. Percent mortalities and abnormalities of both clam and oyster embryos increased significantly after only 6h of exposure to whole cells of K. brevis. For clams, these parameters were significantly higher in whole and lysed treatments (at 3000 cells mL(-1)) than in controls. Percent mortalities of oysters were significantly higher in the whole-cell treatment (3000 cells mL(-1)) than under control conditions. After 24h of exposure, mean larval shell length of both bivalve species was significantly reduced relative to controls. This was evident for clam larvae in both the lysed treatment at 1500 cells mL(-1) and in whole and lysed treatments at 3000 cells mL(-1), and for oyster larvae in the lysed treatment at 3000 cells mL(-1). After 96 h, both species exposed to the lysed cell treatment at 3000 cells mL(-1) had significantly smaller larvae compared to those in the control. Overall, lysed cells of K. brevis had a more pronounced effect on shell length, percent abnormality, and mortality in both clams and oysters than did whole cells. Given the fact that blooms of K. brevis overlap with the spawning periods of these two bivalves, and that cells of this naked dinoflagellate are readily lysed by wave action, these results suggest that exposure to K. brevis during the early life history stages of clams and oysters could adversely affect their population recruitment. Further, the presence of whole or lysed cells of K. brevis in hatcheries could have a major negative impact on production. Copyright © 2014 Elsevier B.V. All rights reserved.

Persistent carry-over effects of planktonic exposure to ocean acidification in the Olympia oyster.

PubMed

Hettinger, Annaliese; Sanford, Eric; Hill, Tessa M; Russell, Ann D; Sato, Kirk N S; Hoey, Jennifer; Forsch, Margaux; Page, Heather N; Gaylord, Brian

2012-12-01

Predicting impacts of global environmental change is challenging due to the complex life cycles that characterize many terrestrial and aquatic taxa. Different life stages often interact with the physical environment in distinct ways, and a growing body of work suggests that stresses experienced during one life stage can "carry over" to influence subsequent stages. Assessments of population responses to environmental perturbation must therefore consider how effects might propagate across life-history transitions. We investigated consequences of ocean acidification (decreased pH and carbonate saturation) for early life stages of the Olympia oyster (Ostrea lurida), a foundation species in estuaries along the Pacific coast of North America. We reared oysters at three levels of seawater pH, including a control (8.0) and two additional levels (7.9 and 7.8). Oysters were cultured through their planktonic larval period to metamorphosis and into early juvenile life. Larvae reared under pH 7.8 exhibited a 15% decrease in larval shell growth rate, and a 7% decrease in shell area at settlement, compared to larvae reared under control conditions. Impacts were even more pronounced a week after settlement, with juveniles that had been reared as larvae under reduced pH exhibiting a 41% decrease in shell growth rate. Importantly, the latter effect arose regardless of the pH level the oysters experienced as juveniles, indicating a strong carry-over effect from the larval phase. Adverse impacts of early exposure to low pH persisted for at least 1.5 months after juveniles were transferred to a common environment. Overall, our results suggest that a stringent focus on a single phase of the life cycle (e.g., one perceived as the "weakest link") may neglect critical impacts that can be transferred across life stages in taxa with complex life histories.

Ecological Functions of Shallow, Unvegetated Esturaine Habitats and Potential Dredging Impacts (With Emphasis on Chesapeake Bay)

DTIC Science & Technology

2005-12-01

than seagrass , Seitz et al. (2005) has recently shown that growth of juvenile blue crabs was greater in unvegetated mud and sand flats of the upper...York River than the same habitats or seagrass beds in the lower river. In a companion study Lipcius et al. (2005) report that survival and overall...that decapod fauna of oyster shell habitats are distinct from that of either seagrass or marsh-edge habitats. Posey et al. (1999) have experimentally

Structural and compositional characterization of the adhesive produced by reef building oysters.

PubMed

Alberts, Erik M; Taylor, Stephen D; Edwards, Stephanie L; Sherman, Debra M; Huang, Chia-Ping; Kenny, Paul; Wilker, Jonathan J

2015-04-29

Oysters have an impressive ability to overcome difficulties of life within the stressful intertidal zone. These shellfish produce an adhesive for attaching to each other and building protective reef communities. With their reefs often exceeding kilometers in length, oysters play a major role in balancing the health of coastal marine ecosystems. Few details are available to describe oyster adhesive composition or structure. Here several characterization methods were applied to describe the nature of this material. Microscopy studies indicated that the glue is comprised of organic fiber-like and sheet-like structures surrounded by an inorganic matrix. Phospholipids, cross-linking chemistry, and conjugated organics were found to differentiate this adhesive from the shell. Symbiosis in material synthesis could also be present, with oysters incorporating bacterial polysaccharides into their adhesive. Oyster glue shows that an organic-inorganic composite material can provide adhesion, a property especially important when constructing a marine ecosystem.

Oyster Saccostrea cucullata as a biomonitor for Hg contamination and the risk to humans on the coast of Qeshm Island, Persian Gulf, Iran.

PubMed

Shirneshan, Golshan; Bakhtiari, Alireza Riyahi; Kazemi, Ali; Mohamadi, Mohsen; Kheirabadi, Nabiallah

2012-06-01

A total of 174 individuals of rocky oysters (Saccostrea cucullata) and 35 surface sediment samples were collected from seven stations off the intertidal zones of Qeshm Island, Persian Gulf, in order to study the concentration of mercury in oysters' tissues, and to investigate whether mercury concentrations in the edible soft tissues are within the permissible limits for public health. The average mercury concentrations were found as 3.44, 50.66 and 2.29 μg kg(-1) dw in the sediments, soft tissues and shells of the oysters, respectively. Results indicated that the levels of mercury in sediment differed significantly between the stations. In addition, results confirmed that the soft tissues of oysters could be a good indicator of mercury in the aquatic system. In comparison with food safety standards, mercury levels in oysters were well within the permissible limits for human consumption.

Ocean acidification increases the vulnerability of native oysters to predation by invasive snails

PubMed Central

Sanford, Eric; Gaylord, Brian; Hettinger, Annaliese; Lenz, Elizabeth A.; Meyer, Kirstin; Hill, Tessa M.

2014-01-01

There is growing concern that global environmental change might exacerbate the ecological impacts of invasive species by increasing their per capita effects on native species. However, the mechanisms underlying such shifts in interaction strength are poorly understood. Here, we test whether ocean acidification, driven by elevated seawater pCO2, increases the susceptibility of native Olympia oysters to predation by invasive snails. Oysters raised under elevated pCO2 experienced a 20% increase in drilling predation. When presented alongside control oysters in a choice experiment, 48% more high-CO2 oysters were consumed. The invasive snails were tolerant of elevated CO2 with no change in feeding behaviour. Oysters raised under acidified conditions did not have thinner shells, but were 29–40% smaller than control oysters, and these smaller individuals were consumed at disproportionately greater rates. Reduction in prey size is a common response to environmental stress that may drive increasing per capita effects of stress-tolerant invasive predators. PMID:24430847

Ocean acidification increases the vulnerability of native oysters to predation by invasive snails.

PubMed

Sanford, Eric; Gaylord, Brian; Hettinger, Annaliese; Lenz, Elizabeth A; Meyer, Kirstin; Hill, Tessa M

2014-03-07

There is growing concern that global environmental change might exacerbate the ecological impacts of invasive species by increasing their per capita effects on native species. However, the mechanisms underlying such shifts in interaction strength are poorly understood. Here, we test whether ocean acidification, driven by elevated seawater pCO₂, increases the susceptibility of native Olympia oysters to predation by invasive snails. Oysters raised under elevated pCO₂ experienced a 20% increase in drilling predation. When presented alongside control oysters in a choice experiment, 48% more high-CO₂ oysters were consumed. The invasive snails were tolerant of elevated CO₂ with no change in feeding behaviour. Oysters raised under acidified conditions did not have thinner shells, but were 29-40% smaller than control oysters, and these smaller individuals were consumed at disproportionately greater rates. Reduction in prey size is a common response to environmental stress that may drive increasing per capita effects of stress-tolerant invasive predators.

Shell extracts of the edible mussel and oyster induce an enhancement of the catabolic pathway of human skin fibroblasts, in vitro.

PubMed

Latire, Thomas; Legendre, Florence; Bouyoucef, Mouloud; Marin, Frédéric; Carreiras, Franck; Rigot-Jolivet, Muriel; Lebel, Jean-Marc; Galéra, Philippe; Serpentini, Antoine

2017-10-01

Mollusc shells are composed of more than 95% calcium carbonate and less than 5% organic matrix consisting mostly of proteins, glycoproteins and polysaccharides. In this study, we investigated the effects of matrix macromolecular components extracted from the shells of two edible molluscs of economic interest, i.e., the blue mussel Mytilus edulis and the Pacific oyster Crassostrea gigas. The potential biological activities of these organic molecules were analysed on human dermal fibroblasts in primary culture. Our results demonstrate that shell extracts of the two studied molluscs modulate the metabolic activities of the cells. In addition, the extracts caused a decrease of type I collagen and a concomitant increase of active MMP-1, both at the mRNA and the protein levels. Therefore, our results suggest that shell extracts from M. edulis and C. gigas contain molecules that promote the catabolic pathway of human dermal fibroblasts. This work emphasises the potential use of these shell matrices in the context of anti-fibrotic strategies, particularly against scleroderma. More generally, it stresses the usefulness to valorise bivalve shells that are coproducts of shellfish farming activity.

Preparation and evaluation of magnetic carbonaceous materials for pesticide and metal removal.

PubMed

Ohno, Masaki; Hayashi, Hiroki; Suzuki, Kazuyuki; Kose, Tomohiro; Asada, Takashi; Kawata, Kuniaki

2011-07-15

Magnetic carbonaceous materials were produced by carbonization of a cation exchange resin loaded with ferrous or ferric iron and activation using sieved oyster shell as the activation agent. The magnetic carbonaceous material with the maximum magnetic flux density on every axis (ESS-1) was obtained from the ferric-loaded resin by carbonization at 700°C, followed by activation with the oyster shell at 900°C, and magnetization. A separate step of carbonization and activation appears to cause more of a reduction reaction of Fe to form γ-Fe(2)O(3). The Fe compound in the magnetic carbonaceous material was identified from the XRD pattern as mainly γ-Fe(2)O(3). The magnetic flux density on every axis increased linearly as the amount of the oyster shell increased. Moreover, the adsorption ability of the products was evaluated for pesticides and metal ions. Both ESS-1 and a carbonaceous material obtained from the resin without ferric ion (RC) appear to have the highest adsorption ability for lead. Furthermore, the adsorption ability of ESS-1 might decrease by blockages of the pores with the loaded Fe compounds. Copyright © 2011 Elsevier Inc. All rights reserved.

The potential of ocean acidification on suppressing larval development in the Pacific oyster Crassostrea gigas and blood cockle Arca inflata Reeve

NASA Astrophysics Data System (ADS)

Li, Jiaqi; Jiang, Zengjie; Zhang, Jihong; Mao, Yuze; Bian, Dapeng; Fang, Jianguang

2014-11-01

We evaluated the effect of pH on larval development in larval Pacific oyster ( Crassostrea gigas) and blood cockle ( Arca inflata Reeve). The larvae were reared at pH 8.2 (control), 7.9, 7.6, or 7.3 beginning 30 min or 24 h post fertilization. Exposure to lower pH during early embryonic development inhibited larval shell formation in both species. Compared with the control, larvae took longer to reach the D-veliger stage when reared under pH 7.6 and 7.3. Exposure to lower pH immediately after fertilization resulted in significantly delayed shell formation in the Pacific oyster larvae at pH 7.3 and blood cockle larvae at pH 7.6 and 7.3. However, when exposure was delayed until 24 h post fertilization, shell formation was only inhibited in blood cockle larvae reared at pH 7.3. Thus, the early embryonic stages were more sensitive to acidified conditions. Our results suggest that ocean acidification will have an adverse effect on embryonic development in bivalves. Although the effects appear subtle, they may accumulate and lead to subsequent issues during later larval development.

The pearl oyster Pinctada fucata martensii genome and multi-omic analyses provide insights into biomineralization

PubMed Central

Fan, Guangyi; Jiao, Yu; Zhang, He; Huang, Ronglian; Zheng, Zhe; Bian, Chao; Deng, Yuewen; Wang, Qingheng; Wang, Zhongduo; Liang, Xinming; Liang, Haiying; Shi, Chengcheng; Zhao, Xiaoxia; Sun, Fengming; Hao, Ruijuan; Bai, Jie; Liu, Jialiang; Chen, Wenbin; Liang, Jinlian; Liu, Weiqing; Xu, Zhe; Shi, Qiong; Xu, Xun

2017-01-01

Abstract Nacre, the iridescent material found in pearls and shells of molluscs, is formed through an extraordinary process of matrix-assisted biomineralization. Despite recent advances, many aspects of the biomineralization process and its evolutionary origin remain unknown. The pearl oyster Pinctada fucata martensii is a well-known master of biomineralization, but the molecular mechanisms that underlie its production of shells and pearls are not fully understood. We sequenced the highly polymorphic genome of the pearl oyster and conducted multi-omic and biochemical studies to probe nacre formation. We identified a large set of novel proteins participating in matrix-framework formation, many in expanded families, including components similar to that found in vertebrate bones such as collagen-related VWA-containing proteins, chondroitin sulfotransferases, and regulatory elements. Considering that there are only collagen-based matrices in vertebrate bones and chitin-based matrices in most invertebrate skeletons, the presence of both chitin and elements of collagen-based matrices in nacre suggests that elements of chitin- and collagen-based matrices have deep roots and might be part of an ancient biomineralizing matrix. Our results expand the current shell matrix-framework model and provide new insights into the evolution of diverse biomineralization systems. PMID:28873964

Intracellular pH Recovery Rates in Bivalve Hemocytes Following Exposure to Acidic Environmental Conditions

NASA Astrophysics Data System (ADS)

Croxton, A.; Wikfors, G. H.

2012-12-01

Predictions of ocean acidification effects upon carbonate shell-forming species have caused great concern for the future of shellfisheries. Nevertheless, bivalve species inhabiting an estuarine environment have evolved in these environments with fluctuating pH levels. Previous experimental studies conducted in our laboratory have demonstrated the ability of oyster hemocytes to maintain intracellular homeostasis under acidic external conditions. However, little information is known of this homeostatic mechanism in other molluscan shellfish species present in these same habitats. In the current study we propose to determine if other bivalve species of aquaculture interest also possess this intracellular regulation by applying an in vitro hemocyte pH-recovery assay, previously developed for oysters, on the northern quahog, Mercenaria mercenaria, the blue mussel, Mytilus edulis, and the softshell clam, Mya arenaria. Preliminary results from the determination of initial intracellular pH levels, the initial step in the rate recovery assay, indicated a pH range between 7.0-7.4. This range was comparable to initial values measured in oysters, and consistent with data reported in the current literature. The second step of the hemocyte pH-recovery assay involves exposing oyster hemocytes to acidic external conditions and measuring the ability of the hemocyte intracellular pH to maintain homeostasis (i.e. recovery rate). Results from the recovery rate process will be presented.

Response of a benthic suspension feeder ( Crassostrea virginica Gmelin) to three centuries of anthropogenic eutrophication in Chesapeake Bay

NASA Astrophysics Data System (ADS)

Kirby, Michael X.; Miller, Henry M.

2005-03-01

Biogenic reefs built by oysters and other suspension feeders are vital components of estuarine ecosystems. By consuming phytoplankton, suspension feeders act to suppress accumulation of organic matter in the water column. Nutrient loading increases the rate of primary production, thereby causing eutrophication. As suspension feeders consume more organic matter from increasing abundance of phytoplankton, their rate of growth should also increase if they are food limited. We show here that the eastern oyster, Crassostrea virginica (Gmelin), from St. Mary's and Patuxent rivers, Chesapeake Bay, grew faster during anthropogenic eutrophication relative to C. virginica before eutrophication. Growth of shell height, shell thickness and adductor muscle increased after eutrophication began in the late 18th century. After 1860, growth decreased, perhaps reflecting the negative effects of hypoxia, harmful algal blooms, disease and fishing on oyster growth. These results are consistent with the view that an increasing supply of phytoplankton resulting from eutrophication enhanced growth of C. virginica between 1760 and 1860, before oyster reefs were degraded by destructive fishing practices between 1870 and 1930. Alternative factors, such as changes in water temperature, salinity, and fishing are less likely to be responsible for this pattern. These results have implications for restoration of oyster reefs in order to mitigate the effects of eutrophication in estuaries, as well as the paleoecological relationship between suspension feeders and paleoproductivity.

The shellfish enigma across the Mesolithic-Neolithic transition in southern Scandinavia

NASA Astrophysics Data System (ADS)

Lewis, J. P.; Ryves, D. B.; Rasmussen, P.; Olsen, J.; Knudsen, K.-L.; Andersen, S. H.; Weckström, K.; Clarke, A. L.; Andrén, E.; Juggins, S.

2016-11-01

The well-known and widespread replacement of oysters (abundant during the Mesolithic period) by cockles and mussels in many Danish Stone Age shell middens ca. 5900 cal yrs BP coincides with the transition to agriculture in southern Scandinavia. This human resource shift is commonly believed to reflect changing resource availability, driven by environmental and/or climatic change at the Mesolithic-Neolithic transition rather than cultural choice. While several hypotheses have been proposed to explain the ;Mesolithic-Neolithic oyster decline;, an explanation based on a sudden freshening of the inner Danish waters has received most attention. Here, for the first time, we test and refute this long-standing hypothesis that declining salinity explains the marked reduction in oysters identified within numerous shell middens across coastal Denmark at the Mesolithic-Neolithic transition using quantitative and qualitative salinity inference from several, independent proxies (diatoms, molluscs and foraminifera) from multiple Danish fjord sites. Alternatively, we attribute the oyster decline to other environmental causes (particularly changing sedimentation), ultimately driven by external climatic forcing. Critical application of such high-quality environmental archives can reinvigorate archaeological debates and can aid in understanding and managing environmental change in increasingly impacted coastal regions.

VIEW ALONG RAW MATERIAL CONVEYOR AT RIGHT WITH CRUSHED SHELL ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW ALONG RAW MATERIAL CONVEYOR AT RIGHT WITH CRUSHED SHELL CONVEYOR ABOVE. ENGINE AND RADIATOR AT LOWER LEFT. - F. & H. Benning Company Oyster Mill, 14430 Solomons Island Road (moved from 1014 Benning Road, Galesville, Anne Arundel County, Maryland), Solomons, Calvert County, MD

Vibrio vulnificus and Vibrio parahaemolyticus in U.S. retail shell oysters: a national survey from June 1998 to July 1999.

PubMed

Cook, David W; Oleary, Paul; Hunsucker, Jeff C; Sloan, Edna M; Bowers, John C; Blodgett, Robert J; Depaola, Angelo

2002-01-01

From June 1998 to July 1999, 370 lots of oysters in the shell were sampled at 275 different establishments (71%, restaurants or oyster bars; 27%, retail seafood markets: and 2%, wholesale seafood markets) in coastal and inland markets throughout the United States. The oysters were harvested from the Gulf (49%). Pacific (14%), Mid-Atlantic (18%), and North Atlantic (11%) Coasts of the United States and from Canada (8%). Densities of Vibrio vulnificus and Vibrio parahaemolyticus were determined using a modification of the most probable number (MPN) techniques described in the Food and Drug Administration's Bacteriological Analytical Manual. DNA probes and enzyme immunoassay were used to identify suspect isolates and to determine the presence of the thermostable direct hemolysin gene associated with pathogenicity of V. parahaemolyticus. Densities of both V. vulnifcus and V. parahaemolyticus in market oysters from all harvest regions followed a seasonal distribution, with highest densities in the summer. Highest densities of both organisms were observed in oysters harvested from the Gulf Coast, where densities often exceeded 10,000 MPN/g. The majority (78%) of lots harvested in the North Atlantic, Pacific, and Canadian Coasts had V. vulnificus densities below the detectable level of 0.2 MPN/g; none exceeded 100 MPN/g. V. parahaemolyticus densities were greater than those of V. vulnificus in lots from these same areas, with some lots exceeding 1,000 MPN/g for V. parahaemolyticus. Some lots from the Mid-Atlantic states exceeded 10,000 MPN/g for both V. vulnificus and V. parahaemolyicus. Overall, there was a significant correlation between V. vulificus and V. parahaemolyticus densities (r = 0.72, n = 202, P < 0.0001), but neither density correlated with salinity. Storage time significantly affected the V. vulnificus (10% decrease per day) and V. parahaemolyticus (7% decrease per day) densities in market oysters. The thermostable direct hemolysin gene associated with V parahaemolyticus virulence was detected in 9 of 3,429 (0.3%) V. parahaemolyticus cultures and in 8 of 198 (4.0%) lots of oysters. These data can be used to estimate the exposure of raw oyster consumers to V. vulnificus and V. parahaemolyticus.

3D printed porous polycaprolactone/oyster shell powder (PCL/OSP) scaffolds for bone tissue engineering

NASA Astrophysics Data System (ADS)

Luo, Wenfeng; Zhang, Shuangying; Lan, Yuewei; Huang, Chen; Wang, Chao; Lai, Xuexu; Chen, Hanwei; Ao, Ningjian

2018-04-01

In this work, oyster shell powder (OSP) was used as the bio-filler and combined with polycaprolactone (PCL) through melt blending methodology. The PCL and PCL/OSP scaffolds were prepared using additive manufacturing process. All the 3D printed scaffolds hold a highly porosity and interconnected pore structures. OSP particles are dispersed in the polymer matrix, which helped to improve the degree of crystallinity and mineralization ability of the scaffolds. There was no significant cytotoxicity of the prepared scaffolds towards MG-63 cells, and all the scaffolds showed a well ALP activity. Therefore, PCL/OSP scaffolds had a high potential to be employed in the bone tissue engineering.

Perception of oyster-based products by French consumers. The effect of processing and role of social representations.

PubMed

Debucquet, Gervaise; Cornet, Josiane; Adam, Isabelle; Cardinal, Mireille

2012-12-01

The search for new markets in the seafood sector, associated with the question of the continuity of raw oyster consumption over generations can be an opportunity for processors to extend their ranges with oyster-based products. The twofold aim of this study was to evaluate the impact of processing and social representation on perception of oyster-based products by French consumers and to identify the best means of development in order to avoid possible failure in the market. Five products with different degrees of processing (cooked oysters in a half-shell, hot preparation for toast, potted oyster, oyster butter and oyster-based soup) were presented within focus groups and consumer tests, at home and in canteens with the staff of several companies in order to reach consumers with different ages and professional activities. The results showed that social representation had a strong impact and that behaviours were contrasted according to the initial profile of the consumer (traditional raw oyster consumers or non-consumers) and their age distribution (younger and older people). The degree of processing has to be adapted to each segment. It is suggested to develop early exposure to influence the food choices and preferences of the youngest consumers on a long-term basis. Copyright © 2012 Elsevier Ltd. All rights reserved.

Pinctada margaritifera responses to temperature and pH: Acclimation capabilities and physiological limits

NASA Astrophysics Data System (ADS)

Le Moullac, Gilles; Soyez, Claude; Latchere, Oihana; Vidal-Dupiol, Jeremie; Fremery, Juliette; Saulnier, Denis; Lo Yat, Alain; Belliard, Corinne; Mazouni-Gaertner, Nabila; Gueguen, Yannick

2016-12-01

The pearl culture is one of the most lucrative aquacultures worldwide. In many South Pacific areas, it depends on the exploitation of the pearl oyster Pinctada margaritifera and relies entirely on the environmental conditions encountered in the lagoon. In this context, assessing the impact of climatic stressors, such as global warming and ocean acidification, on the functionality of the resource in terms of renewal and exploitation is fundamental. In this study, we experimentally addressed the impact of temperature (22, 26, 30 and 34 °C) and partial pressure of carbon dioxide pCO2 (294, 763 and 2485 μatm) on the biomineralization and metabolic capabilities of pearl oysters. While the energy metabolism was strongly dependent on temperature, results showed its independence from pCO2 levels; no interaction between temperature and pCO2 was revealed. The energy metabolism, ingestion, oxygen consumption and, hence, the scope for growth (SFG) were maximised at 30 °C and dramatically fell at 34 °C. Biomineralization was examined through the expression measurement of nine mantle's genes coding for shell matrix proteins involved in the formation of calcitic prisms and/or nacreous shell structures; significant changes were recorded for four of the nine (Pmarg-Nacrein A1, Pmarg-MRNP34, Pmarg-Prismalin 14 and Pmarg-Aspein). These changes showed that the maximum and minimum expression of these genes was at 26 and 34 °C, respectively. Surprisingly, the modelled thermal optimum for biomineralization (ranging between 21.5 and 26.5 °C) and somatic growth and reproduction (28.7 °C) appeared to be significantly different. Finally, the responses to high temperatures were contextualised with the Intergovernmental Panel on Climate Change (IPCC) projections, which highlighted that pearl oyster stocks and cultures would be severely threatened in the next decade.

From artificial structures to self-sustaining oyster reefs

NASA Astrophysics Data System (ADS)

Walles, Brenda; Troost, Karin; van den Ende, Douwe; Nieuwhof, Sil; Smaal, Aad C.; Ysebaert, Tom

2016-02-01

Coastal ecosystems are increasingly recognized as essential elements within coastal defence schemes and coastal adaptation. The capacity of coastal ecosystems, like marshes and oyster reefs, to maintain their own habitat and grow with sea-level rise via biophysical feedbacks is seen as an important advantage of such systems compared to man-made hard engineering structures. Providing a suitable substrate for oysters to settle on offers a kick-start for establishment at places where they were lost or are desirable for coastal protection. Accumulation of shell material, through recruitment and growth, is essential to the maintenance of oyster reefs as it provides substrate for new generations (positive feedback loop), forming a self-sustainable structure. Insight in establishment, survival and growth thresholds and knowledge about the population dynamics are necessary to successfully implement oyster reefs in coastal defence schemes. The aim of this paper is to investigate whether artificial Pacific oyster reefs develop into self-sustaining oyster reefs that contribute to coastal protection. Reef development was investigated by studying recruitment, survival and growth rates of oysters on artificial oyster reefs in comparison with nearby natural Pacific oyster reefs. The artificial reef structure successfully offered substrate for settlement of oysters and therefore stimulated reef formation. Reef development, however, was hampered by local sedimentation and increasing tidal emersion. Tidal emersion is an important factor that can be used to predict where artificial oyster reefs have the potential to develop into self-sustaining reefs that could contribute to coastal protection, but it is also a limiting factor in using oyster reefs for coastal protection.

Production of bio-fertilizer from microwave vacuum pyrolysis of waste palm shell for cultivation of oyster mushroom (Pleurotus ostreatus)

NASA Astrophysics Data System (ADS)

Lun Nam, Wai; Huan Su, Man; Phang, Xue Yee; Chong, Min Yee; Keey Liew, Rock; Ma, Nyuk Ling; Lam, Su Shiung

2017-11-01

Microwave vacuum pyrolysis of waste palm shell (WPS) was performed to produce biochar, which was then tested as bio-fertilizer in growing Oyster mushroom (Pleurotus ostreatus). The pyrolysis approach generated a biochar containing a highly porous structure with a high BET surface area (up to 1250 m2/g) and a low moisture content (≤ 10 wt%), exhibiting desirable adsorption properties to be used as bio-fertilizer since it can act as a housing that provides many sites on which living microorganisms (mycelium or plant-growth promoting bacteria) and organic nutrients can be attached or adsorbed onto. This could in turn stimulate plant growth by increasing the availability and supply of nutrients to the targeted host plant. The results from growing Oyster mushroom using the biochar record an impressive growth rate and a monthly production of up to about 550 g of mushroom. The shorter time for mycelium growth on whole baglog (30 days) and the highest yield of Oyster mushroom (550 g) was obtained from the cultivation medium added with 20 g of biochar. Our results demonstrate that the biochar-based bio-fertilizer produce from microwave vacuum pyrolysis of WPS show exceptional promise as an alternative growing substrate for mushroom cultivation.

Differential response of oyster shell powder on enzyme profile and nutritional value of oyster mushroom Pleurotus florida PF05.

PubMed

Naraian, Ram; Narayan, Om Prakash; Srivastava, Jatin

2014-01-01

Oyster mushroom Pleurotus florida was cultivated on different combinations of wheat straw (WS) as basal substrate and oyster shell powder (OSP) supplement. The OSP supplementation considerably responded to different cultivation phases. The mycelium grew fast and showed rapid growth rate (8.91 mmd(-1)) in WS + OSP (97 + 3) combination while WS + OSP (92 + 8) showed maximum laccase (3.133 U/g) and Mn peroxidase (MnP) activities (0.091 U/g). The climax level of laccase (5.433 U/g) and MnP (0.097 U/g) was recorded during fruit body initiation in WS + OSP (97 + 3) and WS + OSP (98 + 2) combinations, respectively. The WS + OSP (97 + 3) combination represented the best condition for mushroom cultivation and produced the highest biological efficiency (147%). In addition, protein and lipid contents in fruit bodies were slightly improved in response to OSP. The carbohydrate was significantly increased by raising concentration of OSP. The highest values of protein, carbohydrate, and lipid noted were 31.3 μg/g, 0.0639 (g/g), and 0.373 (g/g) correspondingly. Conclusively it was evident that lower concentrations of OSP acted positively and relatively to higher concentrations and improved nutritional content which may suitably be used to enhance both yield and nutritional values of mushroom.

Production of bio-fertilizer from microwave vacuum pyrolysis of palm kernel shell for cultivation of Oyster mushroom (Pleurotus ostreatus).

PubMed

Nam, Wai Lun; Phang, Xue Yee; Su, Man Huan; Liew, Rock Keey; Ma, Nyuk Ling; Rosli, Mohd Haqqi Nazilli Bin; Lam, Su Shiung

2018-05-15

Microwave vacuum pyrolysis of palm kernel shell (PKS) was performed to produce biochar, which was then tested as bio-fertilizer in growing Oyster mushroom (Pleurotus ostreatus). The pyrolysis approach produced biochar containing a highly porous structure with a high BET surface area of up to 270m 2 /g and low moisture content (≤10wt%), exhibiting desirable adsorption properties to be used as bio-fertilizer since it can act as a housing that provides many sites on which living microorganisms (mycelium or plant-growth promoting bacteria) and organic nutrients can be attached or adsorbed onto. This could in turn stimulate plant growth by increasing the availability and supply of nutrients to the targeted host plant. The results from growing Oyster mushroom using the biochar recorded an impressive growth rate and a monthly production of up to about 550g of mushroom. A shorter time for mycelium growth on one whole baglog (21days) and the highest yield of Oyster mushroom (550g) were obtained from cultivation medium added with 20g of biochar. Our results demonstrate that the biochar-based bio-fertilizer produced from microwave vacuum pyrolysis of PKS shows exceptional promise as growth promoting material for mushroom cultivation. Copyright © 2017 Elsevier B.V. All rights reserved.

D1 dopamine receptor is involved in shell formation in larvae of Pacific oyster Crassostrea gigas.

PubMed

Liu, Zhaoqun; Wang, Lingling; Yan, Yunchen; Zheng, Yan; Ge, Wenjing; Li, Meijia; Wang, Weilin; Song, Xiaorui; Song, Linsheng

2018-07-01

Dopamine (DA), a significant member of catecholamines, is reported to induce biomineralization of calcium carbonate vaterite microspheres via dopamine receptor (DR) in bivalves, implying the modulation of dopaminergic system on shell formation during larval development. In this research, a homologue of D1 type DR (CgD1DR-1) was identified from oyster Crassostrea gigas, whose full length cDNA was 1197 bp. It was widely expressed in various tissues of C. gigas, with the significantly higher levels in hepatopancreas, mantle, muscle and gill. During developmental stages, the mRNA transcripts of CgD1DR-1 in D-shape larvae were obviously higher (p < 0.05) than those in trochophore and umbo larvae, and CO 2 exposure could inhibit the synthesis of DA and mRNA expression of CgD1DR-1. After cell transfection and DA treatment, intracellular cAMP in cells with the expression of CgD1DR-1 increased significantly (p < 0.05). Furthermore, the incubation with SCH 23390 for the blockage of CgD1DR-1 significantly restrained the expressions of six shell formation-related genes including CgTyrosinase-1, CgTyrosinase-3, CgChitinaseLP, CgAMC, CgBMP and CgBMPR in trochophore and D-shape larvae. These results jointly suggested that DA together with its receptor CgD1DR-1 might be involved in shell formation during oyster larval development from trochophore to D-shape larvae, and CO 2 -induced ocean acidification (OA) might influence marine bivalves by inhibiting the DA-D1DR pathway to prohibit their shell formation. Copyright © 2018 Elsevier Ltd. All rights reserved.

Non-indigenous predators threaten ecosystem engineers: Interactive effects of green crab and oyster size on American oyster mortality.

PubMed

Pickering, Tyler R; Poirier, Luke A; Barrett, Timothy J; McKenna, Shawn; Davidson, Jeff; Quijón, Pedro A

2017-06-01

Non-indigenous green crabs (Carcinus maenas) are emerging as important predators of autogenic engineers like American oysters (Crassostrea virginica) throughout the eastern seaboard of Canada and the United States. To document the spreading distribution of green crabs, we carried out surveys in seven sites of Prince Edward Island during three fall seasons. To assess the potential impact of green crabs on oyster mortality in relation to predator and prey size, we conducted multiple predator-prey manipulations in the field and laboratory. The surveys confirmed an ongoing green crab spread into new productive oyster habitats while rapidly increasing in numbers in areas where crabs had established already. The experiments measured mortality rates on four sizes of oysters exposed to three sizes of crab, and lasted 3-5 days. The outcomes of experiments conducted in Vexar ® bags, laboratory tanks and field cages were consistent and were heavily dependent on both crab size and oyster size: while little predation occurred on large oysters, large and medium green crabs preyed heavily on small sizes. Oysters reached a refuge within the 35-55 mm shell length range; below that range, oysters suffered high mortality due to green crab predation and thus require management measures to enhance their survival. These results are most directly applicable to aquaculture operations and restoration initiatives but have implications for oyster sustainability. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hyperspectral remote sensing of wild oyster reefs

NASA Astrophysics Data System (ADS)

Le Bris, Anthony; Rosa, Philippe; Lerouxel, Astrid; Cognie, Bruno; Gernez, Pierre; Launeau, Patrick; Robin, Marc; Barillé, Laurent

2016-04-01

The invasion of the wild oyster Crassostrea gigas along the western European Atlantic coast has generated changes in the structure and functioning of intertidal ecosystems. Considered as an invasive species and a trophic competitor of the cultivated conspecific oyster, it is now seen as a resource by oyster farmers following recurrent mass summer mortalities of oyster spat since 2008. Spatial distribution maps of wild oyster reefs are required by local authorities to help define management strategies. In this work, visible-near infrared (VNIR) hyperspectral and multispectral remote sensing was investigated to map two contrasted intertidal reef structures: clusters of vertical oysters building three-dimensional dense reefs in muddy areas and oysters growing horizontally creating large flat reefs in rocky areas. A spectral library, collected in situ for various conditions with an ASD spectroradiometer, was used to run Spectral Angle Mapper classifications on airborne data obtained with an HySpex sensor (160 spectral bands) and SPOT satellite HRG multispectral data (3 spectral bands). With HySpex spectral/spatial resolution, horizontal oysters in the rocky area were correctly classified but the detection was less efficient for vertical oysters in muddy areas. Poor results were obtained with the multispectral image and from spatially or spectrally degraded HySpex data, it was clear that the spectral resolution was more important than the spatial resolution. In fact, there was a systematic mud deposition on shells of vertical oyster reefs explaining the misclassification of 30% of pixels recognized as mud or microphytobenthos. Spatial distribution maps of oyster reefs were coupled with in situ biomass measurements to illustrate the interest of a remote sensing product to provide stock estimations of wild oyster reefs to be exploited by oyster producers. This work highlights the interest of developing remote sensing techniques for aquaculture applications in coastal areas.

The diversity of shell matrix proteins: genome-wide investigation of the pearl oyster, Pinctada fucata.

PubMed

Miyamoto, Hiroshi; Endo, Hirotoshi; Hashimoto, Naoki; Limura, Kurin; Isowa, Yukinobu; Kinoshita, Shigeharu; Kotaki, Tomohiro; Masaoka, Tetsuji; Miki, Takumi; Nakayama, Seiji; Nogawa, Chihiro; Notazawa, Atsuto; Ohmori, Fumito; Sarashina, Isao; Suzuki, Michio; Takagi, Ryousuke; Takahashi, Jun; Takeuchi, Takeshi; Yokoo, Naoki; Satoh, Nori; Toyohara, Haruhiko; Miyashita, Tomoyuki; Wada, Hiroshi; Samata, Tetsuro; Endo, Kazuyoshi; Nagasawa, Hiromichi; Asakawa, Shuichi; Watabe, Shugo

2013-10-01

In molluscs, shell matrix proteins are associated with biomineralization, a biologically controlled process that involves nucleation and growth of calcium carbonate crystals. Identification and characterization of shell matrix proteins are important for better understanding of the adaptive radiation of a large variety of molluscs. We searched the draft genome sequence of the pearl oyster Pinctada fucata and annotated 30 different kinds of shell matrix proteins. Of these, we could identified Perlucin, ependymin-related protein and SPARC as common genes shared by bivalves and gastropods; however, most gastropod shell matrix proteins were not found in the P. fucata genome. Glycinerich proteins were conserved in the genus Pinctada. Another important finding with regard to these annotated genes was that numerous shell matrix proteins are encoded by more than one gene; e.g., three ACCBP-like proteins, three CaLPs, five chitin synthase-like proteins, two N16 proteins (pearlins), 10 N19 proteins, two nacreins, four Pifs, nine shematrins, two prismalin-14 proteins, and 21 tyrosinases. This diversity of shell matrix proteins may be implicated in the morphological diversity of mollusc shells. The annotated genes reported here can be searched in P. fucata gene models version 1.1 and genome assembly version 1.0 ( http://marinegenomics.oist.jp/pinctada_fucata ). These genes should provide a useful resource for studies of the genetic basis of biomineralization and evaluation of the role of shell matrix proteins as an evolutionary toolkit among the molluscs.

Absence of surface-associated microorganisms in adult oysters (Crassostrea gigas).

PubMed Central

Garland, C D; Nash, G V; McMeekin, T A

1982-01-01

Healthy, actively feeding intertidal oysters were removed from an estuarine environment (Pipeclay Lagoon, Tasmania). The epithelial surfaces of various organs of the mantle cavity and alimentary tract were explored by scanning and transmission electron microscopy. All epithelial tissues examined were ciliated, and nearly all were partly covered with secreted mucus. However, microorganisms were seen rarely in the adhesive mucus and never attached to the epithelium. Electron microscopy also failed to demonstrate a surface microflora in emersed oysters which had been incubated at 5 to 25 degrees C for 6 or 24 h. The absence of an internal surface microflora did not vary on a seasonal basis. In laboratory experiments, oysters were allowed to filter feed from seawater containing diverse types of marine bacteria at concentrations of 10(3) to 10(7)/mL. However, no surface microflora could be found within actively feeding oysters or in emersed animals incubated at 20 degrees C for 6 or 24 h. In contrast, surface-associated microorganisms were detected readily by scanning electron microscopy on the external shell of healthy oysters and on various internal tissues in spoiled oysters. It is suggested that the major mechanisms restricting microbial growth within oysters are ciliary movement and mucus secretion. Images PMID:7181503

Interactive effects of elevated temperature and CO2 levels on energy metabolism and biomineralization of marine bivalves Crassostrea virginica and Mercenaria mercenaria.

PubMed

Ivanina, Anna V; Dickinson, Gary H; Matoo, Omera B; Bagwe, Rita; Dickinson, Ashley; Beniash, Elia; Sokolova, Inna M

2013-09-01

The continuing increase of carbon dioxide (CO2) levels in the atmosphere leads to increases in global temperatures and partial pressure of CO2 (PCO2) in surface waters, causing ocean acidification. These changes are especially pronounced in shallow coastal and estuarine waters and are expected to significantly affect marine calcifiers including bivalves that are ecosystem engineers in estuarine and coastal communities. To elucidate potential effects of higher temperatures and PCO2 on physiology and biomineralization of marine bivalves, we exposed two bivalve species, the eastern oysters Crassostrea virginica and the hard clams Mercenaria mercenaria to different combinations of PCO2 (~400 and 800μatm) and temperatures (22 and 27°C) for 15weeks. Survival, bioenergetic traits (tissue levels of lipids, glycogen, glucose and high energy phosphates) and biomineralization parameters (mechanical properties of the shells and activity of carbonic anhydrase, CA) were determined in clams and oysters under different temperature and PCO2 regimes. Our analysis showed major inter-species differences in shell mechanical traits and bioenergetics parameters. Elevated temperature led to the depletion of tissue energy reserves indicating energy deficiency in both species and resulted in higher mortality in oysters. Interestingly, while elevated PCO2 had a small effect on the physiology and metabolism of both species, it improved survival in oysters. At the same time, a combination of high temperature and elevated PCO2 lead to a significant decrease in shell hardness in both species, suggesting major changes in their biomineralization processes. Overall, these studies show that global climate change and ocean acidification might have complex interactive effects on physiology, metabolism and biomineralization in coastal and estuarine marine bivalves. Copyright © 2013 Elsevier Inc. All rights reserved.

The effects of x-ray treatments on bioaccumulated murine norovirus-1 (MNV-1) and survivability, inherent microbiota, color, and firmness of Atlantic oysters (Crassostrea virginica) during storage at 5°C for 20 days

USDA-ARS?s Scientific Manuscript database

In this study, we investigated the inactivation of human norovirus (HuNoV) surrogate Murine norovirus (MNV-1) by X-ray in whole-shell Atlantic oysters (Crassostrea virginica). We also investigated the effects of X-ray treatments on the survivability, inherent microbiota, color, and firmness of treat...

Oysters, estuaries, and Late Pleistocene-Holocene sea level, northeastern Gulf of Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schroeder, W.W.; Shultz, A.W.

1993-03-01

The timing and magnitude of global sea level fluctuations over the past 35 kyr remain nondum ostenduntur after three decades of study. The construction of local relative sea level histories is often complicated by the need to assess regional tectonic and climatic components together. The authors attempt to contribute to an understanding of sea level fluctuations in the northeastern Gulf of Mexico through the application of faunal tracking, using fossil oyster shells as indicators of paleoestuarine environments. They assume that sites on the continental shelf where oysters have been collected were coastal and therefore are reasonable approximations of past shorelinemore » locations and sea-level elevations. They acknowledge that this assumption is a leap of faith for some observers, but is justified as a provisional step toward an independent determination. Insights into Quaternary coastal paleogeography are gathered from locations and radiocarbon ages of American oyster (Crassostrea virginica) shells collected from the Alabama continental shelf. Prior to the onset of the last Wisconsinan glaciation (35 to 26 kyr BP), estuaries occupied a zone 20 to 25 km seaward of today's coastline. As glaciation increased and sea level was lowered (23 to 21 kyr BP), open coastal estuarine conditions developed southward. Oysters dating from the lowstand period (20 to 16 kyr BP) have not been collected. As sea level rose over the next 10 kyr (16 to 6 kyr BP), estuaries were displaced northward in steps. This data on depths and ages can be viewed as supporting an interpretation of fluctuating Holocene sea level, rather than a steady sea-level rise.« less

Interactive Effects of Seawater Acidification and Elevated Temperature on the Transcriptome and Biomineralization in the Pearl Oyster Pinctada fucata.

PubMed

Li, Shiguo; Huang, Jingliang; Liu, Chuang; Liu, Yangjia; Zheng, Guilan; Xie, Liping; Zhang, Rongqing

2016-02-02

Interactive effects of ocean acidification and ocean warming on marine calcifiers vary among species, but little is known about the underlying mechanisms. The present study investigated the combined effects of seawater acidification and elevated temperature (ambient condition: pH 8.1 × 23 °C, stress conditions: pH 7.8 × 23 °C, pH 8.1 × 28 °C, and pH 7.8 × 28 °C, exposure time: two months) on the transcriptome and biomineralization of the pearl oyster Pinctada fucata, which is an important marine calcifier. Transcriptome analyses indicated that P. fucata implemented a compensatory acid-base mechanism, metabolic depression and positive physiological responses to mitigate the effects of seawater acidification alone. These responses were energy-expensive processes, leading to decreases in the net calcification rate, shell surface calcium and carbon content, and changes in the shell ultrastructure. Elevated temperature (28 °C) within the thermal window of P. fucata did not induce significant enrichment of the sequenced genes and conversely facilitated calcification, which was detected to alleviate the negative effects of seawater acidification on biomineralization and the shell ultrastructure. Overall, this study will help elucidate the mechanisms by which pearl oysters respond to changing seawater conditions and predict the effects of global climate change on pearl aquaculture.

Testing the effect of habitat structure and complexity on nekton assemblages using experimental oyster reefs

USGS Publications Warehouse

Humphries, Austin T.; LaPeyre, Megan K.; Kimball, Matthew E.; Rozas, Lawrence P.

2011-01-01

Structurally complex habitats are often associated with more diverse and abundant species assemblages in both aquatic and terrestrial ecosystems. Biogenic reefs formed by the eastern oyster (Crassostrea virginica) are complex in nature and are recognized for their potential habitat value in estuarine systems along the US Atlantic and Gulf of Mexico coasts. Few studies, however, have examined the response of nekton to structural complexity within oyster reefs. We used a quantitative sampling technique to examine how the presence and complexity of experimental oyster reefs influence the abundance, biomass, and distribution of nekton by sampling reefs 4 months and 16 months post-construction. Experimental oyster reefs were colonized immediately by resident fishes and decapod crustaceans, and reefs supported a distinct nekton assemblage compared to mud-bottom habitat. Neither increased reef complexity, nor age of the experimental reef resulted in further changes in nekton assemblages or increases in nekton abundance or diversity. The presence of oyster reefs per se was the most important factor determining nekton usage.

A new non-indigenous Crassostrea species in Southwest Atlantic salt marshes affects mortality of the cordgrass Spartina alterniflora

NASA Astrophysics Data System (ADS)

Lomovasky, Betina J.; Alvarez, Graciela; Addino, Mariana; Montemayor, Diana I.; Iribarne, Oscar

2014-07-01

Biological invasions in marine and coastal systems may produce new trophic and nontrophic interactions influencing the structure of the invaded community. In the intertidal salt marshes of Samborombón Bay (36°19‧20″S, 56°46‧26″W; mouth of La Plata River; Argentina), there is a new non-indigenous oyster species, Crassostrea sp., which settles on the dominant smooth cordgrass Spartina alterniflora. Here, we analyzed if the oyster affects S. alterniflora. Sampling showed that density of live plant was similar across intertidal levels, but there were higher density of dead plant stems at low intertidal levels. This pattern coincides with higher density and larger shell size of Crassostrea sp. at the low intertidal where oysters are attached to the basal part of the plant stems. An experiment manipulating oysters attached to S. alterniflora stems and oyster mimics shows that Crassostrea sp. can indeed increase mortality of S. alterniflora. The negative effect of bivalves on plant could be because several oysters settle around the Spartina stem, and by growing during the year, strangle the plants increasing their mortality rate. Together, all these evidences strongly suggest that these non-indigenous oysters can control the lower intertidal level of plant distribution in this system.

Oyster-bioimmured ammonites from the Upper Albian of Annopol, Poland: stratigraphic and palaeobiogeographic implications

NASA Astrophysics Data System (ADS)

Machalski, Marcin; Kennedy, William J.

2013-12-01

Machalski, M. and Kennedy, W.J. 2013. Oyster-bioimmured ammonites from the Upper Albian of Annopol, Poland: stratigraphic and palaeobiogeographic implications. Acta Geologica Polonica, 63 (4), 545-554. Warszawa. Ammonites Mortoniceras (Subschloenbachia) sp. are preserved as attachment scars on the oyster shells from the topmost portion of the Albian succession at Annopol, Poland. These oyster-bioimmured ammonites show a closest affinity to the representatives of Mortoniceras (Subschloenbachia) characteristic of the upper Upper Albian Mortoniceras perinflatum Zone. No ammonites indicative of the uppermost Albian-lowermost Cenomanian Praeschloenbachia briacensis Zone are recorded. Thus, the hiatus at the Albian-Cenomanian boundary at Annopol embraces the latter zone. The presence (and dominance) of Mortoniceras in the upper Upper Albian ammonite assemblage of Annopol suggests that the representatives of this Tethyan genus could migrate into the epicratonic areas of Poland directly from the Tethyan Realm, via the Lwow (Lviv) region.

A Restoration Suitability Index Model for the Eastern Oyster (Crassostrea virginica) in the Mission-Aransas Estuary, TX, USA

PubMed Central

Beseres Pollack, Jennifer; Cleveland, Andrew; Palmer, Terence A.; Reisinger, Anthony S.; Montagna, Paul A.

2012-01-01

Oyster reefs are one of the most threatened marine habitats on earth, with habitat loss resulting from water quality degradation, coastal development, destructive fishing practices, overfishing, and storm impacts. For successful and sustainable oyster reef restoration efforts, it is necessary to choose sites that support long-term growth and survival of oysters. Selection of suitable sites is critically important as it can greatly influence mortality factors and may largely determine the ultimate success of the restoration project. The application of Geographic Information Systems (GIS) provides an effective methodology for identifying suitable sites for oyster reef restoration and removes much of the uncertainty involved in the sometimes trial and error selection process. This approach also provides an objective and quantitative tool for planning future oyster reef restoration efforts. The aim of this study was to develop a restoration suitability index model and reef quality index model to characterize locations based on their potential for successful reef restoration within the Mission-Aransas Estuary, Texas, USA. The restoration suitability index model focuses on salinity, temperature, turbidity, dissolved oxygen, and depth, while the reef quality index model focuses on abundance of live oysters, dead shell, and spat. Size-specific Perkinsus marinus infection levels were mapped to illustrate general disease trends. This application was effective in identifying suitable sites for oyster reef restoration, is flexible in its use, and provides a mechanism for considering alternative approaches. The end product is a practical decision-support tool that can be used by coastal resource managers to improve oyster restoration efforts. As oyster reef restoration activities continue at small and large-scales, site selection criteria are critical for assisting stakeholders and managers and for maximizing long-term sustainability of oyster resources. PMID:22792410

Identification and characterization of a matrix protein (PPP-10) in the periostracum of the pearl oyster, Pinctada fucata.

PubMed

Nakayama, Seiji; Suzuki, Michio; Endo, Hirotoshi; Iimura, Kurin; Kinoshita, Shigeharu; Watabe, Shugo; Kogure, Toshihiro; Nagasawa, Hiromichi

2013-01-01

The periostracum is a layered structure that is formed as a mollusk shell grows. The shell is covered by the periostracum, which consists of organic matrices that prevent decalcification of the shell. In the present study, we discovered the presence of chitin in the periostracum and identified a novel matrix protein, Pinctada fucata periostracum protein named PPP-10. It was purified from the sodium dodecyl sulfate/dithiothreitol-soluble fraction of the periostracum of the Japanese pearl oyster, P. fucata. The deduced amino acid sequence was determined by a combination of amino acid sequence analysis and cDNA cloning. The open reading frame encoded a precursor protein of 112 amino acid residues including a 21-residue signal peptide. The 91 residues following the signal peptide contained abundant Cys and Tyr residues. PPP-10 was expressed on the outer side of the outer fold in the mantle, indicating that PPP-10 was present in the second or third layer of the periostracum. We also determined that the recombinant PPP-10 had chitin-binding activity and could incorporate chitin into the scaffolds of the periostracum. These results shed light on the early steps in mollusk shell formation.

Identification and characterization of a matrix protein (PPP-10) in the periostracum of the pearl oyster, Pinctada fucata☆

PubMed Central

Nakayama, Seiji; Suzuki, Michio; Endo, Hirotoshi; Iimura, Kurin; Kinoshita, Shigeharu; Watabe, Shugo; Kogure, Toshihiro; Nagasawa, Hiromichi

2013-01-01

The periostracum is a layered structure that is formed as a mollusk shell grows. The shell is covered by the periostracum, which consists of organic matrices that prevent decalcification of the shell. In the present study, we discovered the presence of chitin in the periostracum and identified a novel matrix protein, Pinctada fucata periostracum protein named PPP-10. It was purified from the sodium dodecyl sulfate/dithiothreitol-soluble fraction of the periostracum of the Japanese pearl oyster, P. fucata. The deduced amino acid sequence was determined by a combination of amino acid sequence analysis and cDNA cloning. The open reading frame encoded a precursor protein of 112 amino acid residues including a 21-residue signal peptide. The 91 residues following the signal peptide contained abundant Cys and Tyr residues. PPP-10 was expressed on the outer side of the outer fold in the mantle, indicating that PPP-10 was present in the second or third layer of the periostracum. We also determined that the recombinant PPP-10 had chitin-binding activity and could incorporate chitin into the scaffolds of the periostracum. These results shed light on the early steps in mollusk shell formation. PMID:24251105

Pesticides and Ostreid Herpesvirus 1 Infection in the Pacific Oyster, Crassostrea gigas.

PubMed

Moreau, Pierrick; Faury, Nicole; Burgeot, Thierry; Renault, Tristan

2015-01-01

Since 2008, mass mortality outbreaks have been reported in all French regions producing Pacific oysters, and in several Member States of the European Union. These mass mortality events of Pacific oysters are related to OsHV-1 infection. They occur during spring and summer periods leaving suspect the quality of the marine environment and the role of seasonal use of pesticides associated with the arrival of freshwater in oyster rearing areas. Pesticides have been also detected in French coastal waters, especially in areas of oyster production. Using PMA real-time PCR we showed that a mixture of 14 pesticides has no effect on the integrity of virus capsids from viral suspension in the conditions tested. A contact of oysters with this pesticide mixture was related to higher mortality rates among experimentally infected animals in comparison with control ones (no previous pesticide exposure before experimental infection). We therefore suggest that pesticides at realistic concentration can exert adverse effects on Pacific oysters and causes an increased susceptibility to the viral infection in experimental conditions.

Pesticides and Ostreid Herpesvirus 1 Infection in the Pacific Oyster, Crassostrea gigas

PubMed Central

Moreau, Pierrick; Faury, Nicole; Burgeot, Thierry; Renault, Tristan

2015-01-01

Since 2008, mass mortality outbreaks have been reported in all French regions producing Pacific oysters, and in several Member States of the European Union. These mass mortality events of Pacific oysters are related to OsHV-1 infection. They occur during spring and summer periods leaving suspect the quality of the marine environment and the role of seasonal use of pesticides associated with the arrival of freshwater in oyster rearing areas. Pesticides have been also detected in French coastal waters, especially in areas of oyster production. Using PMA real-time PCR we showed that a mixture of 14 pesticides has no effect on the integrity of virus capsids from viral suspension in the conditions tested. A contact of oysters with this pesticide mixture was related to higher mortality rates among experimentally infected animals in comparison with control ones (no previous pesticide exposure before experimental infection). We therefore suggest that pesticides at realistic concentration can exert adverse effects on Pacific oysters and causes an increased susceptibility to the viral infection in experimental conditions. PMID:26107171

21 CFR 161.130 - Oysters.

Code of Federal Regulations, 2011 CFR

2011-04-01

... thoroughly drained and are packed without any added substance. (c) For the purposes of this section: (1..., in the shell, which, after removal from their beds, have not been floated or otherwise held under...

Stabilization of Pb and Cd contaminated soils and soil quality improvements using waste oyster shells.

PubMed

Ok, Yong Sik; Lim, Jung Eun; Moon, Deok Hyun

2011-02-01

Large amounts of oyster shells are produced as a by-product of shellfish farming in coastal regions without beneficial use options. Accordingly, this study was conducted to evaluate the potential for the use of waste oyster shells (WOS) containing a high amount of CaCO₃ to improve soil quality and to stabilize heavy metals in soil. To accomplish this, an incubation experiment was conducted to evaluate the ability of the addition of 1-5 wt% WOS to stabilize the Pb (total 1,246 mg/kg) and Cd (total 17 mg/kg) in a contaminated soil. The effectiveness of the WOS treatments was evaluated using various single extraction techniques. Soil amended with WOS was cured for 30 days complied with the Korean Standard Test method (0.1 M·HCl extraction). The Pb and Cd concentrations were less than the Korean warning and countermeasure standards following treatment with 5 wt% WOS. Moreover, the concentrations of Cd were greatly reduced in response to WOS treatment following extraction using 0.01 M·CaCl₂, which is strongly associated with phytoavailability. Furthermore, the soil pH and exchangeable Ca increased significantly in response to WOS treatment. Taken together, the results of this study indicated that WOS amendments improved soil quality and stabilized Pb and Cd in contaminated soil. However, extraction with 0.43 M·CH₃ COOH revealed that remobilization of heavy metals can occur when the soil reaches an acidic condition.

Efficiency of a multi-soil-layering system on wastewater treatment using environment-friendly filter materials.

PubMed

Ho, Chia-Chun; Wang, Pei-Hao

2015-03-23

The multi-soil-layering (MSL) system primarily comprises two parts, specifically, the soil mixture layer (SML) and the permeable layer (PL). In Japan, zeolite is typically used as the permeable layer material. In the present study, zeolite was substituted with comparatively cheaper and more environmentally friendly materials, such as expanded clay aggregates, oyster shells, and already-used granular activated carbon collected from water purification plants. A series of indoor tests indicated that the suspended solid (SS) removal efficiency of granular activated carbon was between 76.2% and 94.6%; zeolite and expanded clay aggregates achieved similar efficiencies that were between 53.7% and 87.4%, and oyster shells presented the lowest efficiency that was between 29.8% and 61.8%. Further results show that the oyster shell system required an increase of wastewater retention time by 2 to 4 times that of the zeolite system to maintain similar chemical oxygen demand (COD) removal efficiency. Among the four MSL samples, the zeolite system and granular activated carbon system demonstrated a stable NH3-N removal performance at 92.3%-99.8%. The expanded clay aggregate system present lower removal performance because of its low adsorption capacity and excessively large pores, causing NO3--N to be leached away under high hydraulic loading rate conditions. The total phosphorous (TP) removal efficiency of the MSL systems demonstrated no direct correlation with the permeable layer material. Therefore, all MSL samples achieved a TP efficiency of between 92.1% and 99.2%.

The impact of suspended oyster farming on nitrogen cycling and nitrous oxide production in a sub-tropical Australian estuary

NASA Astrophysics Data System (ADS)

Erler, Dirk V.; Welsh, David T.; Bennet, William W.; Meziane, Tarik; Hubas, Cédric; Nizzoli, Daniele; Ferguson, Angus J. P.

2017-06-01

In this study we quantified nitrate (NO3-) reduction (denitrification, anammox and DNRA) and N2O production in sediments and epibiont communities associated with Sydney Rock Oyster (Saccostrea glomerata) farming. In sediments beneath an active suspended oyster farm, DNRA accounted for 98% of NO3- reduction with rates of up to 169 ± 45 μmol N m-2 h-1. Much of this DNRA was fuelled by NO3- derived from nitrification. Reference sediments had significantly lower DNRA rates of 83.8 ± 28.2 μmol N m-2 h-1, however this constituted 96% of the sites total NO3- reduction. Fatty acid analysis showed that sediment organic matter was more labile in the oyster impacted sediments, facilitating subtle shifts in sediment oxygen demand which increased the Fe2+ availability with respect to the reference sediments. The difference in DNRA rate between the sites was attributed to autotrophic oxidation of soluble Fe2+ in sediments underlying the oyster cultures. DNRA was absent in the oyster shell epibiont communities and rates of anammox and denitrification were lower than in the sediments. Production of NH4+ from the oysters and their associated epibionts was larger than DNRA and reached a rate of 206.2 μmol N m-2 h-1. Nitrous oxide production rates were generally low compared to other aquaculture systems and the net flux of N2O for the combined oyster cultivation system (i.e. sediments plus epibionts) was negative, i.e. there was N2O consumption in the sediments beneath the oysters. Overall, subtropical suspended oyster farming systems favour inorganic N retention over N loss.

Limited impact of an invasive oyster on intertidal assemblage structure and biodiversity: the importance of environmental context and functional equivalency with native species.

PubMed

Zwerschke, Nadescha; Hollyman, Philip R; Wild, Romy; Strigner, Robin; Turner, John R; King, Jonathan W

2018-01-01

Impacts of invasive species are context dependent and linked to the ecosystem they occur within. To broaden the understanding of the impact of a globally widespread invasive oyster, Crassostrea ( Magallana ) gigas, intertidal surveys were carried out at 15 different sites in Europe. The impact of C. gigas on macro- (taxa surrounding oyster > 1 cm) and epifaunal (taxa on oyster < 1 cm) benthic communities and α and β-diversity was assessed and compared to those associated with native ecosystem engineers, including the flat oyster Ostrea edulis . Whilst the effect of C. gigas on benthic community structures was dependent on habitat type, epifaunal communities associated with low densities of O. edulis and C. gigas did not differ and changes in benthic assemblage structure owing to the abundance of C. gigas were therefore attributed to the presence of oyster shells. Macrofaunal α-diversity increased with C. gigas cover in muddy habitats, while epifaunal α-diversity decreased at greater oyster densities. Macrofaunal β-diversity was greatest at low densities of C. gigas ; however, it did not differ between samples without and increased densities of oysters. In contrast, epifaunal β-diversity decreased with increasing oyster cover. Different environmental contexts enabled more independent predictions of the effect of C. gigas on native communities. These were found to be low and more importantly not differing from O. edulis . This indicates that, at low densities, C. gigas may be functionally equivalent to the declining native oyster in terms of biodiversity facilitation and aid in re-establishing benthic communities on shores where O. edulis has become extinct.

Spatial and temporal variations in cadmium concentrations and burdens in the Pacific oyster (Crassostrea gigas) sampled from the Pacific north-west.

PubMed

Bendell, Leah I; Feng, Cindy

2009-08-01

Oysters from the north-west coast of Canada contain high levels of cadmium, a toxic metal, in amounts that exceed food safety guidelines for international markets. A first required step to determine the sources of cadmium is to identify possible spatial and temporal trends in the accumulation of cadmium by the oyster. To meet this objective, rather than sample wild and cultured oysters of unknown age and origin, an oyster "grow-out" experiment was initiated. Cultured oyster seed was suspended in the water column up to a depth of 7 m and the oyster seed allowed to mature a period of 3 years until market size. Oysters were sampled bimonthly and at time of sampling, temperature, chlorophyll-a, turbidity and salinity were measured. Oyster total shell length, dry tissue weights, cadmium concentrations (microg g(-1)) and burdens (microg of cadmium oyster(-1)) were determined. Oyster cadmium concentrations and burdens were then interpreted with respect to the spatial and temporal sampling design as well as to the measured physio-chemical and biotic variables. When expressed as a concentration, there was a marked seasonality with concentrations being greater in winter as compared in summer; however no spatial trend was evident. When expressed as a burden which corrects for differences in tissue mass, there was no seasonality, however cadmium oyster burdens increased from south to north. Comparison of cadmium accumulation rates oyster(-1) among sites indicated three locations, Webster Island, on the west side of Vancouver Island, and two within Desolation Sound, Teakerne Arm and Redonda Bay, where point sources of cadmium which are not present at all other sampling locations may be contributing to overall oyster cadmium burdens. Of the four physio-chemical factors measured only temperature and turbidity weakly correlated with tissue cadmium concentrations (r(2)=-0.13; p<0.05). By expressing oyster cadmium both as concentration and burden, regional and temporal patterns were demonstrated, which may have been missed if just concentration was determined.

Pearl aquaculture-profitable environmental remediation?

PubMed

Gifford, S; Dunstan, R H; O'Connor, W; Roberts, T; Toia, R

2004-02-05

Bivalve molluscs are filter feeders, with pearl oysters able to filter water at rates up to 25 lh(-1)g(-1) of dry wt. tissue. Since this process leads to rapid bioaccumulation of recalcitrant pollutants such as heavy metals, organochlorine pesticides and hydrocarbons from impacted sites, it has prompted the widespread use of molluscs as biomonitors to quantify levels of marine pollution. This paper proposes pearl oyster deployment as a novel bioremediation technology for impacted sites to remove toxic contaminants, reduce nutrient loads and lower concentrations of microbial pathogens. Estimates extrapolated from the literature suggest that a modest pearl oyster farm of 100 t oyster material per year could remove 300 kg heavy metals plus 24 kg of organic contaminants via deposition into the tissue and shell. Furthermore, it was estimated that up to 19 kg of nitrogen may be removed from the coastal ecosystem per tonne of pearl oyster harvested. Pearl oysters are also likely to filter substantial amounts of sewage associated microbial pathogens from the water column. Method of cultivation and site selection are the key to minimising negative environmental impacts of bivalve cultivation. Deployment of oysters at sites with high nutrient and contaminant loadings would be advantageous, as these compounds would be removed from the ecosystem whilst generating a value-added product. Future potential may exist for harvesting bio-concentrated elements for commercial production.

A Novel Acidic Matrix Protein, PfN44, Stabilizes Magnesium Calcite to Inhibit the Crystallization of Aragonite*

PubMed Central

Pan, Cong; Fang, Dong; Xu, Guangrui; Liang, Jian; Zhang, Guiyou; Wang, Hongzhong; Xie, Liping; Zhang, Rongqing

2014-01-01

Magnesium is widely used to control calcium carbonate deposition in the shell of pearl oysters. Matrix proteins in the shell are responsible for nucleation and growth of calcium carbonate crystals. However, there is no direct evidence supporting a connection between matrix proteins and magnesium. Here, we identified a novel acidic matrix protein named PfN44 that affected aragonite formation in the shell of the pearl oyster Pinctada fucata. Using immunogold labeling assays, we found PfN44 in both the nacreous and prismatic layers. In shell repair, PfN44 was repressed, whereas other matrix proteins were up-regulated. Disturbing the function of PfN44 by RNAi led to the deposition of porous nacreous tablets with overgrowth of crystals in the nacreous layer. By in vitro circular dichroism spectra and fluorescence quenching, we found that PfN44 bound to both calcium and magnesium with a stronger affinity for magnesium. During in vitro calcium carbonate crystallization and calcification of amorphous calcium carbonate, PfN44 regulated the magnesium content of crystalline carbonate polymorphs and stabilized magnesium calcite to inhibit aragonite deposition. Taken together, our results suggested that by stabilizing magnesium calcite to inhibit aragonite deposition, PfN44 participated in P. fucata shell formation. These observations extend our understanding of the connections between matrix proteins and magnesium. PMID:24302723

Metabolic Energy Demand Is Not Increased during Initial Shell Formation of Bivalves Exposed to Aragonite Undersaturation

NASA Astrophysics Data System (ADS)

Pan, F.; Frieder, C.; Applebaum, S.; Manahan, D. T.

2016-02-01

The Pacific oyster, Crassostrea gigas, is a major commercial species in global aquaculture. Ocean acidification is having a negative effect on larval production of this species, so the mechanisms of this impact are of considerable interest. Formation of new shell in C. gigas during the first 2-days post-fertilization results in a rapid six-fold increase in total mass. This period of early development has high sensitivity to changes in carbonate chemistry, in particular aragonite saturation state (Ω). An elevated energy cost for calcification at low Ω is often invoked as a mechanism. In this study, we characterized the developmental progression of first shell formation, total metabolic expenditure, and underlying biochemical processes of energy allocation during early development of C. gigas, under control (Ω >> 1) and undersaturated conditions (Ω < 1). While undersaturated conditions delayed the onset of calcification and resulted in decreased shell mass, there was no change in total metabolic energy demand. Furthermore, partitioning of total metabolic energy showed no major re-allocation of ATP to protein synthesis or ion pump activity (Na+, K+-ATPase) between the two treatments. We conclude that early development to the shelled-veliger larval stage does not require more energy at undersaturation. This finding helps constrain potential mechanisms of larval sensitivity to ocean acidification and narrows the focus for possible mitigation strategies for oyster aquaculture production.

Cloning and expression patterns of two Smad genes during embryonic development and shell formation of the Pacific oyster Crassostrea gigas

NASA Astrophysics Data System (ADS)

Liu, Gang; Huan, Pin; Liu, Baozhong

2014-11-01

Increasing evidence indicates that transforming growth factor β (TGF-β) signaling pathways play many important roles in the early development of mollusks. However, limited information is known concerning their detailed mechanisms. Here, we describe the identification, cloning and characterization of two Smad genes, the key components of TGF-β signaling pathways, from the Pacific oyster Crassostrea gigas. Sequence analysis of the two genes, designated as cgi-smad1/ 5/ 8 and cgi-smad4, revealed conserved functional characteristics. The two genes were widely expressed in embryos and larvae, suggesting multiple roles in the early development of C. gigas. The mRNA of the two genes aggregated in the D quadrant and cgi-smad4 was highly expressed on the dorsal side of the gastrula, indicating that TGF-β signaling pathways may be involved in dorsoventral patterning in C. gigas. Furthermore, high expression levels of the two genes in the shell fields of embryos at different stages suggested important roles for TGF-β signaling pathways in particular phases of shell development, including the formation of the initial shell field and the biomineralization of larval shells. The results of this study provide fundamental support for elucidating how TGF-β signaling pathways participate in the early development of bivalve mollusks, and suggest that further work is warranted to this end.

A SoxC gene related to larval shell development and co-expression analysis of different shell formation genes in early larvae of oyster.

PubMed

Liu, Gang; Huan, Pin; Liu, Baozhong

2017-06-01

Among the potential larval shell formation genes in mollusks, most are expressed in cells surrounding the shell field during the early phase of shell formation. The only exception (cgi-tyr1) is expressed in the whole larval mantle and thus represents a novel type of expression pattern. This study reports another gene with such an expression pattern. The gene encoded a SoxC homolog of the Pacific oyster Crassostrea gigas and was named cgi-soxc. Whole-mount in situ hybridization revealed that the gene was highly expressed in the whole larval mantle of early larvae. Based on its spatiotemporal expression, cgi-soxc is hypothesized to be involved in periostracum biogenesis, biomineralization, and regulation of cell proliferation. Furthermore, we investigated the interrelationship between cgi-soxc expression and two additional potential shell formation genes, cgi-tyr1 and cgi-gata2/3. The results confirmed co-expression of the three genes in the larval mantle of early D-veliger. Nevertheless, cgi-gata2/3 was only expressed in the mantle edge, and the other two genes were expressed in all mantle cells. Based on the spatial expression patterns of the three genes, two cell groups were identified from the larval mantle (tyr1 + /soxc + /gata2/3 + cells and tyr1 + /soxc + /gata2/3 - cells) and are important to study the differentiation and function of this tissue. The results of this study enrich our knowledge on the structure and function of larval mantle and provide important information to understand the molecular mechanisms of larval shell formation.

Detection and distribution of ostreid herpesvirus 1 in experimentally infected Pacific oyster spat.

PubMed

Segarra, Amélie; Baillon, Laury; Faury, Nicole; Tourbiez, Delphine; Renault, Tristan

2016-01-01

High mortality rates are reported in spat and larvae of Pacific oyster Crassostrea gigas and associated with ostreid herpesvirus 1 (OsHV-1) detection in France. Although the viral infection has been experimentally reproduced in oyster larvae and spat, little knowledge is currently available concerning the viral entry and its distribution in organs and tissues. This study compares OsHV-1 DNA and RNA detection and localization in experimentally infected oysters using two virus doses: a low dose that did not induce any mortality and a high dose inducing high mortality. Real time PCR demonstrated significant differences in terms of viral DNA amounts between the two virus doses. RNA transcripts were detected in oysters receiving the highest dose of viral suspension whereas no transcript was observed in oysters injected with the low dose. This study also allowed observing kinetics of viral DNA and RNA detection in different tissues of oyster spat. Finally, viral detection was significantly different in function of tissues (p<0.005), time (p<0.005) with an interaction between tissues and time (p<0.005) for each probe. Copyright © 2015 Elsevier Inc. All rights reserved.

Estimates of Heritability for Growth and Shell Color Traits and Their Genetic Correlations in the Black Shell Strain of Pacific Oyster Crassostrea gigas.

PubMed

Xu, Lan; Li, Qi; Yu, Hong; Kong, Lingfeng

2017-10-01

The Pacific oyster Crassostrea gigas has been introduced widely and massively and became an economically important aquaculture species on a global scale. We estimated heritabilities of growth and shell color traits and their genetic correlations in black shell strain of C. gigas. Analyses were performed on 22 full-sib families in a nested mating design including 410 individuals at harvest (24 months of age). The parentage assignment was inferred based on four panels of multiplex PCR markers including 10 microsatellite loci and 94.9% of the offspring were unambiguously assigned to single parent pairs. The Spearman correlation test (r = - 0.992, P < 0.001) demonstrated the high consistency of the shell pigmentation (SP) and L* and their same efficacy in shell color measurements. The narrow-sense heritability estimated under the animal model analysis was 0.18 ± 0.12 for shell height, 0.25 ± 0.16 for shell length, 0.10 ± 0.09 for shell width, 0.42 ± 0.20 for total weight, 0.32 ± 0.18 for shell weight, and 0.68 ± 0.16 for L*, 0.69 ± 0.16 for shell pigmentation, respectively. The considerable additive genetic variation in growth and shell color traits will make it feasible to produce genetic improvements for these traits in selective breeding program. High genetic and phenotypic correlations were found among growth traits and among shell color traits. To optimize a selection strategy for both fast growth and pure dark shell strain of C. gigas, it is proposed to take both total weight and black shell as joint objective traits in selective breeding program. Our study offers an important reference in the process of selective breeding in black shell color stain of C. gigas and will facilitate to develop favorable breeding strategies of genetic improvements for this economically important strain.

Archeological Testing at 16 cm 61, a Prehistoric Shell Midden in Cameron Parish, Louisiana.

DTIC Science & Technology

1986-07-09

Crassostrea virginica Eastern oyster Littoridina sphinctogtoma(? Ep’iscynia inornata hairy vitrinella Fish Amia calva bowfin or choupique Aplodinotus...III Molluscs Rangia cuneata 1198 valves Crassostrea virginica 7 shell pieces Fish -’. Lepisosteus sp. 6 vertebrae, 53 scales Amia calva 2 vertebrae, 7... Amia calva vertebra, toothed bone Aploinots grunniens or Pogonias chromis 2 pharyngeal teeth unidentified teleost 4 vertebrae, ctenoid scale Mammal

Contribution of in Vivo Experimental Challenges to Understanding Flat Oyster Ostrea edulis Resistance to Bonamia ostreae

PubMed Central

Morga, Benjamin; Renault, Tristan; Faury, Nicole; Lerond, Sophie; Garcia, Céline; Chollet, Bruno; Joly, Jean-Pierre; Lapègue, Sylvie; Harrang, Estelle; Arzul, Isabelle

2017-01-01

Bonamiosis due to the parasite Bonamia ostreae has been associated with massive mortality outbreaks in European flat oyster stocks in Europe. As eradication and treatment are not possible, the control of the disease mainly relies on transfer restriction. Moreover, selection has been applied to produce resistant flat oyster families, which present better survival and lower prevalence than non-selected oysters. In order to better understand the mechanisms involved in resistance to bonamiosis, cellular and molecular responses of 2 oyster groups (selected oysters and wild-type oysters) were analyzed in the context of experimental injection and cohabitation infections. Cellular responses including non-specific esterases detection, ROS production and phagocytosis activity were analyzed by flow cytometry. Four genes homologous to those shown to be involved in immunity were selected (Inhibitor of apotosis OeIAP, Fas ligand OeFas-ligand, Oe-SOD, and OeEc-SOD) and monitored by quantitative reverse-transcription PCR (qRT-PCR). Infected oysters showed higher phagocytosis activity than controls. Infected selected oyster show a lower phagocytosis activity which might be a protection against the parasite infection. The expression of OeIAP and OeFas-ligand gene was significantly increased in selected oysters at 5 days post-injection. OeIAP gene expression appeared to be significantly increased in wild-type oysters at 8 days post-injection. Our results suggest that resistance to bonamiosis partly relies on the ability of the oysters to modulate apoptosis. PMID:29057216

Satellite remote sensing reveals a positive impact of living oyster reefs on microalgal biofilm development

NASA Astrophysics Data System (ADS)

Echappé, Caroline; Gernez, Pierre; Méléder, Vona; Jesus, Bruno; Cognie, Bruno; Decottignies, Priscilla; Sabbe, Koen; Barillé, Laurent

2018-02-01

Satellite remote sensing (RS) is routinely used for the large-scale monitoring of microphytobenthos (MPB) biomass in intertidal mudflats and has greatly improved our knowledge of MPB spatio-temporal variability and its potential drivers. Processes operating on smaller scales however, such as the impact of benthic macrofauna on MPB development, to date remain underinvestigated. In this study, we analysed the influence of wild Crassostrea gigas oyster reefs on MPB biofilm development using multispectral RS. A 30-year time series (1985-2015) combining high-resolution (30 m) Landsat and SPOT data was built in order to explore the relationship between C. gigas reefs and MPB spatial distribution and seasonal dynamics, using the normalized difference vegetation index (NDVI). Emphasis was placed on the analysis of a before-after control-impact (BACI) experiment designed to assess the effect of oyster killing on the surrounding MPB biofilms. Our RS data reveal that the presence of oyster reefs positively affects MPB biofilm development. Analysis of the historical time series first showed the presence of persistent, highly concentrated MPB patches around oyster reefs. This observation was supported by the BACI experiment which showed that killing the oysters (while leaving the physical reef structure, i.e. oyster shells, intact) negatively affected both MPB biofilm biomass and spatial stability around the reef. As such, our results are consistent with the hypothesis of nutrient input as an explanation for the MPB growth-promoting effect of oysters, whereby organic and inorganic matter released through oyster excretion and biodeposition stimulates MPB biomass accumulation. MPB also showed marked seasonal variations in biomass and patch shape, size and degree of aggregation around the oyster reefs. Seasonal variations in biomass, with higher NDVI during spring and autumn, were consistent with those observed on broader scales in other European mudflats. Our study provides the first multi-sensor RS satellite evidence of the promoting and structuring effect of oyster reefs on MPB biofilms.

Reducing oyster-associated bacteria levels using supercritical fluid CO2 as an agent of warm pasteurization.

PubMed

Meujo, Damaris A F; Kevin, Dion A; Peng, Jiangnan; Bowling, John J; Liu, Jianping; Hamann, Mark T

2010-03-31

An innovative approach to Post-Harvest Processing (PHP) of oysters is introduced focusing on the effects of supercritical carbon dioxide (scCO(2)) on bacterial contaminants trapped in the digestive system of oysters. Oysters were exposed to scCO(2) under two conditions: (1) 100 bar and 37 degrees C for 30 min and (2) 172 bar and 60 degrees C for 60 min. Using FDA standard guidelines for food analysis, variations in the Aerobic Plate Count (APC) were assessed. It was established that exposing oysters to CO(2) at 100 bar and 37 degrees C for 30 min and at 172 bar and 60 degrees C for 60 min induced 2-log and 3-log reductions in the APC respectively. The decrease in the microbial load as a result of treatment with scCO(2) was found to be significant (P=0.002). A release of adductor muscles from the shell was noted in oysters treated at 172 bar and 60 degrees C for 60 min; this was not the case for oysters treated at 100 bar and 37 degrees C for 30 min. A blind study allowing sensory analysis of treated vs. untreated oysters was also completed and no significant change in the physical appearance, smell, or texture was recorded. In this paper, we also report the effect of scCO(2) on several bacterial isolates, including a referenced ATCC strain of a non-pathogenic Vibrio (Vibrio fischeri) as well as several other bacterial isolates cultured from oyster' tissues and found to share biochemical features common to pathogenic Vibrio strains. A complete inactivation (minimum 7-log reduction) was achieved with these latter bacterial isolates. A 6-log reduction was observed with V. fischeri. Copyright 2009 Elsevier B.V. All rights reserved.

Optimal Site Characterization and Selection Criteria for Oyster Restoration using Multicolinear Factorial Water Quality Approach

NASA Astrophysics Data System (ADS)

Yoon, J.

2015-12-01

Elevated levels of nutrient loadings have enriched the Chesapeake Bay estuaries and coastal waters via point and nonpoint sources and the atmosphere. Restoring oyster beds is considered a Best Management Practice (BMP) to improve the water quality as well as provide physical aquatic habitat and a healthier estuarine system. Efforts include declaring sanctuaries for brood-stocks, supplementing hard substrate on the bottom and aiding natural populations with the addition of hatchery-reared and disease-resistant stocks. An economic assessment suggests that restoring the ecological functions will improve water quality, stabilize shorelines, and establish a habitat for breeding grounds that outweighs the value of harvestable oyster production. Parametric factorial models were developed to investigate multicolinearities among in situ water quality and oyster restoration activities to evaluate posterior success rates upon multiple substrates, and physical, chemical, hydrological and biological site characteristics to systematically identify significant factors. Findings were then further utilized to identify the optimal sites for successful oyster restoration augmentable with Total Maximum Daily Loads (TMDLs) and BMPs. Factorial models evaluate the relationship among the dependent variable, oyster biomass, and treatments of temperature, salinity, total suspended solids, E. coli/Enterococci counts, depth, dissolved oxygen, chlorophyll a, nitrogen and phosphorus, and blocks consist of alternative substrates (oyster shells versus riprap, granite, cement, cinder blocks, limestone marl or combinations). Factorial model results were then compared to identify which combination of variables produces the highest posterior biomass of oysters. Developed Factorial model can facilitate maximizing the likelihood of successful oyster reef restoration in an effort to establish a healthier ecosystem and to improve overall estuarine water quality in the Chesapeake Bay estuaries.

Efficiency of a Multi-Soil-Layering System on Wastewater Treatment Using Environment-Friendly Filter Materials

PubMed Central

Ho, Chia-Chun; Wang, Pei-Hao

2015-01-01

The multi-soil-layering (MSL) system primarily comprises two parts, specifically, the soil mixture layer (SML) and the permeable layer (PL). In Japan, zeolite is typically used as the permeable layer material. In the present study, zeolite was substituted with comparatively cheaper and more environmentally friendly materials, such as expanded clay aggregates, oyster shells, and already-used granular activated carbon collected from water purification plants. A series of indoor tests indicated that the suspended solid (SS) removal efficiency of granular activated carbon was between 76.2% and 94.6%; zeolite and expanded clay aggregates achieved similar efficiencies that were between 53.7% and 87.4%, and oyster shells presented the lowest efficiency that was between 29.8% and 61.8%. Further results show that the oyster shell system required an increase of wastewater retention time by 2 to 4 times that of the zeolite system to maintain similar chemical oxygen demand (COD) removal efficiency. Among the four MSL samples, the zeolite system and granular activated carbon system demonstrated a stable NH3-N removal performance at 92.3%–99.8%. The expanded clay aggregate system present lower removal performance because of its low adsorption capacity and excessively large pores, causing NO3−-N to be leached away under high hydraulic loading rate conditions. The total phosphorous (TP) removal efficiency of the MSL systems demonstrated no direct correlation with the permeable layer material. Therefore, all MSL samples achieved a TP efficiency of between 92.1% and 99.2%. PMID:25809517

Assessment of waste oyster shells and coal mine drainage sludge for the stabilization of As-, Pb-, and Cu-contaminated soil.

PubMed

Moon, Deok Hyun; Cheong, Kyung Hoon; Koutsospyros, Agamemnon; Chang, Yoon-Young; Hyun, Seunghun; Ok, Yong Sik; Park, Jeong-Hun

2016-02-01

A novel treatment mix was designed for the simultaneous immobilization of As, Cu, and Pb in contaminated soils using natural (waste oyster shells (WOS)) and industrial (coal mine drainage sludge (CMDS)) waste materials. The treatments were conducted using the standard U.S. sieve size no. 20 (0.85 mm) calcined oyster shells (COS) and CMDS materials with a curing time of 1 and 28 days. The As immobilization treatments were evaluated using the 1-N HCl extraction fluid, whereas the Pb and Cu immobilization treatments were evaluated using the 0.1-N HCl extraction fluid based on the Korean leaching standards. The treatment results showed that the immobilization of As, Cu, and Pb was best achieved using a combination mix of 10 wt% COS and 10 wt% CMDS. This treatment mix was highly effective leading to superior leachability reductions for all three target contaminants (>93 % for As and >99 % for Cu and Pb) for a curing period of 28 days. The X-ray absorption near-edge structure (XANES) results showed that As was present in the form of As(V) in the control sample and that no changes in As speciation were observed following the COS-CMDS treatments. The scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy (EDX) sample treated with 10 wt% COS and 10 wt% CMDS indicated that As immobilization may be associated with the formation of Ca-As and Fe-As precipitates while Pb and Cu immobilization was most probably linked to calcium silicate hydrates (CSHs) and calcium aluminum hydrates (CAHs).

Preliminary study of transplanting as a process for reducing levels of Vibrio vulnificus and Vibrio parahaemolyticus in shellstock oysters.

PubMed

Walton, William C; Nelson, Chris; Hochman, Mona; Schwarz, John

2013-01-01

Increasingly strict standards for harvest of oysters for the raw, half-shell market (designated as "white tag") should increase the proportion of oysters not meeting these standards (designated as "green tag"). Transplanting of green tag oysters into highsalinity waters (>20 practical salinity units) was explored as a means of returning Vibrio vulnificus and Vibrio parahaemolyticus levels to levels present on initial harvest. In summer 2011, oysters originally harvested in Louisiana were transplanted on two separate occasions (n = 2) to two sites in Mississippi Sound, AL: Sandy Bay and Dauphin Island. Oysters were tested for V. vulnificus and V. parahaemolyticus densities (by using the U.S. Food and Drug Administration enrichment method) after 2, 7, and 14 days deployed, with baseline samples taken (i) at the time of original harvest and iced, (ii) from oysters refrigerated within 1 h of harvest at <45°F ([7.2°C] white tag) and, (iii) from oysters not refrigerated during the harvest trip (green tag) but refrigerated after an 8-h trip. White and green tag oysters were sampled ∼24 h on arrival in Bon Secour, AL, put on ice, and shipped for analysis. Among baseline samples, there were no significant differences in V. vulnificus and V. parahaemolyticus densities, although the densities in the green tag oysters tended to be highest. After transplanting, V. vulnificus densities were significantly highest on day 2, with no significant differences among any of the other days within a site. On day 2, Sandy Bay had significantly greater densities of V. vulnificus than the Dauphin Island site, but no other days differed from time zero. For Vibrio parahaemolyticus, densities were greatest on day 2 and lowest at time zero, but this did not differ significantly from abundance on day 14. Average survival was 83.4% (± 3.13 SD), with no differences between sites. These preliminary results indicate that high-salinity transplanting could be an effective method of converting green tag oysters to oysters suitable for "reharvest" as white tag oysters.

Ocean Acidification Impacts Larval and Juvenile Growth in the Native Oyster Ostrea lurida

NASA Astrophysics Data System (ADS)

Hettinger, A.; Hoey, J. A.; Sanford, E.; Gaylord, B.; Hill, T. M.; Russell, A. D.

2008-12-01

The impacts of ocean acidification have only recently been recognized as a human-induced stressor on marine ecosystems. Ocean acidification can disrupt calcification in organisms that precipitate calcareous structures, including many ecologically and economically important species. We examined how decreased levels of carbonate saturation affected larval and juvenile growth and settlement in the native oyster Ostrea lurida. Larvae were cultured at three carbonate saturation levels that represent present day CO2 concentrations (380 ppm) and two future projected pCO2 scenarios (540 and 970 ppm). These treatments were maintained for 20 days throughout larval duration until settlement occurred. Larval and juvenile growth were determined by calculating change in shell area. Larvae exposed to 970 ppm grew 12% less than larvae held under control conditions (380 ppm). In addition, growth varied among larvae produced by different parents, suggesting that impacts of ocean acidification might vary intraspecifically. Juvenile growth (i.e., new shell added following settlement) was significantly different among CO2 treatments, and juveniles exposed to 970 ppm grew 24% less than juveniles held under control conditions (380 ppm). Carry-over effects from the larval stage influence juvenile growth, and because post-settlement mortality is often high for marine invertebrates, ocean acidification may negatively impact the size of native oyster populations.

Application of Reflectance Transformation Imaging Technique to Improve Automated Edge Detection in a Fossilized Oyster Reef

NASA Astrophysics Data System (ADS)

Djuricic, Ana; Puttonen, Eetu; Harzhauser, Mathias; Dorninger, Peter; Székely, Balázs; Mandic, Oleg; Nothegger, Clemens; Molnár, Gábor; Pfeifer, Norbert

2016-04-01

The world's largest fossilized oyster reef is located in Stetten, Lower Austria excavated during field campaigns of the Natural History Museum Vienna between 2005 and 2008. It is studied in paleontology to learn about change in climate from past events. In order to support this study, a laser scanning and photogrammetric campaign was organized in 2014 for 3D documentation of the large and complex site. The 3D point clouds and high resolution images from this field campaign are visualized by photogrammetric methods in form of digital surface models (DSM, 1 mm resolution) and orthophoto (0.5 mm resolution) to help paleontological interpretation of data. Due to size of the reef, automated analysis techniques are needed to interpret all digital data obtained from the field. One of the key components in successful automation is detection of oyster shell edges. We have tested Reflectance Transformation Imaging (RTI) to visualize the reef data sets for end-users through a cultural heritage viewing interface (RTIViewer). The implementation includes a Lambert shading method to visualize DSMs derived from terrestrial laser scanning using scientific software OPALS. In contrast to shaded RTI no devices consisting of a hardware system with LED lights, or a body to rotate the light source around the object are needed. The gray value for a given shaded pixel is related to the angle between light source and the normal at that position. Brighter values correspond to the slope surfaces facing the light source. Increasing of zenith angle results in internal shading all over the reef surface. In total, oyster reef surface contains 81 DSMs with 3 m x 2 m each. Their surface was illuminated by moving the virtual sun every 30 degrees (12 azimuth angles from 20-350) and every 20 degrees (4 zenith angles from 20-80). This technique provides paleontologists an interactive approach to virtually inspect the oyster reef, and to interpret the shell surface by changing the light source direction. One source of light for shading does show all morphologic features needed for description. Additionally, more details such as fault lines, overlaps and characteristic edges of complex shell structures are clearly detected by simply changing the illumination on the shaded digital surface model. In a further study, the potential of edge detection of the individual shells will be analyzed based on statistical analysis by keeping track of the local accumulative shading gradient. The results are compared to manually identified edges. In a following study phase, the detected edges will be improved by graph cut segmentation. We assume that this technique can lead to automatically extracted teaching set for object segmentation on a complex environment. The project is supported by the Austrian Science Fund (FWF P 25883-N29).

Interactive effects of salinity and elevated CO2 levels on juvenile eastern oysters, Crassostrea virginica.

PubMed

Dickinson, Gary H; Ivanina, Anna V; Matoo, Omera B; Pörtner, Hans O; Lannig, Gisela; Bock, Christian; Beniash, Elia; Sokolova, Inna M

2012-01-01

Rising levels of atmospheric CO(2) lead to acidification of the ocean and alter seawater carbonate chemistry, which can negatively impact calcifying organisms, including mollusks. In estuaries, exposure to elevated CO(2) levels often co-occurs with other stressors, such as reduced salinity, which enhances the acidification trend, affects ion and acid-base regulation of estuarine calcifiers and modifies their response to ocean acidification. We studied the interactive effects of salinity and partial pressure of CO(2) (P(CO2)) on biomineralization and energy homeostasis in juveniles of the eastern oyster, Crassostrea virginica, a common estuarine bivalve. Juveniles were exposed for 11 weeks to one of two environmentally relevant salinities (30 or 15 PSU) either at current atmospheric P(CO2) (∼400 μatm, normocapnia) or P(CO2) projected by moderate IPCC scenarios for the year 2100 (∼700-800 μatm, hypercapnia). Exposure of the juvenile oysters to elevated P(CO2) and/or low salinity led to a significant increase in mortality, reduction of tissue energy stores (glycogen and lipid) and negative soft tissue growth, indicating energy deficiency. Interestingly, tissue ATP levels were not affected by exposure to changing salinity and P(CO2), suggesting that juvenile oysters maintain their cellular energy status at the expense of lipid and glycogen stores. At the same time, no compensatory upregulation of carbonic anhydrase activity was found under the conditions of low salinity and high P(CO2). Metabolic profiling using magnetic resonance spectroscopy revealed altered metabolite status following low salinity exposure; specifically, acetate levels were lower in hypercapnic than in normocapnic individuals at low salinity. Combined exposure to hypercapnia and low salinity negatively affected mechanical properties of shells of the juveniles, resulting in reduced hardness and fracture resistance. Thus, our data suggest that the combined effects of elevated P(CO2) and fluctuating salinity may jeopardize the survival of eastern oysters because of weakening of their shells and increased energy consumption.

Shotgun proteomics reveals physiological response to ocean acidification in Crassostrea gigas.

PubMed

Timmins-Schiffman, Emma; Coffey, William D; Hua, Wilber; Nunn, Brook L; Dickinson, Gary H; Roberts, Steven B

2014-11-03

Ocean acidification as a result of increased anthropogenic CO2 emissions is occurring in marine and estuarine environments worldwide. The coastal ocean experiences additional daily and seasonal fluctuations in pH that can be lower than projected end-of-century open ocean pH reductions. In order to assess the impact of ocean acidification on marine invertebrates, Pacific oysters (Crassostrea gigas) were exposed to one of four different p CO2 levels for four weeks: 400 μatm (pH 8.0), 800 μatm (pH 7.7), 1000 μatm (pH 7.6), or 2800 μatm (pH 7.3). At the end of the four week exposure period, oysters in all four p CO2 environments deposited new shell, but growth rate was not different among the treatments. However, micromechanical properties of the new shell were compromised by elevated p CO2. Elevated p CO2 affected neither whole body fatty acid composition, nor glycogen content, nor mortality rate associated with acute heat shock. Shotgun proteomics revealed that several physiological pathways were significantly affected by ocean acidification, including antioxidant response, carbohydrate metabolism, and transcription and translation. Additionally, the proteomic response to a second stress differed with p CO2, with numerous processes significantly affected by mechanical stimulation at high versus low p CO2 (all proteomics data are available in the ProteomeXchange under the identifier PXD000835). Oyster physiology is significantly altered by exposure to elevated p CO2, indicating changes in energy resource use. This is especially apparent in the assessment of the effects of p CO2 on the proteomic response to a second stress. The altered stress response illustrates that ocean acidification may impact how oysters respond to other changes in their environment. These data contribute to an integrative view of the effects of ocean acidification on oysters as well as physiological trade-offs during environmental stress.

Delineation of surf scoter habitat in Chesapeake Bay, Maryland: macrobenthic and sediment composition of surf scoter feeding sites

USGS Publications Warehouse

Kidwell, D.M.; Perry, M.C.

2005-01-01

Surveys of surf scoters (Melanitta perspicillata) along the Atlantic coast of the United States have shown population declines in recent decades. The Chesapeake Bay has traditionally been a key wintering area for surf scoters. Past and present research has shown that bivalves constitute a major food item for seaducks in the Chesapeake Bay, with surf scoters feeding primarily on hooked mussel (Ischadium recurvum) and dwarf surf clam (Mulinia lateralis). Degraded water quality conditions in the Chesapeake Bay have been well documented and have been shown to greatly influence the composition of benthic communities. Large concentrations of feeding surf scoters (>500 individuals) in the Bay were determined through monthly boat surveys. Locations consistently lacking surf scoters were also determined. Macrobenthos were seasonally sampled at 3 locations containing scoters and 3 locations without scoters. A 1 kilometer square grid was superimposed over each location using GIS and sampling sites within the square were randomly chosen. Benthos were sampled at each site using SCUBA and a meter square quadrat. Biomass and size class estimates were determined for all bivalves within each kilometer square. Results indicated that scoter feeding sites contained significantly greater biomass of M. lateralis, I. recurvum, and Gemma gemma than locations where no scoters were present. Substrate differences were also detected, with scoter feeding sites being composed of a sand/shell mix while non-scoter sites consisted primarily of mud. This data indicates that surf scoters in the Chesapeake Bay are selecting areas with high densities of preferred food items, potentially maximizing there foraging energetics. In addition, two scoter feeding sites also contained a patchwork of eastern oyster (Crassostrea virginica) and oyster shell, on which much of the I. recurvum was attached. This suggests the possibility that surf scoters utilize eastern oyster habitat and the dramatic depletion of oysters in the Bay could be a possible factor in surf scoter decline. More research is needed into the possible relationship between surf scoters and the eastern oyster.

Ecological periodic tables for benthic macrofaunal usage of estuarine habitats in the US Pacific Northwest

EPA Science Inventory

Estuary-wide benthic macrofauna─habitat associations were determined for 9 habitats (intertidal eelgrass [Zostera marina], dwarf eelgrass [Zostera japonica], oyster [Crassostrea gigas], mud shrimp [Upogebia pugettensis], ghost shrimp [Neotrypaea californiensis], shell, sand, mud,...

[Estimation and experiment of carbon sequestration by oysters attached to the enhancement artificial reefs in Laizhou Bay, Shandong, China].

PubMed

Gong, Pi-Hai; Li, Jiao; Guan, Chang-Tao; Li, Meng-Jie; Liu, Chao

2014-10-01

Through sampling investigation of fouling organisms on the enhancement artificial reefs set up in Laizhou Bay, it was proved that oyster (Ostrea plicatula) was the dominant fouling species. Therefore the dry mass of shell (Ms), total fresh mass (Mt) and thickness (T) of oyster attached on the reefs were analyzed. The results showed that the Mt and Ms presented seasonal variation (P < 0.01), that is, the values were the lowest in April and the highest in December. The reef age and the length of the time the enhancement reefs placed in the sea had significant effect on Mt, Ms and T. With the increment of reef ages, all indices increased obviously. The carbon sinks of oysters attaching to the tube enhancement reefs constructed in 2009, 2010 and 2011 in Laizhou Bay were 17.61, 16.33 and 10.45 kg · m(-3), respectively. The oysters on the enhancement reefs of Jincheng marine ranch with an area of 64.25 hm2 had fixed carbon of 297.5 t C (equivalent to 1071 t of CO2) from 2009 to 2013 in Laizhou Bay. To capture and store the same amount of CO2 would cost about 1.6 x 10(5)-6.4 x 10(5) US dollars. Therefore, oysters attaching to the enhancement reefs bring about remarkable ecological benefits.

Irradiated bivalve mollusks: Use of EPR spectroscopy for identification and dosimetry

NASA Astrophysics Data System (ADS)

Alberti, Angelo; Chiaravalle, Eugenio; Fuochi, Piergiorgio; Macciantelli, Dante; Mangiacotti, Michele; Marchesani, Giuliana; Plescia, Elena

2011-12-01

High energy radiation treatment of foodstuff for microbial control and shelf-life extension is being used in many countries. However, for consumer protection and information, the European Union has adopted the Directives 1999/2/EC and 1999/3/EC to harmonize the rules concerning the treatment and trade of irradiated foods in EU countries. Among the validated methods to detect irradiated foods the EU directives also include Electron Paramagnetic Resonance (EPR/ESR) spectroscopy.We describe herein the use of EPR for identification of four species of bivalve mollusks, i.e. brown Venus shells (Callista chione), clams (Tapes semidecussatus), mussels (Mytilus galloprovincialis) and oysters (Ostrea edulis) irradiated with 60Co γ-rays. EPR could definitely identify irradiated seashells due to the presence of long-lived free radicals, primarily CO2-, CO33-, SO2- and SO3- radical anions. The presence of other organic free radicals, believed to originate from conchiolin, a scleroprotein present in the shells, was also ascertained. The use of one of these radicals as a marker for irradiation of brown Venus shells and clams can be envisaged. We also propose a dosimetric protocol for the reconstruction of the administered dose in irradiated oysters.

Populations, not clones, are the unit of vibrio pathogenesis in naturally infected oysters.

PubMed

Lemire, Astrid; Goudenège, David; Versigny, Typhaine; Petton, Bruno; Calteau, Alexandra; Labreuche, Yannick; Le Roux, Frédérique

2015-07-01

Disease in oysters has been steadily rising over the past decade, threatening the long-term survival of commercial and natural stocks. Our understanding and management of such diseases are of critical importance as aquaculture is an important aspect of dealing with the approaching worldwide food shortage. Although some bacteria of the Vibrio genus isolated from diseased oysters have been demonstrated to be pathogenic by experimental infection, direct causality has not been established. Little is known about the dynamics of how the bacterial population hosted by oysters changes during disease progression. Combining experimental ecology, a high-throughput infection assay and genome sequencing, we show that the onset of disease in oysters is associated with progressive replacement of diverse benign colonizers by members of a phylogenetically coherent virulent population. Although the virulent population is genetically diverse, all members of that population can cause disease. Comparative genomics across virulent and nonvirulent populations identified candidate virulence factors that were clustered in population-specific genomic regions. Genetic analyses revealed that one gene for a candidate virulent factor, a putative outer membrane protein, is necessary for infection of oysters. Finally, analyses of oyster mortality following experimental infection suggest that disease onset can be facilitated by the presence of nonvirulent strains. This is a new form of polymicrobial disease, in which nonpathogenic strains contribute to increase mortality.

Populations, not clones, are the unit of vibrio pathogenesis in naturally infected oysters

PubMed Central

Lemire, Astrid; Goudenège, David; Versigny, Typhaine; Petton, Bruno; Calteau, Alexandra; Labreuche, Yannick; Le Roux, Frédérique

2015-01-01

Disease in oysters has been steadily rising over the past decade, threatening the long-term survival of commercial and natural stocks. Our understanding and management of such diseases are of critical importance as aquaculture is an important aspect of dealing with the approaching worldwide food shortage. Although some bacteria of the Vibrio genus isolated from diseased oysters have been demonstrated to be pathogenic by experimental infection, direct causality has not been established. Little is known about the dynamics of how the bacterial population hosted by oysters changes during disease progression. Combining experimental ecology, a high-throughput infection assay and genome sequencing, we show that the onset of disease in oysters is associated with progressive replacement of diverse benign colonizers by members of a phylogenetically coherent virulent population. Although the virulent population is genetically diverse, all members of that population can cause disease. Comparative genomics across virulent and nonvirulent populations identified candidate virulence factors that were clustered in population-specific genomic regions. Genetic analyses revealed that one gene for a candidate virulent factor, a putative outer membrane protein, is necessary for infection of oysters. Finally, analyses of oyster mortality following experimental infection suggest that disease onset can be facilitated by the presence of nonvirulent strains. This is a new form of polymicrobial disease, in which nonpathogenic strains contribute to increase mortality. PMID:25489729

Reducing Oyster-Associated Bacteria Levels Using Supercritical Fluid CO2 as an Agent of Warm Pasteurization

PubMed Central

Meujo, Damaris A.F.; Kevin, Dion; Peng, Jiangnan; Bowling, John J.; Liu, Jianping; Hamann, Mark T.

2010-01-01

An innovative approach to Post-Harvest Processing (PHP) of oysters is introduced focusing on the effects of supercritical carbon dioxide (scCO2) on bacterial contaminants trapped in the digestive system of oysters. Oysters were exposed to scCO2 under two conditions: (1) 100 bar and 37 °C for 30 minutes and (2) 172 bar and 60 °C for 60 minutes. Using FDA standard guidelines for food analysis, variations in the Aerobic Plate Count (APC) was assessed. It was established that exposing oysters to CO2 at 100 bar and 37 °C for 30 minutes and at 172 bar and 60°C for 60 minutes induced 2-log and 3-log reductions in the APC respectively. The decrease in the microbial load as a result of treatment with scCO2 was found to be significant (P=0.002). A release of adductor muscles from the shell was noted in oysters treated at 172 bar and 60 °C for 60 minutes; this was not the case for oysters treated at 100 bar and 37 °C for 30 minutes. A blind study allowing sensory analysis of treated vs. untreated oysters was also completed and no significant change in the physical appearance, smell, or texture was recorded. In this paper, we also report the effect of scCO2 on several bacterial isolates, including a referenced ATCC strain of a non pathogenic Vibrio (V. fisherii) as well as several other bacterial isolates cultured from oyster’ tissues and found to share biochemical features common to pathogenic Vibrio strains. A complete inactivation (minimum 7-log reduction) was achieved with these latter bacterial isolates. A 6-log reduction was observed with V. fisherii. PMID:20022650

Draft Test Guideline: Oyster Acute Toxicity Test (Shell Deposition)

EPA Pesticide Factsheets

The following draft test guideline is part of a series of test guidelines that have been developed by EPA for use in the testing of pesticides and toxic substances, and the development of test data for submission to the Agency for review.

Antiviral Defense and Innate Immune Memory in the Oyster.

PubMed

Green, Timothy J; Speck, Peter

2018-03-16

The Pacific oyster, Crassostrea gigas , is becoming a valuable model for investigating antiviral defense in the Lophotrochozoa superphylum. In the past five years, improvements to laboratory-based experimental infection protocols using Ostreid herpesvirus I (OsHV-1) from naturally infected C. gigas combined with next-generation sequencing techniques has revealed that oysters have a complex antiviral response involving the activation of all major innate immune pathways. Experimental evidence indicates C. gigas utilizes an interferon-like response to limit OsHV-1 replication and spread. Oysters injected with a viral mimic (polyI:C) develop resistance to OsHV-1. Improved survival following polyI:C injection was found later in life (within-generational immune priming) and in the next generation (multi-generational immune priming). These studies indicate that the oyster's antiviral defense system exhibits a form of innate immune-memory. An important priority is to identify the molecular mechanisms responsible for this phenomenon. This knowledge will motivate the development of practical and cost-effective treatments for improving oyster health in aquaculture.

Oyster Shell Dredging in Atchafalaya Bay and Adjacent Waters, Louisiana. Volume 2. Public Comments.

DTIC Science & Technology

1987-11-01

alternatives to the proposed action." (NEPA Sec. 102(C)(iii)) To either renew the permits or deny the permits essentially provides no alternatives...of the more marine-oriented fishes found in the Gulf of Mexico enter these regions, essentially using them as nursery grounds. Shell dredging will...and the release in summer is probably essential to the sustained phytoplankton production observed in Fourleague Bay throughout the spring to fall

Integrating the effects of salinity on the physiology of the eastern oyster, Crassostrea virginica, in the northern Gulf of Mexico through a Dynamic Energy Budget model

USGS Publications Warehouse

Lavaud, Romain; LaPeyre, Megan K.; Casas, Sandra M.; Bacher, C.; La Peyre, Jerome F.

2017-01-01

We present a Dynamic Energy Budget (DEB) model for the eastern oyster, Crassostrea virginica, which enables the inclusion of salinity as a third environmental variable, on top of the standard foodr and temperature variables. Salinity changes have various effects on the physiology of oysters, potentially altering filtration and respiration rates, and ultimately impacting growth, reproduction and mortality. We tested different hypotheses as to how to include these effects in a DEB model for C. virginica. Specifically, we tested two potential mechanisms to explain changes in oyster shell growth (cm), tissue dry weight (g) and gonad dry weight (g) when salinity moves away from the ideal range: 1) a negative effect on filtration rate and 2) an additional somatic maintenance cost. Comparative simulations of shell growth, dry tissue biomass and dry gonad weight in two monitored sites in coastal Louisiana experiencing salinity from 0 to 28 were statistically analyzed to determine the best hypothesis. Model parameters were estimated through the covariation method, using literature data and a set of specifically designed ecophysiological experiments. The model was validated through independent field studies in estuaries along the northern Gulf of Mexico. Our results suggest that salinity impacts C. virginica’s energy budget predominantly through effects on filtration rate. With an overwhelming number of environmental factors impacting organisms, and increasing exposure to novel and extreme conditions, the mechanistic nature of the DEB model with its ability to incorporate more than the standard food and temperature variables provides a powerful tool to verify hypotheses and predict individual organism performance across a range of conditions.

Field evaluation of fly ash in aggregate shoulder materials : final report.

DOT National Transportation Integrated Search

1985-06-01

This study consisted of an evaluation of self-hardening fly ash (Class C) used as an additive in the treatment of shoulders surfaced with sand clay gravel and/or shell (oyster). This was accomplished through construction of fly ash treated aggregate ...

Ocean acidification but not warming alters sex determination in the Sydney rock oyster, Saccostrea glomerata.

PubMed

Parker, Laura M; O'Connor, Wayne A; Byrne, Maria; Dove, Michael; Coleman, Ross A; Pörtner, Hans-O; Scanes, Elliot; Virtue, Patti; Gibbs, Mitchell; Ross, Pauline M

2018-02-14

Whether sex determination of marine organisms can be altered by ocean acidification and warming during this century remains a significant, unanswered question. Here, we show that exposure of the protandric hermaphrodite oyster, Saccostrea glomerata to ocean acidification, but not warming, alters sex determination resulting in changes in sex ratios. After just one reproductive cycle there were 16% more females than males. The rate of gametogenesis, gonad area, fecundity, shell length, extracellular pH and survival decreased in response to ocean acidification. Warming as a sole stressor slightly increased the rate of gametogenesis, gonad area and fecundity, but this increase was masked by the impact of ocean acidification at a level predicted for this century. Alterations to sex determination, sex ratios and reproductive capacity will have flow on effects to reduce larval supply and population size of oysters and potentially other marine organisms. © 2018 The Author(s).

Combined metabolome and proteome analysis of the mantle tissue from Pacific oyster Crassostrea gigas exposed to elevated pCO2.

PubMed

Wei, Lei; Wang, Qing; Ning, Xuanxuan; Mu, Changkao; Wang, Chunlin; Cao, Ruiwen; Wu, Huifeng; Cong, Ming; Li, Fei; Ji, Chenglong; Zhao, Jianmin

2015-03-01

Ocean acidification (OA) has been found to affect an array of normal physiological processes in mollusks, especially posing a significant threat to the fabrication process of mollusk shell. In the current study, the impact of exposure to elevated pCO2 condition was investigated in mantle tissue of Crassostrea gigas by an integrated metabolomic and proteomic approach. Analysis of metabolome and proteome revealed that elevated pCO2 could affect energy metabolism in oyster C. gigas, marked by differentially altered ATP, succinate, MDH, PEPCK and ALDH levels. Moreover, the up-regulated calponin-2, tropomyosins and myosin light chains indicated that elevated pCO2 probably caused disturbances in cytoskeleton structure in mantle tissue of oyster C. gigas. This work demonstrated that a combination of proteomics and metabolomics could provide important insights into the effects of OA at molecular levels. Copyright © 2014 Elsevier Inc. All rights reserved.

Structure and crystallography of foliated and chalk shell microstructures of the oyster Magallana: the same materials grown under different conditions.

PubMed

Checa, Antonio G; Harper, Elizabeth M; González-Segura, Alicia

2018-05-14

Oyster shells are mainly composed of layers of foliated microstructure and lenses of chalk, a highly porous, apparently poorly organized and mechanically weak material. We performed a structural and crystallographic study of both materials, paying attention to the transitions between them. The morphology and crystallography of the laths comprising both microstructures are similar. The main differences were, in general, crystallographic orientation and texture. Whereas the foliated microstructure has a moderate sheet texture, with a defined 001 maximum, the chalk has a much weaker sheet texture, with a defined 011 maximum. This is striking because of the much more disorganized aspect of the chalk. We hypothesize that part of the unanticipated order is inherited from the foliated microstructure by means of, possibly, [Formula: see text] twinning. Growth line distribution suggests that during chalk formation, the mantle separates from the previous shell several times faster than for the foliated material. A shortage of structural material causes the chalk to become highly porous and allows crystals to reorient at a high angle to the mantle surface, with which they continue to keep contact. In conclusion, both materials are structurally similar and the differences in orientation and aspect simply result from differences in growth conditions.

Ocean Acidification Causes Increased Calcium Carbonate Turnover during Larval Shell Formation

NASA Astrophysics Data System (ADS)

Frieder, C.; Pan, F.; Applebaum, S.; Manahan, D. T.

2016-02-01

Mollusca is a major taxon for studies of the evolution and mechanisms of calcification. Under current and future ocean change scenarios, decreases in shell size have been observed in many molluscan species during early development. The mechanistic basis for these decreases are of significant interest. In this study, Pacific oyster larvae (Crassostrea gigas) reared at aragonite undersaturation (Ω < 1) accreted just a third of shell mass relative to control (Ω >> 1). Coupling radioisotope tracer assays with mineral mass measurements allowed calculation of calcification budgets for first shell formation in veliger stage larvae. Three primary mechanisms (in order of increasing effect) contributed to the change in shell mass at undersaturation: delayed onset of calcification, increased dissolution rates, and decreased net calcification rates. The observation of dissolution indicates turnover of the newly formed shell, and physicochemical constraints of undersaturation provide a mechanistic basis for decreased calcification.

High salinity relay as a postharvest processing strategy to reduce vibrio vulnificus levels in Chesapeake Bay oysters (Crassostrea virginica).

PubMed

Audemard, Corinne; Kator, Howard I; Rhodes, Martha W; Gallivan, Thomas; Erskine, A J; Leggett, A Thomas; Reece, Kimberly S

2011-11-01

In 2009 the U.S. Food and Drug Administration (FDA) announced its intention to implement postharvest processing (PHP) methods to eliminate Vibrio vulnificus from oysters intended for the raw, half-shell market that are harvested from the Gulf of Mexico during warmer months. FDA-approved PHP methods can be expensive and may be associated with unfavorable responses from some consumers. A relatively unexplored PHP method that uses relaying to high salinity waters could be an alternative strategy, considering that high salinities appear to negatively affect the survival of V. vulnificus. During relay, however, oysters may be exposed to rapid and large salinity increases that could cause increased mortality. In this study, the effectiveness of high salinity relay to reduce V. vulnificus to <30 most probable number (MPN) per g and the impact on oyster mortality were assessed in the lower Chesapeake Bay. Two relay experiments were performed during the summer and fall of 2010. Oysters collected from three grow-out sites, a low salinity site (14 to 15 practical salinity units [psu]) and two moderate salinity sites (22 to 25 psu), were relayed directly to a high salinity site (≥30 psu) on Virginia's Eastern Shore. Oysters were assayed for V. vulnificus and Vibrio parahaemolyticus (another Vibrio species of concern) densities at time 0 prior to relay and after 7 and 14 days of relay, using the FDA MPN enrichment method combined with detection by real-time PCR. After 14 days, both V. vulnificus and V. parahaemolyticus densities were ≤0.8 MPN/g, and decreases of 2 to 3 log in V. vulnificus densities were observed. Oyster mortalities were low (≤4%) even for oysters from the low salinity harvest site, which experienced a salinity increase of approximately 15 psu. Results, although preliminary and requiring formal validation and economic analysis, suggest that high salinity relay could be an effective PHP method.

Influence of eutrophication on metal bioaccumulation and oral bioavailability in oysters, Crassostrea angulata.

PubMed

Li, Shun-Xing; Chen, Li-Hui; Zheng, Feng-Ying; Huang, Xu-Guang

2014-07-23

Oysters (Crassostrea angulata) are often exposed to eutrophication. However, how these exposures influence metal bioaccumulation and oral bioavailability (OBA) in oysters is unknown. After a four month field experimental cultivation, bioaccumulation factors (BAF) of metals (Fe, Cu, As, Cd, and Pb) from seawater to oysters and metal oral bioavailability in oysters by bionic gastrointestinal tract were determined. A positive effect of macronutrient (nitrate N and total P) concentration in seawater on BAF of Cd in oysters was observed, but such an effect was not significant for Fe, Cu, Pb, and As. Only OBA of As was significantly positively correlated to N and P contents. For Fe, OBA was negatively correlated with N. The regular variation of the OBA of Fe and As may be due to the effect of eutrophication on the synthesis of metal granules and heat-stable protein in oysters, respectively.

Oyster Shell Dredging in Gulf of Mexico Waters, St. Mary and Terrebonne Parishes, Louisiana. Final Environmental Impact Statement and Appendixes

DTIC Science & Technology

1994-04-01

sabinae Sabine shiner x Notropis texanus weed shiner x Notropis volucellus mimic shiner X Ogeocephalus radiatus polka-dot bat fish x Oligoplites saurus ...Elope saurus ladyfish x x Erimyzon oblongus creek chubsucker x Esox americanus vermiculatus grass pickerel x Etheostoma chiorosomum, bluntnose darter

Fractional absorption of active absorbable algal calcium (AAACa) and calcium carbonate measured by a dual stable-isotope method

USDA-ARS?s Scientific Manuscript database

With the use of stable isotopes, this study aimed to compare the bioavailability of active absorbable algal calcium (AAACa), obtained from oyster shell powder heated to a high temperature, with an additional heated seaweed component (Heated Algal Ingredient, HAI), with that of calcium carbonate. In ...

Levels of PCBs in Oysters Coming from Galicia Coast: Comparison to Mussels from the Same Region.

PubMed

Carro, N; García, I; Ignacio, M; Mouteira, A

2016-05-01

PCBs were analyzed in two species of oyster (Crassostrea gigas and Ostrea edulis) cultured in intertidal beds and rafts coming from the Galician Rías during the period 2011-2014. PCBs were also analyzed in mussel (Mytilus galloprovincialis) collected in the same Rías during 2011. The main objective of this work is to investigate the distribution of PCBs in Galician oysters and to study their suitability as bioindicator in comparison to mussels. The levels of ΣPCBs (ten congeners) ranged from 5.58 to 179.49 ng g(-1) d.w. The effect of biological parameters (shell length, lipid content and condition index) on bioaccumulation of PCBs was also evaluated. ANOVA showed a statistically significant difference between species for higher chlorinated biphenyls (CBs 153 and 138). The spatial patterns were investigated. Principal Component Analysis (PCA) showed differences between geographical areas (Rías Altas, Centrales and Baixas) in the distribution of PCBs.

Ecological value of submerged breakwaters for habitat enhancement on a residential scale.

PubMed

Scyphers, Steven B; Powers, Sean P; Heck, Kenneth L

2015-02-01

Estuarine shorelines have been degraded since humans arrived in the coastal zone. In recent history, a major cause of habitat degradation has been the armoring of shorelines with vertical walls to protect property from erosive wave energy; however, a lack of practical alternatives that maintain or enhance ecological function has limited the options of waterfront residents and coastal zone managers. We experimentally investigated the habitat value of two configurations of submerged breakwaters constructed along an eroding shoreline in northwest Mobile Bay, AL (USA). Breakwaters comprised of bagged oyster shell or Reef Ball™ concrete domes were built by a community-based restoration effort. Post-deployment monitoring found that: bagged oyster breakwaters supported much higher densities of live ribbed mussels than Reef Ball breakwaters; both breakwater configurations supported increased species richness of juvenile and smaller fishes compared to controls; and that larger fishes did not appear to be affected by breakwater presence. Our study demonstrates that ecologically degraded shorelines can be augmented with small-scale breakwaters at reasonable cost and that these complex structures can serve as habitat for filter-feeding bivalves, mobile invertebrates, and young fishes. Understanding the degree to which these structures mitigate erosive wave energy and protect uplands will require a longer time frame than our 2-year-long study.

Equatorial seawater temperatures and latitudinal temperature gradients during the Middle to Late Jurassic: the stable isotope record of brachiopods and oysters from Gebel Maghara, Egypt

NASA Astrophysics Data System (ADS)

Alberti, Matthias; Fürsich, Franz T.; Abdelhady, Ahmed A.; Andersen, Nils

2017-04-01

The Jurassic climate has traditionally been described as equable, warmer than today, with weak latitudinal temperature gradients, and no polar glaciations. This view changed over the last decades with studies pointing to distinct climate fluctuations and the occasional presence of polar ice caps. Most of these temperature reconstructions are based on stable isotope analyses of fossil shells from Europe. Additional data from other parts of the world is slowly completing the picture. Gebel Maghara in the northern Sinai Peninsula of Egypt exposes a thick Jurassic succession. After a phase of terrestrial sedimentation in the Early Jurassic, marine conditions dominated since the end of the Aalenian. The stable isotope (δ18O, δ13C) composition of brachiopod and oyster shells was used to reconstruct seawater temperatures from the Bajocian to the Kimmeridgian at a palaeolatitude of ca. 3°N. Throughout this time interval, temperatures were comparatively constant aorund an average of 25.7°C. Slightly warmer conditions existed in the Early Bathonian ( 27.0°C), while the Kimmeridgian shows the lowest temperatures ( 24.3°C). The seasonality has been reconstructed with the help of high-resolution sampling of two oyster shells and was found to be very low (<2°C) as can be expected for a tropical palaeolatitude. A comparison of the results from Egypt with literature data enabled the reconstruction of latitudinal temperature gradients. During the Middle Jurassic, this gradient was much steeper than previously expected and comparable to today. During the Kimmeridgian, temperatures in Europe were generally warmer leading to weaker latitudinal gradients. Based on currently used estimates for the δ18O value of seawater during the Jurassic, reconstructed water temperatures for localities above the thermocline in Egypt and Europe were mostly lower than Recent sea-surface temperatures. These results improve our understanding of the Jurassic climate and its influence on marine faunal diversity patterns.

Stratigraphic implications of trace element and strontium-isotope analyses of Kimmeridgian shell calcite from the Lower Saxony Basin, Germany

NASA Astrophysics Data System (ADS)

Zuo, Fanfan; Heimhofer, Ulrich; Huck, Stefan; Erbacher, Jochen; Bodin, Stephane

2017-04-01

Stratigraphic uncertainties due to the lack of open marine marker fossils (e.g. ammonites) hamper the precise age assignment and stratigraphic correlation of Kimmeridgian strata found in the Lower Saxony Basin of Northern Germany. Correlation of these deposits with the Jurassic standard ammonite zonation is still difficult, since the existing ostracod biostratigraphy is facies-controlled and of only limited stratigraphic precision. In this study, a chemostratigraphic approach has been chosen and biogenic shell material produced by brachiopods, oysters and lithiotids is evaluated for its reliability to act as proxy of the original Jurassic seawater strontium isotope composition. Low-Mg calcite shells have been collected from three stratigraphic sections accessible in open-cast quarries located in the Lower Saxony Basin of Northern Germany. In order to identify diagenetically altered shell calcite, trace element and stable isotope analysis of 227 calcite samples (oysters=101; brachiopods=60; Trichites=52) has been carried out. The geochemical results reveal that (1) concentration of different trace elements varies between the different groups of shell-forming organisms, which may be related to vital effects and (2) high strontium contents, low Mn and Fe contents and the lack of correlation between these elements indicate near-pristine calcite shells, and therefore shells are supposed to record the ambient sea water composition during the Late Jurassic. Strontium-isotope (87Sr/86Sr) analysis of diagenetically screened samples indicates an Early Kimmeridgian age of the studied deposits, which is in accordance with ostracod biostratigraphic data. An increasing trend in 87Sr/86Sr with stratigraphic height fits well with the global strontium-isotope curve. Besides, similar 87Sr/86Sr ratios derived from different organisms from a single stratigraphic level highlight the suitability of the shells for strontium-isotope stratigraphy. Despite the shallow-marine character of the studied deposits, no evidence for significant riverine influence on the strontium-isotope signature is observed. The new chemostratigraphic data will provide a more precise age assignment for Kimmeridgian strata in the Lower Saxony Basin and thus enable the establishment of a solid integrated stratigraphic scheme that can be used for correlation on both regional and global scale.

Spatial analysis of biomineralization associated gene expression from the mantle organ of the pearl oyster Pinctada maxima

PubMed Central

2011-01-01

Background Biomineralization is a process encompassing all mineral containing tissues produced within an organism. One of the most dynamic examples of this process is the formation of the mollusk shell, comprising a variety of crystal phases and microstructures. The organic component incorporated within the shell is said to dictate this architecture. However general understanding of how this process is achieved remains ambiguous. The mantle is a conserved organ involved in shell formation throughout molluscs. Specifically the mantle is thought to be responsible for secreting the protein component of the shell. This study employs molecular approaches to determine the spatial expression of genes within the mantle tissue to further the elucidation of the shell biomineralization. Results A microarray platform was custom generated (PmaxArray 1.0) from the pearl oyster Pinctada maxima. PmaxArray 1.0 consists of 4992 expressed sequence tags (ESTs) originating from mantle tissue. This microarray was used to analyze the spatial expression of ESTs throughout the mantle organ. The mantle was dissected into five discrete regions and analyzed for differential gene expression with PmaxArray 1.0. Over 2000 ESTs were determined to be differentially expressed among the tissue sections, identifying five major expression regions. In situ hybridization validated and further localized the expression for a subset of these ESTs. Comparative sequence similarity analysis of these ESTs revealed a number of the transcripts were novel while others showed significant sequence similarities to previously characterized shell related genes. Conclusions This investigation has mapped the spatial distribution for over 2000 ESTs present on PmaxArray 1.0 with reference to specific locations of the mantle. Expression profile clusters have indicated at least five unique functioning zones in the mantle. Three of these zones are likely involved in shell related activities including formation of nacre, periostracum and calcitic prismatic microstructure. A number of novel and known transcripts have been identified from these clusters. The development of PmaxArray 1.0, and the spatial map of its ESTs expression in the mantle has begun characterizing the molecular mechanisms linking the organics and inorganics of the molluscan shell. PMID:21936921

Flow-sediment-oyster interaction around degraded, restored, and reference oyster reefs in Florida's Indian River Lagoon

NASA Astrophysics Data System (ADS)

Kitsikoudis, V.; Kibler, K. M.; Spiering, D. W.

2017-12-01

This study analyzes flow patterns and sediment distributions around three oyster reefs in a bar-built estuarine lagoon. We studied a degraded reef, a recently restored reef, and a reference condition reef with a healthy live oyster community. The restored reef had been regraded and restored with oyster shell mats to aid in recruitment of oyster spat, with the goal of reestablishing a healthy oyster community. Despite the fact that flow-biota-sediment interaction constitutes a blossoming research field, actual field data are sparse and current knowledge emanates from flume studies and numerical modeling. Moreover, the hydraulic effect of restored oyster reefs has not been thoroughly investigated and it is not clear if the flow field and sediment erosion/deposition are similar or diverge from natural reefs. Instantaneous three-dimensional flow velocities were collected on reefs using a Nortek Vectrino Profiler and an acoustic Doppler current profiler (Nortek Aquadopp). The former measured a 2 - 3 cm velocity profile above the oyster bed, while the latter quantified incoming velocities across the flow profile approximately 10 m from the edge of the reef. Flow measurements were conducted during rising tides and are coupled with simultaneous wind speed and direction data. In addition, 20 cm deep sediment cores were retrieved on and off the investigated reefs. Sediment grain size distributions were determined after individual cores were processed for loss on ignition. Incoming flow velocities were as high as 10 cm/s, relatively higher than those recorded close to reefs. Mean and turbulent flow velocities close to the reefs, varied among the investigated sites, despite the similar wind flow conditions offshore. For instance, the measurements at the degraded reef showed decreased wave attenuation and augmented flow velocities compared to the other sites. Boat wakes exhibited a very distinct signal in the flow velocity time-series and significantly increased the approaching flow velocity at the reefs. The oyster roughness height at the restored reef (68 mm) was higher than the roughness at the reference reef (45 mm); however, the variance was higher at the latter. Sediments from degraded reef and the recently restored reef were coarser and contained less organic matter compared to the reference condition reef.

In-depth proteomic analysis of shell matrix proteins of Pinctada fucata

PubMed Central

Liu, Chuang; Li, Shiguo; Kong, Jingjing; Liu, Yangjia; Wang, Tianpeng; Xie, Liping; Zhang, Rongqing

2015-01-01

The shells of pearl oysters, Pinctada fucata, are composed of calcite and aragonite and possess remarkable mechanical properties. These shells are formed under the regulation of macromolecules, especially shell matrix proteins (SMPs). Identification of diverse SMPs will lay a foundation for understanding biomineralization process. Here, we identified 72 unique SMPs using liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis of proteins extracted from the shells of P. fucata combined with a draft genome. Of 72 SMPs, 17 SMPs are related to both the prismatic and nacreous layers. Moreover, according to the diverse domains found in the SMPs, we hypothesize that in addition to controlling CaCO3 crystallization and crystal organization, these proteins may potentially regulate the extracellular microenvironment and communicate between cells and the extracellular matrix (ECM). Immunohistological localization techniques identify the SMPs in the mantle, shells and synthetic calcite. Together, these proteomic data increase the repertoires of the shell matrix proteins in P. fucata and suggest that shell formation in P. fucata may involve tight regulation of cellular activities and the extracellular microenvironment. PMID:26608573

A pilot study on remediation of sediments enriched by oyster farming wastes using granulated coal ash.

PubMed

Yamamoto, T; Kim, K H; Shirono, K

2015-01-15

In order to evaluate the ability of granulated coal ash (GCA), a byproduct of coal thermal electric power stations, to remove hydrogen sulfide from organically enriched sediments, a pilot study was carried out at oyster farming sites, where sediments were enriched with oyster feces and dead oysters. Concentration of hydrogen sulfide in the interstitial water of the sediment decreased to nearly zero in both experimental sites, whereas it remained over 0.2mg/l in the control site. Concentration of acid volatile sulfide (AVS) in the sediment also decreased significantly in both experimental sites, while remained over 0.4 mg/g in the control site. Increases were observed in both the number of benthic microalgae species and the individual number of benthic animals in the surface sediments. This may have been due to the decrease in hydrogen sulfide. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects of Co-Varying Diel-Cycling Hypoxia and pH on Growth in the Juvenile Eastern Oyster, Crassostrea virginica

PubMed Central

Keppel, Andrew G.; Breitburg, Denise L.; Burrell, Rebecca B.

2016-01-01

Shallow water provides important habitat for many species, but also exposes these organisms to daily fluctuations in dissolved oxygen (DO) and pH caused by cycles in the balance between photosynthesis and respiration that can contribute to repeated, brief periods of hypoxia and low pH (caused by elevated pCO2). The amplitude of these cycles, and the severity and duration of hypoxia and hypercapnia that result, can be increased by eutrophication, and are predicted to worsen with climate change. We conducted laboratory experiments to test the effects of both diel-cycling and constant low DO and pH (elevated pCO2) on growth of the juvenile eastern oyster (Crassostrea virginica), an economically and ecologically important estuarine species. Severe diel-cycling hypoxia (to 0.5 mg O2 L-1) reduced shell growth in juvenile oysters, as did constant hypoxia (1.2 and 2.0 mg O2 L-1), although effects varied among experiments, oyster ages, and exposure durations. Diel-cycling pH reduced growth only in experiments in which calcite saturation state cycled to ≤0.10 and only during the initial weeks of these experiments. In other cases, cycling pH sometimes led to increased growth rates. Comparisons of treatment effects across multiple weeks of exposure, and during a longer post-experiment field deployment, indicated that juvenile oysters can acclimate to, and in some cases compensate for initial reductions in growth. As a result, some ecosystem services dependent on juvenile oyster growth rates may be preserved even under severe cycling hypoxia and pH. PMID:27548256

Sub-chronic exposure to fluoxetine in juvenile oysters (Crassostrea gigas): uptake and biological effects.

PubMed

Di Poi, Carole; Evariste, Lauris; Séguin, Alexis; Mottier, Antoine; Pedelucq, Julie; Lebel, Jean-Marc; Serpentini, Antoine; Budzinski, Hélène; Costil, Katherine

2016-03-01

The bioconcentration potential of fluoxetine (FLX) and its biological effects were investigated in juvenile Pacific oyster exposed for 28 days to environmentally relevant concentrations of FLX (1 ng L(-1), 100 ng L(-1) and up to 10 μg L(-1)). FLX bioaccumulated in oyster flesh resulting in 28-day bioconcentration factors greater than 2,000 and 10,000 by referring to wet and dry weights, respectively. Nevertheless, FLX did not induce oyster mortality, delayed gametogenesis, or lead to adverse histopathological alterations. At the two highest concentrations, despite non-optimal trophic conditions, FLX stimulated shell growth but only in a transient manner, suggesting a role of serotonin in the regulation of feeding and metabolism in bivalves. Those high concentrations seemed to drive bell-shaped responses of catalase and glutathione S-transferase activities throughout the exposure period, which may indicate the activation of antioxidant enzyme synthesis and then an enhanced catabolic rate or direct inhibition of those enzymes. However, no clear oxidative stress was detected because no strong differences in thiobarbituric acid-reactive substance (TBARS) content (i.e. lipid peroxidation) were observed between oyster groups, suggesting that cellular defence mechanisms were effective. These results demonstrate the importance of considering additional biomarkers of oxidative stress to obtain a comprehensive overview of the FLX-induced changes in marine bivalves exposed under realistic conditions. Considering the battery of biomarkers used, FLX appears to induce little or no effects on oyster physiology even at a concentration of 10 μg L(-1). These results do not confirm the lowest observed effect concentration (LOEC) values reported by some authors in other mollusc species.

21 CFR 184.1210 - Calcium oxide.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Calcium oxide. 184.1210 Section 184.1210 Food and....1210 Calcium oxide. (a) Calcium oxide (CaO, CAS Reg. No. 1305-78-8) is also known as lime, quick lime, burnt lime, or calx. It is produced from calcium carbonate, limestone, or oyster shells by calcination...

The effects of elevated temperature and dissolved ρCO2 on a marine foundation species.

PubMed

Speights, Cori J; Silliman, Brian R; McCoy, Michael W

2017-06-01

Understanding how climate change and other environmental stressors will affect species is a fundamental concern of modern ecology. Indeed, numerous studies have documented how climate stressors affect species distributions and population persistence. However, relatively few studies have investigated how multiple climate stressors might affect species. In this study, we investigate the impacts of how two climate change factors affect an important foundation species. Specifically, we tested how ocean acidification from dissolution of CO 2 and increased sea surface temperatures affect multiple characteristics of juvenile eastern oysters ( Crassostrea virginica ). We found strong impacts of each stressor, but no interaction between the two. Simulated warming to mimic heat stressed summers reduced oyster growth, survival, and filtration rates. Additionally, we found that CO 2 -induced acidification reduced strength of oyster shells, which could potentially facilitate crab predation. As past studies have detected few impacts of these stressors on adult oysters, these results indicate that early life stages of calcareous marine organisms may be more susceptible to effects of ocean acidification and global warming. Overall, these data show that predicted changes in temperature and CO 2 can differentially influence direct effects on individual species, which could have important implications for the nature of their trophic interactions.

Noise pollution limits metal bioaccumulation and growth rate in a filter feeder, the Pacific oyster Magallana gigas

PubMed Central

Charifi, Mohcine; Miserazzi, Alison; Sow, Mohamedou; Perrigault, Mickael; Gonzalez, Patrice; Ciret, Pierre; Benomar, Soumaya

2018-01-01

Shipping has increased dramatically in recent decades and oysters can hear them. We studied the interaction between noise pollution and trace metal contamination in the oyster Magallana gigas. Four oyster-groups were studied during a 14-day exposure period. Two were exposed to cadmium in the presence of cargo ship-noise ([Cd++]w ≈ 0.5 μg∙L-1; maximum sound pressure level 150 dBrms re 1 μPa), and 2 were exposed only to cadmium. The Cd concentration in the gills ([Cd]g) and the digestive gland ([Cd]dg), the valve closure duration, number of valve closures and circadian distribution of opening and closure, the daily shell growth-rate and the expression of 19 genes in the gills were studied. Oysters exposed to Cd in the presence of cargo ship-noise accumulated 2.5 times less Cd in their gills than did the controls without ship noise and their growth rate was 2.6 times slower. In the presence of ship noise, oysters were closed more during the daytime, and their daily valve activity was reduced. Changes in gene activity in the gills were observed in 7 genes when the Cd was associated with the ship noise. In the absence of ship noise, a change in expression was measured in 4 genes. We conclude that chronic exposure to cargo ship noise has a depressant effect on the activity in oysters, including on the volume of the water flowing over their gills (Vw). In turn, a decrease in the Vw and valve-opening duration limited metal exposure and uptake by the gills but also limited food uptake. This latter conclusion would explain the slowing observed in the fat metabolism and growth rate. Thus, we propose that cargo ship noise exposure could protect against metal bioaccumulation and affect the growth rate. This latter conclusion points towards a potential risk in terms of ecosystem productivity. PMID:29617387

Development of a Simple Method for Concentrating Enteroviruses from Oysters

PubMed Central

Sobsey, Mark D.; Wallis, Craig; Melnick, Joseph L.

1975-01-01

The development of a simple method for concentrating enteroviruses from oysters is described. In this method viruses in homogenized oyster tissues are efficiently adsorbed to oyster solids at pH 5.5 and low salt concentration. After low-speed centrifugation, the supernatant is discarded and viruses are eluted from the sedimented oyster solids by resuspending them in pH 3.5 glycine-buffered saline. The solids are then removed by low-speed centrifugation, and the virus-containing supernatant is filtered through a 0.2-μm porosity filter to remove bacteria and other small particulates without removing viruses. The virus-containing filtrate is then concentrated to a volume of a few milliliters by ultrafiltration, and the concentrate obtained is inoculated directly into cell cultures for virus assay. When tested with pools of oysters experimentally contaminated with small amounts of different enteroviruses, virus recovery efficiency averaged 63%. PMID:234154

Development of a simple method for concentrating enteroviruses from oysters.

PubMed

Sobsey, M D; Wallis, C; Melnick, J L

1975-01-01

The development of a simple method for concentrating enteroviruses from oysters is described. In this method viruses in homogenized oyster tissues are efficiently absorbed to oyster solids at pH 5.5 and low salt concentration. After low-speed centrifugation, the supernatant is discarded and viruses are eluted from the sedimented oyster solids by resuspending them in pH 3.5 glycine-buffered saline. The solids are then removed by low-speed centrifugation, and the virus-containing supernatant is filtered through a 0.2-micronm porosity filter to remove bacteria and other small particulates without removing viruses. The virus-containing filtrate is then concentrated to a volume of a few milliliters by ultrafiltration, and the concentrate obtained is inoculated directly into cell cultures for virus assay. When tested with pools of oysters experimentally contaminated with small amounts of different enteroviruses, virus recovery efficiency averaged 63%.

Sex differences in the stone tool-use behavior of a wild population of burmese long-tailed macaques (Macaca fascicularis aurea).

PubMed

Gumert, Michael D; Hoong, Low Kuan; Malaivijitnond, Suchinda

2011-12-01

We investigated sex differences in how Burmese long-tailed macaques (Macaca fascicularis aurea) used stone tools to open shelled food items along the shores of two islands in Laemson National Park, Thailand. Over a 2-week period in December 2009, we collected scan and focal samples on macaques when they were visible along the shores and mangroves. We found females used stones more often while feeding and used smaller tools than males. Females also processed sessile oysters more than males, whereas males processed unattached foods more than females. It was unclear which sex was overall more proficient at stone tool use, but males did perform significantly better at opening unattached food items with large pounding stones. Females also struck food items more times during tool-use bouts and at a faster rate, but no significant difference was found in average tool-use bout duration. Males processed foods slightly faster within a tool-use bout, but we were unable to detect a significant difference in the rate of food processing while foraging with tools. In summary females chipped open sessile oysters with an axing technique more than males, while males used larger stones to pound open unattached shelled food more often than females. Despite using pounding more than females, males also regularly utilized the axing technique on sessile oysters. Our results are the first assessment of sex differences in macaque stone tool use, providing a basis for comparison with tool use in other primates, and to nonfunctional forms of stone use in other macaques. © 2011 Wiley Periodicals, Inc.

Inducible variation in anaerobic energy metabolism reflects hypoxia tolerance across the intertidal and subtidal distribution of the Pacific oyster (Crassostrea gigas).

PubMed

Meng, Jie; Wang, Ting; Li, Li; Zhang, Guofan

2018-07-01

Pacific oyster (Crassostrea gigas) distribute a steep gradient of environmental stress between intertidal and subtidal habits and provide insight into population-scale patterns and underlying processes of variation in physiological tolerance. In this study, 1-year-old-F 1 oysters, collected from subtidal and intertidal habitats, were obtained after common garden experiment. Genetic differentiation and physiological responses under air exposure were examined to determine whether they had evolved into local adapted subpopulations. Mortality rate, anaerobic glycolysis metabolism, and energy status indicated that oyster had initiated metabolism depression and anaerobic glycolysis metabolism in both intertidal and subtidal oysters under air exposure. However, the subtidal oysters displayed the larger energy metabolism depressions and the earlier anaerobic glycolysis responses. This may indicate that subtidal oysters were more sensitives to hypoxia stress, which may lead the higher mortality rate under long term of air exposure. Based on a common garden experimental design, we propose that this diversification may have a genetic background. Overall, the clear differences between intertidal and subtidal oysters under air exposure have provided an important reference for their aquaculture and transportation used in commercial production. Copyright © 2018. Published by Elsevier Ltd.

Morphology of the larval shell of three oyster species of the genus Crassostrea Sacco, 1897 (Bivalvia: Ostreidae).

PubMed

Christo, S W; Absher, T M; Boehs, G

2010-08-01

In this study we describe the morphology of the larval shell of three oyster species of Crassostrea genus. Two species, C. rhizophorae and C. brasiliana, are native to the Brazilian coast, and C. gigas is an introduced species. Samples of laboratory reared larvae, obtained through artificial fertilisation, were collected at intervals during the cultivation process for analysis using Scanning Electron Microscopy (SEM). Prodissoconch morphology was observed in relation to the presence, position, form and number of teeth in the three larval stages: D-shaped larva, umbo larva and pediveliger. Characteristic of D-shaped larvae of C. rhizophorae was the total absence of teeth in the provinculum area while C. brasiliana and C. gigas had two anterior and two posterior teeth in each valve. In the umbo larval phase, the three species had the same number of teeth in each valve: two posterior and two anterior teeth in the right valve and three posterior and three anterior in the left valve. In the pediveliger stage the three species could be differentiated by the number of anterior teeth of the right valve: C. rhizophorae had two teeth, C. brasiliana one tooth and C. gigas three teeth.

High resolution mapping and classification of oyster habitats in nearshore Louisiana using sidescan sonar

USGS Publications Warehouse

Allen, Y.C.; Wilson, C.A.; Roberts, H.H.; Supan, J.

2005-01-01

Sidescan sonar holds great promise as a tool to quantitatively depict the distribution and extent of benthic habitats in Louisiana's turbid estuaries. In this study, we describe an effective protocol for acoustic sampling in this environment. We also compared three methods of classification in detail: mean-based thresholding, supervised, and unsupervised techniques to classify sidescan imagery into categories of mud and shell. Classification results were compared to ground truth results using quadrat and dredge sampling. Supervised classification gave the best overall result (kappa = 75%) when compared to quadrat results. Classification accuracy was less robust when compared to all dredge samples (kappa = 21-56%), but increased greatly (90-100%) when only dredge samples taken from acoustically homogeneous areas were considered. Sidescan sonar when combined with ground truth sampling at an appropriate scale can be effectively used to establish an accurate substrate base map for both research applications and shellfish management. The sidescan imagery presented here also provides, for the first time, a detailed presentation of oyster habitat patchiness and scale in a productive oyster growing area.

The effect of structural complexity, prey density, and "predator-free space" on prey survivorship at created oyster reef mesocosms

USGS Publications Warehouse

Humphries, Austin T.; La Peyre, Megan K.; Decossas, Gary A.

2011-01-01

Interactions between predators and their prey are influenced by the habitat they occupy. Using created oyster (Crassostrea virginica) reef mesocosms, we conducted a series of laboratory experiments that created structure and manipulated complexity as well as prey density and “predator-free space” to examine the relationship between structural complexity and prey survivorship. Specifically, volume and spatial arrangement of oysters as well as prey density were manipulated, and the survivorship of prey (grass shrimp, Palaemonetes pugio) in the presence of a predator (wild red drum, Sciaenops ocellatus) was quantified. We found that the presence of structure increased prey survivorship, and that increasing complexity of this structure further increased survivorship, but only to a point. This agrees with the theory that structural complexity may influence predator-prey dynamics, but that a threshold exists with diminishing returns. These results held true even when prey density was scaled to structural complexity, or the amount of “predator-free space” was manipulated within our created reef mesocosms. The presence of structure and its complexity (oyster shell volume) were more important in facilitating prey survivorship than perceived refugia or density-dependent prey effects. A more accurate indicator of refugia might require “predator-free space” measures that also account for the available area within the structure itself (i.e., volume) and not just on the surface of a structure. Creating experiments that better mimic natural conditions and test a wider range of “predator-free space” are suggested to better understand the role of structural complexity in oyster reefs and other complex habitats.

Investigating the Role of Oysters in Altering Net N2 Fluxes Using Novel In-Situ Experimental Design

EPA Science Inventory

Coastal nutrient over-enrichment represents one of the most pressing environmental management issues faced worldwide. Oyster aquaculture and restoration are hypothesized to mitigate excessive nitrogen (N) loads via increasing benthic denitrification rates in coastal systems. Howe...

Disturbance influences oyster community richness and evenness, but not diversity.

PubMed

Kimbro, David L; Grosholz, Edwin D

2006-09-01

Foundation species in space-limited systems can increase diversity by creating habitat, but they may also reduce diversity by excluding primary space competitors. These contrasting forces of increasing associate diversity and suppressing competitor diversity have rarely been examined experimentally with respect to disturbance. In a benthic marine community in central California, where native oysters are a foundation species, we tested how disturbance influenced overall species richness, evenness, and diversity. Surprisingly, overall diversity did not peak across a disturbance gradient because, as disturbance decreased, decreases in overall species evenness opposed increases in overall species richness. Decreasing disturbance intensity (high oyster abundance) led to increasing species richness of sessile and mobile species combined. This increase was due to the facilitation of secondary sessile and mobile species in the presence of oysters. In contrast, decreasing disturbance intensity and high oyster abundance decreased the evenness of sessile and mobile species. Three factors likely contributed to this decreased evenness: oysters reduced abundances of primary sessile species due to space competition; oysters supported more rare mobile species; and oysters disproportionately increased the relative abundance of a few common mobile species. Our results highlight the need for further studies on how disturbance can differentially affect the evenness and richness of different functional groups, and ultimately how these differences affect the relationship between overall diversity and ecosystem function.

Carcinogenicity of Black Rock Harbor sediment to the eastern oyster and trophic transfer of Black Rock Harbor carcinogens from the blue mussel to the winter flounder

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gardner, G.R.; Yevich, P.P.; Malcolm, A.R.

1991-01-01

The eastern oyster (Crassostrea virginica) developed neoplastic disorders when experimentally exposed both in the laboratory and field to chemically contaminated sediment from Black Rock Harbor (BRH), Bridgeport, Connecticut. Neoplasia was observed in oysters after 30 or 60 days of continuous exposure in a laboratory flow-through system to a 20 mg/L suspension of BRH sediment plus postexposure periods of 3, 30, or 60 days. Composite tumor incidence was 13.6% for both exposures. Tumor occurrence was highest in the renal excretory epithelium, followed in order by gill, gonad, gastrointestinal, heart, and embryonic neural tissue. Regression of experimental neoplasia was not observed whenmore » the stimulus was discontinued. In field experiments, gill neoplasms developed in oysters, deployed in cages for 30 days at BRH and 36 days at a BRH dredge material disposal area in Central Long Island Sound, and kidney and gastrointestinal neoplasms developed in caged oysters deployed 40 days in Quincy Bay, Boston Harbor. Oysters exposed to BRH sediment in the laboratory and in the field accumulated high concentrations of polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), and chlorinated pesticides. Chemical analyses demonstrated high concentrations of PCBs, PAHs, chlorinated pesticides, and heavy metals in BRH sediment. Known genotoxic carcinogens, cocarcinogens, and tumor promoters were present as contaminants. The uptake of parent PAH and PCBs from BRH sediment observed in oysters also occurs in blue mussels (Mytilus edulis). Winter flounder fed BRH-contaminated blue mussels contained xenobiotic chemicals analyzed in mussels. The flounder developed renal and pancreatic neoplasms and hepatotoxic neoplastic precursor lesions, demonstrating trophic transfer of sediment-bound carcinogens up the food chain.« less

Response of an estuarine benthic community to application of the pesticide carbaryl and cultivation of Pacific oysters (Crassostrea gigas) in Willapa Bay, Washington.

PubMed

Dumbauld, B R; Brooks, K M; Posey, M H

2001-10-01

Oyster culture operations on the West coast of North America have developed into complete farming operations for the introduced Japanese oyster, Crassostrea gigas, which now covers vast areas of the intertidal landscape, particularly in Washington State where the pesticide carbaryl has also been used to control burrowing thalassinid shrimp for more than 30 years. Field experiments were conducted to examine the effects of these habitat modifications on the benthic community in Willapa, Bay Washington (124 degrees 06'W,46 degrees 24'N) where 50% of the state's oyster production occurs. Results indicated that the primary long-term effect of carbaryl application was removal of the two species of thalassinid shrimp (Neotrypaea californiensis and Upogebia pugettensis), which dominated the community at the start of the experiment and clearly influenced community composition themselves. Small peracarid crustaceans like the amphipods Corophium acherusicum and Eohaustorius estuarius experienced the most significant short-term mortalities, but generally recruited back to treated sites within 3 months, and were often more abundant on treated than untreated sites 1 year after carbaryl application. Results for molluscs were mixed, with no significant effect on Macoma spp, but a significant effect on the commensal clam Crytomya californica and mixed results for the cockle Clinocardium nutalli. Polychaetes were the least susceptible to carbaryl and with the exception of a short-term effect on oligochaetes, no significant negative effects were observed. The addition of oysters did not affect the infaunal community in this study, however greater abundance of epifaunal organisms like mussels, scaleworms, and the amphipod Amphithoe valida, which builds tubes in algae attached to shells, was observed. Carbaryl, which is currently applied to roughly 242 ha (< 6% of the intertidal) in Willapa Bay on an annual basis, has a variable but relatively short-term effect on the benthic community, which should be viewed in the context of other oyster culture operations like the addition of oysters themselves to a community often dominated by burrowing thalassinid shrimp which clearly control its dynamics.

Intertidal oysters reach their physiological limit in a future high-CO2 world.

PubMed

Scanes, Elliot; Parker, Laura M; O'Connor, Wayne A; Stapp, Laura S; Ross, Pauline M

2017-03-01

Sessile marine molluscs living in the intertidal zone experience periods of internal acidosis when exposed to air (emersion) during low tide. Relative to other marine organisms, molluscs have been identified as vulnerable to future ocean acidification; however, paradoxically it has also been shown that molluscs exposed to high CO 2 environments are more resilient compared with those molluscs naive to CO 2 exposure. Two competing hypotheses were tested using a novel experimental design incorporating tidal simulations to predict the future intertidal limit of oysters in a high-CO 2 world; either high-shore oysters will be more tolerant of elevated P CO 2 because of their regular acidosis, or elevated P CO 2  will cause high-shore oysters to reach their limit. Sydney rock oysters, Saccostrea glomerata , were collected from the high-intertidal and subtidal areas of the shore and exposed in an orthogonal design to either an intertidal or a subtidal treatment at ambient or elevated P CO 2 , and physiological variables were measured. The combined treatment of tidal emersion and elevated P CO 2  interacted synergistically to reduce the haemolymph pH (pH e ) of oysters, and increase the P CO 2  in the haemolymph ( P e,CO 2 ) and standard metabolic rate. Oysters in the intertidal treatment also had lower condition and growth. Oysters showed a high degree of plasticity, and little evidence was found that intertidal oysters were more resilient than subtidal oysters. It is concluded that in a high-CO 2 world the upper vertical limit of oyster distribution on the shore may be reduced. These results suggest that previous studies on intertidal organisms that lacked tidal simulations may have underestimated the effects of elevated P CO 2 . © 2017. Published by The Company of Biologists Ltd.

Suitability of oyster restoration sites along the Louisiana coast: Examining site and stock × site interaction

USGS Publications Warehouse

Schwarting Miller, Lindsay; La Peyre, Jerome F.; LaPeyre, Megan K.

2017-01-01

Recognition of the global loss of subtidal oyster reefs has led to a rise in reef restoration efforts, including in the Gulf of Mexico. Created reef success depends entirely on selecting a location that supports long-term oyster growth and survival, including the recruitment and survival of on-reef oysters. Significant changes in estuarine salinity through management of freshwater inflows and through changed precipitation patterns may significantly impact the locations of optimal oyster restoration sites. These rapid shifts in conditions necessitate a need to better understand both impacts to on-reef oyster growth and population development, and variation in oyster stock performance. Oyster growth, mortality, condition, and disease prevalence were examined in three different stocks of oysters located in protected cages, as well as oyster recruitment and mortality on experimental reef units in three different locations representing a salinity gradient, along the Louisiana Gulf coast in 2011 and 2012. Over a 2-y period, the high-salinity site had highest oyster growth rate in protected cages but demonstrated the least likelihood for reef development based on on-reef oyster population failure, likely because of predation-related mortality (high recruitment and 100% mortality). In contrast, the midsalinity site with moderate oyster growth and on-reef recruitment and low mortality demonstrated a higher likelihood for reef development. The lowest salinity site exhibited extreme variability in all oyster responses between years because of extreme variation in environmental conditions during the study, indicating a low likelihood of long-term reef development. Whereas limited differences in stock performance between sites were found, the range of site environmental conditions tested was ultimately much lower than expected and may not have provided a wide enough range of conditions. In areas with limited, low recruitment, or rapidly changing environmental conditions, seeding with stocks selected for best growth and survival under expected future environmental conditions could better ensure reef development by using oyster populations best suited to the predicted conditions. With rapidly changing estuarine conditions from anthropogenic activities and climate change, siting of oyster reef restoration incorporating both oyster population dynamics and in situ biotic and abiotic interactions is critical in better directing site selection for reef restoration efforts.

Evidence of neutralizing activity against T3 coliphage in oyster Crassostrea gigas hemolymph.

PubMed

Bachère, E; Hervio, D; Mialhe, E; Grizel, H

1990-01-01

To investigate defense reactions of bivalve molluscs against viruses, experimental in vitro assays have been developed using T3 coliphage as a test virus. A native neutralizing factor in oyster Crassostrea gigas serum showed high individual variability and was enhanced significantly by repeated sampling of hemolymph from the same oysters. The responsible factor is apparently thermolabile and sensitive to EDTA treatment. Because of an inhibitory effect by the enzymatic inhibitor, phenylmethylsulphonyl fluoride (PMSF), the T3-neutralizing factor may be related to serine protease.

Application of chitosan microparticles for reduction of vibrio species in seawater and live oysters (Crassostrea virginica).

PubMed

Fang, Lei; Wolmarans, Bernhard; Kang, Minyoung; Jeong, Kwang C; Wright, Anita C

2015-01-01

Human Vibrio infections associated with consumption of raw shellfish greatly impact the seafood industry. Vibrio cholerae-related disease is occasionally attributed to seafood, but V. vulnificus and V. parahaemolyticus are the primary targets of postharvest processing (PHP) efforts in the United States, as they pose the greatest threat to the industry. Most successful PHP treatments for Vibrio reduction also kill the molluscs and are not suitable for the lucrative half-shell market, while nonlethal practices are generally less effective. Therefore, novel intervention strategies for Vibrio reduction are needed for live oyster products. Chitosan is a bioactive derivative of chitin that is generally recognized as safe as a food additive by the FDA, and chitosan microparticles (CMs) were investigated in the present study as a potential PHP treatment for live oyster applications. Treatment of broth cultures with 0.5% (wt/vol) CMs resulted in growth cessation of V. cholerae, V. vulnificus, and V. parahaemolyticus, reducing culturable levels to nondetectable amounts after 3 h in three independent experiments. Furthermore, a similar treatment in artificial seawater at 4, 25, and 37°C reduced V. vulnificus levels by ca. 7 log CFU/ml after 24 h of exposure, but 48 h of exposure and elevated temperature were required to achieve similar results for V. parahaemolyticus and V. cholerae. Live oysters that either were artificially inoculated or contained natural populations of V. vulnificus and V. parahaemolyticus showed significant and consistent reductions following CM treatment (5%) compared to the amounts in the untreated controls. Thus, the results strongly support the promising potential for the application of CMs as a PHP treatment to reduce Vibrio spp. in intact live oysters. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Seasonal variations in the concentrations of metals in Crassostrea corteziensis from Sonora, México.

PubMed

García-Rico, L; Tejeda-Valenzuela, L; Burgos-Hernández, A

2010-08-01

This study examines seasonal variations in the concentrations of Cd, Cu, Pb, and Hg in experimentally cultured Crassostrea corteziensis, an oyster species known to have high resistance to physical and chemical stressors. The highest levels of Cd (4.92 mg/kg), Cu (3.45 mg/kg), and Pb (0.67 mg/kg) were detected in oyster samples collected during the summer, while Hg concentrations were similar (0.03 to 0.04 mg/kg) throughout all seasons. Results indicate that except for Cd, Crassostrea corteziensis accumulates metals to levels below those recommended by the US. FDA and the Mexican government. For Cd, its concentration correlates more strongly with the temperature of the oyster's environment rather than to the oyster growth cycle.

Oysters and eelgrass: potential partners in a high pCO2 ocean.

PubMed

Groner, Maya L; Burge, Colleen A; Cox, Ruth; Rivlin, Natalie; Turner, Mo; Van Alstyne, Kathryn L; Wyllie-Echeverria, Sandy; Bucci, John; Staudigel, Philip; Friedman, Carolyn S

2018-05-25

Climate change is affecting the health and physiology of marine organisms and altering species interactions. Ocean acidification (OA) threatens calcifying organisms such as the Pacific oyster, Crassostrea gigas. In contrast, seagrasses, such as the eelgrass Zostera marina, can benefit from the increase in available carbon for photosynthesis found at a lower seawater pH. Seagrasses can remove dissolved inorganic carbon from OA environments, creating local daytime pH refugia. Pacific oysters may improve the health of eelgrass by filtering out pathogens such as Labyrinthula zosterae (LZ), which causes eelgrass wasting disease (EWD). We examined how co-culture of eelgrass ramets and juvenile oysters affected the health and growth of eelgrass and the mass of oysters under different pCO 2 exposures. In Phase I, each species was cultured alone or in co-culture at 12°C across ambient, medium, and high pCO 2 conditions, (656, 1158 and1606 μatm pCO 2 , respectively). Under high pCO 2 , eelgrass grew faster and had less severe EWD (contracted in the field prior to the experiment). Co-culture with oysters also reduced the severity of EWD. While the presence of eelgrass decreased daytime pCO 2 , this reduction was not substantial enough to ameliorate the negative impact of high pCO 2 on oyster mass. In Phase II, eelgrass alone or oysters and eelgrass in co-culture were held at 15°C under ambient and high pCO 2 conditions, (488 and 2013 μatm pCO 2 , respectively). Half of the replicates were challenged with cultured LZ. Concentrations of defensive compounds in eelgrass (total phenolics and tannins), were altered by LZ exposure and pCO 2 treatments. Greater pathogen loads and increased EWD severity were detected in LZ exposed eelgrass ramets; EWD severity was reduced at high relative to low pCO 2 . Oyster presence did not influence pathogen load or EWD severity; high LZ concentrations in experimental treatments may have masked the effect of this treatment. Collectively, these results indicate that, when exposed to natural concentrations of LZ under high pCO 2 conditions, eelgrass can benefit from co-culture with oysters. Further experimentation is necessary to quantify how oysters may benefit from co-culture with eelgrass, examine these interactions in the field and quantify context-dependency. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

An assessment of latest Cretaceous Pycnodonte vesicularis (Lamarck, 1806) shells as records for palaeoseasonality: a multi-proxy investigation

NASA Astrophysics Data System (ADS)

de Winter, Niels J.; Vellekoop, Johan; Vorsselmans, Robin; Golreihan, Asefeh; Soete, Jeroen; Petersen, Sierra V.; Meyer, Kyle W.; Casadio, Silvio; Speijer, Robert P.; Claeys, Philippe

2018-06-01

In order to assess the potential of the honeycomb oyster Pycnodonte vesicularis for the reconstruction of palaeoseasonality, several specimens recovered from late Maastrichtian strata in the Neuquén Basin (Argentina) were subject to a multi-proxy investigation, involving scanning techniques and trace element and isotopic analysis. Combined CT scanning and light microscopy reveals two calcite microstructures in P. vesicularis shells (vesicular and foliated calcite). Micro-XRF analysis and cathodoluminescence microscopy show that reducing pore fluids were able to migrate through the vesicular portions of the shells (aided by bore holes) and cause recrystallization of the vesicular calcite. This renders the vesicular portions not suitable for palaeoenvironmental reconstruction. In contrast, stable isotope and trace element compositions show that the original chemical composition of the foliated calcite is well-preserved and can be used for the reconstruction of palaeoenvironmental conditions. Stable oxygen and clumped isotope thermometry on carbonate from the dense hinge of the shell yield sea water temperatures of 11°C, while previous TEX86H palaeothermometry yielded much higher temperatures. The difference is ascribed to seasonal bias in the growth of P. vesicularis, causing warm seasons to be underrepresented from the record, while TEX86H palaeothermometry seems to be biased towards warmer surface water temperatures. The multi-proxy approach employed here enables us to differentiate between well-preserved and diagenetically altered portions of the shells and provides an improved methodology for reconstructing palaeoenvironmental conditions in deep time. While establishing a chronology for these shells was complicated by growth cessations and diagenesis, cyclicity in trace elements and stable isotopes allowed for a tentative interpretation of the seasonal cycle in late Maastrichtian palaeoenvironment of the Neuquén Basin. Attempts to independently verify the seasonality in sea water temperature by Mg / Ca ratios of shell calcite are hampered by significant uncertainty due to the lack of proper transfer functions for pycnodontein oysters. Future studies of fossil ostreid bivalves should target dense, foliated calcite rather than sampling bulk or vesicular calcite. Successful application of clumped isotope thermometry on fossil bivalve calcite in this study indicates that temperature seasonality in fossil ostreid bivalves may be constrained by the sequential analysis of well-preserved foliated calcite samples using this method.

Oyster Shell Dredging in Atchafalaya Bay and Adjacent Waters, Louisiana. Volume 1. Final Environment Impact Statement and Appendixes.

DTIC Science & Technology

1987-11-01

Preservation Act and the National Environmental Policy Act. 5.3 STATEMENT RECIPIENTS The U.S. Senators and Congressmen, Federal, and state agencies listed...Harry S. Rucker, State Conservationist US Department of Transportation, Deputy Director for Environmental and Policy Review Federal Highway...Affairs Louisiana Department of Natural Resources, Office of Forestry Louisiana State Planning Office, Ms. Joy Bartholomew, Policy Planner Louisiana

VIEW IN OPPOSITE DIRECTION AS MD1351 AND MD1352. RAW MATERIAL ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW IN OPPOSITE DIRECTION AS MD-135-1 AND MD-135-2. RAW MATERIAL CONVEYOR AT LEFT DEPOSITS SHELL INTO MILLING MACHINE AT LOWER LEFT. ENGINE IS AT LOWER RIGHT AND RADIATOR AT LOWER CENTER. ROLLER SORTER IS AT TOP OF CONVEYOR. - F. & H. Benning Company Oyster Mill, 14430 Solomons Island Road (moved from 1014 Benning Road, Galesville, Anne Arundel County, Maryland), Solomons, Calvert County, MD

The influence of food supply on the response of Olympia oyster larvae to ocean acidification

NASA Astrophysics Data System (ADS)

Hettinger, A.; Sanford, E.; Hill, T. M.; Hosfelt, J. D.; Russell, A. D.; Gaylord, B.

2013-03-01

Increases in atmospheric carbon dioxide drive accompanying changes in the marine carbonate system as carbon dioxide (CO2) enters seawater and alters its pH (termed "ocean acidification"). However, such changes do not occur in isolation, and other environmental factors have the potential to modulate the consequences of altered ocean chemistry. Given that physiological mechanisms used by organisms to confront acidification can be energetically costly, we explored the potential for food supply to influence the response of Olympia oyster (Ostrea lurida) larvae to ocean acidification. In laboratory experiments, we reared oyster larvae under a factorial combination of pCO2 and food level. High food availability offset the negative consequences of elevated pCO2 on larval shell growth and total dry weight. Low food availability, in contrast, exacerbated these impacts. In both cases, effects of food and pCO2 interacted additively rather than synergistically, indicating that they operated independently. Despite the potential for abundant resources to counteract the consequences of ocean acidification, impacts were never completely negated, suggesting that even under conditions of enhanced primary production and elevated food availability, impacts of ocean acidification may still accrue in some consumers.

Parameter Estimation of Fossil Oysters from High Resolution 3D Point Cloud and Image Data

NASA Astrophysics Data System (ADS)

Djuricic, Ana; Harzhauser, Mathias; Dorninger, Peter; Nothegger, Clemens; Mandic, Oleg; Székely, Balázs; Molnár, Gábor; Pfeifer, Norbert

2014-05-01

A unique fossil oyster reef was excavated at Stetten in Lower Austria, which is also the highlight of the geo-edutainment park 'Fossilienwelt Weinviertel'. It provides the rare opportunity to study the Early Miocene flora and fauna of the Central Paratethys Sea. The site presents the world's largest fossil oyster biostrome formed about 16.5 million years ago in a tropical estuary of the Korneuburg Basin. About 15,000 up to 80-cm-long shells of Crassostrea gryphoides cover a 400 m2 large area. Our project 'Smart-Geology for the World's largest fossil oyster reef' combines methods of photogrammetry, geology and paleontology to document, evaluate and quantify the shell bed. This interdisciplinary approach will be applied to test hypotheses on the genesis of the taphocenosis (e.g.: tsunami versus major storm) and to reconstruct pre- and post-event processes. Hence, we are focusing on using visualization technologies from photogrammetry in geology and paleontology in order to develop new methods for automatic and objective evaluation of 3D point clouds. These will be studied on the basis of a very dense surface reconstruction of the oyster reef. 'Smart Geology', as extension of the classic discipline, exploits massive data, automatic interpretation, and visualization. Photogrammetry provides the tools for surface acquisition and objective, automated interpretation. We also want to stress the economic aspect of using automatic shape detection in paleontology, which saves manpower and increases efficiency during the monitoring and evaluation process. Currently, there are many well known algorithms for 3D shape detection of certain objects. We are using dense 3D laser scanning data from an instrument utilizing the phase shift measuring principle, which provides accurate geometrical basis < 3 mm. However, the situation is difficult in this multiple object scenario where more than 15,000 complete or fragmentary parts of an object with random orientation are found. The goal is to investigate if the application of state-of-the-art 3D digitizing, data processing, and visualization technologies support the interpretation of this paleontological site. The obtained 3D data (approx. 1 billion points at the respective area) is analyzed with respect to their 3D structure in order to derive geometrical information. The aim of this contribution is to segment the 3D point cloud of laser scanning data into meaningful regions representing particular objects. Geometric parameters (curvature, tangent plane orientation, local minimum and maximum, etc.) are derived for every 3D point of the point cloud. A set of features is computed in each point using different kernel sizes to define neighborhoods of different size. This provides information on convexity (outer surface), concavity (inner surface) and locally flat areas, which shall be further utilized in fitting model of Crassostrea-shells. In addition, digitizing is performed manually in order to obtain a representative set of reference data for the evaluation of the obtained results. For evaluating these results the reference data (length and orientation of specimen) is then compared to the automatically derived segments of the point cloud. The study is supported by the Austrian Science Fund (FWF P 25883-N29).

δ15N Values in Crassostrea virginica Shells Provides Early Direct Evidence for Nitrogen Loading to Chesapeake Bay

NASA Astrophysics Data System (ADS)

Black, H. D.; Andrus, C. F. T.; Lambert, W. J.; Rick, T. C.; Gillikin, D. P.

2017-03-01

Crassostrea virginica is one of the most common estuarine bivalves in the United States’ east coast and is frequently found in archaeological sites and sub-fossil deposits. Although there have been several sclerochronological studies on stable carbon and oxygen isotopes in the shells of this species, less is known about δ15N values within their shells, which could be a useful paleoenvironmental proxy to assess estuarine nitrogen dynamics. Modern C. virginica samples were collected in Chesapeake Bay for comparison with archaeological shells from nearby sites ranging in age from ~100 to 3,200 years old. Left valves were sampled by milling the hinge area and the resulting powder was analyzed for %N and δ15N values. Comparison of δ15N values between C. virginica shells shows relatively constant values from ~1250 BC to ~1800 AD. After ~1800 AD, there are rapid increases in 15N enrichment in the shells, which continue to increase in value up to the modern shell values. The increase in δ15N values is evidence of early anthropogenic impact in Chesapeake Bay. These results corroborate the observation that coastal nitrogen pollution occurred earlier than the 19th century and support the use of oyster shell δ15N values as a useful environmental proxy.

Dissolution of Calcite in the Twilight Zone: Bacterial Control of Dissolution of Sinking Planktonic Carbonates Is Unlikely

PubMed Central

Bissett, Andrew; Neu, Thomas R.; de Beer, Dirk

2011-01-01

We investigated the ability of bacterial communities to colonize and dissolve two biogenic carbonates (Foraminifera and oyster shells). Bacterial carbonate dissolution in the upper water column is postulated to be driven by metabolic activity of bacteria directly colonising carbonate surfaces and the subsequent development of acidic microenvironments. We employed a combination of microsensor measurements, scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and image analysis and molecular documentation of colonising bacteria to monitor microbial processes and document changes in shell surface topography. Bacterial communities rapidly colonised shell surfaces, forming dense biofilms with extracellular polymeric substance (EPS) deposits. Despite this, we found no evidence of bacterially mediated carbonate dissolution. Dissolution was not indicated by Ca2+ microprofiles, nor was changes in shell surface structure related to the presence of colonizing bacteria. Given the short time (days) settling carbonate material is actually in the twilight zone (500–1000 m), it is highly unlikely that microbial metabolic activity on directly colonised shells plays a significant role in dissolving settling carbonates in the shallow ocean. PMID:22102861

Dissolution of calcite in the twilight zone: bacterial control of dissolution of sinking planktonic carbonates is unlikely.

PubMed

Bissett, Andrew; Neu, Thomas R; Beer, Dirk de

2011-01-01

We investigated the ability of bacterial communities to colonize and dissolve two biogenic carbonates (Foraminifera and oyster shells). Bacterial carbonate dissolution in the upper water column is postulated to be driven by metabolic activity of bacteria directly colonising carbonate surfaces and the subsequent development of acidic microenvironments. We employed a combination of microsensor measurements, scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and image analysis and molecular documentation of colonising bacteria to monitor microbial processes and document changes in shell surface topography. Bacterial communities rapidly colonised shell surfaces, forming dense biofilms with extracellular polymeric substance (EPS) deposits. Despite this, we found no evidence of bacterially mediated carbonate dissolution. Dissolution was not indicated by Ca²⁺ microprofiles, nor was changes in shell surface structure related to the presence of colonizing bacteria. Given the short time (days) settling carbonate material is actually in the twilight zone (500-1000 m), it is highly unlikely that microbial metabolic activity on directly colonised shells plays a significant role in dissolving settling carbonates in the shallow ocean.

Oyster reef restoration in the Northern Gulf of Mexico: effect of artificial substrate and sge on nekton and benthic macroinvertebrate assemblage use

USGS Publications Warehouse

Brown, Laura A.; Furlong, Jessica N.; Brown, Kenneth M.; LaPeyre, Megan K.

2013-01-01

In the northern Gulf of Mexico (GOM), reefs built by eastern oysters, Crassostrea virginica, provide critical habitat within shallow estuaries, and recent efforts have focused on restoring reefs to benefit nekton and benthic macroinvertebrates. We compared nekton and benthic macroinvertebrate assemblages at historic, newly created (<5years) and old (>6years) shell and rock substrate reefs. Using crab traps, gill-nets, otter trawls, cast nets, and benthic macroinvertebrate collectors, 20 shallow reefs (<5m) in the northern GOM were sampled throughout the summer of 2011. We compared nekton and benthic assemblage abundance, diversity and composition across reef types. Except for benthic macroinvertebrate abundance, which was significantly higher on old rock reefs as compared to historic reefs, all reefs were similar to historic reefs, suggesting created reefs provide similar support of nekton and benthic assemblages as historic reefs. To determine refuge value of oyster structure for benthic macroinvertebrates compared to bare bottom, we tested preferences of juvenile crabs across depth and refuge complexity in the presence and absence of adult blue crabs (Callinectes sapidus). Juveniles were more likely to use deep water with predators present only when provided oyster structure. Provision of structural material to support and sustain development of benthic and mobile reef communities may be the most important factor in determining reef value to these assemblages, with biophysical characteristics related to reef location influencing assemblage patterns in areas with structure; if so, appropriately locating created reefs is critical.

Disentangling the history of complex multi-phased shell beds based on the analysis of 3D point cloud data

NASA Astrophysics Data System (ADS)

Harzhauser, Mathias; Djuricic, Ana; Mandic, Oleg; Dorninger, Peter; Nothegger, Clemens; Székely, Balázs; Molnár, Gábor; Pfeifer, Norbert

2015-04-01

Shell beds are key features in sedimentary records throughout the Phanerozoic. The interplay between burial rates and population productivity is reflected in distinct degrees of shelliness. Consequently, shell beds may provide informations on various physical processes, which led to the accumulation and preservation of hard parts. Many shell beds pass through a complex history of formation being shaped by more than one factor. In shallow marine settings, the composition of shell beds is often strongly influenced by winnowing, reworking and transport. These processes may cause considerable time averaging and the accumulation of specimens, which have lived thousands of years apart. In the best case, the environment remained stable during that time span and the mixing does not mask the overall composition. A major obstacle for the interpretation of shell beds, however, is the amalgamation of shell beds of several depositional units in a single concentration, as typically for tempestites and tsunamites. Disentangling such mixed assemblages requires deep understanding of the ecological requirements of the taxa involved - which is achievable for geologically young shell beds with living relatives - and a statistic approach to quantify the contribution by the various death assemblages. Furthermore it requires understanding of sedimentary processes potentially involved into their formation. Here we present the first attempt to describe and decipher such a multi-phase shell-bed based on a high resolution digital surface model (1 mm) combined with ortho-photos with a resolution of 0.5 mm per pixel. Documenting the oyster reef requires precisely georeferenced data; owing to high redundancy of the point cloud an accuracy of a few mm was achieved. The shell accumulation covers an area of 400 m2 with thousands of specimens, which were excavated by a three months campaign at Stetten in Lower Austria. Formed in an Early Miocene estuary of the Paratethys Sea it is mainly composed of shells of the giant oyster Crassostrea gryphoides along with numerous other bivalves, gastropods and barnacles. More than 10.000 objects were outlined on the digital surface model and characterized in respect to taxonomy, convex up/down position, left/right shell, orientation, fragmentation and several other features. The outlines and attribute data were stored in a georeferenced ArcGIS database. Already the first analyses and visualizations of the obtained data-sets pointed out different degrees of taxon distribution, composition, and taphonomic grade allowing an identification of at least four discrete ecosystem/depositional phases now amalgamated in a single shell-bed. Based on examples from the present research the presentation will demonstrate enormous potential of high resolution terrestrial laser scanning in paleontology and sedimentology. Representing a pioneering study, lessons have been learned about the benefits as well as the limitations of its application for taphonomic studies. The project is supported by the Austrian Science Fund (FWF P 25883-N29).

Bioaccumulation and elimination of Cryptosporidium parvum oocysts in experimentally exposed Eastern oysters (Crassostrea virginica) held in static tank aquaria.

PubMed

Willis, Jessica E; McClure, J T; McClure, Carol; Spears, Jonathan; Davidson, Jeff; Greenwood, Spencer J

2014-03-03

A variety of human enteropathogens, including viruses, bacteria, and parasites, have been shown to bioaccumulate in suspension-feeding bivalve shellfish. Cryptosporidium parvum is a zoonotic protozoan parasite that has been detected in many shellfish species within both fecally contaminated and clean oyster growing areas across the globe. For this study, C. parvum oocysts (1000 and 10,000) were spiked into 10 L of water in static tank systems housing Crassostrea virginica. Oysters were either held in the contaminated aquaria for 7 days of exposure or were exposed for 24h and subsequently placed in a clean static tank system for the remainder of the trial. Individual oysters, fecal material, and tank water were analyzed for oocysts up to 7 days post-exposure via direct immunofluorescence. Oysters held under chronic exposure conditions gradually accumulated oocysts (1.5 or 34.4 oocysts/oyster/day for low or high dose exposure groups, respectively) between days 1 and 7, with an exponential uptake in oocysts observed within the first 24h post-exposure (mean uptake of 29.6 or 241.9 oocysts/oyster, respectively). Oysters that were transferred to clean water after 24h were capable of slowly depurating oocysts, following a linear trend. During chronic exposure trials 48-49% of the total spiked inoculum was recovered from oyster tissue, whereas 4.8-5.9% and 38-40% was recovered from tank water and from fecal material at day 7, respectively. In acute exposure trials, 30-31% of the total tank inoculum was found in oysters, suggesting that chronically exposed oysters were likely re-filtering some oocysts. Examinations of oyster fecal material from acute exposures revealed that 72-82% of oocysts recovered were already excreted at the time of oyster transfer (day 1), with only 18-28% being excreted during the static depuration phase. These data support that although most C. parvum oocysts are removed by C. virginica oysters within 24h, elimination after this point occurs slowly. Additionally, chronic exposures demonstrate that wild or cultured oysters in saline environments that are frequently exposed to sources of Cryptosporidium may be unable to eliminate the parasites at a rate that balances initial uptake. Copyright © 2013 Elsevier B.V. All rights reserved.

Insights from the Shell Proteome: Biomineralization to Adaptation

PubMed Central

Arivalagan, Jaison; Yarra, Tejaswi; Marie, Benjamin; Sleight, Victoria A.; Duvernois-Berthet, Evelyne; Clark, Melody S.; Marie, Arul; Berland, Sophie

2017-01-01

Bivalves have evolved a range of complex shell forming mechanisms that are reflected by their incredible diversity in shell mineralogy and microstructures. A suite of proteins exported to the shell matrix space plays a significant role in controlling these features, in addition to underpinning some of the physical properties of the shell itself. Although, there is a general consensus that a minimum basic protein tool kit is required for shell construction, to date, this remains undefined. In this study, the shell matrix proteins (SMPs) of four highly divergent bivalves (The Pacific oyster, Crassostrea gigas; the blue mussel, Mytilus edulis; the clam, Mya truncata, and the king scallop, Pecten maximus) were analyzed in an identical fashion using proteomics pipeline. This enabled us to identify the critical elements of a “basic tool kit” for calcification processes, which were conserved across the taxa irrespective of the shell morphology and arrangement of the crystal surfaces. In addition, protein domains controlling the crystal layers specific to aragonite and calcite were also identified. Intriguingly, a significant number of the identified SMPs contained domains related to immune functions. These were often are unique to each species implying their involvement not only in immunity, but also environmental adaptation. This suggests that the SMPs are selectively exported in a complex mix to endow the shell with both mechanical protection and biochemical defense. PMID:27744410

Late Holocene sedimentary environments of south San Francisco Bay, California, illustrated in gravity cores

USGS Publications Warehouse

Woodrow, Donald L.; Fregoso, Theresa A.; Wong, Florence L.; Jaffe, Bruce E.

2014-01-01

Data are reported here from 51 gravity cores collected from the southern part of San Francisco Bay by the U.S. Geological Survey in 1990. The sedimentary record in the cores demonstrates a stable geographic distribution of facies and spans a few thousand years. Carbon-14 dating of the sediments suggests that sedimentation rates average about 1 mm/yr. The geometry of the bay floor and the character of the sediment deposited have remained about the same in the time spanned by the cores. However, the sedimentary record over periods of centuries or decades is likely to be much more variable. Sediments containing a few bivalve shells and bivalve or oyster coquinas are most often found west of the main channel and near the San Mateo Bridge. Elsewhere in the south bay, shells are rare except in the southernmost reaches where scattered gastropod shells are found.

Chester River Study. Volume I,

DTIC Science & Technology

1972-11-01

of the effects of agri- i6 IA -46 cultural activities on the aquatic system. This initial feet (24 meters). The soils of the basin area are suit...to the stocks themselves. The shell crystal struc- ture modification in oysters recalls to mind the eggshell thinning in birds mentioned earlier...with figures provided by Chestertown to the mouth of the River at Love the U.S. Soil Conservation Service as of 1967 (last Point (Table VII). year of

High resolution carbon isotope of Crassostrea cuttakensis: A proxy for seasonally varying carbon dynamics in a tropical delta-estuary system

NASA Astrophysics Data System (ADS)

Sreemany, Arpita

2017-04-01

The exponential increase in the atmospheric CO2 concentration and global temperature is becoming a major threat to the existence of the mankind. It has been proposed that the ˜2 ˚ C rise in the average global temperature may lead to a point of no-return where the balance between the climate and the ecosystem collapses. Therefore, detailed understanding of the major carbon reservoirs and their mutual interactions is needed for better future climate prediction. Among all the reservoirs, ocean holds ˜90 % of the exogenic carbon and promotes long term storage in sediments. However, the majority of the sedimentary carbon is of terrestrial origin and transported through rivers, which play an important role in carbon exchange between the atmosphere, terrestrial biosphere, and oceans. The transportation of organic carbon through river does not follow a simple conveyer belt model. Various organic and inorganic reactions (i.e., organic carbon degradation, inorganic carbon precipitation, primary production, community respiration) modify the state of the carbon to form a major sub-reservoir in the river, i.e., Dissolved Inorganic Carbon (DIC). So, identifying the source/s of the DIC is crucial to understand the carbon dynamics in the river. Stable carbon isotopic composition of the DIC (δ13CDIC) has long been extensively used to reveal the dominant source/s of the DIC. The majority of the large rivers, being situated in the tropical belts, show seasonal fluctuation in the DIC sources. However, seasonal sampling in the remotest reaches of these rivers hindered our thorough understanding of the seasonally varying source/s of DIC in these rivers. Many calcifying organisms precipitate their shell carbonate in equilibrium with water and hence likely to record the δ13CDICof ambient water in their shell. In this study, a living oyster (Crassostrea cuttakensis) was collected from Matla River, which is part of the Ganges Brahmaputra river delta system, and analyzed for its stable isotopic composition (δ13Cshelland δ18Oshell). The oyster shell was cut along the maximum growth line and the umbo of the oyster was analyzed for the stable isotopic measurement. An online laser ablation system, attached to a Delta V Advantage Mass Spectrometer via. Gas-bench II, was used for very high resolution (˜125μm, equivalent to ˜6 days) isotope data. Additionally, water samples were collected from the study area in different seasons and the δ13CDICof the ambient water was analyzed. The shell carbonate δ13C profile shows excellent seasonal variation and very good correlation with the measured δ13CDIC. Though more water samples from different seasons are needed to accurately calibrate the vital effect of this species, it can be suggested from the limited dataset that the carbonate shell of this species was precipitated in equilibrium with the ambient water and can be used as a reliable proxy for the δ13CDIC.

Changing seasonality patterns in Central Europe from Miocene Climate Optimum to Miocene Climate Transition deduced from the Crassostrea isotope archive

NASA Astrophysics Data System (ADS)

Harzhauser, Mathias; Piller, Werner E.; Müllegger, Stefan; Grunert, Patrick; Micheels, Arne

2011-03-01

The Western Tethyan estuarine oyster Crassostrea gryphoides is an excellent climate archive due to its large size and rapid growth. It is geologically long lived and allows a stable isotope-based insight into climatic trends during the Miocene. Herein we utilised the climate archive of 5 oyster shells from the Miocene Climate Optimum (MCO) and the subsequent Miocene Climate Transition (MCT) to evaluate changes of seasonality patterns. MCO shells exhibit highly regular seasonal rhythms of warm-wet and dry-cool seasons. Optimal conditions resulted in extraordinary growth rates of the oysters. δ 13C profiles are in phase with δ 18O although phytoplankton blooms may cause a slight offset. Estuarine waters during the MCO in Central Europe display a seasonal temperature range of c. 9-10 °C. Absolute water temperatures have ranged from 17 to 19 °C during cool seasons and up to 28 °C in warm seasons. Already during the early phase of the MCO, the growth rates are distinctly declining, although gigantic and extremely old shells have been formed at that time. Still, a very regular and well expressed seasonality is dominating the isotope profiles, but episodically occurring extreme climate events influence the environments. The seasonal temperature range is still c. 9 °C but the cool season temperature seems to be slightly lower (16 °C) and the warm season water temperature does not exceed c. 25 °C. In the later MCT at c. 12.5-12.0 Ma the seasonality pattern is breaking down and is replaced by successions of dry years with irregular precipitation events. No correlation between δ 18O and δ 13C is documented maybe due to a suboptimal nutrition level which would explain the low growth rates and small sizes. The amplitude of seasonal temperature range is decreasing to 5-8 °C. No clear cooling trend can be postulated for that time as the winter season water temperatures range from 15 to 20 °C. This may point to unstable precipitation rhythms on a multi-annual to decadal scale as main difference between MCO and MCT climates in Central Europe instead of a simple temperature decline scenario.

Alterations of tissue metallothionein and vitellogenin concentrations in tropical cup oysters (Saccostrea sp.) following short-term (96h) exposure to cadmium.

PubMed

Moncaleano-Niño, Angela M; Barrios-Latorre, Sergio A; Poloche-Hernández, Javier F; Becquet, Vanessa; Huet, Valérie; Villamil, Luisa; Thomas-Guyon, Hélène; Ahrens, Michael J; Luna-Acosta, Andrea

2017-04-01

Metallothioneins and vitellogenins are low molecular weight proteins that have been used widely in environmental monitoring as biomarkers of exposure and damage to metals and estrogenic compounds, respectively. In the present study, the responses of metallothionein and vitellogenin tissue concentrations were measured following acute (96h) aqueous exposures to cadmium in Saccostrea sp., a tropical cup oyster native to the Western Pacific Ocean that has recently established itself in the Caribbean Sea. Adult oysters (1.5-5.0cm shell length) collected from the municipal marina of Santa Marta, Colombia (Caribbean Sea) and acclimated for 5days in the laboratory, were exposed to Cd at five concentrations (0, 1, 10, 100 and 1000μg/L) and their tissues (gills, digestive gland and adductor muscle) were analyzed in pools of 5 individuals (3 replicates per concentration). Metallothioneins in digestive glands of oysters exposed to Cd concentrations≥100μg/L showed a significant increase, from 8.0 to 14.8μg MT/mg total protein, whereas metallothionein concentrations in gills increased to lesser extent, and no differences were observed in adductor muscle. Metallothionein concentrations in digestive gland and gills correlated directly with whole soft tissue Cd concentrations (ranging from 2 to 297μg/g dw Cd). Vitellogenin in homogenates of oyster gonad tissue, after 96h of exposure to 1000μg/L Cd, were significantly lower (0.04mg P/g gonad) compared to control oysters (0.68mg P/g gonad), suggestive of an anti-estrogenic effect of Cd at high concentrations, whereas no significant changes in vitellogenin concentrations were observed at intermediate Cd exposure concentrations. This study confirms acute responses of metallothionein and vitellogenin concentrations in tissues of Saccostrea sp. exposed to high concentrations of cadmium (Cd≥100μg/L, 96h). The present results are first step towards validating the use of these two proteins as biomarkers of metal exposure in this species. Copyright © 2017 Elsevier B.V. All rights reserved.

Oyster reef restoration in the northern Gulf of Mexico: extent, methods and outcomes

USGS Publications Warehouse

LaPeyre, Megan K.; Furlong, Jessica N.; Brown, Laura A.; Piazza, Bryan P.; Brown, Ken

2014-01-01

Shellfish reef restoration to support ecological services has become more common in recent decades, driven by increasing awareness of the functional decline of shellfish systems. Maximizing restoration benefits and increasing efficiency of shellfish restoration activities would greatly benefit from understanding and measurement of system responses to management activities. This project (1) compiles a database of northern Gulf of Mexico inshore artificial oyster reefs created for restoration purposes, and (2) quantitatively assesses a subset of reefs to determine project outcomes. We documented 259 artificial inshore reefs created for ecological restoration. Information on reef material, reef design and monitoring was located for 94, 43 and 20% of the reefs identified. To quantify restoration success, we used diver surveys to quantitatively sample oyster density and substrate volume of 11 created reefs across the coast (7 with rock; 4 with shell), paired with 7 historic reefs. Reefs were defined as fully successful if there were live oysters, and partially successful if there was hard substrate. Of these created reefs, 73% were fully successful, while 82% were partially successful. These data highlight that critical information related to reef design, cost, and success remain difficult to find and are generally inaccessible or lost, ultimately hindering efforts to maximize restoration success rates. Maintenance of reef creation information data, development of standard reef performance measures, and inclusion of material and reef design testing within reef creation projects would be highly beneficial in implementing adaptive management. Adaptive management protocols seek specifically to maximize short and long-term restoration success, but are critically dependent on tracking and measuring system responses to management activities.

Oyster reproduction is affected by exposure to polystyrene microplastics

PubMed Central

Sussarellu, Rossana; Suquet, Marc; Thomas, Yoann; Lambert, Christophe; Fabioux, Caroline; Pernet, Marie Eve Julie; Le Goïc, Nelly; Quillien, Virgile; Mingant, Christian; Epelboin, Yanouk; Corporeau, Charlotte; Guyomarch, Julien; Robbens, Johan; Paul-Pont, Ika; Soudant, Philippe; Huvet, Arnaud

2016-01-01

Plastics are persistent synthetic polymers that accumulate as waste in the marine environment. Microplastic (MP) particles are derived from the breakdown of larger debris or can enter the environment as microscopic fragments. Because filter-feeder organisms ingest MP while feeding, they are likely to be impacted by MP pollution. To assess the impact of polystyrene microspheres (micro-PS) on the physiology of the Pacific oyster, adult oysters were experimentally exposed to virgin micro-PS (2 and 6 µm in diameter; 0.023 mg·L−1) for 2 mo during a reproductive cycle. Effects were investigated on ecophysiological parameters; cellular, transcriptomic, and proteomic responses; fecundity; and offspring development. Oysters preferentially ingested the 6-µm micro-PS over the 2-µm-diameter particles. Consumption of microalgae and absorption efficiency were significantly higher in exposed oysters, suggesting compensatory and physical effects on both digestive parameters. After 2 mo, exposed oysters had significant decreases in oocyte number (−38%), diameter (−5%), and sperm velocity (−23%). The D-larval yield and larval development of offspring derived from exposed parents decreased by 41% and 18%, respectively, compared with control offspring. Dynamic energy budget modeling, supported by transcriptomic profiles, suggested a significant shift of energy allocation from reproduction to structural growth, and elevated maintenance costs in exposed oysters, which is thought to be caused by interference with energy uptake. Molecular signatures of endocrine disruption were also revealed, but no endocrine disruptors were found in the biological samples. This study provides evidence that micro-PS cause feeding modifications and reproductive disruption in oysters, with significant impacts on offspring. PMID:26831072

Oyster reproduction is affected by exposure to polystyrene microplastics.

PubMed

Sussarellu, Rossana; Suquet, Marc; Thomas, Yoann; Lambert, Christophe; Fabioux, Caroline; Pernet, Marie Eve Julie; Le Goïc, Nelly; Quillien, Virgile; Mingant, Christian; Epelboin, Yanouk; Corporeau, Charlotte; Guyomarch, Julien; Robbens, Johan; Paul-Pont, Ika; Soudant, Philippe; Huvet, Arnaud

2016-03-01

Plastics are persistent synthetic polymers that accumulate as waste in the marine environment. Microplastic (MP) particles are derived from the breakdown of larger debris or can enter the environment as microscopic fragments. Because filter-feeder organisms ingest MP while feeding, they are likely to be impacted by MP pollution. To assess the impact of polystyrene microspheres (micro-PS) on the physiology of the Pacific oyster, adult oysters were experimentally exposed to virgin micro-PS (2 and 6 µm in diameter; 0.023 mg·L(-1)) for 2 mo during a reproductive cycle. Effects were investigated on ecophysiological parameters; cellular, transcriptomic, and proteomic responses; fecundity; and offspring development. Oysters preferentially ingested the 6-µm micro-PS over the 2-µm-diameter particles. Consumption of microalgae and absorption efficiency were significantly higher in exposed oysters, suggesting compensatory and physical effects on both digestive parameters. After 2 mo, exposed oysters had significant decreases in oocyte number (-38%), diameter (-5%), and sperm velocity (-23%). The D-larval yield and larval development of offspring derived from exposed parents decreased by 41% and 18%, respectively, compared with control offspring. Dynamic energy budget modeling, supported by transcriptomic profiles, suggested a significant shift of energy allocation from reproduction to structural growth, and elevated maintenance costs in exposed oysters, which is thought to be caused by interference with energy uptake. Molecular signatures of endocrine disruption were also revealed, but no endocrine disruptors were found in the biological samples. This study provides evidence that micro-PS cause feeding modifications and reproductive disruption in oysters, with significant impacts on offspring.

The demographic consequences of growing older and bigger in oyster populations.

PubMed

Moore, Jacob L; Lipcius, Romuald N; Puckett, Brandon; Schreiber, Sebastian J

2016-10-01

Structured population models, particularly size- or age-structured, have a long history of informing conservation and natural resource management. While size is often easier to measure than age and is the focus of many management strategies, age-structure can have important effects on population dynamics that are not captured in size-only models. However, relatively few studies have included the simultaneous effects of both age- and size-structure. To better understand how population structure, particularly that of age and size, impacts restoration and management decisions, we developed and compared a size-structured integral projection model (IPM) and an age- and size-structured IPM, using a population of Crassostrea gigas oysters in the northeastern Pacific Ocean. We analyzed sensitivity of model results across values of local retention that give populations decreasing in size to populations increasing in size. We found that age- and size-structured models yielded the best fit to the demographic data and provided more reliable results about long-term demography. Elasticity analysis showed that population growth rate was most sensitive to changes in the survival of both large (>175 mm shell length) and small (<75 mm shell length) oysters, indicating that a maximum size limit, in addition to a minimum size limit, could be an effective strategy for maintaining a sustainable population. In contrast, the purely size-structured model did not detect the importance of large individuals. Finally, patterns in stable age and stable size distributions differed between populations decreasing in size due to limited local retention and populations increasing in size due to high local retention. These patterns can be used to determine population status and restoration success. The methodology described here provides general insight into the necessity of including both age- and size-structure into modeling frameworks when using population models to inform restoration and management decisions. © 2016 by the Ecological Society of America.

Effect of Oyster Shell Calcium Powder on the Quality of Restructured Pork Ham.

PubMed

Choi, Jung-Seok; Lee, Hyun-Jin; Jin, Sang-Keun; Lee, Hyun-Joo; Choi, Yang-Il

2014-01-01

This study was conducted to evaluate the effects of oyster shell calcium powder (OSCP) as a substitute for phosphates in curing agent, on the quality of restructured pork ham. Restructured pork ham was processed under six treatment conditions: T1 (no additives), T2 (0.3% sodium tripolyphosphate), T3 (1.5% NaCl+0.5% whey protein), T4 (1.5% NaCl+0.5% whey protein+0.15% OSCP), T5 (1.5% NaCl+0.5% whey protein+0.3% OSCP), and T6 (1.5% NaCl+0.5% whey protein+0.5% OSCP). Addition of OSCP significantly increased the ash content and pH of restructured pork ham (p<0.05), but did not affect the cooking loss and water holding capacity values of restructured pork ham. Addition of OSCP had no effect on Hunter a and b surface color values of restructured pork ham, but did decrease the Hunter L surface color value (p<0.05). The addition of 0.5% OSCP showed significantly higher chewiness and springiness values of restructured pork ham, compared with the addition of phosphates (p<0.05). In conclusion, the addition of OSCP combined with low NaCl and 0.5% whey protein can be considered a viable substitute for phosphates in the curing agent, when processing restructured pork ham.

Stabilization of Pb²⁺ and Cu²⁺ contaminated firing range soil using calcined oyster shells and waste cow bones.

PubMed

Moon, Deok Hyun; Cheong, Kyung Hoon; Khim, Jeehyeong; Wazne, Mahmoud; Hyun, Seunghun; Park, Jeong-Hun; Chang, Yoon-Young; Ok, Yong Sik

2013-05-01

Pb(2+) and Cu(2+) contamination at army firing ranges poses serious environmental and health risks to nearby communities necessitating an immediate and prompt remedial action. In this study, a novel mixture of calcined oyster shells (COSs) and waste cow bones (WCBs) was utilized to immobilize Pb(2+) and Cu(2+) in army firing range soils. The effectiveness of the treatment was evaluated based on the Korean Standard leaching test. The treatment results showed that Pb(2+) and Cu(2+) immobilization in the army firing range soil was effective in significantly reducing Pb(2+) and Cu(2+) leachability upon the combined treatment with COS and WCB. A drastic reduction in Pb(2+) (99%) and Cu(2+) leachability (95%) was obtained as compared to the control sample, upon treatment with 5 wt.% COS and 5 wt.% WCB. The combination treatment of COS and WCB was more effective for Pb immobilization, than the treatment with COS or WCB alone. The 5 wt.% COS alone treatment resulted in 95% reduction in Cu(2+) leachability. The SEM-EDX results suggested that Pb(2+) and Cu(2+) immobilization was most probably associated with the formation of ettringite, pozzolanic reaction products and pyromorphite-like phases at the same time. Copyright © 2013 Elsevier Ltd. All rights reserved.

Differential mantle transcriptomics and characterization of growth-related genes in the diploid and triploid pearl oyster Pinctada fucata.

PubMed

Guan, Yunyan; He, Maoxian; Wu, Houbo

2017-06-01

To explore the molecular mechanism of triploidy effect in the pearl oyster Pinctada fucata, two RNA-seq libraries were constructed from the mantle tissue of diploids and triploids by Roche-454 massive parallel pyrosequencing. The identification of differential expressed genes (DEGs) between diploid and triploid may reveal the molecular mechanism of triploidy effect. In this study, 230 down-regulated and 259 up-regulated DEGs were obtained by comparison between diploid and triploid libraries. The gene ontology and KEGG pathway analysis revealed more functional activation in triploids and it may due to the duplicated gene expression in transcriptional level during whole genome duplication (WGD). To confirm the sequencing data, a set of 11 up-regulated genes related to growth and development control and regulation were analyzed by RT-qPCR in independent experiment. According to the validation and annotation of these genes, it is hypothesized that the set of up-regulated expressed genes had the correlated expression pattern involved in shell building or other interactive probable functions during triploidization. The up- regulation of growth-related genes may support the classic hypotheses of 'energy redistribution' from early research. The results provide valuable resources to understand the molecular mechanism of triploidy effect in both shell building and producing high-quality seawater pearls. Copyright © 2017 Elsevier B.V. All rights reserved.

The mining of pearl formation genes in pearl oyster Pinctada fucata by cDNA suppression subtractive hybridization.

PubMed

Wang, Ning; Kinoshita, Shigeharu; Nomura, Naoko; Riho, Chihiro; Maeyama, Kaoru; Nagai, Kiyohito; Watabe, Shugo

2012-04-01

Recent researches revealed the regional preference of biomineralization gene transcription in the pearl oyster Pinctada fucata: it transcribed mainly the genes responsible for nacre secretion in mantle pallial, whereas the ones regulating calcite shells expressed in mantle edge. This study took use of this character and constructed the forward and reverse suppression subtractive hybridization (SSH) cDNA libraries. A total of 669 cDNA clones were sequenced and 360 expressed sequence tags (ESTs) greater than 100 bp were generated. Functional annotation associated 95 ESTs with specific functions, and 79 among them were identified from P. fucata at the first time. In the forward SSH cDNA library, it recognized mass amount of nacre protein genes, biomineralization genes dominantly expressed in the mantle pallial, calcium-ion-binding genes, and other biomineralization-related genes important for pearl formation. Real-time PCR showed that all the examined genes were distributed in oyster mantle tissues with a consistence to the SSH design. The detection of their RNA transcripts in pearl sac confirmed that the identified genes were certainly involved in pearl formation. Therefore, the data from this work will initiate a new round of pearl formation gene study and shed new insights into molluscan biomineralization.

The Molecular Differentiation of Anatomically Paired Left and Right Mantles of the Pacific Oyster Crassostrea gigas.

PubMed

Wei, Lei; Xu, Fei; Wang, Yuzhi; Cai, Zhongqiang; Yu, Wenchao; He, Cheng; Jiang, Qiuyun; Xu, Xiqiang; Guo, Wen; Wang, Xiaotong

2018-03-28

Left-right (L-R) asymmetry is controlled by gene regulation pathways for the L-R axis, and in vertebrates, the gene Pitx2 in TGF-β signaling pathway plays important roles in the asymmetrical formation of organs. However, less is known about the asymmetries of anatomically identical paired organs, as well as the transcriptional regulation mechanism of the gene Pitx in invertebrates. Here, we report the molecular biological differences between the left and right mantles of an invertebrate, the Pacific oyster Crassostrea gigas, and propose one possible mechanism underlying those differences. RNA sequencing (RNA-seq) analysis indicated that the paired organs showed different gene expression patterns, suggesting possible functional differences in shell formation, pheromone signaling, nerve conduction, the stress response, and other physiological processes. RNA-seq and real-time qPCR analysis indicated high right-side expression of the Pitx homolog (cgPitx) in oyster mantle, supporting a conserved role for Pitx in controlling asymmetry. Methylation-dependent restriction-site associated DNA sequencing (MethylRAD) identified a methylation site in the promoter region of cgPitx and showed significantly different methylation levels between the left and right mantles. This is the first report, to our knowledge, of such a difference in methylation in spiralians, and it was further confirmed in 18 other individuals by using a pyrosequencing assay. The miRNome analysis and the TGF-β receptor/Smad inhibition experiment further supported that several genes in TGF-β signaling pathway may be related with the L/R asymmetry of oyster mantles. These results suggested that the molecular differentiation of the oyster's paired left and right mantles is significant, TGF-β signaling pathway could be involved in establishing or maintaining the asymmetry, and the cgPitx gene as one of genes in this pathway; the different methylation levels in its promoter regions between L/R mantles was the one of possible mechanisms regulating the left-right functional differentiation.

Amorphous Calcium Carbonate Precipitation by Cellular Biomineralization in Mantle Cell Cultures of Pinctada fucata

PubMed Central

Xiang, Liang; Kong, Wei; Su, Jingtan; Liang, Jian; Zhang, Guiyou; Xie, Liping; Zhang, Rongqing

2014-01-01

The growth of molluscan shell crystals is generally thought to be initiated from the extrapallial fluid by matrix proteins, however, the cellular mechanisms of shell formation pathway remain unknown. Here, we first report amorphous calcium carbonate (ACC) precipitation by cellular biomineralization in primary mantle cell cultures of Pinctada fucata. Through real-time PCR and western blot analyses, we demonstrate that mantle cells retain the ability to synthesize and secrete ACCBP, Pif80 and nacrein in vitro. In addition, the cells also maintained high levels of alkaline phosphatase and carbonic anhydrase activity, enzymes responsible for shell formation. On the basis of polarized light microscopy and scanning electron microscopy, we observed intracellular crystals production by mantle cells in vitro. Fourier transform infrared spectroscopy and X-ray diffraction analyses revealed the crystals to be ACC, and de novo biomineralization was confirmed by following the incorporation of Sr into calcium carbonate. Our results demonstrate the ability of mantle cells to perform fundamental biomineralization processes via amorphous calcium carbonate, and these cells may be directly involved in pearl oyster shell formation. PMID:25405357

Crassostrea gigas mortality in France: the usual suspect, a herpes virus, may not be the killer in this polymicrobial opportunistic disease.

PubMed

Petton, Bruno; Bruto, Maxime; James, Adèle; Labreuche, Yannick; Alunno-Bruscia, Marianne; Le Roux, Frédérique

2015-01-01

Successive disease outbreaks in oyster (Crassostrea gigas) beds in France have resulted in dramatic losses in production, and subsequent decline in the oyster-farming industry. Deaths of juvenile oysters have been associated with the presence of a herpes virus (OsHV-1 μvar) and bacterial populations of the genus Vibrio. Although the pathogenicity of OsHV-1 μvar, as well as several strains of Vibrio has been demonstrated by experimental infections, our understanding of the complexity of infections occurring in the natural environment remains limited. In the present study, we use specific-pathogen-free (SPF) oysters infected in an estuarine environment to study the diversity and dynamics of cultured microbial populations during disease expression. We observe that rapid Vibrio colonization followed by viral replication precedes oyster death. No correlation was found between the vibrio concentration and viral load in co-infected animals. We show that the quantity of viral DNA is a predictor of mortality, however, in the absence of bacteria, a high load of herpes virus is not sufficient to induce the full expression of the disease. In addition, we demonstrate that juvenile mortalities can occur in the absence of herpes virus, indicating that the herpes virus appears neither essential nor sufficient to cause juvenile deaths; whereas bacteria are necessary for the disease. Finally, we demonstrate that oysters are a reservoir of putative pathogens, and that the geographic origin, age, and cultivation method of oysters influence disease expression.

Hemolymph microbiome of Pacific oysters in response to temperature, temperature stress and infection

PubMed Central

Lokmer, Ana; Mathias Wegner, Karl

2015-01-01

Microbiota provide their hosts with a range of beneficial services, including defense from external pathogens. However, host-associated microbial communities themselves can act as a source of opportunistic pathogens depending on the environment. Marine poikilotherms and their microbiota are strongly influenced by temperature, but experimental studies exploring how temperature affects the interactions between both parties are rare. To assess the effects of temperature, temperature stress and infection on diversity, composition and dynamics of the hemolymph microbiota of Pacific oysters (Crassostrea gigas), we conducted an experiment in a fully-crossed, three-factorial design, in which the temperature acclimated oysters (8 or 22 °C) were exposed to temperature stress and to experimental challenge with a virulent Vibrio sp. strain. We monitored oyster survival and repeatedly collected hemolymph of dead and alive animals to determine the microbiome composition by 16s rRNA gene amplicon pyrosequencing. We found that the microbial dynamics and composition of communities in healthy animals (including infection survivors) were significantly affected by temperature and temperature stress, but not by infection. The response was mediated by changes in the incidence and abundance of operational taxonomic units (OTUs) and accompanied by little change at higher taxonomic levels, indicating dynamic stability of the hemolymph microbiome. Dead and moribund oysters, on the contrary, displayed signs of community structure disruption, characterized by very low diversity and proliferation of few OTUs. We can therefore link short-term responses of host-associated microbial communities to abiotic and biotic factors and assess the potential feedback between microbiota dynamics and host survival during disease. PMID:25180968

Oyster Reefs Support Coastal Resilience by Altering Nearshore Salinity: An Observational and Modeling Study to Quantify a "Keystone" Ecosystem Service

NASA Astrophysics Data System (ADS)

Kaplan, D. A.; Olabarrieta, M.; Frederick, P.; Valle-Levinson, A.

2016-12-01

Oyster reefs provide myriad ecosystem services, including water quality improvement, fisheries and other faunal support, shoreline protection from erosion and storm surge, and economic productivity. However, their role in directing flow during non-storm conditions has been largely neglected. In regions where oyster reefs form near the mouth of estuarine rivers, they likely alter ocean-estuary exchange by acting as fresh water "dams". We hypothesize that these reefs have the potential to detain fresh water and influence salinity over extensive areas, thus providing a "keystone" ecosystem service by supporting estuarine functions that rely on the maintenance of estuarine (i.e., brackish) conditions in the near-shore environment. In this work, we investigated the effects of shore-parallel reefs on near-shore salinity using field data and hydrodynamic modeling in a degraded reef complex in Suwannee Sound (Florida, USA). Results suggested that freshwater detention by long linear chains of oyster reefs plays an important role in modulating salinities, not only in the oysters' local environment, but over extensive estuarine areas (tens of square kilometers). Field data confirmed the presence of salinity differences between landward and seaward sides of the reef, with long-term mean salinity differences of >30% between sides. Modeled results expanded experimental findings by illustrating how oyster reefs affect the lateral and offshore extent of freshwater influence. In general, the effects of simulated reefs were most pronounced when they were highest in elevation, without gaps, and when riverine discharge was low. Taken together, these results describe a poorly documented ecosystem service provided by oyster reefs; provide an estimate of the magnitude and spatial extent of this service; and offer quantitative information to help guide future oyster reef restoration.

Freshwater Detention by Oyster Reefs: Quantifying a Keystone Ecosystem Service.

PubMed

Kaplan, David A; Olabarrieta, Maitane; Frederick, Peter; Valle-Levinson, Arnoldo

2016-01-01

Oyster reefs provide myriad ecosystem services, including water quality improvement, fisheries and other faunal support, shoreline protection from erosion and storm surge, and economic productivity. However, their role in directing flow during non-storm conditions has been largely neglected. In regions where oyster reefs form near the mouth of estuarine rivers, they likely alter ocean-estuary exchange by acting as fresh water "dams". We hypothesize that these reefs have the potential to detain fresh water and influence salinity over extensive areas, thus providing a "keystone" ecosystem service by supporting estuarine functions that rely on the maintenance of estuarine (i.e., brackish) conditions in the near-shore environment. In this work, we investigated the effects of shore-parallel reefs on estuarine salinity using field data and hydrodynamic modeling in a degraded reef complex in the northeastern Gulf of Mexico. Results suggested that freshwater detention by long linear chains of oyster reefs plays an important role in modulating salinities, not only in the oysters' local environment, but over extensive estuarine areas (tens of square kilometers). Field data confirmed the presence of salinity differences between landward and seaward sides of the reef, with long-term mean salinity differences of >30% between sides. Modeled results expanded experimental findings by illustrating how oyster reefs affect the lateral and offshore extent of freshwater influence. In general, the effects of simulated reefs were most pronounced when they were highest in elevation, without gaps, and when riverine discharge was low. Taken together, these results describe a poorly documented ecosystem service provided by oyster reefs; provide an estimate of the magnitude and spatial extent of this service; and offer quantitative information to help guide future oyster reef restoration.

Geotechnical and Geoacoustic Properties of Sediments Off South Florida: Boca Raton, Indian River Beach, Lower Tampa Bay, and the Lower Florida Keys

DTIC Science & Technology

1997-06-24

foraminifers, sea urchin spines, barnacles, spiny oysters, worm shells, bivalves, coral fragments, and few quartz grains. The sediments are composed of...photographing a diver’s compass on the sea bottom as the first photograph of a photographic transect along a tape measure previously laid down on the sea ...measurements for distortion caused by refraction in sea water and lens aberrations. Use of the stereocomparator allows high frequency sampling of bottom

Effects of phosphates on shellfish and on calcium carbonate crystallization in vitro. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilbur, K.M.

1986-07-17

It has been known that inorganic phosphate inhibits the precipitation of calcium carbonate in artificial sea water. This work addresses the question of whether phosphate also affects the deposition of CaCO/sub 3/ in the exoskeletons of invertebrates. Tetrasodiumpyrophosphate and pentasodiumtripolyphosphate in concentrations of 15 ppM caused abnormality, mortality, and inhibition of shell deposition in trochophore larvae of the oyster Crassostrea. Inhibition of shell growth resulting from pollution at 15 ppM could be expected in Rangia with orthophosphate, tetrasodium pyrophosphate, and sodiumtripolyphosphate, in Helisoma with tetrasodium pyrophosphate, and pentasodium tripolyphosphate, and in larvae of Crassostea the relative inhibitory action of shellmore » growth was tetrasodiumpyrophosphate > sodiumtripolyphosphate > sodium orthophosphate greater than or equal to sodium hexametaphosphate. 4 refs.« less

PfSMAD4 plays a role in biomineralization and can transduce bone morphogenetic protein-2 signals in the pearl oyster Pinctada fucata.

PubMed

Zhao, Mi; Shi, Yu; He, Maoxian; Huang, Xiande; Wang, Qi

2016-04-26

Mollusca is the second largest phylum in nature. The shell of molluscs is a remarkable example of a natural composite biomaterial. Biomineralization and how it affects mollusks is a popular research topic. The BMP-2 signaling pathway plays a canonical role in biomineralization. SMAD4 is an intracellular transmitter in the BMP signaling pathway in mammals, and some genomic data show SMAD4's involvement in BMP signaling in invertebrates, but whether SMAD4 plays a conservative role in pearl oyster, Pinctada fucata, still need to be tested. In this study, we identified a SMAD4 gene (hereafter designated PfSMAD4) in pearl oyster Pinctada fucata. Bioinformatics analysis of PfSMAD4 showed high identity with its orthologs. PfSMAD4 was located in the cytoplasm in immunofluorescence assays and analyses of PfSMAD4 mRNA in tissues and developmental stages showed high expression in ovaries and D-shaped larvae. An RNA interference experiment, performed by PfSMAD4 double-stranded RNA (dsRNA) injection, demonstrated inhibition not only of nacre growth but also organic sheet formation with a decrease in PfSMAD4 expression. A knockdown experiment using PfBMP2 dsRNA showed decreased PfBMP2 and PfSMAD4 mRNA and irregular crystallization of the nacreous layer using scanning electron microscopy. In co-transfection experiments, PfBMP2-transactivated reporter constructs contained PfSMAD4 promoter sequences. Our results suggest that PfSMAD4 plays a role in biomineralization and can transduce BMP signals in P. fucata. Our data provides important clues about the molecular mechanisms that regulate biomineralization in pearl oyster.

Histopathological effect and stress response of mantle proteome following TBT exposure in the Hooded oyster Saccostrea cucullata.

PubMed

Khondee, Phattirapa; Srisomsap, Chantragan; Chokchaichamnankit, Daranee; Svasti, Jisnuson; Simpson, Richard J; Kingtong, Sutin

2016-11-01

Tributyltin (TBT), an environmental pollutant in marine ecosystems, is toxic to organisms. Although contamination by and bioaccumulation and toxicity of this compound have been widely reported, its underlying molecular mechanisms remain unclear. In the present study, we exposed the Hooded oyster Saccostrea cucullata to TBT to investigate histopathological effects and proteome stress response. Animals were exposed to three TBT sub-lethal concentrations, 10, 50 and 150 μg/l for 48 h. TBT produced stress leading to histopathological changes in oyster tissues including mantle, gill, stomach and digestive diverticula. TBT induced mucocyte production in epithelia and hemocyte aggregation in connective tissue. Cell necrosis occurred when exposure dosages were high. Comparative proteome analyses of mantle protein of oysters exposed to 10 μg/l and control animals were analyzed by a 2-DE based proteomic approach. In total, 32 protein spots were found to differ (p < 0.05). Of these, 17 proteins were identified which included 14 up-regulated and 3 down-regulated proteins. TBT induced the expression of proteins involved in defensive mechanisms (HSP-78, HSP-70, aldehyde dehydrogenase and catalase), calcium homeostasis (VDAC-3), cytoskeleton and cytoskeleton-associated proteins, energy metabolism and amino acid metabolism. Our study revealed that TBT disturbs calcium homeostasis via VDAC-3 protein in mantle and this probably is the key molecular mechanism of TBT acting to distort shell calcification. Moreover, proteins involved in cell structure (tubulin-alpha and tubulin-beta) and protein synthesis were reduced after TBT exposure. Additionally, differential proteins obtained from this work will be useful as potential TBT biomarkers. Copyright © 2016 Elsevier Ltd. All rights reserved.

Living Shorelines: Assessing Geomorphic Change and Water Quality in an Urban Waterway

NASA Astrophysics Data System (ADS)

Huggins, A.; Schwartz, M. C.; Schmutz, P. P.

2017-12-01

In recent years, alternative strategies for shoreline armoring have become increasingly popular with coastal property owners. In Northwest Florida, local agencies implemented plans to attenuate wave action and reduce landward shore recession in an urban bayou by installing living shorelines. Living shorelines are constructed in the inter-tidal zones and incorporate both hard and soft structured stabilization. Generally, the hard component is fossilized oyster shells and the soft component is planted intertidal vegetation, such as Spartina alterniflora (Smooth cordgrass) and Juncus roemererianus (Black needlerush). Living shorelines were intended to comprise both ecological and societal implications by significantly slowing erosion processes for property owners, by utilizing oyster beds to improve water quality, and by fostering new ecological habitats in the marsh grasses. The issue presented with living shoreline management is long-term studies have not been carried out on these engineered systems. For this study, geospatial technology was utilized to create 3D images of terrain by interpolation of data points using a TotalStation to compute geomorphic change. Additionally, water samples were analyzed using traditional wet chemistry laboratory methods to determine total oxidized nitrogen (TON), ammonium, and orthophosphate content in water. Over a short three-month preliminary study, sediment accretion was observed primarily within the vegetation with the bulk of the erosion occurring around the oyster beds. TON was detected at levels between 10 µM and 30 µM, ammonium up to 5 µM, and orthophosphate was only detected in very low levels, consistently < 2 µM. The project is in its infancy, as the topographic profiles and water quality data will be used to establish baseline data for future research to determine volumetric geomorphic change,and to set a standard for water quality trends, surrounding oyster beds and vegetation in response to climatic events.

A Feedback Mechanism to Control Apoptosis Occurs in the Digestive Gland of the Oyster Crassostrea gigas Exposed to the Paralytic Shellfish Toxins Producer Alexandrium catenella

PubMed Central

Rolland, Jean-Luc; Medhioub, Walid; Vergnes, Agnes; Abi-khalil, Celina; Savar, Véronique; Abadie, Eric; Masseret, Estelle; Amzil, Zouher; Laabir, Mohamed

2014-01-01

To better understand the effect of Paralytic Shellfish Toxins (PSTs) accumulation in the digestive gland of the Pacific oyster, Crassostrea gigas, we experimentally exposed individual oysters for 48 h to a PSTs producer, the dinoflagellate Alexandrium catenella. In comparison to the effect of the non-toxic Alexandrium tamarense, on the eight apoptotic related genes tested, Bax and BI.1 were significantly upregulated in oysters exposed 48 h to A. catenella. Among the five detoxification related genes tested, the expression of cytochrome P450 (CYP1A) was shown to be correlated with toxin concentration in the digestive gland of oysters exposed to the toxic dinoflagellate. Beside this, we observed a significant increase in ROS production, a decrease in caspase-3/7 activity and normal percentage of apoptotic cells in this tissue. Taken together, these results suggest a feedback mechanism, which may occur in the digestive gland where BI.1 could play a key role in preventing the induction of apoptosis by PSTs. Moreover, the expression of CYP1A, Bax and BI.1 were found to be significantly correlated to the occurrence of natural toxic events, suggesting that the expression of these genes together could be used as biomarker to assess the biological responses of oysters to stress caused by PSTs. PMID:25257788

Longitudinal study of winter mortality disease in Sydney rock oysters Saccostrea glomerata.

PubMed

Spiers, Zoe B; Gabor, Melinda; Fell, Shayne A; Carnegie, Ryan B; Dove, Michael; O'Connor, Wayne; Frances, Jane; Go, Jeffrey; Marsh, Ian B; Jenkins, Cheryl

2014-07-24

Winter mortality (WM) is a poorly studied disease affecting Sydney rock oysters Saccostrea glomerata in estuaries in New South Wales, Australia, where it can cause significant losses. WM is more severe in oysters cultured deeper in the water column and appears linked to higher salinities. Current dogma is that WM is caused by the microcell parasite Bonamia roughleyi, but evidence linking clinical signs and histopathology to molecular data identifying bonamiasis is lacking. We conducted a longitudinal study between February and November 2010 in 2 estuaries where WM has occurred (Georges and Shoalhaven Rivers). Results from molecular testing of experimental oysters for Bonamia spp. were compared to clinical disease signs and histopathology. Available environmental data from the study sites were also collated and compared. Oyster condition declined over the study period, coinciding with decreasing water temperatures, and was inversely correlated with the presence of histological lesions. While mortalities occurred in both estuaries, only oysters from the Georges River study site showed gross clinical signs and histological changes characteristic of WM (lesions were prevalent and intralesional microcell-like structures were sometimes noted). PCR testing for Bonamia spp. revealed the presence of an organism belonging to the B. exitiosa-B. roughleyi clade in some samples; however, the very low prevalence of this organism relative to histological changes and the lack of reactivity of affected oysters in subsequent in situ hybridisation experiments led us to conclude that this Bonamia sp. is not responsible for WM. Another aetiological agent and a confluence of environmental factors are a more likely explanation for the disease.

Crassostrea gigas mortality in France: the usual suspect, a herpes virus, may not be the killer in this polymicrobial opportunistic disease

PubMed Central

Petton, Bruno; Bruto, Maxime; James, Adèle; Labreuche, Yannick; Alunno-Bruscia, Marianne; Le Roux, Frédérique

2015-01-01

Successive disease outbreaks in oyster (Crassostrea gigas) beds in France have resulted in dramatic losses in production, and subsequent decline in the oyster-farming industry. Deaths of juvenile oysters have been associated with the presence of a herpes virus (OsHV-1 μvar) and bacterial populations of the genus Vibrio. Although the pathogenicity of OsHV-1 μvar, as well as several strains of Vibrio has been demonstrated by experimental infections, our understanding of the complexity of infections occurring in the natural environment remains limited. In the present study, we use specific-pathogen-free (SPF) oysters infected in an estuarine environment to study the diversity and dynamics of cultured microbial populations during disease expression. We observe that rapid Vibrio colonization followed by viral replication precedes oyster death. No correlation was found between the vibrio concentration and viral load in co-infected animals. We show that the quantity of viral DNA is a predictor of mortality, however, in the absence of bacteria, a high load of herpes virus is not sufficient to induce the full expression of the disease. In addition, we demonstrate that juvenile mortalities can occur in the absence of herpes virus, indicating that the herpes virus appears neither essential nor sufficient to cause juvenile deaths; whereas bacteria are necessary for the disease. Finally, we demonstrate that oysters are a reservoir of putative pathogens, and that the geographic origin, age, and cultivation method of oysters influence disease expression. PMID:26217318

Image analysis method to quantify the effect of different treatments on the visual meat/shell ratio of half-shelled green lipped mussels (Perna canaliculus).

PubMed

Kim, Min Geun; Alçiçek, Zayde; Balaban, Murat O; Atar, Hasan Huseyin

2014-04-01

Aquacultured green lipped mussel (Perna canaliculus) is the New Zealand export leader of seafood in terms of weight. Different treatments shrink mussel meat differently and affect the consumer perception of half-shelled mussels. In order to quantify this, digital images of half-shelled green lipped mussels subjected to two postharvest treatments (ultrahigh pressure (UHP) and heat treatment (HT)) and raw controls were taken. The ratio of the view area of the meat to that of the shell (labelled as 'visual condition index' (VCI)) was measured using image analysis. A polygonal region of interest was defined on the image to depict the boundary of the meat and to calculate the view area. Raw mussels had a VCI of 85%. HT mussels had a much reduced VCI of 41%, indicating shrinkage of the meat due to heat. UHP treatment used as a shucking method resulted in a VCI of 83%. Since VCI is one measure of quality for the consumer, this quantitative method can be used in the optimization of shucking treatment (HT or UHP). VCI can be used to optimize postharvest treatments to minimize meat shrinkage. This method can also be applied to other shellfish such as oysters and clams. © 2013 Society of Chemical Industry.

Impacts of ocean acidification on gene expression and biomineralisation in the Pacific oyster Crassostrea gigas Thunberg, 1793

NASA Astrophysics Data System (ADS)

Bagusche, F.; Pouvreau, S.; Trueman, C.; Long, S.; Hauton, C.

2012-04-01

The published evidence of impacts of ocean acidification and on marine calcifiers has emphasized the need to understand the molecular mechanisms of biomineralisation. Crassostrea gigas is an ideal organism to examine these processes as: 1) the hatchery rearing of larval stages is well constrained, 2) studies have established an ontogenetic switch in deposition of carbonate polymorphs from aragonite in larval shells to calcite in adults and 3) it is a globally-important commercial species. Research summarized in this presentation will identify some of the molecular mechanisms involved in calcification processes during ontogeny of Crassostrea gigas, as well as possible impacts of changes in environmental conditions such as temperature and pH. Data will be presented from a quantitative real-time PCR study of the changes in gene expression during development in different environments. Additionally scanning electron microscopy and infrared spectroscopy analyses of shell microstructures and composition will be summarised to correlate changes in gene expression with end-point differences in shell structure. Preliminary results suggest that changes in the environmental conditions lead to differences in expression patterns of genes involved in biomineralisation processes. The combined effects of ambient seawater temperature and low pH show the greatest negative effect on larval shell development, identified as malformations, eroded shell surfaces and a significant decrease in shell size. However, the effect of higher seawater temperature seems to amend the effects of ocean acidification on larval shell development.

Freshwater Detention by Oyster Reefs: Quantifying a Keystone Ecosystem Service

PubMed Central

Olabarrieta, Maitane; Frederick, Peter; Valle-Levinson, Arnoldo

2016-01-01

Oyster reefs provide myriad ecosystem services, including water quality improvement, fisheries and other faunal support, shoreline protection from erosion and storm surge, and economic productivity. However, their role in directing flow during non-storm conditions has been largely neglected. In regions where oyster reefs form near the mouth of estuarine rivers, they likely alter ocean-estuary exchange by acting as fresh water “dams”. We hypothesize that these reefs have the potential to detain fresh water and influence salinity over extensive areas, thus providing a “keystone” ecosystem service by supporting estuarine functions that rely on the maintenance of estuarine (i.e., brackish) conditions in the near-shore environment. In this work, we investigated the effects of shore-parallel reefs on estuarine salinity using field data and hydrodynamic modeling in a degraded reef complex in the northeastern Gulf of Mexico. Results suggested that freshwater detention by long linear chains of oyster reefs plays an important role in modulating salinities, not only in the oysters’ local environment, but over extensive estuarine areas (tens of square kilometers). Field data confirmed the presence of salinity differences between landward and seaward sides of the reef, with long-term mean salinity differences of >30% between sides. Modeled results expanded experimental findings by illustrating how oyster reefs affect the lateral and offshore extent of freshwater influence. In general, the effects of simulated reefs were most pronounced when they were highest in elevation, without gaps, and when riverine discharge was low. Taken together, these results describe a poorly documented ecosystem service provided by oyster reefs; provide an estimate of the magnitude and spatial extent of this service; and offer quantitative information to help guide future oyster reef restoration. PMID:27936184

Dual transcriptomics of virus-host interactions: comparing two Pacific oyster families presenting contrasted susceptibility to ostreid herpesvirus 1.

PubMed

Segarra, Amélie; Mauduit, Florian; Faury, Nicole; Trancart, Suzanne; Dégremont, Lionel; Tourbiez, Delphine; Haffner, Philippe; Barbosa-Solomieu, Valérie; Pépin, Jean-François; Travers, Marie-Agnès; Renault, Tristan

2014-07-09

Massive mortality outbreaks affecting Pacific oyster (Crassostrea gigas) spat in various countries have been associated with the detection of a herpesvirus called ostreid herpesvirus type 1 (OsHV-1). However, few studies have been performed to understand and follow viral gene expression, as it has been done in vertebrate herpesviruses. In this work, experimental infection trials of C. gigas spat with OsHV-1 were conducted in order to test the susceptibility of several bi-parental oyster families to this virus and to analyze host-pathogen interactions using in vivo transcriptomic approaches. The divergent response of these oyster families in terms of mortality confirmed that susceptibility to OsHV-1 infection has a significant genetic component. Two families with contrasted survival rates were selected. A total of 39 viral genes and five host genes were monitored by real-time PCR. Initial results provided information on (i) the virus cycle of OsHV-1 based on the kinetics of viral DNA replication and transcription and (ii) host defense mechanisms against the virus. In the two selected families, the detected amounts of viral DNA and RNA were significantly different. This result suggests that Pacific oysters are genetically diverse in terms of their susceptibility to OsHV-1 infection. This contrasted susceptibility was associated with dissimilar host gene expression profiles. Moreover, the present study showed a positive correlation between viral DNA amounts and the level of expression of selected oyster genes.

Experimental infections of Pacific oyster Crassostrea gigas using the Australian ostreid herpesvirus-1 (OsHV-1) µVar strain.

PubMed

Paul-Pont, Ika; Evans, Olivia; Dhand, Navneet K; Whittington, Richard J

2015-03-09

In Australia, the spread of the ostreid herpesvirus-1 microvariant (OsHV-1 µVar) threatens the Pacific oyster industry. There is an urgent need to develop an experimental infection model in order to study the pathogenesis of the virus under controlled laboratory conditions. The present study constitutes the first attempt to use archived frozen oysters as a source of inoculum, based on the Australian OsHV-1 µVar strain. Experiments were conducted to test (1) virus infectivity, (2) the dose-response relationship for OsHV-1, and (3) the best conditions in which to store infective viral inoculum. Intramuscular injection of a viral inoculum consistently led to an onset of mortality 48 h post-injection and a final cumulative mortality exceeding 90%, in association with high viral loads (1 × 105 to 3 × 107 copies of virus mg-1) in dead individuals. For the first time, an infective inoculum was produced from frozen oysters (tissues stored at -80°C for 6 mo). Storage of purified viral inoculum at +4°C for 3 mo provided similar results to use of fresh inoculum, whereas storage at -20°C, -80°C and room temperature was detrimental to infectivity. A dose-response relationship for OsHV-1 was identified but further research is recommended to determine the most appropriate viral concentration for development of infection models that would be used for different purposes. Overall, this work highlights the best practices and potential issues that may occur in the development of a reproducible and transferable infection model for studying the pathogenicity of the Australian OsHV-1 strain in Crassostrea gigas under experimental conditions.

Transcriptomic study of 39 ostreid herpesvirus 1 genes during an experimental infection.

PubMed

Segarra, Amélie; Faury, Nicole; Pépin, Jean-François; Renault, Tristan

2014-06-01

Massive mortality outbreaks have been reported in France since 2008 among Pacific oysters, Crassostrea gigas, with the detection of a particular OsHV-1 variant called μVar. Virus infection can be induced in healthy spat in experimental conditions allowing to better understand the disease process, including viral gene expression. Although gene expression of other herpesviruses has been widely studied, we provide the first study following viral gene expression of OsHV-1 over time. In this context, an in vivo transcriptomic study targeting 39 OsHV-1 genes was carried out during an experimental infection of Pacific oyster spat. For the first time, several OsHV-1 mRNAs were detected by real-time PCR at 0 h, 2 h, 4 h, 18 h, 26 h and 42 h post-injection. Several transcripts were detected at 2h post-infection and at 18 h post-infection for all selected ORFs. Quantification of virus gene expression at different times of infection was also carried out using an oyster housekeeping gene, Elongation factor. Developing an OsHV-1-specific reverse transcriptase real time PCR targeting 39 viral gene appears a new tool in terms of diagnosis and can be used to complement viral DNA detection in order to monitor viral replication. Copyright © 2014. Published by Elsevier Inc.

Oyster Shell Dredging in Atchafalaya Bay and Adjacent Waters, Louisiana. Draft Environmental Impact Statement and Appendixes,

DTIC Science & Technology

1987-04-01

importance with the development of the Atchafalaya Delta region (Thompson and Deegan , 1980). Although several works have been prepared which dealt with the...47:189-228. Craig , N.J., R.E. Turner, and J.W. Day, Jr. 1979. Land loss in coastal Louisiana (USA). J. Environ. Management 3(1): 133-144. Cratsley, D.W...University, Baton Rouge. 285 pp. EI-114 Thompson, B.A and L.A. Deegan . 1983. The Atchafalaya River delta: a "new" fishery nursery with recommendations for

Analysis of Vibrio vulnificus Infection Risk When Consuming Depurated Raw Oysters.

PubMed

Deng, Kai; Wu, Xulei; Fuentes, Claudio; Su, Yi-Cheng; Welti-Chanes, Jorge; Paredes-Sabja, Daniel; Torres, J Antonio

2015-06-01

A beta Poisson dose-response model for Vibrio vulnificus food poisoning cases leading to septicemia was used to evaluate the effect of depuration at 15 °C on the estimated health risk associated with raw oyster consumption. Statistical variability sources included V. vulnificus level at harvest, time and temperature during harvest and transportation to processing plants, decimal reductions (SV) observed during experimental circulation depuration treatments, refrigerated storage time before consumption, oyster size, and number of oysters per consumption event. Although reaching nondetectable V. vulnificus levels (<30 most probable number per gram) throughout the year and a 3.52 SV were estimated not possible at the 95% confidence level, depuration for 1, 2, 3, and 4 days would reduce the warm season (June through September) risk from 2,669 cases to 558, 93, 38, and 47 cases per 100 million consumption events, respectively. At the 95% confidence level, 47 and 16 h of depuration would reduce the warm and transition season (April through May and October through November) risk, respectively, to 100 cases per 100 million consumption events, which is assumed to be an acceptable risk; 1 case per 100 million events would be the risk when consuming untreated raw oysters in the cold season (December through March).

Impact of different catalysis supported by oyster shells on the pyrolysis of tyre wastes in a single and a double fixed bed reactor.

PubMed

Kordoghli, Sana; Khiari, Besma; Paraschiv, Maria; Zagrouba, Fethi; Tazerout, Mohand

2017-09-01

The treatment and disposal of tyres from vehicles has long been of considerable environmental importance. Studies have been undertaken to reduce their environmental impact. In this study, an alternative gas was produced from automobile tyre wastes by the means of a controlled pyrolysis. To do so, a novel catalytic system was designed with the aim of increasing the rate of conversion and improving the quality of the pyrolysis products. This work aimed also to reduce the severity of the overall reactions, by using powder catalysts (MgO, Al 2 O 3 , CaCO 3 , and zeolite ZSM-5) uniformly distributed on two layers of oyster shells (OS) particles. The catalyst/tyres mass ratio was kept for all the tests at 1/30. The pyrolysis reactor was maintained at 500°C and the influence of each catalyst and of the number of shell beds (0, 1 or 2), on the yield and composition of the derived products, was examined. The gas yields could contribute by 1.2% of total consumption in Tunisia. Furthermore, some combinations could upgrade the derived gas and made it possible to use it as such or with the minimum of post-treatment. It was found that, with the use of supported catalyst, the gas produced is 45% greater compared to classical thermal pyrolysis. The Heating value of the produced gas was also improved by the use of supported catalysts; it was found 16% greater with the use of Al 2 O 3 /OS compared to non-catalytic pyrolysis. When compared to the gas obtained from only one catalytic supported bed, the sulfur content was reduced by 80% with the use of CaCO 3 /OS on two catalytic beds. Copyright © 2017 Elsevier Ltd. All rights reserved.

Surveying a fossil oyster reef using terrestrial laser scanning

NASA Astrophysics Data System (ADS)

Haring, A.; Exner, U.; Harzhauser, M.

2009-04-01

The Korneuburg Basin, situated north-west of Vienna, is well known to contain a rich variety of fossils from the Early Miocene (16.5 ma) and therefore has been investigated extensively by scientists in the past decades. An exceptional discovery was made in 2005: a large fossil oyster reef has been excavated and documented carefully during the last years. Aside from the giant-sized oyster (Crassostrea gryphoides), the excavation site contains numerous species of molluscs along with teeth of sharks and rays and even isolated bones of sea cows. The oysters, having lengths of up to 80 cm, are protruding from the ground surface, which is more or less a tilted plane (25˚ ) with a size of about 300 m2. The entire site is crosscut by a network of geological faults, often also offsetting individual oyster shells. Displacements along the normal faults do not exceed ~ 15 cm. The faulted fossils offer a unique opportunity to measure displacement distribution along the faults in great detail and provide insight in deformation mechanisms in porous, barely lithified sediments. In order to get a precise 3D model of the oyster reef, the terrestrial laser scanner system Leica HDS 6000 is used. It is a phase-based laser scanner, i.e. the distance measurement is performed using the phase-shift principle. Compared to the time-of-flight principle, this method is generally more appropriate to projects like this one, where the distances to be measured are relatively small (< 35 m) and where a high point density (point spacing of about 1 cm) and precision (some mm) is required for capturing the oysters adequately. However, due to fact that they occlude each other, one single scan is not sufficient to get all sides of their surface. Therefore, scans from different positions had to be acquired. These scans have to be merged, which involves the problem of sensor orientation as well as sampling of the entire 3D point cloud. Furthermore, a representation of the surface data is required that is suitable for answering certain questions of paleontologists and geologists. Finally, structural measurements may be performed in a geological software application, without treading on the fragile surface. On the other hand, paleontologists are interested in knowing if the oyster axes are aligned randomly or if they show a systematic alignment, in order to draw conclusions on the ocean currents at that time. For data processing, we use the 3D modeling software Geomagic Studio and the DTM (Digital Terrain Model) software SCOP++. The entire site has also been systematically documented by a large number of digital photographs. The obtained texture information allows a visual interpretation of the underlying surface. We discuss in how far such a 3D model derived from terrestrial laser scanner data may be useful to support the research work of geoscientists.

Detection of Toxoplasma gondii DNA in Brazilian oysters (Crassostrea rhizophorae).

PubMed

Ribeiro, L A; Santos, L K N S S; Brito, P A; Maciel, B M; Da Silva, A V; Albuquerque, G R

2015-05-04

The aim of this study was to detect evidence of Toxoplasma gondii using polymerase chain reaction (PCR)-based techniques in oysters (Crassostrea rhizophorae) obtained from the southern coastal region of Bahia, Brazil. A total of 624 oysters were collected, and the gills and digestive glands were dissected. Each tissue sample was separated into pools containing tissues (of the same type) from three animals, leading to a total of 416 experimental samples for analysis (208 samples each from the gills and digestive glands). Molecular analysis using PCR-based detection of the T. gondii AF 146527 repetitive fragment yielded negative results for all samples. However, when nested-PCR was used for detection of the T. gondii SAG-1 gene, 17 samples were positive, with the gills being the tissue with maximal detection of the parasite. These positive results were confirmed by sample sequencing. It is therefore suggested that C. rhizophorae oysters are capable of filtering and retaining T. gondii oocysts in their tissue. This represents a risk to public health because they are traditionally ingested in natura.

Effects of microplastics on European flat oysters, Ostrea edulis and their associated benthic communities.

PubMed

Green, Dannielle Senga

2016-09-01

Plastic pollution is recognised as an emerging threat to aquatic ecosystems, with microplastics now the most abundant type of marine debris. Health effects caused by microplastics have been demonstrated at the species level, but impacts on ecological communities remain unknown. In this study, impacts of microplastics on the health and biological functioning of European flat oysters (Ostrea edulis) and on the structure of associated macrofaunal assemblages were assessed in an outdoor mesocosm experiment using intact sediment cores. Biodegradable and conventional microplastics were added at low (0.8 μg L(-1)) and high (80 μg L(-1)) doses in the water column repeatedly for 60 days. Effects on the oysters were minimal, but benthic assemblage structures differed and species richness and the total number of organisms were ∼1.2 and 1.5 times greater in control mesocosms than in those exposed to high doses of microplastics. Notably, abundances of juvenile Littorina sp. (periwinkles) and Idotea balthica (an isopod) were ∼2 and 8 times greater in controls than in mesocosms with the high dose of either type of microplastic. In addition, the biomass of Scrobicularia plana (peppery furrow shell clam) was ∼1.5 times greater in controls than in mesocosms with the high dose of microplastics. This work indicates that repeated exposure to high concentrations of microplastics could alter assemblages in an important marine habitat by reducing the abundance of benthic fauna. Copyright © 2016 Elsevier Ltd. All rights reserved.

Oxygen isotopes of marine mollusc shells record Eocene elevation change in the Pyrenees

NASA Astrophysics Data System (ADS)

Huyghe, Damien; Mouthereau, Frédéric; Emmanuel, Laurent

2012-09-01

Constraining paleoaltimetry of collisional orogens is critical to understand the dynamics of topographic evolution and climate/tectonics retroactions. Here, we use oxygen stable-isotope record on oyster shells, preserved in marine foreland deposits, to examine the past elevation of the Pyrenees during the Eocene. Our approach is based on the comparison with the Paris basin, an intracratonic basin not influenced by orogenic growth. The finding of a shift of 1.5‰ between 49 and 41 Ma, indicating more negative δ18Oc in the south Pyrenean foreland, is interpreted to reflect the inflow of river water sourced from higher elevation in the Pyrenees. To test this and provide paleoelevation estimate, we adopt a morphologic-hydrological model accounting for the hypsometry of drainage basin. Our best fitting model shows that the Pyrenees rose up to 2000 m. This indicates that the Pyrenees reached high elevation in the Eocene, thus providing new critical constraints on their long-term orogenic development. δ18O of marine mollusc shells are proved potentially attractive for paleoelevation studies, especially for mountain belts where elevated continental surfaces have not been preserved.

78 FR 62293 - Safety Zone, Oyster Festival 30th Anniversary Fireworks Display, Oyster Bay; Oyster Bay, NY

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-15

... Safety Zone, Oyster Festival 30th Anniversary Fireworks Display, Oyster Bay; Oyster Bay, NY AGENCY: Coast... zone on the navigable waters of Oyster Bay near Oyster Bay, NY for the Oyster Festival 30th Anniversary... Oyster Festival 30th Anniversary Fireworks Display is scheduled for October 19, 2013 and is one of...

Nacre formation by epithelial cell cultures from mantle of the black-lip pearl oyster, Pinctada margaritifera.

PubMed

Jayasankar, Vidya; Vasudevan, Srinivasa Raghavan; Poulose, Suja C; Divipala, Indira

2018-06-12

Mantle tissue from the black-lip pearl oyster, Pinctada margaritifera, was cultured in vitro using sterilized seawater supplemented with 0.1% yeast extract as the culture medium. Granular and agranular epithelial cells, hyalinocytes, and fibroblast-like cells were observed in the initial stages of culture. Epithelial cells later formed pseudopodial cell networks containing clusters of granulated cells, which upon maturation released their colored granules. These granules induced formation of nacre crystal deposits on the bottom of the culture plate. Cultures comprised of only granulated epithelial cells were established through periodic sub-culturing of mantle cells and maintained for over 18 mo in a viable condition. Reverse transcriptase PCR of cultured cells demonstrated gene expression of the shell matrix protein, nacrein. To further evaluate the functional ability of cultured granulated epithelial cells, nuclear shell beads were incubated in culture medium containing these cells to induce nacre formation on the beads. Observation of the bead surface under a stereomicroscope at periodic intervals showed the gradual formation of blackish yellow colored nacre deposits. Examination of the bead surface by scanning electron microscopy and energy dispersive X-ray analysis at periodic intervals revealed a distinct brick and mortar formation characteristic of nacre, comprised of aragonite platelets and matrix proteins. Calcium, carbon, and oxygen were the major elements in all stages examined. Our study shows that mantle epithelial cells in culture retain the ability to secrete nacre and can therefore form the basis for future studies on the biomineralization process and its application in development of sustainable pearl culture.

Giant Upper Cretaceous oysters from the Gulf coast and Caribbean

USGS Publications Warehouse

Sohl, Norman F.; Kauffman, Erle G.

1964-01-01

Two unusually massive ostreid species, representing the largest and youngest Mesozoic members of their respective lineages, occur in Upper Cretaceous sediment of the gulf coast and Caribbean areas. Their characteristics and significance, as well as the morphologic terminology of ostreids in general, are discussed. Crassostrea cusseta Sohl and Kauffman n. sp. is the largest known ostreid from Mesozoic rocks of North America; it occurs sporadically in the Cusseta Sand and rarely in the Blufftown Formation of the Chattahoochee River region in Georgia and Alabama. It is especially notable in that it lacks a detectable posterior adductor muscle scar on large adult shells. C. cusseta is the terminal Cretaceous member of the C. soleniscus lineage in gulf coast sediments; the lineage continues, however, with little basic modification, throughout the Cenozoic, being represented in the Eocene by C. gigantissima (Finch) and probably, in modern times, by C. virginica (Gmelin). The C. soleniscus lineage is the first typically modern crassostreid group recognized in the Mesozoic. Arctostrea aguilerae (Böse) occurs in Late Campanian and Early Maestrichtian sediments of Alabama, Mississippi, Texas(?), Mexico, and Cuba. The mature shell of this species is larger and more massive than that of any other known arctostreid. Arctostrea is well represented throughout the Upper Jurassic and Cretaceous of Europe, but in North America, despite the great numbers and diversity of Cretaceous oysters, only A. aguilerae and the Albian form A. carinata are known. The presence of A. aquilerae in both the Caribbean and gulf coast faunas is exceptional, as the Late Cretaceous faunas of these provinces are generally distinct and originated in different faunal realms.

Modelling the influence of time and temperature on the respiration rate of fresh oyster mushrooms.

PubMed

Azevedo, Sílvia; Cunha, Luís M; Fonseca, Susana C

2015-12-01

The respiration rate of mushrooms is an important indicator of postharvest senescence. Storage temperature plays a major role in their rate of respiration and, therefore, in their postharvest life. In this context, reliable predictions of respiration rates are critical for the development of modified atmosphere packaging that ultimately will maximise the quality of the product to be presented to consumers. This work was undertaken to study the influence of storage time and temperature on the respiration rate of oyster mushrooms. For that purpose, oyster mushrooms were stored at constant temperatures of 2, 6, 10, 14 and 18 ℃ under ambient atmosphere. Respiration rate data were measured with 8-h intervals up to 240 h. A decrease of respiration rate was found after cutting of the carpophores. Therefore, time effect on respiration rate was modelled using a first-order decay model. The results also show the positive influence of temperature on mushroom respiration rate. The model explaining the effect of time on oyster mushroom's respiration rate included the temperature dependence according to the Arrhenius equation, and the inclusion of a parameter describing the decrease of the respiration rate, from the initial time until equilibrium. These yielded an overall model that fitted well to the experimental data. Moreover, results show that the overall model is useful to predict respiration rate of oyster mushrooms at different temperatures and times, using the initial respiration rate of mushrooms. Furthermore, predictive modelling can be relevant for the choice of an appropriate packaging system for fresh oyster mushrooms. © The Author(s) 2014.

Fragmentation of the large subunit ribosomal RNA gene in oyster mitochondrial genomes.

PubMed

Milbury, Coren A; Lee, Jung C; Cannone, Jamie J; Gaffney, Patrick M; Gutell, Robin R

2010-09-02

Discontinuous genes have been observed in bacteria, archaea, and eukaryotic nuclei, mitochondria and chloroplasts. Gene discontinuity occurs in multiple forms: the two most frequent forms result from introns that are spliced out of the RNA and the resulting exons are spliced together to form a single transcript, and fragmented gene transcripts that are not covalently attached post-transcriptionally. Within the past few years, fragmented ribosomal RNA (rRNA) genes have been discovered in bilateral metazoan mitochondria, all within a group of related oysters. In this study, we have characterized this fragmentation with comparative analysis and experimentation. We present secondary structures, modeled using comparative sequence analysis of the discontinuous mitochondrial large subunit rRNA genes of the cupped oysters C. virginica, C. gigas, and C. hongkongensis. Comparative structure models for the large subunit rRNA in each of the three oyster species are generally similar to those for other bilateral metazoans. We also used RT-PCR and analyzed ESTs to determine if the two fragmented LSU rRNAs are spliced together. The two segments are transcribed separately, and not spliced together although they still form functional rRNAs and ribosomes. Although many examples of discontinuous ribosomal genes have been documented in bacteria and archaea, as well as the nuclei, chloroplasts, and mitochondria of eukaryotes, oysters are some of the first characterized examples of fragmented bilateral animal mitochondrial rRNA genes. The secondary structures of the oyster LSU rRNA fragments have been predicted on the basis of previous comparative metazoan mitochondrial LSU rRNA structure models.

δ15N as a proxy for historic anthropogenic nitrogen loading in Charleston Harbor, SC, USA

NASA Astrophysics Data System (ADS)

Payne, T. N.; Andrus, C. F. T.

2015-12-01

Bivalve shell geochemistry can serve as a useful indicator of changes in coastal environments. There is increasing interest in developing paleoenvironmental proxies from mollusk shell organic components. Numerous studies have focused on how the δ15N obtained from bivalve tissues can be used to trace present-day wastewater input into estuaries. However, comparatively little attention has been paid to tracing the impact of anthropogenic nitrogen loading into estuaries over time. By measuring historic levels of δ15N in the organic fraction of oyster shells (Crassostrea virginica) from archaeological sites around Charleston Harbor and comparing those levels to the δ15N content of modern shells, it is possible to assess how nitrogen has fluctuated historically in the area. Whole-shell samples from the Late Archaic Period (~3000-4000 BP, Late Woodland Period (~1400-800 BP), 18th and 19th centuries, and modern controls were measured for %N and d15N. Evidence of increased anthropogenic input of N is expected to begin in the early historic period based on similar analysis in Chesapeake Bay. More ancient samples may give insight into baseline conditions prior to recent population growth and industrialization. This information could help understand how large-scale anthropogenic nitrogen loading has affected coastal ecosystems over time and guide future remediation. Furthermore, this project will help refine and improve this novel proxy of past environmental conditions.

Nitrogen extraction potential of wild and cultured bivalves harvested from nearshore waters of Cape Cod, USA.

PubMed

Reitsma, Joshua; Murphy, Diane C; Archer, Abigail F; York, Richard H

2017-03-15

As nitrogen entering coastal waters continues to be an issue, much attention has been generated to identify potential options that may help alleviate this stressor to estuaries, including the propagation of bivalves to remove excess nitrogen. Oysters (Crassostrea virginica) and quahogs (Mercenaria mercenaria) from numerous Cape Cod, MA, (USA) sources were analyzed for nitrogen content stored in tissues that would represent a net removal of nitrogen from a water body if harvested. Results showed local oysters average 0.69% nitrogen by total dry weight (mean 0.28gN/animal) and quahogs average 0.67% nitrogen by total dry weight (mean 0.22gN/animal); however, these values did vary by season and to a lesser extent by location or grow-out method. The differences in nitrogen content were largely related to the mass of shell or soft tissue. Nitrogen isotope data indicate shellfish from certain water bodies in the region are incorporating significant amounts of nitrogen from anthropogenic sources. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Optimization of exposure factors for X-ray radiography non-destructive testing of pearl oyster

NASA Astrophysics Data System (ADS)

Susilo; Yulianti, I.; Addawiyah, A.; Setiawan, R.

2018-03-01

One of the processes in pearl oyster cultivation is detecting the pearl nucleus to gain information whether the pearl nucleus is still attached in the shell or vomited. The common tool used to detect pearl nucleus is an X-ray machine. However, an X-ray machine has a drawback that is the energy used is higher than that used by digital radiography. The high energy make the resulted image is difficult to be analysed. One of the advantages of digital radiography is the energy used can be adjusted so that the resulted image can be analysed easily. To obtain a high quality of pearl image using digital radiography, the exposure factors should be optimized. In this work, optimization was done by varying the voltage, current, and exposure time. Then, the radiography images were analysed using Contrast to Noise Ratio (CNR). From the analysis, it can be determined that the optimum exposure factors are 60 kV of voltage, 16 mA of current, and 0.125 s of exposure time which result in CNR of 5.71.

Vibrio vulnificus: death on the half shell. A personal journey with the pathogen and its ecology.

PubMed

Oliver, James D

2013-05-01

Vibrio vulnificus is an estuarine bacterium which occurs in high numbers in filter-feeding molluscan shellfish, such as oysters. In individuals with certain underlying diseases, ingestion of the bacterium, e.g., in raw or undercooked oysters, can lead to a rapid and extremely fatal infection. Indeed, this one bacterium is responsible for 95 % of all seafood-borne deaths. In addition, the bacterium is capable of entering a preexisting lesion or cut obtained during coastal recreational activities, resulting in potentially fatal wound infections. This brief review, which comprised a presentation made at the Gordon Research Conference on "Oceans and Human Health," reflects over 35 years of research on this bacterium in the author's laboratory. It describes some of the known virulence factors and why males account for ca 85 % of all V. vulnificus cases. It notes the two genotypes now known to exist and how this pathogen enters a dormant, "viable but nonculturable" state during the winter months. Finally, the review discusses how global warming may be causing worldwide increases in the frequency and geographical extent of Vibrio infections.

Paralytic Toxins Accumulation and Tissue Expression of α-Amylase and Lipase Genes in the Pacific Oyster Crassostrea gigas Fed with the Neurotoxic Dinoflagellate Alexandrium catenella

PubMed Central

Rolland, Jean-Luc; Pelletier, Kevin; Masseret, Estelle; Rieuvilleneuve, Fabien; Savar, Veronique; Santini, Adrien; Amzil, Zouher; Laabir, Mohamed

2012-01-01

The pacific oyster Crassostrea gigas was experimentally exposed to the neurotoxic Alexandrium catenella and a non-producer of PSTs, Alexandrium tamarense (control algae), at concentrations corresponding to those observed during the blooming period. At fixed time intervals, from 0 to 48 h, we determined the clearance rate, the total filtered cells, the composition of the fecal ribbons, the profile of the PSP toxins and the variation of the expression of two α-amylase and triacylglecerol lipase precursor (TLP) genes through semi-quantitative RT-PCR. The results showed a significant decrease of the clearance rate of C. gigas fed with both Alexandrium species. However, from 29 to 48 h, the clearance rate and cell filtration activity increased only in oysters fed with A. tamarense. The toxin concentrations in the digestive gland rose above the sanitary threshold in less than 48 h of exposure and GTX6, a compound absent in A. catenella cells, accumulated. The α-amylase B gene expression level increased significantly in the time interval from 6 to 48 h in the digestive gland of oysters fed with A. tamarense, whereas the TLP gene transcript was significantly up-regulated in the digestive gland of oysters fed with the neurotoxic A. catenella. All together, these results suggest that the digestion capacity could be affected by PSP toxins. PMID:23203275

Streptomyces effect on the bacterial microbiota associated to Crassostrea sikamea oyster.

PubMed

García Bernal, M; Trabal Fernández, N; Saucedo Lastra, P E; Medina Marrero, R; Mazón-Suástegui, J M

2017-03-01

To determine the composition and diversity of the microbiota associated to Crassostrea sikamea treated during 30 days with Streptomyces strains N7 and RL8. DNA was extracted from oysters followed by 16S rRNA gene amplification and pyrosequencing. The highest and lowest species diversity richness was observed in the initial and final control group, whereas Streptomyces-treated oysters exhibited intermediate values. Proteobacteria was the most abundant phylum (81·4-95·1%), followed by Bacteroidetes, Actinobacteria and Firmicutes. The genera Anderseniella, Oceanicola, Roseovarius, Ruegeria, Sulfitobacter, Granulosicoccus and Marinicella encompassed the core microbiota of all experimental groups. The genus Bacteriovorax was detected in all groups except in the final control and the depurated N7, whereas Vibrio remained undetected in all Streptomyces-treated groups. RL8 was the only group that harboured the genus Streptomyces in its microbiota. Principal component analysis showed that Streptomyces strains significantly changed oyster microbiota with respect to the initial and final control. Crassostrea sikamea treated with Streptomyces showed high species diversity and a microbiota composition shift, characterized by keeping the predator genus Bacteriovorax and decreasing the pathogenic Vibrio. This is the first culture-independent study showing the effect of Streptomyces over the oyster microbiota. It also sheds light about the potential use of Streptomyces to improve mollusc health and safety for consumers after the depuration process. © 2016 The Society for Applied Microbiology.

δ15N as a Potential Paleoenvironmental Proxy for Nitrogen Loading in Chesapeake Bay

NASA Astrophysics Data System (ADS)

Black, H. D.; Andrus, C. F.; Rick, T.; Hines, A.

2013-12-01

Stable isotope analysis of Eastern Oyster (Crassostrea virginica) and other mollusk shells from archaeological sites is a useful means of acquiring paleoenvironmental data. Recently, nitrogen isotopes have been identified as a potential new proxy in these shells. δ15N content in mollusk shells is affected by numerous anthropogenic and natural influences and may be used as an environmental proxy for nitrogen loading conditions. Chesapeake Bay is well known for both historic and modern pollution problems from numerous anthropogenic sources, such as fertilizer runoff, sewage discharge, and densely populated land use and serves as an ideal study location for long-term nitrogen loading processes. Longer records of these processes may be recorded in abundant archaeological remains around the bay, however, little is known about the stability of δ15N and %N in shell material over recent geologic time. In this study, 90 archaeological C. virginica shells were collected by the Smithsonian Institution from the Rhode River Estuary within Chesapeake Bay and range in age from ~150 to 3200 years old. Twenty-two modern C. virginica shells were also collected from nearby beds in the bay. All shell samples were subsampled from the resilifer region of the calcitic shell using a hand-held micro drill and were analyzed using EA-IRMS analysis to determine the potential temporal variability of δ15N and %N as well as creating a baseline for ancient nitrogen conditions in the bay area. Modern POM water samples and C. virginica soft tissues were also analyzed in this study to determine the degree of seasonal variation of δ15N and %N in Chesapeake Bay.

Soft shell clams Mya arenaria with disseminated neoplasia demonstrate reverse transcriptase activity

USGS Publications Warehouse

House, M.L.; Kim, C.H.; Reno, P.W.

1998-01-01

Disseminated neoplasia (DN), a proliferative cell disorder of the circulatory system of bivalves, was first reported in oysters in 1969. Since that time, the disease has been determined to be transmissible through water-borne exposure, but the etiological agent has not been unequivocally identified. In order to determine if a viral agent, possibly a retrovirus, could be the causative agent of DN, transmission experiments were performed, using both a cell-free filtrate and a sucrose gradient-purified preparation of a cell-free filtrate of DN positive materials. Additionally, a PCR-enhanced reverse transcriptase assay was used to determine if reverse transcriptase was present in tissues or hemolymph from DN positive soft shell clams Mya arenaria. DN was transmitted to healthy clams by injection with whole DN cells, but not with cell-free flitrates prepared from either tissues from DN positive clams, or DN cells. The cell-free preparations from DN-positive tissues and hemolymph having high levels of DN cells in circulation exhibited positive reactions in the PCR-enhanced reverse transcriptase assay. Cell-free preparations of hemolymph from clams having low levels of DN (<0.1% of cells abnormal), hemocytes from normal soft shell clams, and normal soft shell clam tissues did not produce a positive reaction in the PCR enhanced reverse transcriptase assay.

Composition, shell strength, and metabolizable energy of Mulinia lateralis and Ischadium recurvum as food for wintering surf scoters (Melanitta perspicillata)

USGS Publications Warehouse

Berlin, Alicia; Perry, Matthew C.; Kohn, R.A.; Paynter, K.T.; Ottinger, Mary Ann

2015-01-01

Decline in surf scoter (Melanitta perspicillata) waterfowl populations wintering in the Chesapeake Bay has been associated with changes in the availability of benthic bivalves. The Bay has become more eutrophic, causing changes in the benthos available to surf scoters. The subsequent decline in oyster beds (Crassostrea virginica) has reduced the hard substrate needed by the hooked mussel (Ischadium recurvum), one of the primary prey items for surf scoters, causing the surf scoter to switch to a more opportune species, the dwarf surfclam (Mulinia lateralis). The composition (macronutrients, minerals, and amino acids), shell strength (N), and metabolizable energy (kJ) of these prey items were quantified to determine the relative foraging values for wintering scoters. Pooled samples of each prey item were analyzed to determine composition. Shell strength (N) was measured using a shell crack compression test. Total collection digestibility trials were conducted on eight captive surf scoters. For the prey size range commonly consumed by surf scoters (6-12 mm for M. lateralis and 18-24 mm for I. recurvum), I. recurvum contained higher ash, protein, lipid, and energy per individual organism than M. lateralis. I. recurvum required significantly greater force to crack the shell relative to M. lateralis. No difference in metabolized energy was observed for these prey items in wintering surf scoters, despite I. recurvum's higher ash content and harder shell than M. lateralis. Therefore, wintering surf scoters were able to obtain the same amount of energy from each prey item, implying that they can sustain themselves if forced to switch prey.

Composition, Shell Strength, and Metabolizable Energy of Mulinia lateralis and Ischadium recurvum as Food for Wintering Surf Scoters (Melanitta perspicillata)

PubMed Central

Wells-Berlin, Alicia M.; Perry, Matthew C.; Kohn, Richard A.; Paynter, Kennedy T.; Ottinger, Mary Ann

2015-01-01

Decline in surf scoter (Melanitta perspicillata) waterfowl populations wintering in the Chesapeake Bay has been associated with changes in the availability of benthic bivalves. The Bay has become more eutrophic, causing changes in the benthos available to surf scoters. The subsequent decline in oyster beds (Crassostrea virginica) has reduced the hard substrate needed by the hooked mussel (Ischadium recurvum), one of the primary prey items for surf scoters, causing the surf scoter to switch to a more opportune species, the dwarf surfclam (Mulinia lateralis). The composition (macronutrients, minerals, and amino acids), shell strength (N), and metabolizable energy (kJ) of these prey items were quantified to determine the relative foraging values for wintering scoters. Pooled samples of each prey item were analyzed to determine composition. Shell strength (N) was measured using a shell crack compression test. Total collection digestibility trials were conducted on eight captive surf scoters. For the prey size range commonly consumed by surf scoters (6–12 mm for M. lateralis and 18–24 mm for I. recurvum), I. recurvum contained higher ash, protein, lipid, and energy per individual organism than M. lateralis. I. recurvum required significantly greater force to crack the shell relative to M. lateralis. No difference in metabolized energy was observed for these prey items in wintering surf scoters, despite I. recurvum’s higher ash content and harder shell than M. lateralis. Therefore, wintering surf scoters were able to obtain the same amount of energy from each prey item, implying that they can sustain themselves if forced to switch prey. PMID:25978636

Genetic Mapping and QTL Analysis of Growth-Related Traits in Pinctada fucata Using Restriction-Site Associated DNA Sequencing

PubMed Central

Li, Yaoguo; He, Maoxian

2014-01-01

The pearl oyster, Pinctada fucata (P. fucata), is one of the marine bivalves that is predominantly cultured for pearl production. To obtain more genetic information for breeding purposes, we constructed a high-density linkage map of P. fucata and identified quantitative trait loci (QTL) for growth-related traits. One F1 family, which included the two parents, 48 largest progeny and 50 smallest progeny, was sampled to construct a linkage map using restriction site-associated DNA sequencing (RAD-Seq). With low coverage data, 1956.53 million clean reads and 86,342 candidate RAD loci were generated. A total of 1373 segregating SNPs were used to construct a sex-average linkage map. This spanned 1091.81 centimorgans (cM), with 14 linkage groups and an average marker interval of 1.41 cM. The genetic linkage map coverage, Coa, was 97.24%. Thirty-nine QTL-peak loci, for seven growth-related traits, were identified using the single-marker analysis, nonparametric mapping Kruskal-Wallis (KW) test. Parameters included three for shell height, six for shell length, five for shell width, four for hinge length, 11 for total weight, eight for soft tissue weight and two for shell weight. The QTL peak loci for shell height, shell length and shell weight were all located in linkage group 6. The genotype frequencies of most QTL peak loci showed significant differences between the large subpopulation and the small subpopulation (P<0.05). These results highlight the effectiveness of RAD-Seq as a tool for generation of QTL-targeted and genome-wide marker data in the non-model animal, P. fucata, and its possible utility in marker-assisted selection (MAS). PMID:25369421

Carbon and nitrogen mineralization and enzyme activities in soil aggregate-size classes: Effects of biochar, oyster shells, and polymers.

PubMed

Awad, Yasser Mahmoud; Lee, Sang Soo; Kim, Ki-Hyun; Ok, Yong Sik; Kuzyakov, Yakov

2018-05-01

Biochar (BC) and polymers are cost-effective additives for soil quality improvement and long-term sustainability. The additional use of the oyster shells (OS) powder in BC- or polymer-treated soils is recommended as a nutrient source, to enhance aggregation and to increase enzyme activities. The effects of soil treatments (i.e., BC (5 Mg ha -1 ) and polymers (biopolymer at 0.4 Mg ha -1 or polyacrylamide at 0.4 Mg ha -1 ) with or without the OS (1%)) on the short-term changes were evaluated based on a 30-day incubation experiment with respect to several variables (e.g., CO 2 release, NH 4 + and NO 3 - concentrations, aggregate-size classes, and enzyme activities in an agricultural Luvisol). The BC and BP with the addition of OS increased the portion of microaggregates (<0.25 mm) relative to the control soil without any additions, while PAM alone increased the portion of large macroaggregates (1-2 mm). Concentrations of NO 3 - also increased in soils treated with OS, OS + BC, and OS + BP as result of the increased chitinase and leucine aminopeptidase activities. The BC and BP when treated with the additional OS had significant short-term impacts on N mineralization without affecting C mineralization in soil. Consequently, the combination of BC or BP with OS was seen to accelerate N turnover without affecting C turnover (and related C losses) from soil. As such, the addition of these additives contributed considerably to the improvement of soil fertility and C sequestration. Copyright © 2018 Elsevier Ltd. All rights reserved.

High Removal of Effluent-borne Nitrogen with Multiple External Electron Donors in the Engineered Drainfield of an Advanced Septic System.

PubMed

De, Mriganka; Toor, Gurpal S

2016-11-01

Septic systems can be a major source of nitrogen (N) in shallow groundwater. We designed an in situ engineered drainfield with aerobic-anaerobic (sand-woodchips) and anaerobic (elemental sulfur-oyster shell) media to remove N in the vadose zone and reduce N transport to groundwater. Effluent was dispersed on top of the engineered drainfield (3.72 m infiltrative surface) and then infiltrated through the aerobic-anaerobic and anaerobic media before reaching natural soil. Water samples were collected over 64 sampling events (May 2012-December 2013) from three parts of the drainfield: (i) a suction cup lysimeter installed at the sand-woodchips interface, (ii) a pipe after effluent passed through the aerobic-anaerobic media, and (iii) a tank containing anaerobic media. In the effluent, most of the total N (66 mg L) was present as NH-N (88.8%), whereas at the sand-woodchips interface the dominant N form was NO-N (31 mg L; 85% of total N). As the effluent passed through the aerobic-anaerobic media in the drainfield, heterotrophic denitrification reduced NO-N to 5.4 mg L. In the tank containing anaerobic media, autotrophic denitrification, facilitated by elemental sulfur, further reduced NO-N to 1 mg L. Overall, 90% of total added N was removed as the effluent passed through the aerobic-anaerobic and anaerobic media within the engineered drainfield. We conclude that the use of multiple electron donors from external media (sand-woodchips and elemental sulfur-oyster shell) was effective at removing N in the engineered drainfield and will reduce the risk of groundwater N contamination from septic systems in areas with shallow groundwater. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Ubiquitylation Functions in the Calcium Carbonate Biomineralization in the Extracellular Matrix

PubMed Central

Fang, Dong; Pan, Cong; Lin, Huijuan; Lin, Ya; Xu, Guangrui; Zhang, Guiyou; Wang, Hongzhong; Xie, Liping; Zhang, Rongqing

2012-01-01

Mollusks shell formation is mediated by matrix proteins and many of these proteins have been identified and characterized. However, the mechanisms of protein control remain unknown. Here, we report the ubiquitylation of matrix proteins in the prismatic layer of the pearl oyster, Pinctada fucata. The presence of ubiquitylated proteins in the prismatic layer of the shell was detected with a combination of western blot and immunogold assays. The coupled ubiquitins were separated and identified by Edman degradation and liquid chromatography/mass spectrometry (LC/MS). Antibody injection in vivo resulted in large amounts of calcium carbonate randomly accumulating on the surface of the nacreous layer. These ubiquitylated proteins could bind to specific faces of calcite and aragonite, which are the two main mineral components of the shell. In the in vitro calcium carbonate crystallization assay, they could reduce the rate of calcium carbonate precipitation and induce the calcite formation. Furthermore, when the attached ubiquitins were removed, the functions of the EDTA-soluble matrix of the prismatic layer were changed. Their potency to inhibit precipitation of calcium carbonate was decreased and their influence on the morphology of calcium carbonate crystals was changed. Taken together, ubiquitylation is involved in shell formation. Although the ubiquitylation is supposed to be involved in every aspect of biophysical processes, our work connected the biomineralization-related proteins and the ubiquitylation mechanism in the extracellular matrix for the first time. This would promote our understanding of the shell biomineralization and the ubiquitylation processes. PMID:22558208

Estimating the impact of oyster restoration scenarios on transient fish production

USGS Publications Warehouse

McCoy, Elizabeth; Borrett, Stuart R.; LaPeyre, Megan K.; Peterson, Bradley J.

2017-01-01

Oyster reef restoration projects are increasing in number both to enhance oyster density and to retain valuable ecosystem services provided by oyster reefs. Although some oyster restoration projects have demonstrated success by increasing density and biomass of transient fish, it still remains a challenge to quantify the effects of oyster restoration on transient fish communities. We developed a bioenergetics model to assess the impact of selected oyster reef restoration scenarios on associated transient fish species. We used the model to analyze the impact of changes in (1) oyster population carrying capacity; (2) oyster population growth rate; and (3) diet preference of transient fish on oyster reef development and associated transient fish species. Our model results indicate that resident fish biomass is directly affected by oyster restoration and oyster biomass, and oyster restoration can have cascading impacts on transient fish biomass. Furthermore, the results highlight the importance of a favorable oyster population growth rate during early restoration years, as it can lead to rapid increases in mean oyster biomass and biomass of transient fish species. The model also revealed that a transient fish's diet solely dependent on oyster reef-derived prey could limit the biomass of transient fish species, emphasizing the importance of habitat connectivity in estuarine areas to enhance transient fish species biomass. Simple bioenergetics models can be developed to understand the dynamics of a system and make qualitative predictions of management and restoration scenarios.

Prevalence and characterization of Salmonella serovars isolated from oysters served raw in restaurants.

PubMed

Brillhart, Crystal D; Joens, Lynn A

2011-06-01

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.

Experimental infection of European flat oyster Ostrea edulis with ostreid herpesvirus 1 microvar (OsHV-1μvar): Mortality, viral load and detection of viral transcripts by in situ hybridization.

PubMed

López Sanmartín, Monserrat; Power, Deborah M; de la Herrán, Roberto; Navas, José I; Batista, Frederico M

2016-06-02

Ostreid herpesvirus 1 (OsHV-1) infections have been reported in several bivalve species. Mortality of Pacific oyster Crassostrea gigas spat has increased considerably in Europe since 2008 linked to the spread of a variant of OsHV-1 called μvar. In the present study we demonstrated that O. edulis juveniles can be infected by OsHV-1μvar when administered as an intramuscular injection. Mortality in the oysters injected with OsHV-1μvar was first detected 4 days after injection and reached 25% mortality at day 10. Moreover, the high viral load observed and the detection of viral transcripts by in situ hybridization in several tissues of dying oysters suggested that OsHV-1μvar was the cause of mortality in the O. edulis juveniles. This is therefore the first study to provide evidence about the pathogenicity of OsHV-1μvar in a species that does not belong to the Crassostrea genus. Additionally, we present a novel method to detect OsHV-1 transcripts in infected individuals' using in situ hybridization. Copyright © 2016 Elsevier B.V. All rights reserved.

Development of an in situ hybridization assay for the detection of ostreid herpesvirus type 1 mRNAs in the Pacific oyster, Crassostrea gigas.

PubMed

Corbeil, Serge; Faury, Nicole; Segarra, Amélie; Renault, Tristan

2015-01-01

An in situ hybridization protocol for detecting mRNAs of ostreid herpesvirus type 1 (OsHV-1) which infects Pacific oysters, Crassostrea gigas, was developed. Three RNA probes were synthesized by cloning three partial OsHV-1 genes into plasmids using three specific primer pairs, and performing a transcription in the presence of digoxigenin dUTP. The RNA probes were able to detect the virus mRNAs in paraffin sections of experimentally infected oysters 26 h post-injection. The in situ hybridization showed that the OsHV-1 mRNAs were mainly present in connective tissues in gills, mantle, adductor muscle, digestive gland and gonads. DNA detection by in situ hybridization using a DNA probe and viral DNA quantitation by real-time PCR were also performed and results were compared with those obtained using RNA probes. Copyright © 2014 Elsevier B.V. All rights reserved.

Counting the dead to determine the source and transmission of the marine herpesvirus OsHV-1 in Crassostrea gigas.

PubMed

Whittington, Richard J; Paul-Pont, Ika; Evans, Olivia; Hick, Paul; Dhand, Navneet K

2018-04-10

Marine herpesviruses are responsible for epizootics in economically, ecologically and culturally significant taxa. The recent emergence of microvariants of Ostreid herpesvirus 1 (OsHV-1) in Pacific oysters Crassostrea gigas has resulted in socioeconomic losses in Europe, New Zealand and Australia however, there is no information on their origin or mode of transmission. These factors need to be understood because they influence the way the disease may be prevented and controlled. Mortality data obtained from experimental populations of C. gigas during natural epizootics of OsHV-1 disease in Australia were analysed qualitatively. In addition we compared actual mortality data with those from a Reed-Frost model of direct transmission and analysed incubation periods using Sartwell's method to test for the type of epizootic, point source or propagating. We concluded that outbreaks were initiated from an unknown environmental source which is unlikely to be farmed oysters in the same estuary. While direct oyster-to-oyster transmission may occur in larger oysters if they are in close proximity (< 40 cm), it did not explain the observed epizootics, point source exposure and indirect transmission being more common and important. A conceptual model is proposed for OsHV-1 index case source and transmission, leading to endemicity with recurrent seasonal outbreaks. The findings suggest that prevention and control of OsHV-1 in C. gigas will require multiple interventions. OsHV-1 in C. gigas, which is a sedentary animal once beyond the larval stage, is an informative model when considering marine host-herpesvirus relationships.

Persistence of Caliciviruses in Artificially Contaminated Oysters during Depuration▿

PubMed Central

Ueki, You; Shoji, Mika; Suto, Atsushi; Tanabe, Toru; Okimura, Yoko; Kikuchi, Yoshihiko; Saito, Noriyuki; Sano, Daisuke; Omura, Tatsuo

2007-01-01

The fate of calicivirus in oysters in a 10-day depuration was assessed. The norovirus gene was persistently detected from artificially contaminated oysters during the depuration, whereas feline calicivirus in oysters was promptly eliminated. The prolonged observation of norovirus in oysters implies the existence of a selective retention mechanism for norovirus within oysters. PMID:17630304

High-pressure treatment for shelf-life extension and quality improvement of oysters cooked in a traditional Taiwanese oyster omelet.

PubMed

Lai, Kung-Ming; Chi, Hsin-Yi; Hsu, Kuo-Chiang

2010-01-01

Whole oysters were processed using high-pressure (HP) treatment at 250 and 300 MPa for 0 to 10 min and stored at 4 degrees Celsius for up to 28 days. HP-treated oysters and untreated oysters were evaluated for lipid oxidation, growth of microorganisms, and sensory characteristics after cooking at 160 degrees Celsius for 90 s. Microbial counts after HP treatment revealed that the bacterial load was initially reduced at all pressures. HP-treated oysters had significantly higher pH and moisture (P < 0.05) relative to control (untreated) oysters during storage. HP treatment increased lipid oxidation with unpleasant odor during storage compared with the control. HP treatment decreased redness but did not significantly affect the brightness and yellowness of cooked oysters. From tests of mechanical properties, 300 MPa-treated oysters after cooking had significantly increased toughness as measured by cutting force. HP-treated oysters after cooking received higher quality scores than did the control during the storage trial. Results indicated that 300 MPa for 2 min is the optimum HP treatment that results in oysters most acceptable for oyster omelets during storage at 4 degrees Celsius, and this treatment may extend the shelf life of these oysters to 21 days.

The hot oyster: levels of virulent Vibrio parahaemolyticus strains in individual oysters.

PubMed

Klein, Savannah L; Lovell, Charles R

2017-02-01

Vibrio parahaemolyticus is the leading cause of seafood-associated gastroenteritis and is most commonly transmitted by raw oysters. Consequently, detection of virulent strains of this organism in oysters is a primary concern for seafood safety. Vibrio parahaemolyticus levels were determined in 110 individual oysters harvested from two sampling sites in SC, USA. The majority of oysters (98%) contained low levels of presumptive V. parahaemolyticus However, two healthy oysters contained presumptive V. parahaemolyticus numbers that were unusually high. These two 'hot' oysters contained levels of presumptive V. parahaemolyticus within the gills that were ∼100-fold higher than the average for other oysters collected at the same date and location. Current V. parahaemolyticus detection practices require homogenizing a dozen oysters pooled together to determine V. parahaemolyticus numbers, a procedure that would dilute out V. parahaemolyticus in these 'hot' oysters. This study demonstrates the variability of V. parahaemolyticus densities taken from healthy, neighboring individual oysters in the environment. Additionally, environmental V parahaemolyticus isolates were screened for the virulence-related genes, tdh and trh, using improved polymerase chain reaction primers and protocols. We detected these genes, previously thought to be rare in environmental isolates, in approximately half of the oyster isolates. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Biocatalytic CO2 sequestration based on shell regeneration

NASA Astrophysics Data System (ADS)

Lee, S.

2012-04-01

Carbon dioxide, CO2, is one of the green gases, being uniformly distributed over the earth's surface. Recently, a variety of methods exists or has been proposed for pre- or post-emission capture and sequestration of CO2. However, CCS (carbon capture & storage) do not quarntee permanent treatment of CO2 and could ingenerate environment risks. Some organisms convert CO2 into exoskeleton (e.g., mollusks) or energy sources (e.g., plants) during metabolism under atmospheric conditions. One of representative biomaterials in ocean is bivalve shell to be composed of CaCO3. Calcium carbonate is not only abundant material in the world but also thermodynamically stable mineral in the capture of CO2. Bivalve has produced CaCO3 under seawater condition, in other word, near atmospheric conditions (1 atm. and around 20-25 oC). At the inorganic point, the synthesis of CaCO3 is as followed. Ca2+ + CO32- -> CaCO3 The bivalve shell plays an important role to protect bivalve's internal organs from prodetor. What will be happened if the shell is damaged and a hole is made? Bivalve must cover the hole to prevent the oxidation of internal organs as fast as possible. From in vitro crystallization test of a notched shell, rapid CaCO3 production was identified at the damaged area. The biocatalyst related to shell regeneration was purified and named as SPSR (Soluble Protein related to Shell Regeneration) that is obtained from the oyster, Crassostrea gigas. And in vitro CaCO3 crystallization test was used to calculate the crystal growth rate of SPSR on CaCO3 crystallization. The characteristics of SPRR are discussed at the point of CO2 hydration and rapid CaCO3 synthesis. To develop the bioinspired process based on shell regeneration concept, the analysis of protein structure has been studied and the immobilization has been carried out for easy recovery of SPSR.

Identification and Characterization of the Lysine-Rich Matrix Protein Family in Pinctada fucata: Indicative of Roles in Shell Formation.

PubMed

Liang, Jian; Xie, Jun; Gao, Jing; Xu, Chao-Qun; Yan, Yi; Jia, Gan-Chu; Xiang, Liang; Xie, Li-Ping; Zhang, Rong-Qing

2016-12-01

Mantle can secret matrix proteins playing key roles in regulating the process of shell formation. The genes encoding lysine-rich matrix proteins (KRMPs) are one of the most highly expressed matrix genes in pearl oysters. However, the expression pattern of KRMPs is limited and the functions of them still remain unknown. In this study, we isolated and identified six new members of lysine-rich matrix proteins, rich in lysine, glycine and tyrosine, and all of them are basic matrix proteins. Combined with four members of the KRMPs previously reported, all these proteins can be divided into three subclasses according to the results of phylogenetic analyses: KRMP1-3 belong to subclass KPI, KRMP4-5 belong to KPII, and KRMP6-10 belong to KPIII. Three subcategories of lysine-rich matrix proteins are highly expressed in the D-phase, the larvae and adult mantle. Lysine-rich matrix proteins are involved in the shell repairing process and associated with the formation of the shell and pearl. What's more, they can cause abnormal shell growth after RNA interference. In detail, KPI subgroup was critical for the beginning formation of the prismatic layer; both KPII and KPIII subgroups participated in the formation of prismatic layer and nacreous layer. Compared with different temperatures and salinity stimulation treatments, the influence of changes in pH on KRMPs gene expression was the greatest. Recombinant KRMP7 significantly inhibited CaCO 3 precipitation, changed the morphology of calcite, and inhibited the growth of aragonite in vitro. Our results are beneficial to understand the functions of the KRMP genes during shell formation.

A Glycoprotein in Shells of Conspecifics Induces Larval Settlement of the Pacific Oyster Crassostrea gigas

PubMed Central

Vasquez, Hebert Ely; Hashimoto, Kyotaro; Yoshida, Asami; Hara, Kenji; Imai, Chisato Chris; Kitamura, Hitoshi; Satuito, Cyril Glenn

2013-01-01

Settlement of larvae of Crassostrea gigas on shell chips (SC) prepared from shells of 11 different species of mollusks was investigated. Furthermore, the settlement inducing compound in the shell of C. gigas was extracted and subjected to various treatments to characterize the chemical cue. C. gigas larvae settled on SC of all species tested except on Patinopecten yessoensis and Atrina pinnata. In SC of species that induced C. gigas larvae to settle, settlement was proportionate to the amount of SC supplied to the larvae. When compared to C. gigas SC, all species except Crassostrea nippona showed lower settlement inducing activities, suggesting that the cue may be more abundant or in a more available form to the larvae in shells of conspecific and C. nippona than in other species. The settlement inducing activity of C. gigas SC remained intact after antibiotic treatment. Extraction of C. gigas SC with diethyl ether (Et2O-ex), ethanol (EtOH-ex), and water (Aq-ex) did not induce larval settlement of C. gigas larvae. However, extraction of C. gigas SC with 2N of hydrochloric acid (HCl-ex) induced larval settlement that was at the same level as the SC. The settlement inducing compound in the HCl-ex was stable at 100°C but was destroyed or degraded after pepsin, trypsin, PNGase F and trifluoromethanesulfonic acid treatments. This chemical cue eluted between the molecular mass range of 45 and 150 kDa after gel filtration and revealed a major band at 55 kDa on the SDS-PAGE gel after staining with Stains-all. Thus, a 55 kDa glycoprotein component in the organic matrix of C. gigas shells is hypothesized to be the chemical basis of larval settlement on conspecifics. PMID:24349261

Transcriptome of American oysters, Crassostrea virginica, in response to bacterial challenge: insights into potential mechanisms of disease resistance.

PubMed

McDowell, Ian C; Nikapitiya, Chamilani; Aguiar, Derek; Lane, Christopher E; Istrail, Sorin; Gomez-Chiarri, Marta

2014-01-01

The American oyster Crassostrea virginica, an ecologically and economically important estuarine organism, can suffer high mortalities in areas in the Northeast United States due to Roseovarius Oyster Disease (ROD), caused by the gram-negative bacterial pathogen Roseovarius crassostreae. The goals of this research were to provide insights into: 1) the responses of American oysters to R. crassostreae, and 2) potential mechanisms of resistance or susceptibility to ROD. The responses of oysters to bacterial challenge were characterized by exposing oysters from ROD-resistant and susceptible families to R. crassostreae, followed by high-throughput sequencing of cDNA samples from various timepoints after disease challenge. Sequence data was assembled into a reference transcriptome and analyzed through differential gene expression and functional enrichment to uncover genes and processes potentially involved in responses to ROD in the American oyster. While susceptible oysters experienced constant levels of mortality when challenged with R. crassostreae, resistant oysters showed levels of mortality similar to non-challenged oysters. Oysters exposed to R. crassostreae showed differential expression of transcripts involved in immune recognition, signaling, protease inhibition, detoxification, and apoptosis. Transcripts involved in metabolism were enriched in susceptible oysters, suggesting that bacterial infection places a large metabolic demand on these oysters. Transcripts differentially expressed in resistant oysters in response to infection included the immune modulators IL-17 and arginase, as well as several genes involved in extracellular matrix remodeling. The identification of potential genes and processes responsible for defense against R. crassostreae in the American oyster provides insights into potential mechanisms of disease resistance.

Transcriptome of American Oysters, Crassostrea virginica, in Response to Bacterial Challenge: Insights into Potential Mechanisms of Disease Resistance

PubMed Central

McDowell, Ian C.; Nikapitiya, Chamilani; Aguiar, Derek; Lane, Christopher E.; Istrail, Sorin; Gomez-Chiarri, Marta

2014-01-01

The American oyster Crassostrea virginica, an ecologically and economically important estuarine organism, can suffer high mortalities in areas in the Northeast United States due to Roseovarius Oyster Disease (ROD), caused by the gram-negative bacterial pathogen Roseovarius crassostreae. The goals of this research were to provide insights into: 1) the responses of American oysters to R. crassostreae, and 2) potential mechanisms of resistance or susceptibility to ROD. The responses of oysters to bacterial challenge were characterized by exposing oysters from ROD-resistant and susceptible families to R. crassostreae, followed by high-throughput sequencing of cDNA samples from various timepoints after disease challenge. Sequence data was assembled into a reference transcriptome and analyzed through differential gene expression and functional enrichment to uncover genes and processes potentially involved in responses to ROD in the American oyster. While susceptible oysters experienced constant levels of mortality when challenged with R. crassostreae, resistant oysters showed levels of mortality similar to non-challenged oysters. Oysters exposed to R. crassostreae showed differential expression of transcripts involved in immune recognition, signaling, protease inhibition, detoxification, and apoptosis. Transcripts involved in metabolism were enriched in susceptible oysters, suggesting that bacterial infection places a large metabolic demand on these oysters. Transcripts differentially expressed in resistant oysters in response to infection included the immune modulators IL-17 and arginase, as well as several genes involved in extracellular matrix remodeling. The identification of potential genes and processes responsible for defense against R. crassostreae in the American oyster provides insights into potential mechanisms of disease resistance. PMID:25122115

Suspension of oysters reduces the populations of Vibrio parahaemolyticus and Vibrio vulnificus.

PubMed

Cole, K M; Supan, J; Ramirez, A; Johnson, C N

2015-09-01

Vibrio parahaemolyticus (Vp) and Vibrio vulnificus (Vv) are associated with the consumption of raw oysters and cause illnesses ranging from simple gastroenteritis to life-threatening septicaemia. These halophilic bacteria are frequently found in marine and estuarine systems, accumulating within the tissues of a number of aquatic organisms and passing on to humans after consumption, through contaminated water, or via open wounds. As benthic organisms capable of filtering 40 gallons of water per hour, sediment is an important source of potentially pathogenic vibrios in oysters destined for raw consumption. This research used off-bottom oyster culture to reduce vibrio concentrations in oysters. Colony hybridization was used to enumerate Vp and Vv in bottom and suspended oysters. Vv and Vp concentrations were generally lower in oysters suspended off-bottom, and suspension decreased vibrio loads in oysters by an average of 13%. Suspension of oysters reduced vibrio concentrations. This study found that oyster suspension significantly reduced some populations of potentially pathogenic vibrios. These results indicate that oyster suspension could be a viable approach for preharvest treatment to reduce illness in consumers of raw oysters. © 2015 The Society for Applied Microbiology.

Functional characterization and molecular mechanism exploration of three granulin epithelin precursor splice variants in biomineralization of the pearl oyster Pinctada fucata.

PubMed

Zhao, Mi; He, Maoxian; Huang, Xiande; Wang, Qi; Shi, Yu

2016-02-01

The granulin/epithelin precursor (GEP) encodes a glycoprotein precursor which exhibits pleiotropic tissue growth factor activity with multiple functions. Here, GEP was isolated and its role in the shell biomineralization process of the pearl oyster Pinctada fucata was investigated. Three forms of GEP mRNA were isolated from the pearl oyster (designated PfGEP-1, PfGEP-2 and PfGEP-3). Genomic DNA flanking the splicing region of the PfGEP variants was sequenced and it was found that PfGEP-2 splices out Exon 4, whereas PfGEP-3 splices out Exon 3 compared to PfGEP-1. PfGEP-1 (1505 amino acids) consists of 18 granulin domains, whereas PfGEP-2 (1459 amino acids) and PfGEP-3 (1471 amino acids) consist of 17.5 granulin domains, respectively. Analyses of PfGEP-1 and PfGEP-3 mRNA showed differential patterns in the tissues and developmental stages. Western blotting results showed that the three splice variants can translate to proteins in HEK293T cells. A knockdown experiment using PfGEP dsRNA showed decreased PfGEP-1/PfGEP-3 and PfMSX mRNA, and irregular crystallization of the nacreous layer using scanning electron microscopy. In luciferase assays, co-transfection of PfGEP-1 could activate as well as repress luciferase expression of the reporter plasmid driven by the PfMSX promoter, whereas PfGEP-3 stimulated the expression, elucidating the molecular mechanisms involved in the correlation between PfGEP and PfMSX. These results suggested that GEP variants might function differently during the biomineralization process, which provides new knowledge on the mechanism regulating nacre formation.

Molecular Epidemiology of Oyster-Related Human Noroviruses and Their Global Genetic Diversity and Temporal-Geographical Distribution from 1983 to 2014

PubMed Central

Yu, Yongxin; Cai, Hui; Hu, Linghao; Lei, Rongwei; Pan, Yingjie; Yan, Shuling

2015-01-01

Noroviruses (NoVs) are a leading cause of epidemic and sporadic cases of acute gastroenteritis worldwide. Oysters are well recognized as the main vectors of environmentally transmitted NoVs, and disease outbreaks linked to oyster consumption have been commonly observed. Here, to quantify the genetic diversity, temporal distribution, and circulation of oyster-related NoVs on a global scale, 1,077 oyster-related NoV sequences deposited from 1983 to 2014 were downloaded from both NCBI GenBank and the NoroNet outbreak database and were then screened for quality control. A total of 665 sequences with reliable information were obtained and were subsequently subjected to genotyping and phylogenetic analyses. The results indicated that the majority of oyster-related NoV sequences were obtained from coastal countries and regions and that the numbers of sequences in these regions were unevenly distributed. Moreover, >80% of human NoV genotypes were detected in oyster samples or oyster-related outbreaks. A higher proportion of genogroup I (GI) (34%) was observed for oyster-related sequences than for non-oyster-related outbreaks, where GII strains dominated with an overwhelming majority of >90%, indicating that the prevalences of GI and GII are different in humans and oysters. In addition, a related convergence of the circulation trend was found between oyster-related NoV sequences and human pandemic outbreaks. This suggests that oysters not only act as a vector of NoV through environmental transmission but also serve as an important reservoir of human NoVs. These results highlight the importance of oysters in the persistence and transmission of human NoVs in the environment and have important implications for the surveillance of human NoVs in oyster samples. PMID:26319869

Cholinesterase activity in the cup oyster Saccostrea sp. exposed to chlorpyrifos, imidacloprid, cadmium and copper.

PubMed

Moncaleano-Niño, Angela M; Luna-Acosta, Andrea; Gómez-Cubillos, Maria Camila; Villamil, Luisa; Ahrens, Michael J

2018-04-30

In the present study, the sensitivity and concentration dependence of three functionally-defined components of cholinesterase activity (total: T-ChE; eserine-sensitive: Es-ChE; and eserine-resistant: Er-ChE) were quantified in the gill, digestive gland and adductor muscle of the tropical cup oyster Saccostrea sp., following acute (96h) aqueous exposure to commercial formulations of the organophosphate (OP) insecticide chlorpyrifos and the neonicotinoid (NN) imidacloprid (concentration range: 0.1-100mg/L), as well as to dissolved cadmium and copper (concentration range: 1-1000μg/L). Oysters (1.5-5.0cm shell length), field-collected from a boating marina in Santa Marta, Colombia (Caribbean Sea) were exposed in the laboratory to each substance at five concentrations. T-ChE, Es-ChE, and Er-ChE activity were quantified in the three tissues in pools of 5 individuals (3 replicates per concentration), before and after inhibition with the total cholinesterase inhibitor eserine (physostigmine, 100µM). Oysters exposed to chlorpyrifos, imidacloprid and Cd showed reduced T-ChE and Es-ChE activity in gills at highest exposure concentrations, with Es-ChE activity being inhibited proportionally more so than T-ChE, whereas Er-ChE activity showed no significant concentration-response. Digestive gland also showed diminished T-ChE, Es-ChE and Er-ChE activity for highest chlorpyrifos and Cd concentrations relative to controls, but an increase of T-ChE and Er-ChE activity at the highest imidacloprid concentration (100mg/L). For Cu, T-ChE, Es-ChE and Er-ChE activities in gills and digestive gland were elevated relative to controls in oysters exposed to Cu concentrations > 100µg/L. In adductor muscle, T-ChE, Es-ChE and Er-ChE activity showed no apparent pattern for any of the four xenobiotics and concentration levels tested. Although this study confirms acute (96h) concentration-dependent reduction of tissue T-ChE and Es-ChE activity in gills and digestive glands of Saccostrea sp. exposed to high concentrations of chlorpyrifos (100mg/L), significant changes in T-ChE, Es-ChE and Er-ChE were also caused by exposure to Cd and Cu at concentrations > 100µg/L and by exposure to imidacloprid (100mg/L), indicating that cholinesterase activity is not a specific biomarker of organophosphate exposure in this species, but, rather, a biomarker of diverse xenobiotic exposure. Copyright © 2018 Elsevier Inc. All rights reserved.

Millennial-scale sustainability of the Chesapeake Bay Native American oyster fishery

PubMed Central

Rick, Torben C.; Reeder-Myers, Leslie A.; Hofman, Courtney A.; Breitburg, Denise; Lockwood, Rowan; Henkes, Gregory; Kellogg, Lisa; Lowery, Darrin; Luckenbach, Mark W.; Mann, Roger; Ogburn, Matthew B.; Southworth, Melissa; Wah, John; Wesson, James; Hines, Anson H.

2016-01-01

Estuaries around the world are in a state of decline following decades or more of overfishing, pollution, and climate change. Oysters (Ostreidae), ecosystem engineers in many estuaries, influence water quality, construct habitat, and provide food for humans and wildlife. In North America’s Chesapeake Bay, once-thriving eastern oyster (Crassostrea virginica) populations have declined dramatically, making their restoration and conservation extremely challenging. Here we present data on oyster size and human harvest from Chesapeake Bay archaeological sites spanning ∼3,500 y of Native American, colonial, and historical occupation. We compare oysters from archaeological sites with Pleistocene oyster reefs that existed before human harvest, modern oyster reefs, and other records of human oyster harvest from around the world. Native American fisheries were focused on nearshore oysters and were likely harvested at a rate that was sustainable over centuries to millennia, despite changing Holocene climatic conditions and sea-level rise. These data document resilience in oyster populations under long-term Native American harvest, sea-level rise, and climate change; provide context for managing modern oyster fisheries in the Chesapeake Bay and elsewhere around the world; and demonstrate an interdisciplinary approach that can be applied broadly to other fisheries. PMID:27217572

Reductions of Vibrio parahaemolyticus in Pacific oysters (Crassostrea gigas) by depuration at various temperatures.

PubMed

Phuvasate, Sureerat; Chen, Ming-Hui; Su, Yi-Cheng

2012-08-01

Consumption of raw oysters has been linked to several outbreaks of Vibrio parahaemolyticus infection in the United States. This study investigated effects of ice storage and UV-sterilized seawater depuration at various temperatures on reducing V. parahaemolyticus in oysters. Raw Pacific oysters (Crassostrea gigas) were inoculated with a mixed culture of five clinical strains of V. parahaemolyticus (10290, 10292, 10293, BE 98-2029 and 027-1c1) at levels of 10⁴⁻⁶ MPN/g. Inoculated oysters were either stored in ice or depurated in recirculating artificial seawater at 2, 3, 7, 10, 12.5, and 15 °C for 4-6 days. Holding oysters in ice or depuration of oysters in recirculating seawater at 2 or 3 °C for 4 days did not result in significant reductions (P > 0.05) of V. parahaemolyticus in the oysters. However, depuration at temperatures between 7 and 15 °C reduced V. parahaemolyticus populations in oysters by >3.0 log MPN/g after 5 days with no loss of oysters. Depuration at refrigerated temperatures (7-15 °C) can be applied as a post-harvest treatment for reducing V. parahaemolyticus in Pacific oysters. Copyright © 2012 Elsevier Ltd. All rights reserved.

Millennial-scale sustainability of the Chesapeake Bay Native American oyster fishery.

PubMed

Rick, Torben C; Reeder-Myers, Leslie A; Hofman, Courtney A; Breitburg, Denise; Lockwood, Rowan; Henkes, Gregory; Kellogg, Lisa; Lowery, Darrin; Luckenbach, Mark W; Mann, Roger; Ogburn, Matthew B; Southworth, Melissa; Wah, John; Wesson, James; Hines, Anson H

2016-06-07

Estuaries around the world are in a state of decline following decades or more of overfishing, pollution, and climate change. Oysters (Ostreidae), ecosystem engineers in many estuaries, influence water quality, construct habitat, and provide food for humans and wildlife. In North America's Chesapeake Bay, once-thriving eastern oyster (Crassostrea virginica) populations have declined dramatically, making their restoration and conservation extremely challenging. Here we present data on oyster size and human harvest from Chesapeake Bay archaeological sites spanning ∼3,500 y of Native American, colonial, and historical occupation. We compare oysters from archaeological sites with Pleistocene oyster reefs that existed before human harvest, modern oyster reefs, and other records of human oyster harvest from around the world. Native American fisheries were focused on nearshore oysters and were likely harvested at a rate that was sustainable over centuries to millennia, despite changing Holocene climatic conditions and sea-level rise. These data document resilience in oyster populations under long-term Native American harvest, sea-level rise, and climate change; provide context for managing modern oyster fisheries in the Chesapeake Bay and elsewhere around the world; and demonstrate an interdisciplinary approach that can be applied broadly to other fisheries.

Bactericidal effects of wine on Vibrio parahaemolyticus in oysters.

PubMed

Liu, Chengchu; Chen, Ruiying; Su, Yi-Cheng

2006-08-01

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 degrees 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 degrees C but increased to 7.37 log MPN/g over the same period at 25 degrees 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 degrees 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 x 10(3) MPN/g) decreased rapidly to nondetectable levels (< 3 MPN/g) after 30 min of mixing with wine at 25 degrees 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.

Haemocytes collected from experimentally infected Pacific oysters, Crassostrea gigas: Detection of ostreid herpesvirus 1 DNA, RNA, and proteins in relation with inhibition of apoptosis.

PubMed

Martenot, Claire; Gervais, Ophélie; Chollet, Bruno; Houssin, Maryline; Renault, Tristan

2017-01-01

Recent transcriptomic approaches focused on anti-viral immunity in molluscs lead to the assumption that the innate immune system, such as apoptosis, plays a crucial role against ostreid herpesvirus type 1 (OsHV-1), infecting Pacific cupped oyster, Crassostrea gigas. Apoptosis constitutes a major mechanism of anti-viral response by limiting viral spread and eliminating infected cells. In this way, an OsHV-1 challenge was performed and oysters were monitored at three times post injection to investigate viral infection and host response: 2h (early after viral injection in the adductor muscle), 24h (intermediate time), and 48h (just before first oyster mortality record). Virus infection, associated with high cumulative mortality rates (74% and 100%), was demonstrated in haemocytes by combining several detection techniques such as real-time PCR, real-time RT PCR, immunofluorescence assay, and transmission electron microscopy examination. High viral DNA amounts ranged from 5.46×104 to 3.68×105 DNA copies ng-1 of total DNA, were detected in dead oysters and an increase of viral transcripts was observed from 2, 24, and 48hpi for the five targeted OsHV-1 genes encoding three putative membrane proteins (ORFs 25, 41, and 72), a putative dUTPase (ORF 75), and a putative apoptosis inhibitor (ORF 87). Apoptosis was studied at molecular and cellular levels with an early marker (phosphatidyl-serine externalisation measured by flow cytometry and epifluorescence microscopy) and a later parameter (DNA fragmentation by terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling assay (TUNEL)). The down-regulation of genes encoding proteins involved in the activation of the apoptotic pathway (TNF and caspase 3) and the up-regulation of genes encoding anti-apoptotic proteins (IAP-2, and Bcl-2) suggested an important anti-apoptosis phenomenon in haemocytes from OsHV-1 infected oysters at 24 and 48hpi. Additionally, more phosphatidyl-serines were externalized and more cells with DNA fragmentation were observed in haemocytes collected from artificial seawater injected oysters than in haemocytes collected from OsHV-1 infected oysters at 24 and 48hpi, suggesting an inhibition of the apoptotic process in presence of the virus. In conclusion, this study is the first to focus on C. gigas haemocytes, cells involved in the host immune defense, during an OsHV-1 challenge in controlled conditions by combining various and original approaches to investigate apoptosis at molecular and cellular levels.

Automated Non-invasive Video-Microscopy of Oyster Spat Heart Rate during Acute Temperature Change: Impact of Acclimation Temperature

PubMed Central

Domnik, Nicolle J.; Polymeropoulos, Elias T.; Elliott, Nicholas G.; Frappell, Peter B.; Fisher, John T.

2016-01-01

We developed an automated, non-invasive method to detect real-time cardiac contraction in post-larval (1.1–1.7 mm length), juvenile oysters (i.e., oyster spat) via a fiber-optic trans-illumination system. The system is housed within a temperature-controlled chamber and video microscopy imaging of the heart was coupled with video edge-detection to measure cardiac contraction, inter-beat interval, and heart rate (HR). We used the method to address the hypothesis that cool acclimation (10°C vs. 22°C—Ta10 or Ta22, respectively; each n = 8) would preserve cardiac phenotype (assessed via HR variability, HRV analysis and maintained cardiac activity) during acute temperature changes. The temperature ramp (TR) protocol comprised 2°C steps (10 min/experimental temperature, Texp) from 22°C to 10°C to 22°C. HR was related to Texp in both acclimation groups. Spat became asystolic at low temperatures, particularly Ta22 spat (Ta22: 8/8 vs. Ta10: 3/8 asystolic at Texp = 10°C). The rate of HR decrease during cooling was less in Ta10 vs. Ta22 spat when asystole was included in analysis (P = 0.026). Time-domain HRV was inversely related to temperature and elevated in Ta10 vs. Ta22 spat (P < 0.001), whereas a lack of defined peaks in spectral density precluded frequency-domain analysis. Application of the method during an acute cooling challenge revealed that cool temperature acclimation preserved active cardiac contraction in oyster spat and increased time-domain HRV responses, whereas warm acclimation enhanced asystole. These physiologic changes highlight the need for studies of mechanisms, and have translational potential for oyster aquaculture practices. PMID:27445833

Exposure to the Neurotoxic Dinoflagellate, Alexandrium catenella, Induces Apoptosis of the Hemocytes of the Oyster, Crassostrea gigas

PubMed Central

Medhioub, Walid; Ramondenc, Simon; Vanhove, Audrey Sophie; Vergnes, Agnes; Masseret, Estelle; Savar, Veronique; Amzil, Zouher; Laabir, Mohamed; Rolland, Jean Luc

2013-01-01

This study assessed the apoptotic process occurring in the hemocytes of the Pacific oyster, Crassostrea gigas, exposed to Alexandrium catenella, a paralytic shellfish toxins (PSTs) producer. Oysters were experimentally exposed during 48 h to the toxic algae. PSTs accumulation, the expression of 12 key apoptotic-related genes, as well as the variation of the number of hemocytes in apoptosis was measured at time intervals during the experiment. Results show a significant increase of the number of hemocytes in apoptosis after 29 h of exposure. Two pro-apoptotic genes (Bax and Bax-like) implicated in the mitochondrial pathway were significantly upregulated at 21 h followed by the overexpression of two caspase executor genes (caspase-3 and caspase-7) at 29 h, suggesting that the intrinsic pathway was activated. No modulation of the expression of genes implicated in the cell signaling Fas-Associated protein with Death Domain (FADD) and initiation-phase (caspase-2) was observed, suggesting that only the extrinsic pathway was not activated. Moreover, the clear time-dependent upregulation of five (Bcl2, BI-1, IAP1, IAP7B and Hsp70) inhibitors of apoptosis-related genes associated with the return to the initial number of hemocytes in apoptosis at 48 h of exposure suggests the involvement of strong regulatory mechanisms of apoptosis occurring in the hemocytes of the Pacific oyster. PMID:24317471

Molecular epidemiology of oyster-related human noroviruses and their global genetic diversity and temporal-geographical distribution from 1983 to 2014.

PubMed

Yu, Yongxin; Cai, Hui; Hu, Linghao; Lei, Rongwei; Pan, Yingjie; Yan, Shuling; Wang, Yongjie

2015-11-01

Noroviruses (NoVs) are a leading cause of epidemic and sporadic cases of acute gastroenteritis worldwide. Oysters are well recognized as the main vectors of environmentally transmitted NoVs, and disease outbreaks linked to oyster consumption have been commonly observed. Here, to quantify the genetic diversity, temporal distribution, and circulation of oyster-related NoVs on a global scale, 1,077 oyster-related NoV sequences deposited from 1983 to 2014 were downloaded from both NCBI GenBank and the NoroNet outbreak database and were then screened for quality control. A total of 665 sequences with reliable information were obtained and were subsequently subjected to genotyping and phylogenetic analyses. The results indicated that the majority of oyster-related NoV sequences were obtained from coastal countries and regions and that the numbers of sequences in these regions were unevenly distributed. Moreover, >80% of human NoV genotypes were detected in oyster samples or oyster-related outbreaks. A higher proportion of genogroup I (GI) (34%) was observed for oyster-related sequences than for non-oyster-related outbreaks, where GII strains dominated with an overwhelming majority of >90%, indicating that the prevalences of GI and GII are different in humans and oysters. In addition, a related convergence of the circulation trend was found between oyster-related NoV sequences and human pandemic outbreaks. This suggests that oysters not only act as a vector of NoV through environmental transmission but also serve as an important reservoir of human NoVs. These results highlight the importance of oysters in the persistence and transmission of human NoVs in the environment and have important implications for the surveillance of human NoVs in oyster samples. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Food Safety Impacts from Post-Harvest Processing Procedures of Molluscan Shellfish.

PubMed

Baker, George L

2016-04-18

Post-harvest Processing (PHP) methods are viable food processing methods employed to reduce human pathogens in molluscan shellfish that would normally be consumed raw, such as raw oysters on the half-shell. Efficacy of human pathogen reduction associated with PHP varies with respect to time, temperature, salinity, pressure, and process exposure. Regulatory requirements and PHP molluscan shellfish quality implications are major considerations for PHP usage. Food safety impacts associated with PHP of molluscan shellfish vary in their efficacy and may have synergistic outcomes when combined. Further research for many PHP methods are necessary and emerging PHP methods that result in minimal quality loss and effective human pathogen reduction should be explored.

Co-Option and De Novo Gene Evolution Underlie Molluscan Shell Diversity

PubMed Central

Aguilera, Felipe; McDougall, Carmel

2017-01-01

Abstract Molluscs fabricate shells of incredible diversity and complexity by localized secretions from the dorsal epithelium of the mantle. Although distantly related molluscs express remarkably different secreted gene products, it remains unclear if the evolution of shell structure and pattern is underpinned by the differential co-option of conserved genes or the integration of lineage-specific genes into the mantle regulatory program. To address this, we compare the mantle transcriptomes of 11 bivalves and gastropods of varying relatedness. We find that each species, including four Pinctada (pearl oyster) species that diverged within the last 20 Ma, expresses a unique mantle secretome. Lineage- or species-specific genes comprise a large proportion of each species’ mantle secretome. A majority of these secreted proteins have unique domain architectures that include repetitive, low complexity domains (RLCDs), which evolve rapidly, and have a proclivity to expand, contract and rearrange in the genome. There are also a large number of secretome genes expressed in the mantle that arose before the origin of gastropods and bivalves. Each species expresses a unique set of these more ancient genes consistent with their independent co-option into these mantle gene regulatory networks. From this analysis, we infer lineage-specific secretomes underlie shell diversity, and include both rapidly evolving RLCD-containing proteins, and the continual recruitment and loss of both ancient and recently evolved genes into the periphery of the regulatory network controlling gene expression in the mantle epithelium. PMID:28053006

OYSTER POPULATUION ESTIMATION IN SUPPORT OF THE TEN-YEAR GOAL FOR OYSTER RESOTRATION IN THE CHESAPEAKE BAY: DEVELOPING STRATEGIES FOR RESTORING AND MANAGING THE EASTERN OYSTER

EPA Science Inventory

Mann, Roger, Steve Jordan, Gary Smith, Kennedy Paynter, James Wesson, Mary Christman, Jessica Vanisko, Juliana Harding, Kelly Greenhawk and Melissa Southworth. 2003. Oyster Population Estimation in Support of the Ten-Year Goal for Oyster Restoration in the Chesapeake Bay: Develop...

Shucking the Limitations of Hawai'i's Aquaculture Industry with Oysters

Science.gov Websites

-CASTRO | October 2015 VIDEO | Oyster Farming in a Hawaiian Fishpond, Featuring Ku'uipo McCarty It's a about oyster farming. "Our process started in 2008, beginning with doing some research and comparison, Hawai'i imports an estimated 400,000 oysters a month, she says. Oyster farming could become a

Increased temperatures combined with lowered salinities differentially impact oyster size class growth and mortality

USGS Publications Warehouse

LaPeyre, Megan K.; Rybovich, Molly; Hall, Steven G.; La Peyre, Jerome F.

2016-01-01

Changes in the timing and interaction of seasonal high temperatures and low salinities as predicted by climate change models could dramatically alter oyster population dynamics. Little is known explicitly about how low salinity and high temperature combinations affect spat (<25mm), seed (25–75mm), andmarket (>75mm) oyster growth and mortality. Using field and laboratory studies, this project quantified the combined effects of extremely low salinities (<5) and high temperatures (>30°C) on growth and survival of spat, seed, andmarket-sized oysters. In 2012 and 2013, hatchery-produced oysters were placed in open and closed cages at three sites in Breton Sound, LA, along a salinity gradient that typically ranged from 5 to 20. Growth and mortality were recorded monthly. Regardless of size class, oysters at the lowest salinity site (annualmean = 4.8) experienced significantly highermortality and lower growth than oysters located in higher salinity sites (annual means = 11.1 and 13.0, respectively); furthermore, all oysters in open cages at the two higher salinity sites experienced higher mortality than in closed cages, likely due to predation. To explicitly examine oyster responses to extreme low salinity and high temperature combinations, a series of laboratory studies were conducted. Oysters were placed in 18 tanks in a fully crossed temperature (25°C, 32°C) by salinity (1, 5, and 15) study with three replicates, and repeated at least twice for each oyster size class. Regardless of temperature, seed and market oysters held in low salinity tanks (salinity 1) experienced 100% mortality within 7 days. In contrast, at salinity 5, temperature significantly affected mortality; oysters in all size classes experienced greater than 50%mortality at 32°C and less than 40%mortality at 25°C. At the highest salinity tested (15), only market-sized oysters held at 32°C experienced significant mortality (>60%). These studies demonstrate that high water temperatures (>30°C) and low salinities (<5) negatively impact oyster growth and survival differentially and that high temperatures alone may negatively impact market-sized oysters. It is critical to understand the potential impacts of climate and anthropogenic changes on oyster resources to better adapt and manage for long-term sustainability.

Water quality assessment by means of HFNI valvometry and high-frequency data modeling.

PubMed

Sow, Mohamedou; Durrieu, Gilles; Briollais, Laurent; Ciret, Pierre; Massabuau, Jean-Charles

2011-11-01

The high-frequency measurements of valve activity in bivalves (e.g., valvometry) over a long period of time and in various environmental conditions allow a very accurate study of their behaviors as well as a global analysis of possible perturbations due to the environment. Valvometry uses the bivalve's ability to close its shell when exposed to a contaminant or other abnormal environmental conditions as an alarm to indicate possible perturbations in the environment. The modeling of such high-frequency serial valvometry data is statistically challenging, and here, a nonparametric approach based on kernel estimation is proposed. This method has the advantage of summarizing complex data into a simple density profile obtained from each animal at every 24-h period to ultimately make inference about time effect and external conditions on this profile. The statistical properties of the estimator are presented. Through an application to a sample of 16 oysters living in the Bay of Arcachon (France), we demonstrate that this method can be used to first estimate the normal biological rhythms of permanently immersed oysters and second to detect perturbations of these rhythms due to changes in their environment. We anticipate that this approach could have an important contribution to the survey of aquatic systems.

Tea waste: an effective and economic substrate for oyster mushroom cultivation.

PubMed

Yang, Doudou; Liang, Jin; Wang, Yunsheng; Sun, Feng; Tao, Hong; Xu, Qiang; Zhang, Liang; Zhang, Zhengzhu; Ho, Chi-Tang; Wan, Xiaochun

2016-01-30

Tea waste is the residue that remains after tea leaves have been extracted by hot water to obtain water-soluble components. The waste contains a re-usable energy substrate and nutrients which may pollute the environment if they are not dealt with appropriately. Other agricultural wastes have been widely studied as substrates for cultivating mushrooms. In the present study, we cultivated oyster mushroom using tea waste as substrate. To study the feasibility of re-using it, tea waste was added to the substrate at different ratios in different experimental groups. Three mushroom strains (39, 71 and YOU) were compared and evaluated. Mycelia growth rate, yield, biological efficiency and growth duration were measured. Substrates with different tea waste ratios showed different growth and yield performance. The substrate containing 40-60% of tea waste resulted in the highest yield. Tea waste could be used as an effective and economic substrate for oyster mushroom cultivation. This study also provided a useful way of dealing with massive amounts of tea waste. © 2015 Society of Chemical Industry.

New Hampshire recreational oyster harvesters: profile, perceptions, and attitudes

Treesearch

Alberto B. Manalo; Bruce E. Lindsay; George E. Frick

1992-01-01

A survey of holders of a 1989 New Hampshire oyster-harvesting license revealed that recreational oyster harvesting is pursued mostly by older men. The 1988 closing of some parts of Great Bay to oyster harvesting resulted in license holders' taking one fewer trip and taking about six minutes longer to harvest one bushel of oysters in 1989. The average annual...

Investigations of Salmonella enterica serovar newport infections of oysters by using immunohistochemistry and knockout mutagenesis.

PubMed

Morrison, Christopher M; Dial, Sharon M; Day, William A; Joens, Lynn A

2012-04-01

The consumption of raw oysters is an important risk factor in the acquisition of food-borne disease, with Salmonella being one of a number of pathogens that have been found in market oysters. Previous work by our lab found that Salmonella was capable of surviving in oysters for over 2 months under laboratory conditions, and this study sought to further investigate Salmonella's tissue affinity and mechanism of persistence within the oysters. Immunohistochemistry was used to show that Salmonella was capable of breaching the epithelial barriers, infecting the deeper connective tissues of the oysters, and evading destruction by the oysters' phagocytic hemocytes. To further investigate the mechanism of these infections, genes vital to the function of Salmonella's two main type III secretion systems were disrupted and the survivability of these knockout mutants within oysters was assayed. When the Salmonella pathogenicity island 1 and 2 mutant strains were exposed to oysters, there were no detectable deficiencies in their abilities to survive, suggesting that Salmonella's long-term infection of oysters does not rely upon these two important pathogenicity islands and must be due to some other, currently unknown, mechanism.

Exploring spatial and temporal variations of cadmium concentrations in pacific oysters from british columbia.

PubMed

Feng, Cindy Xin; Cao, Jiguo; Bendell, Leah

2011-09-01

Oysters from the Pacific Northwest coast of British Columbia, Canada, contain high levels of cadmium, in some cases exceeding some international food safety guidelines. A primary goal of this article is the investigation of the spatial and temporal variation in cadmium concentrations for oysters sampled from coastal British Columbia. Such information is important so that recommendations can be made as to where and when oysters can be cultured such that accumulation of cadmium within these oysters is minimized. Some modern statistical methods are applied to achieve this goal, including monotone spline smoothing, functional principal component analysis, and semi-parametric additive modeling. Oyster growth rates are estimated as the first derivatives of the monotone smoothing growth curves. Some important patterns in cadmium accumulation by oysters are observed. For example, most inland regions tend to have a higher level of cadmium concentration than most coastal regions, so more caution needs to be taken for shellfish aquaculture practices occurring in the inland regions. The semi-parametric additive modeling shows that oyster cadmium concentration decreases with oyster length, and oysters sampled at 7 m have higher average cadmium concentration than those sampled at 1 m. © 2010, The International Biometric Society.

Investigations of Salmonella enterica Serovar Newport Infections of Oysters by Using Immunohistochemistry and Knockout Mutagenesis

PubMed Central

Morrison, Christopher M.; Dial, Sharon M.; Day, William A.

2012-01-01

The consumption of raw oysters is an important risk factor in the acquisition of food-borne disease, with Salmonella being one of a number of pathogens that have been found in market oysters. Previous work by our lab found that Salmonella was capable of surviving in oysters for over 2 months under laboratory conditions, and this study sought to further investigate Salmonella's tissue affinity and mechanism of persistence within the oysters. Immunohistochemistry was used to show that Salmonella was capable of breaching the epithelial barriers, infecting the deeper connective tissues of the oysters, and evading destruction by the oysters' phagocytic hemocytes. To further investigate the mechanism of these infections, genes vital to the function of Salmonella's two main type III secretion systems were disrupted and the survivability of these knockout mutants within oysters was assayed. When the Salmonella pathogenicity island 1 and 2 mutant strains were exposed to oysters, there were no detectable deficiencies in their abilities to survive, suggesting that Salmonella's long-term infection of oysters does not rely upon these two important pathogenicity islands and must be due to some other, currently unknown, mechanism. PMID:22307286

Bacterial microbiota profile in gills of modified atmosphere-packaged oysters stored at 4 °C.

PubMed

Chen, Huibin; Wang, Meiying; Lin, Xiangzhi; Shi, Caihua; Liu, Zhiyu

2017-02-01

As filter-feeding bivalves, oysters can accumulate microorganisms into their gills, causing spoilage and potential safety issues. This study aims to investigate the changes in the gill microbiota of oysters packed under air and modified atmospheres (MAs, 50% CO 2 : 50% N 2 , 70% CO 2 : 30% O 2 , and 50% CO 2 : 50% O 2 ) during storage at 4 °C. The diversity of bacterial microbiota in oyster gills was profiled through polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis on the 16S rRNA gene V3 region to describe the variation during the entire storage period. The DGGE profile revealed high bacterial diversity in the air- and MA-packaged oyster gills, and the spoilage bacterial microbiota varied in the MA-packaged oyster gills. Results indicated that CO 2 :O 2 (70%:30%) was suitable for oyster MA packaging and that high bacterial loads in oyster gills need to be considered during storage. In addition, Lactobacillus and Lactococcus species were found to grow dominantly in fresh oyster gills under MA packaging, which supports the potential application of MA packaging for oyster storage. Copyright © 2016 Elsevier Ltd. All rights reserved.

Reproductive responses and detoxification of estuarine oyster Crassostrea hongkongensis under metal stress: a seasonal study.

PubMed

Weng, Nanyan; Wang, Wen-Xiong

2015-03-03

Understanding the impacts of metal stress on the reproduction of dominant species, such as oysters, in seriously contaminated estuarine environments has great ecological implications. In the present study, the reproductive conditions were examined monthly for 1 year in oysters Crassostrea hongkongensis from a heavily metal-contaminated site (Baijiao, mainly by Cu and Zn) in the Jiulong River estuary and a relatively clean nearby estuary (Jiuzhen). Oysters sampled in the contaminated site showed a delayed gametogenesis, a relatively shorter spawning period, and a lower gonad condition index in comparison to the oysters sampled in the reference site. In particular, we found that the proportion of females increased significantly in the contaminated oysters, which provided the first evidence that the feminization in wild oyster populations could be related to trace metal pollution. Additionally, the potential detoxification mechanism of trace metals in oysters was also investigated. Compartmentalization of trace metals in membrane-limited vesicles in hemocytes could be an important detoxification mechanism for the contaminated oysters. Our findings indicated that the long-term metal exposure may greatly influence the reproduction of the oysters and finally affect the recruitment and population of this species.

Numerical and experimental study on buckling and postbuckling behavior of cracked cylindrical shells

NASA Astrophysics Data System (ADS)

Saemi, J.; Sedighi, M.; Shariati, M.

2015-09-01

The effect of crack on load-bearing capacity and buckling behavior of cylindrical shells is an essential consideration in their design. In this paper, experimental and numerical buckling analysis of steel cylindrical shells of various lengths and diameters with cracks have been studied using the finite element method, and the effect of crack position, crack orientation and the crack length-to-cylindrical shell perimeter ( λ = a/(2 πr)) and shell length-to-diameter ( L/ D) ratios on the buckling and post-buckling behavior of cylindrical shells has been investigated. For several specimens, buckling test was performed using an INSTRON 8802 servo hydraulic machine, and the results of experimental tests were compared to numerical results. A very good correlation was observed between numerical simulation and experimental results. Finally, based on the experimental and numerical results, sensitivity of the buckling load to the shell length, crack length and orientation has also been investigated.

Immune and stress responses in oysters with insights on adaptation.

PubMed

Guo, Ximing; He, Yan; Zhang, Linlin; Lelong, Christophe; Jouaux, Aude

2015-09-01

Oysters are representative bivalve molluscs that are widely distributed in world oceans. As successful colonizers of estuaries and intertidal zones, oysters are remarkably resilient against harsh environmental conditions including wide fluctuations in temperature and salinity as well as prolonged air exposure. Oysters have no adaptive immunity but can thrive in microbe-rich estuaries as filter-feeders. These unique adaptations make oysters interesting models to study the evolution of host-defense systems. Recent advances in genomic studies including sequencing of the oyster genome have provided insights into oyster's immune and stress responses underlying their amazing resilience. Studies show that the oyster genomes are highly polymorphic and complex, which may be key to their resilience. The oyster genome has a large gene repertoire that is enriched for immune and stress response genes. Thousands of genes are involved in oyster's immune and stress responses, through complex interactions, with many gene families expanded showing high sequence, structural and functional diversity. The high diversity of immune receptors and effectors may provide oysters with enhanced specificity in immune recognition and response to cope with diverse pathogens in the absence of adaptive immunity. Some members of expanded immune gene families have diverged to function at different temperatures and salinities or assumed new roles in abiotic stress response. Most canonical innate immunity pathways are conserved in oysters and supported by a large number of diverse and often novel genes. The great diversity in immune and stress response genes exhibited by expanded gene families as well as high sequence and structural polymorphisms may be central to oyster's adaptation to highly stressful and widely changing environments. Copyright © 2015 Elsevier Ltd. All rights reserved.

Oysters and Oyster Reef Communities in Florida.

ERIC Educational Resources Information Center

Knight, Jean; Bly, Joe

1989-01-01

The habitat, life history, feeding, classification, anatomy and pearl production of the American oyster (Crassostrea virginica) are presented. A list of other oyster reef inhabitants and predators is provided. Harvest and habitat loss are discussed. (CW)

Long-term spatiotemporal trends and health risk assessment of oyster arsenic levels in coastal waters of northern South China Sea.

PubMed

Wang, Xuefeng; Wang, Lifei; Jia, Xiaoping; Jackson, Donald A

2017-09-01

Long-term spatiotemporal trends and health risk assessment of oyster arsenic levels in the coastal waters of northern South China Sea were investigated in order to help improve the quality and safety control and sustainable aquaculture for mollusks in China. Cultured oysters (Crassostrea rivularis) collected from the waters of 23 bays, harbors, and estuaries along the coast of northern South China Sea from 1989 to 2012 were examined for spatial patterns and long-term temporal trends of oyster arsenic levels. Single-factor index and health risk assessment were used to quantify arsenic exposure to human health through oyster consumption. Overall, arsenic was detected in 97.4% of the oyster samples, and oyster arsenic levels were non-detectable-2.51 mg/kg with an average of 0.63 ± 0.54 mg/kg. Oyster arsenic levels in the coastal waters of northern South China Sea showed an overall decline from 1989 to 2012, remained relatively low since 2005, and slightly increased after 2007. Oyster arsenic levels in Guangdong coastal waters were much higher with more variation than in Guangxi and Hainan coastal waters, and the long-term trends of oyster arsenic levels in Guangdong coastal waters dominated the overall trends of oyster arsenic levels in the coastal waters of northern South China Sea. Within Guangdong Province, oyster arsenic levels were highest in east Guangdong coastal waters, followed by the Pearl River estuary and west Guangdong coastal waters. Single-factor index ranged between 0.27 and 0.97, and average health risk coefficient was 3.85 × 10 -5 , both suggesting that oyster arsenic levels in northern South China Sea are within the safe range for human consumption. However, long-term attention should be given to seafood market monitoring in China and the risk of arsenic exposure to human health through oyster consumption.

Application of oysters as useful concentration indicators to evaluate the fate of xenoestrogenic alkylphenols along the western coastal areas of Taiwan

NASA Astrophysics Data System (ADS)

Ding, Wanghsien

2016-04-01

The oyster is an important aquacultural species in Taiwan. Since oysters naturally inhabit shelves near the coast, samples from particular "oyster cultural sites" can be applied to evaluate the pollution levels of segments of coastal water. Insufficient wastewater treatment has caused untreated wastewaters to flow into rivers, and hence, into oyster cultural areas in estuaries as well as shallow coastal waters. Therefore, the concentration of pollutants in the oysters can be used as concentration indicators to evaluate the fate of the pollutants on the western coastal areas of Taiwan. In this study, xenoestrogenic alkylphenols were determined in oyster samples by extractive steam distillation prior to their determination by gas chromatography - mass spectrometry. The results show that a group of 4-nonylphenol isomers (4-NPs) were ubiquitous in oysters with concentration levels ranging from 23 to 3370 ng/g (wet weight). The concentrations of 4-NPs varied with different levels of 4-NPs found across unrelated estuaries water samples, and higher level of 4-NPs in water samples caused higher concentration of 4-NPs found in oyster tissue samples. Moreover, at the same oyster sites mentioned previously, the levels of 4-NPs in oysters decreased significantly after the year 2008. This drop in 4-NPs level can be attributed to environmental regulations that banned 4-NPs as additives in household cleaning agents since January 2008 in Taiwan. Due to the mentioned reasons, oysters are concluded to be useful organic pollutant concentration indicators in marine environments.

A norovirus outbreak associated with consumption of NSW oysters: implications for quality assurance systems.

PubMed

Huppatz, Clare; Munnoch, Sally A; Worgan, Tory; Merritt, Tony D; Dalton, Craig; Kelly, Paul M; Durrheim, David N

2008-03-01

Norovirus is a common cause of gastroenteritis outbreaks associated with raw shellfish consumption. In Australia there have been several reports of norovirus outbreaks associated with oysters despite the application of regulatory measures recommended by Food Standards Australia New Zealand. This study describes an outbreak of norovirus gastroenteritis following the consumption of New South Wales oysters. In September 2007, OzFoodNet conducted a cohort study of a gastroenteritis outbreak amongst people that had dined at a Port Macquarie restaurant. Illness was strongly associated with oyster consumption, with all cases having eaten oysters from the same lease (RR undefined, p < 0.0001). Norovirus was detected in a faecal specimen. Although no pathogen was identified during the environmental investigation, the source oyster lease had been closed just prior to harvesting due to sewage contamination. Australian quality assurance programs do not routinely test oysters for viral contamination that pose a risk to human health. It is recommended that the feasibility of testing oysters for norovirus, particularly after known faecal contamination of oyster leases, be assessed.

Seasonal changes in mRNA encoding for cell stress markers in the oyster Crassostrea gigas exposed to radioactive discharges in their natural environment.

PubMed

Farcy, Emilie; Voiseux, Claire; Lebel, Jean-Marc; Fievet, Bruno

2007-03-15

The North Cotentin area (Normandy, France) hosts several nuclear facilities among which the AREVA reprocessing plant of La Hague is responsible for controlled discharges of liquid radioactive wastes into the marine environment. The resulting increase in radioactivity is very small compared to natural radioactivity. However, concerns about environment protection prompted the scientific community to focus on the effects of the chronic exposure to low concentrations of radionuclides in non-human biota. This study contributes to the evaluation of the possible impact of radioactive discharges on the oyster Crassostrea gigas in the field. Real-time polymerase chain reaction was used to quantify the expression levels of genes involved in cell stress in the oyster. They included members of the heat shock protein family (Hsp70, Hsc72, Hsp90), superoxide dismutase (SOD) and metallothionein (MT). Times series measurements were built from periodic samplings in the natural environment in order to characterize the natural variability as well as possible seasonal fluctuations. The genes studied exhibited a general seasonal expression pattern with a peak value in winter. The data inversely correlated with seawater temperature and the nature of the relationship between gene expression and temperature is discussed. In parallel, oysters were collected in four locations on the French shores, exposed or not to radioactive liquid wastes from the nuclear facilities hosted in the North Cotentin. The comparison of data obtained in the reference location on the Atlantic coast (not exposed) and data from oysters of the English Channel (exposed) gave no evidence for any statistical difference. However, because of the complexity of the natural environment, we cannot rule out the possibility that other parameters may have masked the impact of radioactive discharges. This dense set of data is a basis for the use of the expression levels of those genes as biomarkers to address the question of the possible effects of chronic exposure of the oyster to low concentrations of radionuclides in controlled laboratory experimental conditions.

Pyrosequencing Analysis of Norovirus Genogroup II Distribution in Sewage and Oysters: First Detection of GII.17 Kawasaki 2014 in Oysters.

PubMed

Pu, Jian; Kazama, Shinobu; Miura, Takayuki; Azraini, Nabila Dhyan; Konta, Yoshimitsu; Ito, Hiroaki; Ueki, You; Cahyaningrum, Ermaya Eka; Omura, Tatsuo; Watanabe, Toru

2016-12-01

Norovirus GII.3, GII.4, and GII.17 were detected using pyrosequencing in sewage and oysters in January and February 2015, in Japan. The strains in sewage and oyster samples were genetically identical or similar, predominant strains belonging to GII.17 Kawasaki 2014 lineage. This is the first report of GII.17 Kawasaki 2014 in oysters.

A Spirochaete is suggested as the causative agent of Akoya oyster disease by metagenomic analysis

PubMed Central

Yasuike, Motoshige; Fujiwara, Atushi; Nakamura, Yoji; Takano, Tomokazu; Takeuchi, Takeshi; Satoh, Noriyuki; Adachi, Yoshikazu; Tsuchihashi, Yasushi; Aoki, Hideo; Odawara, Kazushi; Iwanaga, Shunsuke; Kurita, Jun; Kamaishi, Takashi; Nakayasu, Chihaya

2017-01-01

Mass mortality that is acompanied by reddish browning of the soft tissues has been occurring in cultured pearl oyster, Pinctada fucata martensii. The disease is called Akoya oyster disease (AOD). Although spreading pattern of the disease and transmission experiments suggest that the disease is infectious, the causative agent has not yet been identified. We used shotgun and 16S rRNA-based metagenomic analysis to identify genes that are present specifically in affected oysters. The genes found only in diseased oysters were mostly bacterial origin, suggesting that the causative agent was a bacterial pathogen. This hypothesis was supported by the inhibition of AOD development in naïve oysters injected with the hemolymph of diseased animals followed immediately with penicillin bath-administration. Further analyses of the hemolymph and mantle specifically and universally detected genes of bacteria that belong to phylum Spirochaetes in diseased pearl oysters but not in healthy oysters. By in situ hybridization or immunostaining, a Brachyspira-like bacterium was observed in the smears of hemolymph from affected oysters, but not from healthy oysters. Phylogenetic analysis using 16S rRNA sequences showed that the presumptive causative bacterium was outside of but most closely related to family Brachyspiraceae. We propose ‘Candidatus Maribrachyspira akoyae’ gen. nov, sp nov., for this bacterium. PMID:28771537

Mercury, cadmium and arsenic contents of calcium dietary supplements.

PubMed

Kim, Meehye

2004-08-01

The cadmium (Cd) and arsenic (As) contents of calcium (Ca) supplements available on the Korean market were determined by a graphite furnace atomic absorption spectrometer using Zeeman background correction and peak area mode after microwave digestion. The mercury (Hg) content of the supplements was measured using an Hg analyser. Recoveries ranged from 92 to 98% for Hg, Cd and As analyses. Fifty-five brands of Ca supplements were classified into seven categories based on the major composite: bone, milk, oyster/clam shell, egg shell, algae, shark cartilage and chelated. The means of Hg, Cd and As in Ca supplements were 0.01, 0.02, and 0.48 mg kg(-1), respectively. Ca supplements made of shark cartilage had the highest means of Hg (0.06 mg kg(-1)) and Cd (0.13 mg kg(-1)). The mean daily intakes of Hg and Cd from the supplement were estimated as about 0.1-0.2 microg, with both contributing less than 0.4% of provisional tolerable daily intakes set by the Food and Agricultural Organization/World Health Organization Joint Food Additive and Contaminants Committee.

The bivalve Placuna (Indoplacuna) miocenica from the Middle Miocene of Siwa Oasis, Western Desert of Egypt: Systematic paleontology, paleoecology, and taphonomic implications

NASA Astrophysics Data System (ADS)

El-Sabbagh, Ahmed M.; El Hedeny, Magdy M.; Rashwan, Mohammed A.; Abdel Aal, Abdel Aal A.

2016-04-01

The present study investigated the epifaunal, free lying bivalve Placuna (Indoplacuna) miocenica (Fuchs, 1883) encountered in the Middle Miocene Marmarica Formation of Siwa Oasis, Western Desert, Egypt, in terms of systematic paleontology, paleoecology and taphonomy. Well to moderately preserved shells of this species were collected from three sections. They have been found embedded in sandy, marly and chalky limestones. Although they are extremely thin and fragile, they occurred as complete disarticulated and articulated valves. Specimens of P. (I.) miocenica are highly accumulated in the north Siwa section forming a coquinoid band (30 cm thick). In addition, they are generally distributed sporadically in different stratigraphic levels within the three studied sequences. Taphonomic observations indicated that these shells were affected by encrustation, bioerosion, disarticulation, fragmentation and abrasion. Moreover, valves of this species suffered minor chipping along their fragile margins. The occurrence of the studied species associated with oysters and other benthic faunal assemblages within carbonate sediments revealed shallow, low energy, warm and intertidal environments with periods of relatively agitated conditions.

Differential proteomic responses of selectively bred and wild-type Sydney rock oyster populations exposed to elevated CO2.

PubMed

Thompson, E L; O'Connor, W; Parker, L; Ross, P; Raftos, D A

2015-03-01

Previous work suggests that larvae from Sydney rock oysters that have been selectively bred for fast growth and disease resistance are more resilient to the impacts of ocean acidification than nonselected, wild-type oysters. In this study, we used proteomics to investigate the molecular differences between oyster populations in adult Sydney rock oysters and to identify whether these form the basis for observations seen in larvae. Adult oysters from a selective breeding line (B2) and nonselected wild types (WT) were exposed for 4 weeks to elevated pCO2 (856 μatm) before their proteomes were compared to those of oysters held under ambient conditions (375 μatm pCO2 ). Exposure to elevated pCO2 resulted in substantial changes in the proteomes of oysters from both the selectively bred and wild-type populations. When biological functions were assigned, these differential proteins fell into five broad, potentially interrelated categories of subcellular functions, in both oyster populations. These functional categories were energy production, cellular stress responses, the cytoskeleton, protein synthesis and cell signalling. In the wild-type population, proteins were predominantly upregulated. However, unexpectedly, these cellular systems were downregulated in the selectively bred oyster population, indicating cellular dysfunction. We argue that this reflects a trade-off, whereby an adaptive capacity for enhanced mitochondrial energy production in the selectively bred population may help to protect larvae from the effects of elevated CO2 , whilst being deleterious to adult oysters. © 2015 John Wiley & Sons Ltd.

Effect of linear alkylbenzene mixtures and sanitary sewage in biochemical and molecular responses in pacific oyster Crassostrea gigas.

PubMed

Flores-Nunes, Fabrício; Mattos, Jacó J; Zacchi, Flávia L; Serrano, Miguel A S; Piazza, Clei E; Sasaki, Silvio T; Taniguchi, Satie; Bicego, Márcia C; Melo, Cláudio M R; Bainy, Afonso C D

2015-11-01

Urban effluents are rich in nutrients, organic matter, pharmaceuticals and personal care products (PPCPs), pesticides, hydrocarbons, surfactants, and others. Previous studies have shown that oysters Crassostrea gigas accumulate significant levels of linear alkylbenzenes (LABs) in sanitary sewage contaminated sites, but there is little information about its toxicological effects in marine bivalves. The aim of this study was to analyze the transcription of genes in two tissues of C. gigas exposed for 12, 24, and 36 h to LABs or sanitary sewage. Likewise, the activity of antioxidant and biotransformation enzymes was measured in oysters exposed for 36 h in all groups. Oysters exposed to LABs and oysters exposed to sanitary sewage showed different patterns of transcriptional responses. LAB-exposed oysters showed lower level of biological responses than the oysters exposed to sanitary sewage. Despite the ability of the oyster C. gigas to accumulate LABs (28-fold), the data indicate that these contaminants are not the cause for the transcriptional responses observed in oysters exposed to sanitary sewage. Possibly, the biological changes observed in the sanitary sewage-exposed oysters are associated with the presence of other contaminants, which might have caused synergistic, additive, or antagonistic effects. The results show that FABP-like and GST-ω-like messenger RNAs (mRNAs) have a rapid response in tissues of oyster C. gigas exposed to sanitary sewage, suggesting a possible protective response and a role in maintaining homeostasis of these organisms.

Effects of Antifouling Biocides on Molecular and Biochemical Defense System in the Gill of the Pacific Oyster Crassostrea gigas.

PubMed

Park, Mi Seon; Kim, Young Dae; Kim, Bo-Mi; Kim, Youn-Jung; Kim, Jang Kyun; Rhee, Jae-Sung

2016-01-01

Antifouling biocides such as organotin compounds and their alternatives are potent toxicants in marine ecosystems. In this study, we employed several molecular and biochemical response systems of the Pacific oyster Crassostrea gigas to understand a potential mode of action of antifouling biocides (i.e. tributyltin (TBT), diuron and irgarol) after exposure to different concentrations (0.01, 0.1, and 1 μg L-1) for 96 h. As a result, all the three antifouling biocides strongly induced the antioxidant defense system. TBT reduced both enzymatic activity and mRNA expression of Na+/K+-ATPase and acetylcholinesterase (AChE). Lower levels of both Na+/K+-ATPase activity and AChE mRNA expression were observed in the diuron-exposed oysters compared to the control, while the irgarol treatment reduced only the transcriptional expression of AChE gene. We also analyzed transcript profile of heat shock protein (Hsp) superfamily in same experimental conditions. All antifouling biocides tested in this study significantly modulated mRNA expression of Hsp superfamily with strong induction of Hsp70 family. Taken together, overall results indicate that representative organotin TBT and alternatives have potential hazardous effects on the gill of C. gigas within relatively short time period. Our results also suggest that analyzing a series of molecular and biochemical parameters can be a way of understanding and uncovering the mode of action of emerging antifouling biocides. In particular, it was revealed that Pacific oysters have different sensitivities depend on the antifouling biocides.

Factors affecting the uptake and retention of Vibrio vulnificus in oysters.

PubMed

Froelich, Brett A; Noble, Rachel T

2014-12-01

Vibrio 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 examined in vitro by placing oysters in seawater amended with V. 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 using in vitro oyster studies and a multiyear in situ case 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 of Vibrio is 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 of Vibrio but 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. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Oyster resource zones of the Barataria and Terrebonne estuaries of Louisiana

USGS Publications Warehouse

Melancon, E.; Soniat, T.; Cheramie, V.; Dugas, R.; Barras, J.; Lagarde, M.

1998-01-01

A 1:100,000 scale map delineating the subtidal oyster resource zones within the Barataria and Terrebonne estuaries was developed. Strategies to accomplish the task included interviews with Louisiana oystermen and state biologists to develop a draft map, field sampling to document oyster (Crassostrea virginica), Dermo (Perkinsus marinus), and oyster drill (Stramonita haemastoma) abundances, use of historical salinity data to aid in map verification, and public meetings to allow comment on a draft before final map preparation. Four oyster resource zones were delineated on the final map: a dry zone where subtidal oysters may be found when salinities increase, a wet zone where subtidal oysters may be found when salinities are suppressed, a wet-dry zone where subtidal oysters may be consistently found due to favorable salinities, and a high-salinity zone where natural oyster populations are predominantly found in intertidal and shallow waters. The dry zone is largely coincident with the brackish-marsh habitat, with some intermediate-type marsh. The wet-dry zone is found at the interface of the brackish and saline marshes, but extends further seaward than up-estuary. The wet zone and the high salinity zones are areas of mostly open water fringed by salt marshes. The dry zone encompasses 91,775 hectares, of which 48,788 hectares are water (53%). The wet zone encompasses 83,525 hectares, of which 66,958 hectares are water (80%). The wet-dry zone encompasses 171,893 hectares, of which 104,733 hectares are water (61%). The high salinity zone encompasses 125,705 hectares, of which 113,369 hectares are water (90%). There is a clear trend of increasing water habitat in the four zones over the past 30 years, and oysters are now cultivated on bottoms that were once marsh. The map should be useful in managing the effects upon oysters of freshwater diversions into the estuaries. It provides a pre-diversion record of the location of oyster resource zones and should prove helpful in the seaward relocation of oysters leases.

Hemolymph chemistry and histopathological changes in Pacific oysters (Crassostrea gigas) in response to low salinity stress.

PubMed

Knowles, Graeme; Handlinger, Judith; Jones, Brian; Moltschaniwskyj, Natalie

2014-09-01

This study described seasonal differences in the histopathological and hemolymph chemistry changes in different family lines of Pacific oysters, Crassostrea gigas, in response to the stress of an abrupt change to low salinity, and mechanical grading. The most significant changes in pallial cavity salinity, hemolymph chemistry and histopathological findings occurred in summer at low salinity. In summer (water temperature 18°C) at low salinity, 9 (25.7% of full salinity), the mean pallial cavity salinity in oysters at day 3 was 19.8±1.6 (SE) and day 10 was 22.8±1.6 (SE) lower than oysters at salinity 35. Associated with this fall in pallial cavity salinity, mean hemolymph sodium for oysters at salinity 9 on day 3 and 10 were 297.2mmol/L±20(SE) and 350.4mmol/L±21.3(SE) lower than oysters at salinity 35. Similarly mean hemolymph potassium in oysters held at salinity 9 at day 3 and 10 were 5.6mmol/L±0.6(SE) and 7.9mmol/L±0.6 (SE) lower than oysters at salinity 35. These oysters at low salinity had expanded intercellular spaces and significant intracytoplasmic vacuolation distending the cytoplasm of epithelial cells in the alimentary tract and kidney and hemocyte infiltrate (diapedesis) within the alimentary tract wall. In contrast, in winter (water temperature 8°C) oyster mean pallial cavity salinity only fell at day 10 and this was by 6.0±0.6 (SE) compared to that of oysters at salinity 35. There were limited histopathological changes (expanded intercellular spaces and moderate intracytoplasmic vacuolation of renal epithelial cells) in these oysters at day 10 in low salinity. Mechanical grading and family line did not influence the oyster response to sudden low salinity. These findings provide additional information for interpretation of non-lethal, histopathological changes associated with temperature and salinity variation. Copyright © 2014 Elsevier Inc. All rights reserved.

Integrated application of transcriptomics and metabolomics provides insights into glycogen content regulation in the Pacific oyster Crassostrea gigas.

PubMed

Li, Busu; Song, Kai; Meng, Jie; Li, Li; Zhang, Guofan

2017-09-11

The Pacific oyster Crassostrea gigas is an important marine fishery resource, which contains high levels of glycogen that contributes to the flavor and the quality of the oyster. However, little is known about the molecular and chemical mechanisms underlying glycogen content differences in Pacific oysters. Using a homogeneous cultured Pacific oyster family, we explored these regulatory networks at the level of the metabolome and the transcriptome. Oysters with the highest and lowest natural glycogen content were selected for differential transcriptome and metabolome analysis. We identified 1888 differentially-expressed genes, seventy-five differentially-abundant metabolites, which are part of twenty-seven signaling pathways that were enriched using an integrated analysis of the interaction between the differentially-expressed genes and the differentially-abundant metabolites. Based on these results, we found that a high expression of carnitine O-palmitoyltransferase 2 (CPT2), indicative of increased fatty acid degradation, is associated with a lower glycogen content. Together, a high level of expression of phosphoenolpyruvate carboxykinase (PEPCK), and high levels of glucogenic amino acids likely underlie the increased glycogen production in high-glycogen oysters. In addition, the higher levels of the glycolytic enzymes hexokinase (HK) and pyruvate kinase (PK), as well as of the TCA cycle enzymes malate dehydrogenase (MDH) and pyruvate carboxylase (PYC), imply that there is a concomitant up-regulation of energy metabolism in high-glycogen oysters. High-glycogen oysters also appeared to have an increased ability to cope with stress, since the levels of the antioxidant glutathione peroxidase enzyme 5 (GPX5) gene were also increased. Our results suggest that amino acids and free fatty acids are closely related to glycogen content in oysters. In addition, oysters with a high glycogen content have a greater energy production capacity and a greater ability to cope with stress. These findings will not only provide insights into the molecular mechanisms underlying oyster quality, but also promote research into the molecular breeding of oysters.

Real-time PCR quantification of Vibrio parahaemolyticus in oysters using an alternative matrix.

PubMed

Kaufman, G E; Blackstone, G M; Vickery, M C L; Bej, A K; Bowers, J; Bowen, Michael D; Meyer, Richard F; DePaola, A

2004-11-01

This study examined the relationship between levels of total Vibrio parahaemolyticus found in oyster tissues and mantle fluid with the goal of using mantle fluid as a template matrix in a new quantitative real-time PCR assay targeting the thermolabile hemolysin (tlh) gene for the enumeration of total V. parahaemolyticus in oysters. Oysters were collected near Mobile Bay, Ala., in June, July, and September and tested immediately after collection and storage at 26 degrees C for 24 h. Initial experiments using DNA colony hybridization targeting tlh demonstrated that natural V. parahaemolyticus levels in the mantle fluid of individual oysters were strongly correlated (r = 0.85, P < 0.05) with the levels found in their tissues. When known quantities of cultured V. parahaemolyticus cells were added to real-time PCR reactions that contained mantle fluid and oyster tissue matrices separately pooled from multiple oysters, a strong linear correlation was observed between the real-time PCR cycle threshold and the log concentration of cells inoculated into each PCR reaction (mantle fluid: r = 0.98, P < 0.05; and oyster: r = 0.99, P < 0.05). However, the mantle fluid exhibited less inhibition of the PCR amplification than the homogenized oyster tissue. Analysis of natural V. parahaemolyticus populations in mantle fluids using both colony hybridization and real-time PCR demonstrated a significant (P < 0.05) but reduced correlation (r = -0.48) between the two methods. Reductions in the efficiency of the real-time PCR that resulted from low population densities of V. parahaemolyticus and PCR inhibitors present in the mantle fluid of some oysters (with significant oyster-to-oyster variation) contributed to the reduction in correlation between the methods that was observed when testing natural V. parahaemolyticus populations. The V. parahaemolyticus-specific real-time PCR assay used for this study could estimate elevated V. parahaemolyticus levels in oyster mantle fluid within 1 h from sampling time.

Faunal community use of enhanced and natural oyster reefs in Delaware Bay: A field study and classroom inquiry

NASA Astrophysics Data System (ADS)

Paterno, Jenny L.

In addition to its value as a fisheries resource, the eastern oyster Crassostrea virginica, is a reef building, cornerstone species that provides ecosystem services to the environment. Oysters provide habitat for associated resident and transient species. With widespread declines in oyster populations, restoration efforts have focused on improving oyster stocks and enhancing the ecosystem services they provide. Community-based oyster restoration programs engage the public and local community in planning, construction and/or monitoring of restoration projects. Since 2007, a K-12 student centered community-based restoration venture, Project PORTS, Promoting Oyster Restoration Through Schools, has been working to educate students, promote stewardship values, and enhance oyster habitat in the Delaware Bay. The overarching goals of the present study were to (1) assess fish and macroinvertebrate utilization on the Project PORTS community-created, subtidal, low-relief oyster restoration area in the Delaware Bay, and (2) convert the data collected into a STEM (Science, Technology, Engineering and Mathematics) activity that can be implemented in the classroom. I examined six subtidal natural oyster reefs of varying oyster densities and one community-based restoration reef as habitat for fishes and invertebrates. Sampling methods on these low-relief reefs consisted of otter trawl tows and benthic habitat tray collections. Results revealed that the enhancement area supported a diverse faunal community consistent with nearby, natural oyster habitats. Data collected during the field study were then transformed into an educational lesson plan, "One Fish, Two Fish-Assessing Habitat Value of Restored Oyster Reefs", that fulfilled national and state (NJ) curriculum standards. The lesson was piloted in a middle school classroom and student learning was evaluated through summative assessments pre and post-participation in the activity. Results of the assessments indicated that students made strong gains in knowledge of oyster ecology and improved analytical skills by graphing data. This dual interest study demonstrated that a novel education program with a local, real-world connection positively enhanced crucial estuarine habitat while expanding STEM knowledge and skills of participating students.

Denman Island disease (causative agent Mikrocytos mackini) in a new host, Kumamoto oysters Crassostrea sikamea.

PubMed

Elston, Ralph A; Moore, James; Abbott, Cathryn L

2012-12-03

Mikrocytos mackini, causative agent of Denman Island disease in Pacific oysters Crassostrea gigas and other oyster species, was found in 2011 in a previously unreported host, the Kumamoto oyster C. sikamea, in Humboldt Bay, California, USA. The detection was also the first reported finding of M. mackini in California. Prevalence was estimated as high as approximately 27% from pooled samples analyzed by PCR. Higher prevalence appeared related to longer residence time in the bay and somewhat colder than typical winter seawater temperatures. No M. mackini was detected in Humboldt Bay juvenile Kumamoto oysters or Pacific oyster brood or seed stock in 2011 or 2012.

Soundscapes and Larval Settlement: Larval Bivalve Responses to Habitat-Associated Underwater Sounds.

PubMed

Eggleston, David B; Lillis, Ashlee; Bohnenstiehl, DelWayne R

2016-01-01

We quantified the effects of habitat-associated sounds on the settlement response of two species of bivalves with contrasting habitat preferences: (1) Crassostrea virginicia (oyster), which prefers to settle on other oysters, and (2) Mercenaria mercenaria (clam), which settles on unstructured habitats. Oyster larval settlement in the laboratory was significantly higher when exposed to oyster reef sound compared with either off-reef or no-sound treatments. Clam larval settlement did not vary according to sound treatments. Similar to laboratory results, field experiments showed that oyster larval settlement in "larval housings" suspended above oyster reefs was significantly higher compared with off-reef sites.

Behavior of pathogenic bacteria in the oyster, Crassostrea commercialis, during depuration, re-laying, and storage.

PubMed Central

Son, N T; Fleet, G H

1980-01-01

Oysters (Crassostrea commercials) harvested from major cultivation areas within the state of New South Wales, Australia, were commonly contaminated with low levels of the food-poisoning organisms Bacillus cereus, Clostridium perfringens, and Vibrio parahaemolyticus. Salmonella was found in oysters on only one occasion. These bacteria were cleansed from oysters during oyster purification by re-laying in a non-polluted waterway. Oysters were laboratory contaminated to levels in excess 1,000 cells per g with either B. cereus, C. perfringens, V. parahaemolyticus, Salmonella typhimurium, or S. senftenberg. These species were cleansed from such oysters during purification in a laboratory depuration unit that used ultraviolet light for sterilizing the depuration water. Escherichia coli was also cleansed from oysters under the same re-laying or depuration conditions so that its measurement alone could be used to indicate the cleansing of the above pathogenic species. The levels of these bacteria were also measured during the storage of oysters under conditions that occur during marketing. While B. cereus counts remained relatively stable during storage, the Salmonella spp. gradually decreased in numbers and C. perfringens rapidly died off. V. parahaemolyticus counts increased slightly during the first 4 days of storage, after which decreases occurred. PMID:6257164

Behavior of pathogenic bacteria in the oyster, Crassostrea commercialis, during depuration, re-laying, and storage.

PubMed

Son, N T; Fleet, G H

1980-12-01

Oysters (Crassostrea commercials) harvested from major cultivation areas within the state of New South Wales, Australia, were commonly contaminated with low levels of the food-poisoning organisms Bacillus cereus, Clostridium perfringens, and Vibrio parahaemolyticus. Salmonella was found in oysters on only one occasion. These bacteria were cleansed from oysters during oyster purification by re-laying in a non-polluted waterway. Oysters were laboratory contaminated to levels in excess 1,000 cells per g with either B. cereus, C. perfringens, V. parahaemolyticus, Salmonella typhimurium, or S. senftenberg. These species were cleansed from such oysters during purification in a laboratory depuration unit that used ultraviolet light for sterilizing the depuration water. Escherichia coli was also cleansed from oysters under the same re-laying or depuration conditions so that its measurement alone could be used to indicate the cleansing of the above pathogenic species. The levels of these bacteria were also measured during the storage of oysters under conditions that occur during marketing. While B. cereus counts remained relatively stable during storage, the Salmonella spp. gradually decreased in numbers and C. perfringens rapidly died off. V. parahaemolyticus counts increased slightly during the first 4 days of storage, after which decreases occurred.

Microcontroller based automatic temperature control for oyster mushroom plants

NASA Astrophysics Data System (ADS)

Sihombing, P.; Astuti, T. P.; Herriyance; Sitompul, D.

2018-03-01

In the cultivation of Oyster Mushrooms need special treatment because oyster mushrooms are susceptible to disease. Mushroom growth will be inhibited if the temperature and humidity are not well controlled because temperature and inertia can affect mold growth. Oyster mushroom growth usually will be optimal at temperatures around 22-28°C and humidity around 70-90%. This problem is often encountered in the cultivation of oyster mushrooms. Therefore it is very important to control the temperature and humidity of the room of oyster mushroom cultivation. In this paper, we developed an automatic temperature monitoring tool in the cultivation of oyster mushroom-based Arduino Uno microcontroller. We have designed a tool that will control the temperature and humidity automatically by Android Smartphone. If the temperature increased more than 28°C in the room of mushroom plants, then this tool will turn on the pump automatically to run water in order to lower the room temperature. And if the room temperature of mushroom plants below of 22°C, then the light will be turned on in order to heat the room. Thus the temperature in the room oyster mushrooms will remain stable so that the growth of oyster mushrooms can grow with good quality.

Plugging the leak: barrier island restoration following Hurricane Katrina enhances larval retention and improves salinity regime for oysters in Mobile Bay, Alabama.

PubMed

Park, Kyeong; Powers, Sean P; Bosarge, George S; Jung, Hoon-Shin

2014-03-01

Changes in geomorphology of estuaries are common following major perpetuations such as hurricanes and may have profound impacts on biological systems. Hurricane Katrina in 2005 created a new pass, called Katrina Cut, halving Dauphin Island in Mobile Bay, Alabama. Significant decline in oyster population at Cedar Point Reef, the primary oyster harvest grounds in Mobile Bay, had persisted since then until the Cut was artificially closed in 2010. A bio-physical model for hydrodynamics and oyster larval transport was used to evaluate two potential mechanisms responsible for oyster population declines: salinity changes in the context of oyster habitat suitability and retention of oyster larvae. The model results revealed that when open Katrina Cut increased salinity at Cedar Point Reef. During high freshwater discharge, in particular, water exchange through Katrina Cut increased the bottom salinity from <5 psu to well over 15 (sometimes >20) psu during the tropic tides. Elevated salinities are associated with greater predation on oysters and higher disease incidence. The presence of the Katrina Cut also reduced larval retention in the spawning area regardless of tidal or river discharge conditions. We conclude that closing the Cut likely improved conditions for oysters within Mobile Bay and eastern Mississippi Sound and that these improved conditions have contributed to increased oyster landings. Copyright © 2013 Elsevier Ltd. All rights reserved.

The mismatch of bioaccumulated trace metals (Cu, Pb and Zn) in field and transplanted oysters (Saccostrea glomerata) to ambient surficial sediments and suspended particulate matter in a highly urbanised estuary (Sydney estuary, Australia).

PubMed

Lee, Jung-Ho; Birch, Gavin F

2016-04-01

A significant correlation between sedimentary metals, particularly the 'bio-available' fraction, and bioaccumulated metal concentrations in the native Sydney rock oyster (Saccostrea glomerata) tissues has been successfully demonstrated previously for Cu and Zn in a number of estuaries in New South Wales, Australia. However, this relationship has been difficult to establish in a highly modified estuary (Sydney estuary, Australia) where metal contamination is of greatest concern and where a significant relationship would be most useful for environmental monitoring. The use of the Sydney rock oyster as a biomonitoring tool for metal contamination was assessed in the present study by investigating relationships between metals attached to sediments and suspended particulate matter (SPM) to bioaccumulated concentrations in oyster tissues. Surficial sediments (both total and fine-fraction), SPM and wild oysters were collected over 3 years from three embayments (Chowder Bay, Mosman Bay and Iron Cove) with each embayment representing a different physiographic region of Sydney estuary. In addition, a transplant experiment of farmed oysters was conducted in the same embayments for 3 months. No relationship was observed between sediments or SPM metals (Cu, Pb and Zn) to tissue of wild oysters; however, significant relationship was observed against transplanted oysters. The mismatch between wild and farmed, transplanted oysters is perplexing and indicates that wild oysters are unsuitable to be used as a biomonitoring tool due to the involvement of unknown complex factors while transplanted oysters hold strong potential.

Impact of Environment and Ontogeny on Relative Fecundity and Egg Quality of Female Oysters (Crassostrea virginica) from Four Sites in Northern Chesapeake Bay.

PubMed

Glandon, Hillary Lane; Michaelis, Adriane K; Politano, Vincent A; Alexander, Stephanie T; Vlahovich, Emily A; Reece, Kimberly S; Koopman, Heather N; Meritt, Donald W; Paynter, Kennedy T

2016-12-01

Resource allocation to reproduction is a primary physiological concern for individuals, and can vary with age, environment, or a combination of both factors. In this study we quantified the impact of environment and individual age on the reproductive output of female oysters Crassostrea virginica. We determined the relative fecundity, egg total lipid content, and overall and omega-3/omega-6 (ω3/ω6) fatty acid signatures (FAS) of eggs spawned by female oysters over a 2-year period (n = 32 and n = 64). Variation was quantified spatially and ontogenetically by sampling young and old oyster populations from two rivers in Chesapeake Bay, totaling four collection sites. During Year 1, when oysters underwent oogenesis in different locations, overall and ω3/ω6 egg FAS varied significantly by river, with no significant differences observed in the FAS of oysters by age in Year 1. In Year 2, when oysters from different sites underwent oogenesis in a single location, no significant differences in the overall egg FAS or ω3/ω6 egg FAS by river or age were observed. These findings suggest that oysters integrate environment into their reproductive output, but that time spent growing at a specific location (in this case, represented by oyster age) plays a relatively minor role in the biochemical composition of oyster eggs. These results have consequences for our understanding of how resources are allocated from the female oyster to eggs and, more generally, the impact of environment and ontogeny on reproductive physiology.

Mortalities of eastern and pacific oyster larvae caused by the pathogens Vibrio coralliilyticus and Vibrio tubiashii

USDA-ARS?s Scientific Manuscript database

Vibrio tubiashii is 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 cora...

7 CFR 701.54 - Oysters.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 7 2010-01-01 2010-01-01 false Oysters. 701.54 Section 701.54 Agriculture Regulations... ADMINISTERED UNDER THIS PART § 701.54 Oysters. (a) Notwithstanding § 701.5(b), but otherwise subject to the... be made available under this section for the eligible cost of refurbishing public or private oyster...

40 CFR 408.250 - Applicability; description of the Pacific Coast hand-shucked oyster processing subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Pacific Coast hand-shucked oyster processing subcategory. 408.250 Section 408.250 Protection of... SEAFOOD PROCESSING POINT SOURCE CATEGORY Pacific Coast Hand-Shucked Oyster Processing Subcategory § 408.250 Applicability; description of the Pacific Coast hand-shucked oyster processing subcategory. The...

40 CFR 408.270 - Applicability; description of the steamed and canned oyster processing subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... steamed and canned oyster processing subcategory. 408.270 Section 408.270 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Steamed and Canned Oyster Processing Subcategory § 408.270 Applicability; description of the steamed and canned oyster processing subcategory. The provisions of this subpart are...

PARASITIC AND SYMBIOTIC FAUNA INHABITING OYSTERS (CRASSOSTREA VIRGINICA) SAMPLED FROM THE CALOOSAHATCHEE ESTUARY, FL

EPA Science Inventory

Oysters, Crassostrea virginica, inhabiting 5 sites in the Caloosahatchee River estuary were studied over a 13 month period to determine the suitability of oyster habitat in relation to their health and condition. Histological examination of 650 oysters (10 animals per station per...

Study on elemental fingerprint of traditional marine Chinese medicine oysters from Jiaozhou Bay, China

NASA Astrophysics Data System (ADS)

Zheng, Yongjun; Zheng, Kang; Li, Yantuan

2012-09-01

In order to investigate the relationship between the trace elements and the characteristics of the oysters, we analyzed the trace elements present in the germplasm of oysters from different producing areas in the Jiaozhou Bay. The element fingerprints were established to reflect the elemental characteristics of the oysters. Concentration patterns of the elements were deciphered by principle component analysis (PCA) and hierarchical cluster analysis (HCA). The six regions were discriminated with accuracy using HCA and PCA based on the concentration of 16 trace elements. The elements were viewed as characteristic elements of the oysters and the fingerprints of these elements could be used to distinguish the quality of the oysters.

76 FR 59423 - Drakes Bay Oyster Company Special-Use Permit, Draft Environmental Impact Statement, Point Reyes...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-26

... Bay Oyster Company Special-Use Permit, Draft Environmental Impact Statement, Point Reyes National... Drakes Bay Oyster Company Special-use permit in Drakes Estero, Point Reyes National Seashore, California... site, at http://parkplanning.nps.gov/pore (click on the Drakes Bay Oyster Company Special-use permit...

40 CFR 408.260 - Applicability; description of the Atlantic and Gulf Coast hand-shucked oyster processing...

Code of Federal Regulations, 2010 CFR

2010-07-01

... Atlantic and Gulf Coast hand-shucked oyster processing subcategory. 408.260 Section 408.260 Protection of... SEAFOOD PROCESSING POINT SOURCE CATEGORY Atlantic and Gulf Coast Hand-Shucked Oyster Processing Subcategory § 408.260 Applicability; description of the Atlantic and Gulf Coast hand-shucked oyster processing...

75 FR 33656 - Exelon Generation Company, LLC Oyster Creek Nuclear Generating Station Environmental Assessment...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-14

... Oyster Creek Nuclear Generating Station Environmental Assessment and Finding of No Significant Impact The... Company, LLC (the licensee), for operation of the Oyster Creek Nuclear Generating Station (Oyster Creek), located in Ocean County, New Jersey. Therefore, as required by 10 CFR Section 51.21, the NRC performed an...

75 FR 33366 - Exelon Generation Company, LLC; Oyster Creek Nuclear Generating Station; Notice of Withdrawal of...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-11

...; Oyster Creek Nuclear Generating Station; Notice of Withdrawal of Application for Amendment to Facility... Operating License No. DPR-16 for the Oyster Creek Nuclear Generating Station (Oyster Creek), located in Ocean County, New Jersey. The proposed amendment would have revised the Technical Specifications to...

Histological Alterations in Pacific Oysters Crassostrea gigas that Survived a Summer Mortality Event in Baja California, Mexico.

PubMed

Cáceres-Martínez, Jorge; Vásquez-Yeomans, Rebeca; Danigo, Philippe; Reyes-Roel, Carlos

2018-03-01

A mortality episode (>90%) of triploid and diploid Pacific oysters Crassostrea gigas cultured in Baja California Sur occurred during summer 2012, coinciding with a thermal anomaly, an algal bloom, and low oxygen values. To help explain the cause of the mortalities, histological analyses and molecular tests for specific pathogens (ostreid herpesvirus 1 [OsHV-1] and Perkinsus marinus) were performed on oysters surviving at the end of the episode. Triploid oysters showed a high percentage of males (43%) and hermaphrodites (30%); 93% of these oysters were in the gonadic reabsorption stage, and in some cases, hemocytes completely filled the lumen of the gonadic follicles. Oysters presented large areas with severe hemocyte infiltration that extended toward the digestive gland. Diploid oysters showed similar gonad alterations. None of samples showed histological or molecular evidence of OsHV-1 or P. marinus. Histological alterations can be related to physiological disorders caused by the mechanism driving summer mortality. This is the first case history of a summer mortality episode among Pacific oysters in Mexico. © 2017 American Fisheries Society.

Increases in the amounts of Vibrio spp. in oysters upon addition of exogenous bacteria.

PubMed

Froelich, Brett; Oliver, James

2013-09-01

The bacterial pathogen Vibrio vulnificus is found naturally in brackish coastal waters but can be greatly concentrated by filter-feeding organisms such as shellfish. Numerous experiments in which exogenous V. vulnificus cells are added to oysters in an attempt to measure uptake and depuration have been performed. In nearly all cases, results have shown that laboratory-grown bacteria are rapidly taken up by the oysters but ultimately eliminated, while naturally present Vibrio populations in oysters are resistant to depuration. In this study, oysters harvested during winter months, with low culturable Vibrio concentrations, were incubated in aquaria supplemented with strains of V. vulnificus that were either genotypically or phenotypically distinct from the background bacteria. These exogenous cells were eliminated from the oysters, as previously seen, but other vibrios already inhabiting the oysters responded to the V. vulnificus inoculum by rapidly increasing in number and maintaining a large stable population. The presence of such an oyster-adapted Vibrio population would be expected to prevent colonization by exogenous V. vulnificus cells, thus explaining the rapid depuration of these added bacteria.

Statistical optimization of ultraviolet irradiate conditions for vitamin D₂ synthesis in oyster mushrooms (Pleurotus ostreatus) using response surface methodology.

PubMed

Wu, Wei-Jie; Ahn, Byung-Yong

2014-01-01

Response surface methodology (RSM) was used to determine the optimum vitamin D2 synthesis conditions in oyster mushrooms (Pleurotus ostreatus). Ultraviolet B (UV-B) was selected as the most efficient irradiation source for the preliminary experiment, in addition to the levels of three independent variables, which included ambient temperature (25-45°C), exposure time (40-120 min), and irradiation intensity (0.6-1.2 W/m2). The statistical analysis indicated that, for the range which was studied, irradiation intensity was the most critical factor that affected vitamin D2 synthesis in oyster mushrooms. Under optimal conditions (ambient temperature of 28.16°C, UV-B intensity of 1.14 W/m2, and exposure time of 94.28 min), the experimental vitamin D2 content of 239.67 µg/g (dry weight) was in very good agreement with the predicted value of 245.49 µg/g, which verified the practicability of this strategy. Compared to fresh mushrooms, the lyophilized mushroom powder can synthesize remarkably higher level of vitamin D2 (498.10 µg/g) within much shorter UV-B exposure time (10 min), and thus should receive attention from the food processing industry.

Habitat use by Red Knots (Calidris canutus rufa): Experiments with oyster racks and reefs on the beach and intertidal of Delaware Bay, New Jersey

NASA Astrophysics Data System (ADS)

Burger, Joanna; Niles, Lawrence J.

2017-07-01

Sea level rise and increasing human activities have decreased intertidal habitat in many places in the world. The expansion of aquaculture in intertidal areas may impact birds and other organisms using these habitats, leading to questions of sustainability of both aquaculture and functioning estuarine ecosystems. Understanding the effect of oyster culture on shorebird activity, particularly on Red Knots (Calidris canutus rufa), a species on the U.S. Threatened List, is important for adaptive management and the expansion of oyster culture. In May 2013 we experimentally compared Red Knot and shorebird use of a beach section with racks and a control, and in 2016 we compared the use of sections with artificial reefs, oyster racks, and control on Delaware Bay, New Jersey (USA). The data included only times when no workers or other people were present. Censuses, conducted every 30 min throughout the day (279 censuses in 2013, 231 censuses in 2016), included the number of Red Knots and other shorebirds in each treatment section. In 2013, the total number of shorebirds was significantly higher in the rack section than in the control section, except for Red Knots and Ruddy Turnstones (Arenaria interpres) that occurred in higher numbers in the control than in the rack section. In 2016 Red Knot numbers were also significantly lower in the rack section. In 2013, the mean number of Red Knots/census was 13 for racks vs 59 for the control (P < 0.0002). In 2016, the mean number of Red Knots/census was 13 for racks and over 68 for other treatments (P < 0.0001). Treatment, date, and number of non-Knot shorebirds explained 60% (2013) and 69% (2016) of the variation in Red Knot numbers. Red Knots avoided the sections with racks while both foraging and roosting, suggesting that caution should be used before placing oyster racks in areas used for foraging by Red Knots.

Evaluation of the proximate quality of the combination of Tuna (Thunnus albacares) and white oyster mushroom (Pleurotus ostreatus) nuggets

NASA Astrophysics Data System (ADS)

Yufidasari, H. S.; Prihanto, A. A.; Nurdiani, R.; Jaziri, A. A.

2018-04-01

Nugget is a processed meat product which has great market demand but need variations to increase its nutritional content. Tuna is rich in omega-3 protein, vitamins, and minerals. White oyster mushrooms have high nutritional content which are about 23-33% protein, 36-68 % carbohydrates and 12-22 % amino acids. The purpose of this research is to evaluate the chemical quality of Tuna nugget (Thunnus albacores) with combination of white oyster mushroom (Pleurotus ostreatus). Complete Randomized Design (RAL) with parameters of Tuna and white oyster mushroom formulation, TJ1 (70 % Tuna: 30 % white oyster mushroom), TJ2 (50 % Tuna: 50 % white oyster mushroom), TJ3 (30 % Tuna: 70 % white oyster mushroom), and Control or K Treatment (100 % Tuna) is used. Results of Tuna nuggets with white oyster mushroom combination showed the highest value of water content in TJ3 50.14 %, protein K 19.6 %, fat TJ3 22.98 %, ash K 3.99 % and 2.47 % crude fiber. From these results, there is a need for further research on fat, ash and coarse fiber content that is used in the manufacture of fish nuggets combined with oyster mushrooms because it failed to meet Indonesian National Standard (SNI).

Seasonal dynamics and diversity of bacteria in retail oyster tissues.

PubMed

Wang, Dapeng; Zhang, Qian; Cui, Yan; Shi, Xianming

2014-03-03

Oysters are one of the important vehicles for the transfer of foodborne pathogens. It was reported that bacteria could be bio-accumulated mainly in the gills and digestive glands. In artificially treated oysters, bacterial communities have been investigated by culture-independent methods after harvest. However, little information is available on the seasonal dynamics of bacterial accumulation in retail oyster tissues. In this study, retail oysters were collected from local market in different seasons. The seasonal dynamics and diversity of bacteria in oyster tissues, including the gills, digestive glands and residual tissues, were analyzed by denaturing gradient gel electrophoresis (DGGE). It was interesting that the highest bacterial diversity appeared in the Fall season, not in summer. Our results indicated that Proteobacteria was the predominant member (23/46) in oyster tissues. Our results also suggested that bacterial diversity in gills was higher than that in digestive glands and other tissues. In addition, not all the bacteria collected from surrounding water by gills were transferred to digestive glands. On the other hand, few bacteria were found in oyster tissues except in the gills. Therefore, the gills could be the best candidate target tissue for monitoring of pathogenic bacteria either to human or to oyster. Copyright © 2013 Elsevier B.V. All rights reserved.

Sensitivity to ocean acidification differs between populations of the Sydney rock oyster: Role of filtration and ion-regulatory capacities.

PubMed

Stapp, Laura S; Parker, Laura M; O'Connor, Wayne A; Bock, Christian; Ross, Pauline M; Pörtner, Hans O; Lannig, G

2018-04-01

Understanding mechanisms of intraspecific variation in resilience to environmental drivers is key to predict species' adaptive potential. Recent studies show a higher CO 2 resilience of Sydney rock oysters selectively bred for increased growth and disease resistance ('selected oysters') compared to the wild population. We tested whether the higher resilience of selected oysters correlates with an increased ability to compensate for CO 2 -induced acid-base disturbances. After 7 weeks of exposure to elevated seawater PCO 2 (1100 μatm), wild oysters had a lower extracellular pH (pH e = 7.54 ± 0.02 (control) vs. 7.40 ± 0.03 (elevated PCO 2 )) and increased hemolymph PCO 2 whereas extracellular acid-base status of selected oysters remained unaffected. However, differing pH e values between oyster types were not linked to altered metabolic costs of major ion regulators (Na + /K + -ATPase, H + -ATPase and Na + /H + -exchanger) in gill and mantle tissues. Our findings suggest that selected oysters possess an increased systemic capacity to eliminate metabolic CO 2 , possibly through higher and energetically more efficient filtration rates and associated gas exchange. Thus, effective filtration and CO 2 resilience might be positively correlated traits in oysters. Copyright © 2017 Elsevier Ltd. All rights reserved.

Bioaccumulation and metabolomics responses in oysters Crassostrea hongkongensis impacted by different levels of metal pollution.

PubMed

Cao, Chen; Wang, Wen-Xiong

2016-09-01

Jiulong River Estuary, located in southern China, was heavily contaminated by metal pollution. In this study, the estuarine oysters Crassostrea hongkongensis were transplanted to two sites with similar hydrological conditions but different levels of metal pollution in Jiulong River Estuary over a six-month period. We characterized the time-series change of metal bioaccumulation and final metabolomics responses of oysters. Following transplantation, all metals (Cd, Cu, Cr, Ni, Pb, and Zn) in the oyster digestive glands had elevated concentrations over time. By the end of six-month exposure, Cu, Zn and Cd were the main metals significantly differentiating the two sites. Using (1)H NMR metabolite approach, we further demonstrated the disturbance in osmotic regulation, energy metabolism, and glycerophospholipid metabolism induced by metal contaminations. Six months later, the oysters transplanted in the two sites showed a similar metabolite variation pattern when compared with the initial oysters regardless of different metal levels in the tissues. Interestingly, by comparing the oysters from two sites, the more severely polluted oysters accumulated significantly higher amounts of osmolytes (betaine and homarine) and lower energy storage compounds (glycogen) than the less polluted oysters; these changes could be the potential biomarkers for different levels of metal pollution. Our study demonstrated the complexity of biological effects under field conditions, and NMR metabolomics provides an important approach to detect sensitive variation of oyster inner status. Copyright © 2016 Elsevier Ltd. All rights reserved.

APPLICATION OF RADIOISOTOPE-LABELED BACTERIA IN FOOD SANITATION STUDIES. IV. ON THE BACTERIAL CONTAMINATION AND DECONTAMINATION OF LIVING OYSTER (in Japanese)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bito, T.; Takase, A.

Decontamination of the living oyster was studied by Y/sup 90/or Y/sup 91/ -labeled coliform bacteria. At low temperature, precultural temperature affected the contamination of the oyster but the uptake of bacteria by the oyster was distinctly observed below 5 deg C. In a study on elapsing change of contamination, it was determined that the whole bacterial load of the oyster depended mainly on the gill, but was not negligible on the digestive tract. The contaminating rate of the oyster was successfully measured by automatic recording of the shift of radioactivity in the contaminated cultural water with a dip-type G-M countermore » ratemeter and chart recorder, because the bacterial concentration of the closed cultural water decrease according to the bacterial uptake of the oyster. On decontamination of the oyster, it was observed that the most effective temperature existed in the region of 15 to 25 deg C, and at the upper or lower of this region the decontaminating efficiency decreased. As for the exchange rate of the culture water, the decontaminating effect on the oyster was proportional to an increase of the rate to 7.5 times per hour. However, more was of no effect. An increase in the cultured water volume was harmful for the decontamination of the oyster because of the exchanging efficiency of the water. (P.C.H.)« less

Cadmium Bioaccumulation in European Flat Oysters (Ostrea Edulis) from Middle Adriatic Sea (San Benedetto Del Tronto District, Italy)

PubMed Central

Semeraro, Angela Marisa; Aliventi, Alessandra; Di Trani, Vittoria; Capocasa, Piero

2014-01-01

Bivalve molluscs represent an important source of cadmium exposure in humans, in particular oysters, because of their high filter feeding capability and high concentration of metal-binding metallothionein in tissues. In this study the authors investigated the difference in cadmium bioaccumulation in European flat oysters harvested from production areas in the district of San Benedetto del Tronto (Ascoli Piceno province, Italy), as a function of their origin (farming or natural beds) and the time of gathering. The beds lie 3 nm off-shore at a depth of 20-40 m and are collected by dredging. In the farms, baskets are suspended in the water column 2.5-3 nm offshore at a depth of 4 m. The authors analysed the results of cadmium monitoring plan carried out in oyster natural beds for a total of 15 samples collected from 2004 to 2012 and in two oyster farms for a total of 11 samples from 2009 to 2012. Although the few data did not allow to find a significant statistical association, they suggested two findings: i) cadmium concentration in oysters from natural beds seemed to be lower than in farmed oysters; and ii) in farmed oysters cadmium concentration even exceeded allowed maximum level for human consumption, in particular in autumn. The vertical stratification in the water column of phytoplankton and a cadmium dilution at oyster gonadal maturation might cause changes in oyster cadmium accumulation. PMID:27800338

Developing tools for the study of molluscan immunity: The sequencing of the genome of the eastern oyster, Crassostrea virginica.

PubMed

Gómez-Chiarri, Marta; Warren, Wesley C; Guo, Ximing; Proestou, Dina

2015-09-01

The eastern oyster, Crassostrea virginica, provides important ecological and economical services, making it the target of restoration projects and supporting a significant fishery/aquaculture industry with landings valued at more than $100 million in 2012 in the United States of America. Due to the impact of infectious diseases on wild, restored, and cultured populations, the eastern oyster has been the focus of studies on host-pathogen interactions and immunity, as well as the target of selective breeding efforts for disease resistant oyster lines. Despite these efforts, relatively little is known about the genetic basis of resistance to diseases or environmental stress, not only in eastern oyster, but also in other molluscan species of commercial interest worldwide. In order to develop tools and resources to assist in the elucidation of the genomic basis of traits of commercial, biological, and ecological interest in oysters, a team of genome and bioinformatics experts, in collaboration with the oyster research community, is sequencing, assembling, and annotating the first reference genome for the eastern oyster and producing an exhaustive transcriptome from a variety of oyster developmental stages and tissues in response to a diverse set of environmentally-relevant stimuli. These transcriptomes and reference genome for the eastern oyster, added to the already available genome and transcriptomes for the Pacific oyster (Crassostrea gigas) and other bivalve species, will be an essential resource for the discovery of candidate genes and markers associated with traits of commercial, biological, and ecologic importance in bivalve molluscs, including those related to host-pathogen interactions and immunity. Copyright © 2015 Elsevier Ltd. All rights reserved.

Does reef structure affect oyster food resources? A stable isotope assessment.

PubMed

Blomberg, Brittany N; Lebreton, Benoit; Palmer, Terence A; Guillou, Gaël; Beseres Pollack, Jennifer; Montagna, Paul A

2017-06-01

As ecosystem engineers, oysters create and maintain structured habitat and can influence trophodynamics and benthic-pelagic coupling in the surrounding landscape. The physical reef structure and associated biotic parameters can affect the availability of food resources for oysters. Oysters and potential composite food sources - suspended particulate organic matter (SPOM) and surface sediment organic matter (SSOM) - were assessed using a dual stable isotope (δ 13 C, δ 15 N) approach at three reef types (natural, restored, and unconsolidated) seasonally for two years to determine if changes in physical and/or biotic parameters affected the relative availability and/or use of food resources by oysters. SPOM was more depleted in 13 C (-24.2 ± 0.6‰, mean ± SD) than SSOM (-21.2 ± 0.8‰). SPOM composition is likely dominated by autochthonous phytoplankton production, while SSOM includes trapped phytoplankton and benthic microalgae. SSOM was used by oysters in increasing proportions relative to SPOM over time at all reef types. This temporal trend is likely due to increased oyster biomass over time, promoting enhanced microphytobenthos growth through feedback effects related to oyster biodeposits. Structural differences between reef types observed in this study had no effect on food resource availability and use by oysters, indicating strong bentho-pelagic coupling likely due to shallow depths as well as strong and consistent winds. This study provides insights for restoration of oyster reefs as it highlights that food resources used by oysters remain similar among reef types despite changes in abiotic and biotic parameters among habitats and over time. Copyright © 2017 Elsevier Ltd. All rights reserved.

The effect of a novel photodynamic activation method mediated by curcumin on oyster shelf life and quality.

PubMed

Liu, Fang; Li, Zhaojie; Cao, Binbin; Wu, Juan; Wang, Yuming; Xue, Yong; Xu, Jie; Xue, Changhu; Tang, Qing Juan

2016-09-01

In this paper, the effect of photodynamic method mediated by curcumin (PDT) on the shelf life and quality of pacific oysters during storage at 5±1°C were analyzed. In our previous study we investigated the optimal treatment conditions of photodynamic method mediated by curcumin to sterilization were 10uM photosensitizer concentration and 5.4J/cm 2 light energy density. Under these conditions, the effect of a novel photodynamic activation method mediated by curcumin on oyster shelf life and quality was researched. The total bacterial counts, TVB-N content and sensory analysis were used to evaluate the effects on oyster shelf life. The oyster shelf life was prolonged from 8days to 12days after photodynamic treatment and the oysters in the treatment group displayed notable odor retention, produced fewer odor corrupting substances when the control group oysters reached the end of their shelf life (day 8). Texture, free amino acid contents and fatty acid levels were applied to estimate the quality of the treated oysters. The texture had no significant change after treated with PDT. At the end of oyster shelf life, compared PDT group (PDT) with control group (control), total free amino acid contents (control: 234.30mg/100g, PDT: 813.02mg/100g) was higher and free fatty acid levels (control: 0.071mEq/L, PDT: 0.0455mEq/L) displayed lower in PDT group. This indicated that the treated oysters oxidized minimally, decayed slowly, decomposed fewer nutrients and had lower metabolic levels of spoilage microorganisms. PDT has a positive effect on prolonging oyster shelf life and its quality. Copyright © 2016 Elsevier Ltd. All rights reserved.

Microbial quality of oysters sold in Western Trinidad and potential health risk to consumers.

PubMed Central

Rampersad, F. S.; Laloo, S.; La Borde, A.; Maharaj, K.; Sookhai, L.; Teelucksingh, J.; Reid, S.; McDougall, L.; Adesiyun, A. A.

1999-01-01

The prevalence and characteristics of Escherichia coli and Salmonella spp. as well as counts of E. coli in raw oysters, condiments/spices, and raw oyster cocktails sampled from 72 vendors across Western Trinidad were determined. The microbial quality of the water used in the preparation of raw oysters was also investigated. Of 200 samples each of raw oysters, condiments/spices and oyster cocktails tested, 154 (77.0%), 89 (44.5%) and 154 (77.0%) respectively yielded E. coli. The differences were statistically significant (P = < 0.001; chi square = 62.91). The mean E. coli count per g in the ready-to-eat oyster cocktail ranged from 1.5 x 10(3) +/- 2.7 x 10(3) in Couva to 8.7x10(6) +/- 4.9x10(7) in San Fernando. One hundred and forty-six (73.0%) oyster cocktails contaminated with E. coli had counts that exceeded the recommended standard of 16 per g. Of a total of 590 E. coli isolates from various sources tested, 24 (4.1%), 20 (3.4%) and 69 (11.7%) were mucoid, haemolytic and non-sorbitol fermenters respectively. Twelve (2.0%) isolates of E. coli were O157 strains, while 92 (46.0%) of 200 E. coli isolates tested belonged to enteropathogenic serogroups. Ninety (45.0%) and 73 (36.5%) of 200 water samples contained total coliforms and faecal coliforms respectively, with counts that exceeded 2.2 coliforms per 100 ml. Salmonella spp. were isolated from 7 (3.5%), 1 (0.5%) and 2 (1.0%) of 200 samples each, of raw oysters, condiments/spices and oyster cocktails respectively. Oysters pose a health risk to consumers in Trinidad, particularly from colibacillosis and salmonellosis, and the need for increased public awareness of this hazard cannot be over-emphasized. PMID:10579443

Biotransformation and detoxification of inorganic arsenic in Bombay oyster Saccostrea cucullata.

PubMed

Zhang, Wei; Guo, Zhiqiang; Zhou, Yanyan; Liu, Huaxue; Zhang, Li

2015-01-01

Arsenic (As) exists as the toxic inorganic forms in marine water and sediment, while marine oysters usually accumulate high As contents mostly as the less toxic organic forms. It has not yet been clear that how As is biotransformed in marine oysters. This study therefore investigated the biotransformation and detoxification of two inorganic As forms (As(III) and As(V)) in Bombay oyster Saccostrea cucullata after waterborne exposures for 30 days. Seven treatments of dissolved As exposure (clean seawater, 1, 5, 20 mg/L As(III), and 1, 5, 20 mg/L As(V)) were performed. Body As concentration increased significantly after all As exposure treatments except 1mg/L As(V). Total As, As(III), and As(V) concentration were positive correlated with glutathione-S-transferases (GST) activities, suggesting GST might play an important role in the As biotransformation and detoxification process. Organic As species were predominant in control and the low As exposed oysters, whereas a large fraction of As was remained as the inorganic forms in the high As exposed oysters, suggesting As could be biotransformed efficiently in the oysters in clean or light contaminated environment. The results of As speciation demonstrated the As biotransformation in the oysters included As(V) reduction, methylation to monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), and subsequent conversion to arsenobetaine (AsB). More As was distributed in the subcellular metallothionein-like proteins fraction (MTLP) functioning sequestration and detoxification in the inorganic As exposed oysters, suggesting it was also a strategy for oysters against As stress. In summary, this study elucidated that marine oysters had high ability to accumulate, biotransform, and detoxify inorganic As. Copyright © 2014 Elsevier B.V. All rights reserved.

Effects of electrolyzed oxidizing water treatment on reducing Vibrio parahaemolyticus and Vibrio vulnificus in raw oysters.

PubMed

Ren, Tingting; Su, Yi-Cheng

2006-08-01

Contamination of Vibrio parahaemolyticus and Vibrio vulnificus in oysters is a food safety concern. This study investigated effects of electrolyzed oxidizing (EO) water treatment on reducing V. parahaemolyticus and V. vulnificus in laboratory-contaminated oysters. EO water exhibited strong antibacterial activity against V. parahaemolyticus and V. vulnificus in pure cultures. Populations of V. parahaemolyticus (8.74 x 10(7) CFU/ml) and V. vulnificus (8.69 x 10(7) CFU/ml) decreased quickly in EO water containing 0.5% NaCl to nondetectable levels (> 6.6 log reductions) within 15 s. Freshly harvested Pacific oysters were inoculated with a five-strain cocktail of V. parahaemolyticus or V. vulnificus at levels of 10(4) and 10(6) most probable number (MPN)/g and treated with EO water (chlorine, 30 ppm; pH 2.82; oxidation-reduction potential, 1131 mV) containing 1% NaCl at room temperature. Reductions of V. parahaemolyticus and V. vulnificus in oysters were determined at 0 (before treatment), 2, 4, 6, and 8 h of treatment. Holding oysters inoculated with V. parahaemolyticus or V. vulnificus in the EO water containing 1% NaCl for 4 to 6 h resulted in significant (P < 0.05) reductions of V. parahaemolyticus and V. vulnificus by 1.13 and 1.05 log MPN/g, respectively. Extended exposure (> 12 h) of oysters in EO water containing high levels of chlorine (> 30 ppm) was found to be detrimental to oysters. EO water could be used as a postharvest treatment to reduce Vibrio contamination in oysters. However, treatment should be limited to 4 to 6 h to avoid death of oysters. Further studies are needed to determine effects of EO water treatment on sensory characteristics of oysters.

High Salinity Relaying to Reduce Vibrio parahaemolyticus and Vibrio vulnificus in Chesapeake Bay Oysters (Crassostrea virginica).

PubMed

Parveen, Salina; Jahncke, Michael; Elmahdi, Sara; Crocker, Helen; Bowers, John; White, Chanelle; Gray, Stephanie; Morris, Amanda C; Brohawn, Kathy

2017-02-01

Cases of Vibrio infections in the United States have tripled from 1996 to 2009 and these infections are most often associated with the consumption of seafood, particularly oysters (Crassostrea virginica). Information is needed on how to reduce numbers of Vibrio parahaemolyticus and Vibrio vulnificus in bi-valve molluscan shellfish (for example, oysters). The purpose of this study was to evaluate the effectiveness of high salinity relaying or treatment in recirculating aquaculture systems (RASs) as methods to reduce the abundance of V. parahaemolyticus and V. vulnificus in oysters. For relaying field trials, oysters were collected from approved harvest waters, temperature abused outside under a tarp for 4 h, and then transferred to high (29 to 33 ppt.) and moderate (12 to 19 ppt.) salinities. For RAS treatment trial, oysters were transferred to 32 to 34 ppt. salinity at 15 °C. After 7, 14, 21, and in some instances 28 d, oysters were collected and analyzed for V. parahaemolyticus and V. vulnificus levels using multiplex real-time PCR. Initial levels of V. parahaemolyticus and V. vulnificus ranged from 3.70 to 5.64 log 10 MPN/g, and were reduced by 2 to 5 logs after 21 to 28 d in high salinity water (29 to 34 ppt.). Oyster mortalities averaged 4% or less, and did not exceed 7%. Relaying of oysters to high salinity field sites or transfer to high salinity RAS tanks was more effective in reducing V. vulnificus compared with V. parahaemolyticus. These results suggest that high salinity relaying of oysters is more effective in reducing V. vulnificus than V. parahaemolyticus in the oyster species used in this study. © 2016 Institute of Food Technologists®.

The biofilteration ability of oysters (Crassostrea gigas) to reduce Aeromonas salmonicida in salmon culture.

PubMed

Ma, Xiaona; Li, Xian; Sun, Guoxiang; Sharawy, Zaki Zaki; Qiu, Tianlong; Du, Yishuai; Liu, Ying

2017-07-01

Pathogen contamination in the environment is inevitable with the rapid development of intensive aquaculture. Therefore, alternative ecofriendly biological strategies to control pathogenic bacteria are required. However, our aim was to investigate the ability of oysters (Crassostrea gigas) to filter the important opportunistic pathogen, Aeromonas salmonicida (strain C4), using a green fluorescent protein tag (GFP) in the Atlantic salmon (Salmo salar) farming wastewater. Hence, A. salmonicida removal efficiency and ingestion rate were detected in two different oyster stages (larvae and adults). To evaluate the practical performance of oysters as A. salmonicida biofilter, adult oysters were applied to an integrated constructed wetlands system (ICWS) and their long-term C4-GFP removal efficiency was recorded for 60 days. Overall, our results clearly indicated that oysters had substantial A. salmonicida removal ability via their ingestion process when observed under a fluorescent microscope. Approximately 88-95% of C4-GFP was removed by oyster larvae at an ingestion rate of 6.4 × 10 3 -6.2 × 10 5  CFU/h·ind, while 79-92% of C4-GFP was removed by adult oysters at an ingestion rate of 2.1 × 10 4 -3.1 × 10 6  CFU/h·ind. Furthermore, 57.9 ± 17.2% of C4-GFP removal efficiency was achieved when oysters were applied to ICWS. We, therefore, concluded that using oysters as a biofilter represents an effective alternative for removing A. salmonicida from aquaculture wastewater. However, the fate of oysters after ingesting the pathogenic bacteria, acting as a potential reservoir or vector for pathogens, is still debatable. This research provides the basis for the application of oysters as a biofilter to remove pathogens from aquaculture wastewater in industrialized production.

Mapping Oyster Reef Habitats in Mobile Bay

NASA Technical Reports Server (NTRS)

Bolte, Danielle

2011-01-01

Oyster reefs around the world are declining rapidly, and although they haven t received as much attention as coral reefs, they are just as important to their local ecosystems and economies. Oyster reefs provide habitats for many species of fish, invertebrates, and crustaceans, as well as the next generations of oysters. Oysters are also harvested from many of these reefs and are an important segment of many local economies, including that of Mobile Bay, where oysters rank in the top five commercial marine species both by landed weight and by dollar value. Although the remaining Mobile Bay oyster reefs are some of the least degraded in the world, projected climate change could have dramatic effects on the health of these important ecosystems. The viability of oyster reefs depends on water depth and temperature, appropriate pH and salinity levels, and the amount of dissolved oxygen in the water. Projected increases in sea level, changes in precipitation and runoff patterns, and changes in pH resulting from increases in the amount of carbon dioxide dissolved in the oceans could all affect the viability of oyster reefs in the future. Human activities such as dredging and unsustainable harvesting practices are also adversely impacting the oyster reefs. Fortunately, several projects are already under way to help rebuild or support existing or previously existing oyster reefs. The success of these projects will depend on the local effects of climate change on the current and potential habitats and man s ability to recognize and halt unsustainable harvesting practices. As the extent and health of the reefs changes, it will have impacts on the Mobile Bay ecosystem and economy, changing the resources available to the people who live there and to the rest of the country, since Mobile Bay is an important national source of seafood. This project identified potential climate change impacts on the oyster reefs of Mobile Bay, including the possible addition of newly viable habitats in the southeastern regions of the Bay.

Effects of Dry Storage and Resubmersion of Oysters on Total Vibrio vulnificus and Total and Pathogenic (tdh+/trh+) Vibrio parahaemolyticus Levels.

PubMed

Kinsey, Thomas P; Lydon, Keri A; Bowers, John C; Jones, Jessica L

2015-08-01

Vibrio vulnificus (Vv) and Vibrio parahaemolyticus (Vp) are the two leading causes of bacterial illnesses associated with raw shellfish consumption. Levels of these pathogens in oysters can increase during routine antifouling aquaculture practices involving dry storage in ambient air conditions. After storage, common practice is to resubmerge these stored oysters to reduce elevated Vv and Vp levels, but evidence proving the effectiveness of this practice is lacking. This study examined the changes in Vv and in total and pathogenic (thermostable direct hemolysin gene and the tdh-related hemolysin gene, tdh+ and trh+) Vp levels in oysters after 5 or 24 h of dry storage (28 to 32°C), followed by resubmersion (27 to 32°C) for 14 days. For each trial, replicate oyster samples were collected at initial harvest, after dry storage, after 7 days, and after 14 days of resubmersion. Oysters not subjected to dry storage were collected and analyzed to determine natural undisturbed vibrio levels (background control). Vibrio levels were measured using a most-probable-number enrichment followed by real-time PCR. After storage, vibrio levels (excluding tdh+ and trh+ Vp during 5-h storage) increased significantly (P < 0.001) from initial levels. After 7 days of resubmersion, Vv and total Vp levels (excluding total Vp in oysters stored for 5 h) were not significantly different (P < 0.1) from levels in background oysters. Vv and total and pathogenic Vp levels were not significantly different (P > 0.1) from levels in background oysters after 14 days of resubmersion, regardless of dry storage time. These data demonstrate that oyster resubmersion after dry storage at elevated ambient temperatures allows vibrio levels to return to those of background control samples. These results can be used to help minimize the risk of Vv and Vp illnesses and to inform the oyster industry on the effectiveness of routine storing and resubmerging of aquaculture oysters.

Oyster Reef Communities in the Chesapeake Bay: A Brief Primer. VORTEX: Virginia's Oyster Reef Teaching EXperience.

ERIC Educational Resources Information Center

Harding, Juliana M.; Mann, Roger; Clark, Vicki P.

This document introduces Virginia's Oyster Reef Teaching EXperience (VORTEX), which is an interdisciplinary program focusing on the importance of oyster reef communities in the Chesapeake Bay ecosystem. The VORTEX program uses field and laboratory experience supported by multimedia instruction. This document presents an overview on the biology of…

Water quality parameters and total aerobic bacterial and vibrionaceae loads in eastern oysters (Crassostrea virginica) from oyster gardening sites

USDA-ARS?s Scientific Manuscript database

Oyster gardening is a practice designed to restore habitat for marine life and to improve water quality. This study determined physical and chemical water quality parameters at two oyster gardening sites in the Delaware Inland Bays and compared them with total aerobic bacteria and Vibrionaceae conc...

The risk of Vibrio parahaemolyticus infections associated with consumption of raw oysters as affected by processing and distribution conditions in Taiwan

USDA-ARS?s Scientific Manuscript database

The steadily increased consumption of raw oysters in Taiwan warrants an assessment of the risk (probability of illness) of raw oyster consumption attributed by Vibrio parahaemolyticus. The aim of this study was to estimate the risk of V. parahaemolyticus infection associated with raw oyster consumpt...

Interspecific hybridization between Crassostrea angulata and C. ariakensis

NASA Astrophysics Data System (ADS)

Yao, Tuo; Zhang, Yuehuan; Yan, Xiwu; Wang, Zhaoping; Li, Dongchun; Su, Jiaqi; Yu, Ruihai

2015-08-01

Interspecific hybridization can generate heterosis, which is proven to be a useful tool in selective breeding programs for oyster culture. Crassostrea angulata and C. ariakensis are two important economic shellfish species in China. We conducted 2 × 2 reciprocal crosses to determine whether these two species can cross-fertilize and their hybrids can hatch, survive and perform heterosis. Fertilization was found symmetrical without delay. The rate of fertilization success of C. angulata ♀ × C. ariakensis ♂ was lower than that of C. ariakensis ♀ × C. angulata ♂, and the success rate of both hybridizations was lower than that of two intraspecific crosses each. During the planktonic period, survival rate of the progeny was lower in the hybrid crosses than in the intraspecific crosses. On day 360, mean shell height of the progeny of C. angulata ♀ × C. angulata ♂ was highest, which was followed by that of C. angulata ♀ × C. ariakensis ♂, C. ariakensis ♀ × C. ariakensis ♂ and C. ariakensis ♀ × C. angulata ♂ in a descending order. Morphology of adults produced by the hybrid crosses was similar to that of C. angulata. Both hybrids underwent normal gonad development and produced mature gametes in the mating season. This study provided new insights into the quantitative traits in interspecific crosses of Crassostrea species, thus being of guidance value for selective breeding of oyster.

The Manciano Sandstone: a shoreface deposit of Miocene basins of the Northern Apennines, Italy

NASA Astrophysics Data System (ADS)

Martini, I. P.; Cascella, A.; Rau, A.

1995-09-01

Well exposed, diamond-line cut, quarry-exposures of the Manciano Sandstone allow a detailed analysis of sandy, fossiliferous, nearshore deposits of the shelf of the Northern Apennines. The Manciano Sandstone is characterized by medium to very coarse, washed, fairly well sorted, lithic sandstone, with thin interlayers of sandy conglomerates. It displays two principal, rhythmically alternating sandy facies: (a) slightly burrowed (mostly Macaronichnus, Ophiomorpha, Skolithos) units, trough cross-bedded, locally showing possible tidal bundles with few whole Scutella (echinoid) shells reworked on foresets, or occasional large-scale (approximately 2 m) planar cross-bedded, bar-accretion units; and (b) slightly finer, darker-coloured reddish-brown sandstone units, heavily bioturbated ( Cruziana-Skolithos) ichnofauna) representing slightly more sheltered settings. Large oysters are present in near-living position in a few thin layers and, more commonly, as reworked, comminuted fragments in sandy layers. Many calcareous pebbles and oyster fragments are bored. Other fossils consist of echinoids ( Scutella), some balanids and reworked foraminifera and bryozoa. The Manciano sands were deposited primarily in a wave-dominated shoreface, containing migrating bars/ridges and affected by wave-induced, possibly tidal-enhanced currents. This tidal influence confirms the opening of the Miocene Apenninic Sea to oceans, both the developing Atlantic Ocean to the west and, through a long, narrow seaway, the Asian portion of the Tethys Sea to the east.

Transcriptome and biomineralization responses of the pearl oyster Pinctada fucata to elevated CO2 and temperature.

PubMed

Li, Shiguo; Liu, Chuang; Huang, Jingliang; Liu, Yangjia; Zhang, Shuwen; Zheng, Guilan; Xie, Liping; Zhang, Rongqing

2016-01-06

Ocean acidification and global warming have been shown to significantly affect the physiological performances of marine calcifiers; however, the underlying mechanisms remain poorly understood. In this study, the transcriptome and biomineralization responses of Pinctada fucata to elevated CO2 (pH 7.8 and pH 7.5) and temperature (25 °C and 31 °C) are investigated. Increases in CO2 and temperature induced significant changes in gene expression, alkaline phosphatase activity, net calcification rates and relative calcium content, whereas no changes are observed in the shell ultrastructure. "Ion and acid-base regulation" related genes and "amino acid metabolism" pathway respond to the elevated CO2 (pH 7.8), suggesting that P. fucata implements a compensatory acid-base mechanism to mitigate the effects of low pH. Additionally, "anti-oxidation"-related genes and "Toll-like receptor signaling", "arachidonic acid metabolism", "lysosome" and "other glycan degradation" pathways exhibited responses to elevated temperature (25 °C and 31 °C), suggesting that P. fucata utilizes anti-oxidative and lysosome strategies to alleviate the effects of temperature stress. These responses are energy-consuming processes, which can lead to a decrease in biomineralization capacity. This study therefore is important for understanding the mechanisms by which pearl oysters respond to changing environments and predicting the effects of global climate change on pearl aquaculture.

Indices, multispecies and synthesis descriptors in benthic assessments: Intertidal organic enrichment from oyster farming

NASA Astrophysics Data System (ADS)

Quintino, Victor; Azevedo, Ana; Magalhães, Luísa; Sampaio, Leandro; Freitas, Rosa; Rodrigues, Ana Maria; Elliott, Michael

2012-09-01

Intertidal off-bottom oyster culture is shown to cause organic enrichment of the shore and although there are two stressors of interest (the presence of a structure, the trestles, and also the sediment and organic waste from the oysters), these can be separated and their relative impacts determined using an appropriate nested experimental design and data treatments. Although no artificial food sources are involved, the oysters feeding activity and intensity of culture enhances biodeposition and significantly increases the sediment fines content and total organic matter. This in general impoverished the benthic community in culture areas rather than a species succession with the installation of opportunists or a resulting increase in the abundance and biomass of benthic species; the findings can be a direct consequence of the intertidal situation which is less-amenable recruitment of species more common to the subtidal environment. Thus the most appropriate biological descriptors to diagnose the effects associated with the organic enrichment were the multispecies abundance data as well as the primary biological variables species richness and abundance. The effects were however spatially and statistically significantly confined to the area located directly underneath the culture bags compared to the corridors located between the trestles, which do not show such enrichment effects. Synthesis biotic indices were much less effective to diagnose the benthic alterations associated with this organic enrichment. These results show that special attention must be paid when using indices in areas where the organic enrichment induces an impoverishment of the benthic community but not necessarily a species replacement with the installation of opportunists.

Bioaccumulation of trace metals in farmed pacific oysters Crassostrea gigas from SW Gulf of California coast, Mexico.

PubMed

Jonathan, M P; Muñoz-Sevilla, N P; Góngora-Gómez, Andrés Martin; Luna Varela, Raquel Gabriela; Sujitha, S B; Escobedo-Urías, D C; Rodríguez-Espinosa, P F; Campos Villegas, Lorena Elizabeth

2017-11-01

The aim of the study was to evaluate the bioavailability of trace metals (Chromium, Copper, Nickel, Lead, Zinc, Cadmium, Arsenic, and Mercury) in the commercially consumed Crassostrea gigas oysters collected over a 12-month growth period (2011-12) from an experimental cultivation farm in La Pitahaya, Sinaloa State, Mexico. Sediment and water samples were also collected from four different zones adjacent to the cultivation area to identify the concentration patterns of metals. The results revealed that sewage disposals, fertilizers used for agricultural practices and shrimp culture are the major sources for the enrichment of certain toxic metals. The metal concentrations in oysters presented a decreasing order of abundance (all values in mg Kg -1 ): Zn (278.91 ± 93.03) > Cu (63.13 ± 31.72) > Cr (22.29 ± 30.23) > Cd (14.54 ± 4.28) > Ni (9.41 ± 11.33) > Pb (2.22 ± 1.33) > As (0.58 ± 0.91) > Hg (0.04 ± 0.06). Bioconcentration Factor (BCF) and Biota Sediment Accumulation Factor (BSAF) exhibited that C. gigas in the region are strong accumulators for Zn and Cd respectively. Thus, the present study proves to fulfill the gap in understanding the rate of bioaccumulation of metals in C. gigas which is regarded as the most sought after oyster species globally. Copyright © 2017 Elsevier Ltd. All rights reserved.

Prostaglandin E receptor 4 (PTGER4) involved in host protection against immune challenge in oyster, Crassostrea hongkongensis.

PubMed

Qu, Fufa; Xiang, Zhiming; Wang, Fuxuan; Qi, Lin; Xu, Fengjiao; Xiao, Shu; Yu, Ziniu

2015-02-01

Prostaglandin E receptor 4 (PTGER4) is an essential receptor that can detect various physiological and pathological stimuli and has been implicated in a wide variety of biological processes, including the regulation of immune responses, cytokine production, and apoptosis. In this report, the first mollusk PTGER4, referred to as ChPTGER4, was cloned and characterized from the Hong Kong oyster Crassostrea hongkongensis. Its full-length cDNA is 1734 bp in length, including 5'- and 3'-untranslated region (UTRs) of 354 bp and 306 bp, respectively, and an open reading frame (ORF) of 1074 bp. ChPTGER4 comprises 357 amino acids and shares significant homology with its vertebrate homologs. The results of phylogenetic analysis revealed that ChPTGER4 clusters with PTGER4 from the Pacific oyster. In addition, quantitative real-time PCR analysis revealed that ChPTGER4 was constitutively expressed in all tissues examined and that its expression was significantly up-regulated in hemocytes and gills following challenge by pathogens (Vibrio alginolyticus, Staphylococcus haemolyticus and Saccharomyces cerevisiae) and pathogen-associated molecular patterns (PAMPs: lipopolysaccharide (LPS) and peptidoglycan (PGN). Moreover, fluorescence microscopy analysis revealed that ChPTGER4 localized to the membrane, and its overexpression significantly enhanced NF-κB reporter gene activation in the HEK293T cell line. In summary, this study provides the first experimental evidence of a functional PTGER4 in mollusks, which suggests its involvement in the innate immune response in oyster. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects of Antifouling Biocides on Molecular and Biochemical Defense System in the Gill of the Pacific Oyster Crassostrea gigas

PubMed Central

Park, Mi Seon; Kim, Young Dae; Kim, Bo-Mi; Kim, Youn-Jung; Kim, Jang Kyun; Rhee, Jae-Sung

2016-01-01

Antifouling biocides such as organotin compounds and their alternatives are potent toxicants in marine ecosystems. In this study, we employed several molecular and biochemical response systems of the Pacific oyster Crassostrea gigas to understand a potential mode of action of antifouling biocides (i.e. tributyltin (TBT), diuron and irgarol) after exposure to different concentrations (0.01, 0.1, and 1 μg L-1) for 96 h. As a result, all the three antifouling biocides strongly induced the antioxidant defense system. TBT reduced both enzymatic activity and mRNA expression of Na+/K+-ATPase and acetylcholinesterase (AChE). Lower levels of both Na+/K+-ATPase activity and AChE mRNA expression were observed in the diuron-exposed oysters compared to the control, while the irgarol treatment reduced only the transcriptional expression of AChE gene. We also analyzed transcript profile of heat shock protein (Hsp) superfamily in same experimental conditions. All antifouling biocides tested in this study significantly modulated mRNA expression of Hsp superfamily with strong induction of Hsp70 family. Taken together, overall results indicate that representative organotin TBT and alternatives have potential hazardous effects on the gill of C. gigas within relatively short time period. Our results also suggest that analyzing a series of molecular and biochemical parameters can be a way of understanding and uncovering the mode of action of emerging antifouling biocides. In particular, it was revealed that Pacific oysters have different sensitivities depend on the antifouling biocides. PMID:28006823

Hemocytes Are Sites of Enteric Virus Persistence within Oysters ▿

PubMed Central

Provost, Keleigh; Dancho, Brooke A.; Ozbay, Gulnihal; Anderson, Robert S.; Richards, Gary P.; Kingsley, David H.

2011-01-01

The goal of this study was to determine how enteric viruses persist within shellfish tissues. Several lines of novel evidence show that phagocytic blood cells (hemocytes) of Eastern oysters (Crassostrea virginica) play an important role in the retention of virus particles. Our results demonstrated an association of virus contamination with hemocytes but not with hemolymph. Live oysters contaminated overnight with hepatitis A virus (HAV) and murine norovirus (MNV) had 56% and 80% of extractable virus associated with hemocytes, respectively. Transfer of HAV-contaminated hemocytes to naïve (virus-free) oysters resulted in naïve oyster meat testing HAV positive for up to 3 weeks. Acid tolerance of HAV, MNV, poliovirus (PV), and feline calicivirus (FCV) correlated with the ability of each virus to persist within oysters. Using reverse transcription-PCR (RT-PCR) to evaluate persistence of these viruses in oysters, we showed that HAV persisted the longest (>21 days) and was most acid resistant, MNV and PV were less tolerant of acidic pH, persisting for up to 12 days and 1 day, respectively, and FCV did not persist (<1 day) within oysters and was not acid tolerant. This suggests that the ability of a virus to tolerate the acidic conditions typical of phagolysosomal vesicles within hemocytes plays a role in determining virus persistence in shellfish. Evaluating oyster and hemocyte homogenates and live contaminated oysters as a prelude to developing improved viral RNA extraction methods, we found that viruses were extracted more expediently from hemocytes than from whole shellfish tissues and gave similar RT-PCR detection sensitivities. PMID:21948840

Human enteroviruses in oysters and their overlying waters.

PubMed Central

Goyal, S M; Gerba, C P; Melnick, J L

1979-01-01

The presence of enteroviruses in oysters and oyster-harvesting waters of the Texas Gulf coast was monitored over a period of 10 months. Viruses were detected in water and oyster samples obtained from areas both open and closed to shellfish harvesting. Viruses were detected periodically in waters that met current bacteriological standards for shellfish harvesting. No significant statistical relationship was demonstrated between virus concentration in oysters and the bacteriological and physiochemical quality of water and shellfish. Viruses in water were, however, moderately correlated with total coliforms in water and oysters and with fecal coliforms in oysters. Total coliforms in water were realted to total coliforms in sediment were related only to total coliforms in sediment. Among the physiochemical characteristics of water, turbidity was related statistically to the organic matter content of water and to fecal coliforms in water. There was a marked effect of rainfall on the bacteriological quality of water. Of a total of 44 water samples, 26 yielded virus in concentrations from 4 to 167 plaque-forming units per 100-gallon (ca. 378.5-liter) sample. Of a total of 40 pools of 10 to 12 oysters each, virus was found in 14 pools at a concentration of 6 to 224 plaque-forming units per 100 g of oyster meat. On five occasions, virus was found in water samples when no virus could be detected in oysters harvested from the same sites. This study indicates that current bacteriological standards for determining the safety of shellfish and shellfish-growing waters do no reflect the occurrence of enteroviruses. PMID:222210

Influence of Salmonella enterica Serovar Typhimurium ssrB on Colonization of Eastern Oysters (Crassostrea virginica) as Revealed by a Promoter Probe Screen

PubMed Central

Cox, Clayton E.; Wright, Anita C.; McClelland, Michael

2015-01-01

Although Salmonella has 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 by Salmonella. This study tested the hypothesis that specific regulatory changes enable a portion of the invading Salmonella population to colonize oysters. An in vivo promoter 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, in ssrB, resulted in a significantly reduced ability to colonize oysters compared to that of wild-type Salmonella. Because ssrB regulates Salmonella pathogenicity island 2 (SPI-2)-dependent infections in vertebrate macrophages, the possibility that ssrB mediated colonization of oyster hemocytes in a similar manner was examined. However, no difference in hemocyte colonization was observed. The complementary hypothesis that signal exchange between Salmonella and 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 observed in vivo. The sdiA reporter responded to salinity, suggesting that SdiA may also have a role in environmental sensing. Overall, this study suggests the initial colonization of live oysters by Salmonella is controlled by a limited number of regulators, including ssrB. PMID:26497459

Microbiological quality and bacterial diversity of the tropical oyster Crassostrea rhizophorae in a monitored farming system and from natural stocks.

PubMed

Silva Neta, M T; Maciel, B M; Lopes, A T S; Marques, E L S; Rezende, R P; Boehs, G

2015-12-02

Microbiological evaluation is one of the most important parameters for analyzing the viability of an oyster farming system, which addresses public health and ecological concerns. Here, the microbiological quality of the oyster Crassostrea rhizophorae cultivated in a monitored environment and from natural beds in Bahia, northeastern Brazil, was determined. Bacterial diversity in oysters was measured by polymerase chain reaction-denaturing gradient gel electrophoresis. Sequence analysis revealed that most bacterial species showed similarity with uncultured or unidentified bacteria from environmental samples, and were clustered into the phylum Proteobacteria. Diverse bacteria from cultivated (monitored) oyster samples were grouped in the same cluster with a high similarity index (above 79%). Microbiological analyses revealed that these oysters did not contain pathogens. These results reflect the natural balance of the microbial communities essential to the maintenance of health and in inhibiting pathogen colonization in the oyster. On the other hand, bacterial diversity of samples from native stocks in extractive areas displayed a similarity index varying between 55 and 77%, and all samples were clustered separately from each other and from the cluster of samples derived from the cultivation area. Microbiological analyses showed that oysters from the extractive area were not fit for human consumption. This reflected a different composition of the microbial community in this area, probably resulting from anthropic impact. Our study also demonstrated that low temperatures and high rainfall limits the bacterial concentration in tropical oysters. This is the first study analyzing the total bacterial community profiles of the oyster C. rhizophorae.

Human enteroviruses in oysters and their overlying waters.

PubMed

Goyal, S M; Gerba, C P; Melnick, J L

1979-03-01

The presence of enteroviruses in oysters and oyster-harvesting waters of the Texas Gulf coast was monitored over a period of 10 months. Viruses were detected in water and oyster samples obtained from areas both open and closed to shellfish harvesting. Viruses were detected periodically in waters that met current bacteriological standards for shellfish harvesting. No significant statistical relationship was demonstrated between virus concentration in oysters and the bacteriological and physiochemical quality of water and shellfish. Viruses in water were, however, moderately correlated with total coliforms in water and oysters and with fecal coliforms in oysters. Total coliforms in water were realted to total coliforms in sediment were related only to total coliforms in sediment. Among the physiochemical characteristics of water, turbidity was related statistically to the organic matter content of water and to fecal coliforms in water. There was a marked effect of rainfall on the bacteriological quality of water. Of a total of 44 water samples, 26 yielded virus in concentrations from 4 to 167 plaque-forming units per 100-gallon (ca. 378.5-liter) sample. Of a total of 40 pools of 10 to 12 oysters each, virus was found in 14 pools at a concentration of 6 to 224 plaque-forming units per 100 g of oyster meat. On five occasions, virus was found in water samples when no virus could be detected in oysters harvested from the same sites. This study indicates that current bacteriological standards for determining the safety of shellfish and shellfish-growing waters do no reflect the occurrence of enteroviruses.

Prevalence of Perkinsus marinus (dermo), Haplosporidium nelsoni (MSX), and QPX in bivalves of Delaware's inland bays and quantitative, high-throughput diagnosis of dermo by QPCR.

PubMed

Ulrich, Paul N; Ewart, John W; Marsh, Adam G

2007-01-01

Restoration of oyster reef habitat in the Inland Bays of Delaware was accompanied by an effort to detect and determine relative abundance of the bivalve pathogens Perkinsus marinus, Haplosporidium nelsoni, and QPX. Both the oyster Crassostrea virginica and the clam Mercenaria mercenaria were sampled from the bays. In addition, oysters were deployed at eight sites around the bays as sentinels for the three parasites. Perkinsus marinus prevalence was measured with a real-time, quantitative polymerase chain reaction (PCR) methodology that enabled high-throughput detection of as few as 31 copies of the ribosomal non-transcribed spacer region in 500 ng oyster DNA. The other pathogens were assayed using PCR with species-specific primers. Perkinsus marinus was identified in Indian River Bay at moderate prevalence ( approximately 40%) in both an artificial reef and a wild oyster population whereas sentinel oysters were PCR-negative after 3-months exposure during summer and early fall. Haplosporidium nelsoni was restricted to one oyster deployed in Little Assawoman Bay. QPX and P. marinus were not detected among wild clams. While oysters in these bays have historically been under the greatest threat by MSX, it is apparent that P. marinus currently poses a greater threat to recovery of oyster aquaculture in Delaware's Inland Bays.

Oyster Reef Communities in the Chesapeake Bay. Virginia Institute of Marine Science Educational Series. [CD-ROM].

ERIC Educational Resources Information Center

Harding, Juliana M.; Mann, Roger; Clark, Vicki P.

This CD-ROM, Oyster Reef Communities in the Chesapeake Bay, describes oyster reefs, reef communities, and their roles in the Chesapeake Bay ecosystem. Detailed descriptions of scientific research methods and techniques used to monitor and describe oyster reef communities as well as applications of the resulting data are provided. The CD-ROM was…

46 CFR 2.01-50 - Persons other than crew on towing, oyster, or fishing steam vessels.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 1 2011-10-01 2011-10-01 false Persons other than crew on towing, oyster, or fishing... than crew on towing, oyster, or fishing steam vessels. (a) A steam vessel engaged in towing, oyster dredging and planting, and fishing may be permitted to carry persons in addition to its crew. (b) The...

46 CFR 2.01-50 - Persons other than crew on towing, oyster, or fishing steam vessels.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 1 2012-10-01 2012-10-01 false Persons other than crew on towing, oyster, or fishing... than crew on towing, oyster, or fishing steam vessels. (a) A steam vessel engaged in towing, oyster dredging and planting, and fishing may be permitted to carry persons in addition to its crew. (b) The...

46 CFR 2.01-50 - Persons other than crew on towing, oyster, or fishing steam vessels.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 1 2010-10-01 2010-10-01 false Persons other than crew on towing, oyster, or fishing steam vessels. 2.01-50 Section 2.01-50 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY PROCEDURES... than crew on towing, oyster, or fishing steam vessels. (a) A steam vessel engaged in towing, oyster...

Effects of oyster harvest activities on Louisiana reef habitat and resident nekton communities

USGS Publications Warehouse

Beck, Steve; LaPeyre, Megan K.

2015-01-01

Oysters are often cited as “ecosystem engineers” because they modify their environment. Coastal Louisiana contains extensive oyster reef areas that have been harvested for decades, and whether differences in habitat functions exist between those areas and nonharvested reefs is unclear. We compared reef physical structure and resident community metrics between these 2 subtidal reef types. Harvested reefs were more fragmented and had lower densities of live eastern oysters (Crassostrea virginica) and hooked mussels (Ischadium recurvum) than the nonharvested reefs. Stable isotope values (13C and 15N) of dominant nekton species and basal food sources were used to compare food web characteristics. Nonpelagic source contributions and trophic positions of dominant species were slightly elevated at harvested sites. Oyster harvesting appeared to have decreased the number of large oysters and to have increased the percentage of reefs that were nonliving by decreasing water column filtration and benthopelagic coupling. The differences in reef matrix composition, however, had little effect on resident nekton communities. Understanding the thresholds of reef habitat areas, the oyster density or oyster size distribution below which ecosystem services may be compromised, remains key to sustainable management.

Analysis of environmental factors influencing salinity patterns, oyster growth, and mortality in lower Breton Sound Estuary, Louisiana using 20 years of data

USGS Publications Warehouse

LaPeyre, Megan K.; Geaghan, James; Decossas, Gary A.; La Peyre, Jerome F.

2016-01-01

Freshwater inflow characteristics define estuarine functioning by delivering nutrients, sediments, and freshwater, which affect biological resources and ultimately system production. Using 20 years of water quality, weather, and oyster growth and mortality data from Breton Sound Estuary (BSE), Louisiana, we examined the relationship of riverine, weather, and tidal influence on estuarine salinity, and the relationship of salinity to oyster growth and mortality. Mississippi River discharge was found to be the most important factor determining salinity patterns over oyster grounds within lower portions of BSE, with increased river flow associated with lowered salinities, while easterly winds associated with increased salinity were less influential. These patterns were consistent throughout the year. Salinity and temperature (season) were found to critically control oyster growth and mortality, suggesting that seasonal changes to river discharge affecting water quality over the oyster grounds have profound impacts on oyster populations. The management of oyster reefs in estuaries (such as BSE) requires an understanding of how estuarine hydrodynamics and salinity are influenced by forcing factors such as winds, river flow, and by the volume, timing, and location of controlled releases of riverine water.

Inactivation and elimination of human enteric viruses by Pacific oysters.

PubMed

McLeod, C; Hay, B; Grant, C; Greening, G; Day, D

2009-12-01

To investigate the comparative elimination of three different human enterically transmitted viruses [i.e. hepatitis A virus (HAV), norovirus (NoV) and poliovirus (PV)] and inactivation of HAV and PV by Pacific oysters. New Zealand grown Pacific oysters (Crassostrea gigas) were allowed to bioaccumulate HAV, NoV and PV. Samples of oyster gut, faeces and pseudofaeces were then analysed by using real-time RT-PCR to determine the amount of viral RNA and cell culture methods to identify changes in the number of plaque forming units. The results suggest that the majority of the PV present in the oyster gut and oyster faeces is noninfectious, while in contrast, most of the HAV detected in the oyster gut are infectious. Depuration experiments identified a large drop in the count of PV in the gut over a 23-h cleansing period, whereas the levels of HAV and NoV did not significantly decrease. Human enterically transmitted viruses are eliminated and inactivated at different rates by Pacific oysters. The research presented in this article has implications for risk management techniques that are used to improve the removal of infectious human enteric viruses from bivalve molluscs.

Annual dose of Taiwanese from the ingestion of 210Po in oysters.

PubMed

Lee, Hsiu-wei; Wang, Jeng-Jong

2013-03-01

Oysters around the coast of Taiwan were collected, dried, spiked with a (209)Po tracer for yield, digested with concentrated HNO(3) and H(2)O(2), and finally dissolved in 0.5 N HCl. The polonium was then spontaneously deposited onto a silver disc, and the activity of (210)Po was measured using an alpha spectrum analyzer equipped with a silicon barrier detector. Meanwhile, the internal effective dose of (210)Po coming from the intake of oysters by Taiwanese was evaluated. The results of the present study indicate that (210)Po average activity concentrations ranged from 23.4 ± 0.4 to 126 ± 94 Bq kg(-1) of fresh oysters. The oysters coming from Penghu island and Kinmen island regions contain higher concentrations of (210)Po in comparison with oysters from other regions of Taiwan. The value of (210)Po weighted average activity concentrations for all oyster samples studied is 25.9 Bq kg(-1). The annual effective dose of Taiwanese due to the ingestion of (210)Po in oysters was estimated to be 4.1 × 10(-2) mSv y(-1). Copyright © 2013. Published by Elsevier Ltd.

Incorporation of metabolites into glycogen and lipids of the oyster, crassostrea virginica

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swift, M.L.; Humphrey, C.L.

1987-05-01

Groups of oysters, either fed or unfed, were exposed to U-{sup 14}C labelled D-glucose, L-asp, L-leu, L-ala or acetate for 6 hrs. Except for the glucose trials, the disappearance of radioactivity from the saline of the unfed oysters was greater (83%) than for the fed animals (65%). With glucose, 88% of the radioactivity disappeared in each trial. The specific radioactivity of glycogen isolated from oysters exposed to labelled glucose, asp and ala was 1283, 468 and 8.22 dpm/mg glycogen respectively. Radioactivity was found primarily in the triacylglycerols and phospholipids (PL) in fed oysters and in PL only in unfed oysters.more » Phosphatidyl choline, phosphatidyl ethanolamine, and a fraction containing phosphatidyl serine and phosphatidyl inositol, had 32%, 25% and 35-40% of the radioactivity respectively. Incorporation of total radioactivity into PL was 70% lower in unfed vs. fed trials, but the distribution of counts among the phospholipids classes was unchanged. Glycogenesis does not appear to be a significant pathway in the oyster. Apparently well-fed oysters are able to store excess dietary calories as lipid. During periods of starvation exogenous small metabolites along with glucose from glycogen are catabolized.« less

Cultivation of the culinary-medicinal Lung Oyster mushroom, Pleurotus pulmonarius (Fr.) Quél. (Agaricomycetideae) on grass plants in Taiwan.

PubMed

Liang, Zeng-Chin; Wu, Kuan-Jzen; Wang, Jinn-Chyi; Lin, Chorng-Horng; Wu, Chiu-Yeh

2011-01-01

Cultivation of the culinary-medicinal Lung Oyster mushroom, Pleurotus pulmonarius, on the stalks of three grass plants, i.e., Panicum repens, Pennisetum purpureum, and Zea mays were investigated. The effects of various combinatorial substrates on mushroom mycelial growth and yield calculated as biological efficiency (BE) were determined. Among 9 experimental substrates, the most suitable substrate for mycelial growth was 45ZMS:45S, followed by 45PRS:45S; their mycelial growth rates were obviously quicker than that of the control substrate. The BEs of all the experimental substrates respectively containing P. repens stalk, P. purpureum stalk and Z. mays stalk were higher than that of the control (39.55%) during the 2.5 months of cultivation period. The best substrate in terms of BE was 60ZMS:30S (58.33%), followed by 45PRS:45S (57.16%), 45ZMS:45S (49.86%), and 30ZMS:60S (47.20%). Based on the BE of the tested substrates, Z mays stalk appeared to be the best alternative material for the production of P. pulmonarius.

Is there a direct relationship between stress biomarkers in oysters and the amount of metals in the sediments where they inhabit?

PubMed

Rodriguez-Iruretagoiena, A; Rementeria, A; Zaldibar, B; de Vallejuelo, S Fdez-Ortiz; Gredilla, A; Arana, G; de Diego, A

2016-10-15

The effects exerted by metals in oysters are still a matter of debate and require more detailed studies. In this work we have investigated whether the health status of oysters are affected by the amount of metals present in the sediments of their habitat. Sediments and oysters were collected in the tidal part of the estuary of the Oka River (Basque Country), representative of other mesotidal, well mixed and short estuaries of the European Atlantic coast. The concentrations of 14 elements were determined in all the samples. Several biomarkers were also measured in the soft tissues of oysters. According to the concentrations found, the sediments were classified as non-toxic or slightly toxic. In good agreement, the histological alterations observed in oysters were not severe. Interestingly, in those sampling sites where the sediments showed relatively high metal concentrations, the metallic content in oysters was lower, and vice versa. Copyright © 2016 Elsevier Ltd. All rights reserved.

Benthic surveys of the historic pearl oyster beds of Qatar reveal a dramatic ecological change.

PubMed

Smyth, D; Al-Maslamani, I; Chatting, M; Giraldes, B

2016-12-15

The study aimed to confirm the presence of historic oyster banks of Qatar and code the biotopes present. The research also collated historical records and scientific publications to create a timeline of fishery activity. The oyster banks where once an extremely productive economic resource however, intense overfishing, extreme environmental conditions and anthropogenic impacts caused a fishery collapse. The timeline highlighted the vulnerability of ecosystem engineering bivalves if overexploited. The current status of the oyster banks meant only one site could be described as oyster dominant. This was unexpected as the sites were located in areas which once supported a highly productive oyster fishery. The research revealed the devastating effect that anthropogenic impacts can have on a relatively robust marine habitat like an oyster bed and it is hoped these findings will act as a driver to investigate and map other vulnerable habitats within the region before they too become compromised. Copyright © 2016 Elsevier Ltd. All rights reserved.

Sponge bioerosion accelerated by ocean acidification across species and latitudes?

NASA Astrophysics Data System (ADS)

Wisshak, M.; Schönberg, C. H. L.; Form, A.; Freiwald, A.

2014-06-01

In many marine biogeographic realms, bioeroding sponges dominate the internal bioerosion of calcareous substrates such as mollusc beds and coral reef framework. They biochemically dissolve part of the carbonate and liberate so-called sponge chips, a process that is expected to be facilitated and accelerated in a more acidic environment inherent to the present global change. The bioerosion capacity of the demosponge Cliona celata Grant, 1826 in subfossil oyster shells was assessed via alkalinity anomaly technique based on 4 days of experimental exposure to three different levels of carbon dioxide partial pressure ( pCO2) at ambient temperature in the cold-temperate waters of Helgoland Island, North Sea. The rate of chemical bioerosion at present-day pCO2 was quantified with 0.08-0.1 kg m-2 year-1. Chemical bioerosion was positively correlated with increasing pCO2, with rates more than doubling at carbon dioxide levels predicted for the end of the twenty-first century, clearly confirming that C. celata bioerosion can be expected to be enhanced with progressing ocean acidification (OA). Together with previously published experimental evidence, the present results suggest that OA accelerates sponge bioerosion (1) across latitudes and biogeographic areas, (2) independent of sponge growth form, and (3) for species with or without photosymbionts alike. A general increase in sponge bioerosion with advancing OA can be expected to have a significant impact on global carbonate (re)cycling and may result in widespread negative effects, e.g. on the stability of wild and farmed shellfish populations, as well as calcareous framework builders in tropical and cold-water coral reef ecosystems.

Elucidating the life cycle of Marteilia sydneyi, the aetiological agent of QX disease in the Sydney rock oyster (Saccostrea glomerata).

PubMed

Adlard, Robert D; Nolan, Matthew J

2015-05-01

Marteilia sydneyi (Phylum Paramyxea, Class Marteiliidea, Order Marteiliida) (the causative agent of QX disease) is recognised as the most severe parasite to infect Saccostrea glomerata, the Sydney rock oyster, on the east coast of Australia. Despite its potential impact on industry (>95% mortality), research towards lessening these effects has been hindered by the lack of an experimental laboratory model of infection as a consequence of our incomplete understanding of the life cycle of this parasite. Here, we explored the presence of this parasite in hosts other than a bivalve mollusc from two study sites on the Hawkesbury River, New South Wales, Australia. We employed PCR-based in situ hybridisation and sequence analysis of a portion of the first internal transcribed spacer of rDNA in an attempt to detect M. sydneyi DNA in 21 species of polychaete worm. Marteilia DNA was detected in 6% of 1247 samples examined by PCR; the analysis of all amplicons defined one distinct sequence type for first internal transcribed spacer, representing M. sydneyi. Of the polychaete operational taxonomic units test-positive in PCR, we examined 116 samples via in situ hybridisation DNA probe staining and identified M. sydneyi DNA in the epithelium of the intestine of two specimens of Nephtys australiensis. Two differing morphological forms were identified: a 'primordial' cell that contained a well-defined nucleus but had little differentiation in the cytoplasm, and a 'plasmodial' cell that showed an apparent syncytial structure. This finding represents the first known record of the identification of M. sydneyi being parasitic in an organism other than an oyster, and only the third record of any species of Marteilia identified from non-molluscan hosts. Future work aims at determining if N. australiensis and S. glomerata are the only hosts in the life cycle of this paramyxean, and the development of experimental models to aid the production of QX disease-resistant oysters. Copyright © 2015 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

Shell architecture, element composition, and stable isotope signature of the giant deep-sea oyster Neopycnodonte zibrowii sp. n. from the NE Atlantic

NASA Astrophysics Data System (ADS)

Wisshak, Max; López Correa, Matthias; Gofas, Serge; Salas, Carmen; Taviani, Marco; Jakobsen, Joachim; Freiwald, André

2009-03-01

A conspicuous new deep-sea oyster, Neopycnodonte zibrowii sp. n., is described from the Azores Archipelago, where it thrives in 420 to >500 m water depth in high densities concealed underneath overhangs. The new species reaches a relatively large size, which may exceed 20 cm, and is characterised by a very unusual hinge line morphology, straight without a bulge of the resilium. It is compared to the extant Indo-Pacific Empressostrea kostini Huber and Lorenz, 2007 and to the cosmopolitan Neopycnodonte cochlear (Poli, 1791), which has a broadly sympatric distribution at shallower depths in the Azores and Bay of Biscay. Radiocarbon dating reveals that individuals reach an impressive lifespan of one to more than five centuries, placing them among the longest-lived molluscs known to date. They often grow on top of each other, forming stacks that resemble dish piles—an effective measure to optimise shell stability with minimal biomineralisation effort, but with the drawback of increased bioerosion ultimately leading to detachment. Three microstructure types are developed in N. zibrowii: (1) the cross-foliated, calcitic, dorsal to central endostracum and aragonitic ligostracum, (2) the porous vesicular structure of the calcitic ventral endostracum, and (3) the simple prismatic aragonitic myostracum. Foliated and vesicular shell portions show sub-millimetre-scale first-order increments delineated by conchiolin-rich growth breaks (interpreted as reproductive cyclicity), and less distinct second-order increments (interpreted as annual in nature). This pattern is clearly reflected by the elemental composition with the primary growth breaks lacking Ca and Sr but including Mg and S as organic matrix constituents. The second-order increments within the calcite are mirrored by moderately co-varying Mg/Ca and S/Ca fluctuations at stable Sr concentrations, reflecting varying proportions of organic matrix. Dorsal and central endostracum transects reveal a low inter-valve, but considerable inter-specimen variability with high Mg/Ca molar ratios and fluctuations (22.5±17.6 mmol/mol), low Sr/Ca values (0.2±0.1 mmol/mol), and a typical to high S/Ca content (6.9±2.2 mmol/mol), when compared to other calcitic bivalves. Unlike short-lived, shallow-water oysters, N. zibrowii thrives under very stable environmental conditions. Minimal temperature fluctuations and stable open marine salinity provide an optimal basis to recognise biological fractionation processes. Strong Mg/Ca fluctuations indicate a physiological control related to metabolism and biomineralisation, prohibiting the use of this ratio as a temperature or ocean chemistry proxy. Low Sr/Ca ratios indicate rather constant and low long-term accretion rates, while short-scale fluctuations may be attributed to short-term variations in growth rate and Mg incorporation. Oxygen isotopes yield a considerable spread of 1.8‰ with a mean of 2.0±0.3‰ δ18O V-PDB, and low correlation between different contemporaneous parts of the shell and between specimens. These values surprisingly exceed expected equilibrium conditions, calculated from in situ temperature data (annual mean 12.3±0.3 °C) and seawater isotopic composition (0.5±0.1‰ δ18O SMOW), by 0.5‰ on average. Such positively shifting vital effects, previously reported for limpets and barnacles, are often overlooked in high-temperature and high-amplitude settings and may be more common than is currently believed. Carbon isotopes range from 0.2 to 3.5‰ δ13C V-PDB (mean 1.8±0.7‰) and show an ontogenetic decrease, but may incorporate an environmental signal in adult portions, indicated by a strong correspondence of peaks between specimens. This signal is likely driven by a complex interplay of different factors, such as primary production, current-based food supply and metabolism.

Defining optimal freshwater flow for oyster production: effects of freshet rate and magnitude of change and duration on eastern oysters and Perkinsus marinus infection

USGS Publications Warehouse

LaPeyre, Megan K.; Gossman, B.; La Peyre, Jerome F.

2009-01-01

In coastal Louisiana, the development of large-scale freshwater diversion projects has led to controversy over their effects on oyster resources. Using controlled laboratory experiments in combination with a field study, we examined the effects of pulsed freshwater events (freshet) of different magnitude, duration, and rate of change on oyster resources. Laboratory and field evidence indicate that low salinity events (<5 psu) decreased Perkinsus marinus infection intensities. Furthermore, when salinity was low (<5 psu), parasite infection intensities continued to decrease even as temperatures exceeded 20°C. At the same time, oyster growth was positively correlated with salinity. To maximize oyster production, data indicate that both low and high salinity events will be necessary.

Analytical and experimental studies of natural vibrations modes of ring-stiffened truncated-cone shells with variable theoretical ring fixity

NASA Technical Reports Server (NTRS)

Naumann, E. C.; Catherines, D. S.; Walton, W. C., Jr.

1971-01-01

Experimental and analytical investigations of the vibratory behavior of ring-stiffened truncated-cone shells are described. Vibration tests were conducted on 60 deg conical shells having up to four ring stiffeners and for free-free and clamped-free edge constraints and 9 deg conical shells, for two thicknesses, each with two angle rings and for free-free, free-clamped, and clamped-clamped edge constraints. The analytical method is based on linear thin shell theory, employing the Rayleigh-Ritz method. Discrete rings are represented as composed of one or more segments, each of which is a short truncated-cone shell of uniform thickness. Equations of constraint are used to join a ring and shell along a circumferential line connection. Excellent agreement was obtained for comparisons of experimental and calculated frequencies.

Rapid methods for extraction and concentration of poliovirus from oyster tissues.

PubMed

Richards, G P; Goldmintz, D; Green, D L; Babinchak, J A

1982-12-01

A procedure is discussed for the extraction of poliovirus from oyster meats by modification of several enterovirus extraction techniques. The modified method uses meat extract and Cat-Floc, a polycationic electrolyte, for virus extraction and concentration. Virus recovery from inoculated oyster homogenates is 93-120%. Adsorption of viruses to oyster proteins by acidification of homogenates does not affect virus recovery. Elution of viruses from oyster proteins appears more efficient at pH 9.5 than at pH 8.0. This technique is relatively simple, economical and requires only 2.5 h to complete the combined extraction and concentration procedure.

A Nonautochthonous U.S. Strain of Vibrio parahaemolyticus Isolated from Chesapeake Bay Oysters Caused the Outbreak in Maryland in 2010

PubMed Central

Haendiges, Julie; Jones, Jessica; Myers, Robert A.; Mitchell, Clifford S.; Butler, Erin

2016-01-01

ABSTRACT In the summer of 2010, Vibrio parahaemolyticus caused an outbreak in Maryland linked to the consumption of oysters. Strains isolated from both stool and oyster samples were indistinguishable by pulsed-field gel electrophoresis (PFGE). However, the oysters contained other potentially pathogenic V. parahaemolyticus strains exhibiting different PFGE patterns. In order to assess the identity, genetic makeup, relatedness, and potential pathogenicity of the V. parahaemolyticus strains, we sequenced 11 such strains (2 clinical strains and 9 oyster strains). We analyzed these genomes by in silico multilocus sequence typing (MLST) and determined their phylogeny using a whole-genome MLST (wgMLST) analysis. Our in silico MLST analysis identified six different sequence types (STs) (ST8, ST676, ST810, ST811, ST34, and ST768), with both of the clinical and four of the oyster strains being identified as belonging to ST8. Using wgMLST, we showed that the ST8 strains from clinical and oyster samples were nearly indistinguishable and belonged to the same outbreak, confirming that local oysters were the source of the infections. The remaining oyster strains were genetically diverse, differing in >3,000 loci from the Maryland ST8 strains. eBURST analysis comparing these strains with strains of other STs available at the V. parahaemolyticus MLST website showed that the Maryland ST8 strains belonged to a clonal complex endemic to Asia. This indicates that the ST8 isolates from clinical and oyster sources were likely not endemic to Maryland. Finally, this study demonstrates the utility of whole-genome sequencing (WGS) and associated analyses for source-tracking investigations. IMPORTANCE Vibrio parahaemolyticus is an important foodborne pathogen and the leading cause of bacterial infections in the United States associated with the consumption of seafood. In the summer of 2010, Vibrio parahaemolyticus caused an outbreak in Maryland linked to oyster consumption. Strains isolated from stool and oyster samples were indistinguishable by pulsed-field gel electrophoresis (PFGE). The oysters also contained other potentially pathogenic V. parahaemolyticus strains with different PFGE patterns. Since their identity, genetic makeup, relatedness, and potential pathogenicity were unknown, their genomes were determined by using next-generation sequencing. Whole-genome sequencing (WGS) analysis by whole-genome multilocus sequence typing (wgMLST) allowed (i) identification of clinical and oyster strains with matching PFGE profiles as belonging to ST8, (ii) determination of oyster strain diversity, and (iii) identification of the clinical strains as belonging to a clonal complex (CC) described only in Asia. Finally, WGS and associated analyses demonstrated their utility for trace-back investigations. PMID:26994080

A Nonautochthonous U.S. Strain of Vibrio parahaemolyticus Isolated from Chesapeake Bay Oysters Caused the Outbreak in Maryland in 2010.

PubMed

Haendiges, Julie; Jones, Jessica; Myers, Robert A; Mitchell, Clifford S; Butler, Erin; Toro, Magaly; Gonzalez-Escalona, Narjol

2016-06-01

In the summer of 2010, Vibrio parahaemolyticus caused an outbreak in Maryland linked to the consumption of oysters. Strains isolated from both stool and oyster samples were indistinguishable by pulsed-field gel electrophoresis (PFGE). However, the oysters contained other potentially pathogenic V. parahaemolyticus strains exhibiting different PFGE patterns. In order to assess the identity, genetic makeup, relatedness, and potential pathogenicity of the V. parahaemolyticus strains, we sequenced 11 such strains (2 clinical strains and 9 oyster strains). We analyzed these genomes by in silico multilocus sequence typing (MLST) and determined their phylogeny using a whole-genome MLST (wgMLST) analysis. Our in silico MLST analysis identified six different sequence types (STs) (ST8, ST676, ST810, ST811, ST34, and ST768), with both of the clinical and four of the oyster strains being identified as belonging to ST8. Using wgMLST, we showed that the ST8 strains from clinical and oyster samples were nearly indistinguishable and belonged to the same outbreak, confirming that local oysters were the source of the infections. The remaining oyster strains were genetically diverse, differing in >3,000 loci from the Maryland ST8 strains. eBURST analysis comparing these strains with strains of other STs available at the V. parahaemolyticus MLST website showed that the Maryland ST8 strains belonged to a clonal complex endemic to Asia. This indicates that the ST8 isolates from clinical and oyster sources were likely not endemic to Maryland. Finally, this study demonstrates the utility of whole-genome sequencing (WGS) and associated analyses for source-tracking investigations. Vibrio parahaemolyticus is an important foodborne pathogen and the leading cause of bacterial infections in the United States associated with the consumption of seafood. In the summer of 2010, Vibrio parahaemolyticus caused an outbreak in Maryland linked to oyster consumption. Strains isolated from stool and oyster samples were indistinguishable by pulsed-field gel electrophoresis (PFGE). The oysters also contained other potentially pathogenic V. parahaemolyticus strains with different PFGE patterns. Since their identity, genetic makeup, relatedness, and potential pathogenicity were unknown, their genomes were determined by using next-generation sequencing. Whole-genome sequencing (WGS) analysis by whole-genome multilocus sequence typing (wgMLST) allowed (i) identification of clinical and oyster strains with matching PFGE profiles as belonging to ST8, (ii) determination of oyster strain diversity, and (iii) identification of the clinical strains as belonging to a clonal complex (CC) described only in Asia. Finally, WGS and associated analyses demonstrated their utility for trace-back investigations. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Monitoring tectonic uplift and paleoenvironmental reconstruction for marine terraces near Maǧaracik and Samandaǧ, Hatay Province, Turkey.

PubMed

Florentin, Jonathan A; Blackwell, Bonnie A B; Tüysüz, Okan; Tarı, Ufuk; Can Genç, Ş; İmren, Caner; Mo, Shirley; Huang, Yiwen E W; Blickstein, Joel I B; Skinner, Anne R; Kim, Maria

2014-06-01

Near Hatay, the Antakya-Samandağ-Cyprus Fault (ASCF), East Anatolian and Dead Sea Fault Zones, the large faults that form the edges of the African, Anatolian, Cyprus and Arabian Plates, all produce large earthquakes, which have decimated Hatay repeatedly. Near Samandağ, Hatay, differential vertical displacement on the ASCF has uplifted the southeastern side relative to northwestern side, producing large fault scarps that parallel the Asi (Orontes) River. Tectonic uplift coupled with Quaternary sealevel fluctuations has produced several stacked marine terraces stranded above current sealevel. This study dated 24 mollusc samples from 10 outcrops on six marine terraces near Samandağ electron spin resonance (ESR). Ages were calculated using time-averaged and volumetrically averaged external dose rates, modelled by assuming typical water depths for the individual species and sediment thicknesses estimated from geological criteria. Uplift rates were then calculated for each fault block. At all the Mağaracık terraces, the dates suggest that many shells were likely reworked. On the 30 m terrace at Mağaracık IV (UTM 766588-3999880), Lithophagus burrows with in situ shells cross the unconformity. One such shell dated to 62 ± 6 ka, setting the minimum possible age for the terrace. For all the Mağaracık terraces at ∼30 m above mean sealevel (amsl), the youngest ages for the reworked shells, which averaged 60 ± 3 ka for six separate analyses, sets the maximum possible age for this unit. Thus, the terrace must date to 60-62 ± 3 ka, at the MIS 3/4 boundary when temperatures and sealevels were fluctuating rapidly. Older units dating to MIS 7, 6, and 5 likely were being eroded to supply some fossils found in this terrace. At Mağaracık Dump (UTM 765391-4001048), ∼103 m amsl, Ostrea and other shells were found cemented in growth position to the limestone boulders outcropping there <2.0 m above a wave-eroded notch. If the oysters grew at the same time as the wave-cut notch and the related terrace, the date, 91 ± 13 ka, for the oysters, this fault block has been uplifted at 1.19 ± 0.15 m ky(-1), since MIS 5c. At Samandağ Kurt Stream at 38 m amsl, molluscs were deposited fine sandy gravel, which was likely formed in a large tidal channel. Four molluscs averaged 116 ± 5 ka. If these molluscs have not been reworked, this fault block has uplifted at 0.34 ± 0.05 m ky(-1) since the MIS 5d/5e boundary. The differences in these uplift rates suggests that at least one, and possibly two, hitherto undiscovered faults may separate the Mağaracık Dump site from the other Mağaracık sites and from the Samandağ Kurt Stream site. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Predicting the impacts of Mississippi River diversions and sea-level rise on spatial patterns of eastern oyster growth rate and production

USGS Publications Warehouse

Wang, Hongqing; Chen, Qin; La Peyre, Megan K.; Hu, Kelin; La Peyre, Jerome F.

2017-01-01

There remains much debate regarding the perceived tradeoffs of using freshwater and sediment diversions for coastal restoration in terms of balancing the need for wetland restoration versus preserving eastern oyster (Crassostrea virginica) production. Further complicating the issue, climate change-induced sea-level rise (SLR) and land subsidence are also expected to affect estuarine water quality. In this study, we developed a process-based numerical modeling system that couples hydrodynamic, water quality, and oyster population dynamics. We selected Breton Sound Estuary (BSE) (∼2740 km2) in the eastern Mississippi River Deltaic Plain since it is home to several of the largest public oyster seed grounds and private leases for the Gulf coast. The coupled oyster population model was calibrated and validated against field observed oyster growth data. We predicted the responses of oyster population in BSE to small- (142 m3 s−1) and large-scale (7080 m3 s−1) river diversions at the Caernarvon Freshwater Diversion structure planned in the 2012 Coastal Master Plan (Louisiana) under low (0.38 m) and high (1.44 m) relative sea-level rise (RSLR = eustatic SLR + subsidence) compared to a baseline condition (Year 2009). Model results showed that the large-scale diversion had a stronger negative impact on oyster population dynamics via freshening of the entire estuary, resulting in reduced oyster growth rate and production than RSLR. Under the large-scale diversion, areas with optimal oyster growth rates (>15 mg ash-free dry weight (AFDW) oyster−1 wk−1) and production (>500 g AFDW m−2 yr−1) would shift seaward to the southeastern edge of the estuary, turning the estuary into a very low oyster production system. RSLR however played a greater role than the small-scale diversion on the magnitude and spatial pattern of oyster growth rate and production. RSLR would result in an overall estuary-wide decrease in oyster growth rate and production as a consequence of decreased salinities in the middle and lower estuary because rising sea level likely causes increased stage and overbank flow downstream along the lower Mississippi River.

Survival of Salmonella Newport in oysters.

PubMed

Morrison, Christopher M; Armstrong, Alexandra E; Evans, Sanford; Mild, Rita M; Langdon, Christopher J; Joens, Lynn A

2011-08-02

Salmonella enterica is the leading cause of laboratory-confirmed foodborne illness in the United States and raw shellfish consumption is a commonly implicated source of gastrointestinal pathogens. A 2005 epidemiological study done in our laboratory by Brands et al., showed that oysters in the United States are contaminated with Salmonella, and in particular, a specific strain of the Newport serovar. This work sought to further investigate the host-microbe interactions between Salmonella Newport and oysters. A procedure was developed to reliably and repeatedly expose oysters to enteric bacteria and quantify the subsequent levels of bacterial survival. The results show that 10 days after an exposure to Salmonella Newport, an average concentration of 3.7 × 10(3)CFU/g remains within the oyster meat, and even after 60 days there still can be more than 10(2)CFU/g remaining. However, the strain of Newport that predominated in the market survey done by Brands et al. does not survive within oysters or the estuarine environment better than any other strains of Salmonella we tested. Using this same methodology, we compared Salmonella Newport's ability to survive within oysters to a non-pathogenic strain of E. coli and found that after 10 days the concentration of Salmonella was 200-times greater than that of E. coli. We also compared those same strains of Salmonella and E. coli in a depuration process to determine if a constant 120 L/h flux of clean seawater could significantly reduce the concentration of bacteria within oysters and found that after 3 days the oysters retained over 10(4)CFU/g of Salmonella while the oysters exposed to the non-pathogenic strain of E. coli contained 100-times less bacteria. Overall, the results of this study demonstrate that any of the clinically relevant serovars of Salmonella can survive within oysters for significant periods of time after just one exposure event. Based on the drastic differences in survivability between Salmonella and a non-pathogenic relative, the results of this study also suggest that unidentified virulence factors may play a role in Salmonella's interactions with oysters. Published by Elsevier B.V.

The Effect of Oyster Reef Morphology on Particulate Transfer in a North Carolina Tidal Creek

NASA Astrophysics Data System (ADS)

Lemon, M. G.; Posey, M.; Mallin, M.; Alphin, T.

2014-12-01

The eastern oyster (Crassostrea virginica) is a vital ecosystem engineer species, providing a number of ecosystem services that structure and maintain estuarine environments through the construction of large, hard-bottom reef complexes. Through suspension feeding, oysters clear the water column of particulates, leading to decreased suspended material and enhanced benthic pelagic coupling. Past field studies have indicated the potential importance of the physical reef structure in regulating the transfer of particulate material in the seston. In order to directly assess the existence of the physical reef effect, multiple field experiments were performed in a small tidal creek estuary along the south eastern coast of North Carolina. Comparison of clearance rates derived from two different in situ methods, one accounting for the physical structure of the oyster reef in addition to oyster filtration and one looking at oyster filtration alone, indicate that the reef structure may increase the amount of particulate removal performed by the reef by more than 4 times the removal performed by oyster filtration alone. A defaunation experiment was performed by eliminating the live component of the oyster reef and comparing particulate transfer of this defaunated transect to that of an adjacent faunated transect. The defaunated transect had reduced but not significantly lower material removal when compared to the faunated transect prior to defaunation. Results from short and long term sediment collection and flow velocity measurements indicate that the physical effect of oyster reefs is strong over short temporal scales (days) but is much smaller when evaluated over longer time periods (months). Generally, large silt and small sand sized material is permanently removed from the seston due to the interaction of oyster reef structure and tidal flows, however the transfer of small and medium sized silt grains is only slowed down by the presence of large reef complexes. This effect has important ecological implications for downstream water quality and must be accounted for when modeling water quality improvements performed by oysters.

The density and spatial arrangement of the invasive oyster Crassostrea gigas determines its impact on settlement of native oyster larvae

PubMed Central

Wilkie, Emma M; Bishop, Melanie J; O'Connor, Wayne A

2013-01-01

Understanding how the density and spatial arrangement of invaders is critical to developing management strategies of pest species. The Pacific oyster, Crassostrea gigas, has been translocated around the world for aquaculture and in many instances has established wild populations. Relative to other species of bivalve, it displays rapid suspension feeding, which may cause mortality of pelagic invertebrate larvae. We compared the effect on settlement of Sydney rock oyster, Saccostrea glomerata, larvae of manipulating the spatial arrangement and density of native S. glomerata, and non-native C. gigas. We hypothesized that while manipulations of dead oysters would reveal the same positive relationship between attachment surface area and S. glomerata settlement between the two species, manipulations of live oysters would reveal differing density-dependent effects between the native and non-native oyster. In the field, whether oysters were live or dead, more larvae settled on C. gigas than S. glomerata when substrate was arranged in monospecific clumps. When, however, the two species were interspersed, there were no differences in larval settlement between them. By contrast, in aquaria simulating a higher effective oyster density, more larvae settled on live S. glomerata than C. gigas. When C. gigas was prevented from suspension feeding, settlement of larvae on C. gigas was enhanced. By contrast, settlement was similar between the two species when dead. While the presently low densities of the invasive oyster C. gigas may enhance S. glomerata larval settlement in east Australian estuaries, future increases in densities could produce negative impacts on native oyster settlement. Synthesis and applications: Our study has shown that both the spatial arrangement and density of invaders can influence their impact. Hence, management strategies aimed at preventing invasive populations reaching damaging sizes should not only consider the threshold density at which impacts exceed some acceptable limit, but also how patch formation modifies this. PMID:24455120

Enhanced Detection of Vibrio Cholerae in Oyster Homogenate Based on Centrifugal Removal of Inhibitory Agents

NASA Technical Reports Server (NTRS)

Alexander, Donita; DePaola, Angelo; Young, Ronald B.

1998-01-01

The disease cholera, caused by Vibrio cholerae, has been associated with consumption of contaminated seafood, including raw oysters. Detection of V. cholerae in foods typically involves blending the oysters, diluting the homogenate in alkaline peptone water (APW), overnight enrichment, and isolation on selective agar. Unfortunately, the oyster homogenate must be diluted to large volumes because lower dilutions inhibit the growth of V. cholerae. The goals of this study were to develop an alternative to large dilutions and to evaluate the basis for the inhibition observed in lower dilutions of oyster homogenates. Centrifugation of oyster homogenates at 10,000 x g for 15 min, followed by enrichment of the resulting pellet in APW, was found to eliminate the inhibition of V. cholerae growth. Inhibition appears not to be due to competing microflora but to a component(s) released when V. cholerae grows in the presence of oyster homogenate. The inhibitory component(s) kills the V. cholerae after the cell concentration reaches > 10(exp 8) cells/mL, rather than initially preventing their growth. The pH also declines from 8.0 to 5.5 during this period; however, the pH decline by itself appears not to cause V. cholerae death. Seven strains of V. cholerae (01 and non-01) and two strains of V. vulnificus were susceptible to the inhibitory agent(s). However, other Vibrio and non-Vibrio species tested were not inhibited by the oyster homogenates. Based on digestion of oyster homogenates with pronase, trypsin and lipase, the inhibitory reaction involves a protein(s). In a preliminary trial with oyster homogenate seeded with 1 cfu/g of V. cholerae, the modified centrifugation technique detected a slightly higher percentage of samples at a 1:10 dilution than the standard FDA Bacteriological Analytical Method (BAM) detected in uncentrifuged oyster homogenate at a 1:100 dilution. V. cholerae in seeded samples could also be detected more frequently by the modified centrifugation method than by PCR at a 1:10 dilution.

Mortalities of Eastern and Pacific oyster Larvae caused by the pathogens Vibrio coralliilyticus and Vibrio tubiashii.

PubMed

Richards, Gary P; Watson, Michael A; Needleman, David S; Church, Karlee M; Häse, Claudia C

2015-01-01

Vibrio tubiashii is 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 of V. coralliilyticus, such as ATCC 19105 and Pacific isolates RE22 and RE98, were misidentified as V. tubiashii until recently. We compared the mortalities caused by two V. tubiashii and four V. coralliilyticus strains in Eastern and Pacific oyster larvae. The 50% lethal dose (LD50) of V. coralliilyticus in Eastern oysters (defined here as the dose required to kill 50% of the population in 6 days) ranged from 1.1 × 10(4) to 3.0 × 10(4) CFU/ml seawater; strains RE98 and RE22 were the most virulent. This study shows that V. coralliilyticus causes mortality in Eastern oyster larvae. Results for Pacific oysters were similar, with LD50s between 1.2 × 10(4) and 4.0 × 10(4) CFU/ml. Vibrio tubiashii ATCC 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 × 10(4) CFU/ml. These data, coupled with the fact that several isolates originally thought to be V. tubiashii are actually V. coralliilyticus, suggest that V. coralliilyticus has been a more significant pathogen for larval bivalve shellfish than V. tubiashii, particularly on the U.S. West Coast, contributing to substantial hatchery-associated morbidity and mortality in recent years. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Drought Increases Consumer Pressure on Oyster Reefs in Florida, USA

PubMed Central

Garland, Hanna G.; Kimbro, David L.

2015-01-01

Coastal economies and ecosystems have historically depended on oyster reefs, but this habitat has declined globally by 85% because of anthropogenic activities. In a Florida estuary, we investigated the cause of newly reported losses of oysters. We found that the oyster reefs have deteriorated from north to south and that this deterioration was positively correlated with the abundance of carnivorous conchs and water salinity. In experiments across these gradients, oysters survived regardless of salinity if conchs were excluded. After determining that conchs were the proximal cause of oyster loss, we tested whether elevated water salinity was linked to conch abundance either by increasing conch growth and survivorship or by decreasing the abundance of a predator of conchs. In field experiments across a salinity gradient, we failed to detect spatial variation in predation on conchs or in conch growth and survivorship. A laboratory experiment, however, demonstrated the role of salinity by showing that conch larvae failed to survive at low salinities. Because this estuary’s salinity increased in 2006 in response to reduced inputs of freshwater, we concluded that the ultimate cause of oyster decline was an increase in salinity. According to records from 2002 to 2012, oyster harvests have remained steady in the northernmost estuaries of this ecoregion (characterized by high reef biomass, low salinity, and low conch abundance) but have declined in the southernmost estuaries (characterized by lower reef biomass, increases in salinity, and increases in conch abundance). Oyster conservation in this ecoregion, which is probably one of the few that still support viable oyster populations, may be undermined by drought-induced increases in salinity causing an increased abundance of carnivorous conchs. PMID:26275296

Contrasting impacts of ocean acidification and warming on the molecular responses of CO2-resilient oysters.

PubMed

Goncalves, Priscila; Thompson, Emma L; Raftos, David A

2017-06-02

This study characterises the molecular processes altered by both elevated CO 2 and increasing temperature in oysters. Differences in resilience of marine organisms against the environmental stressors associated with climate change will have significant implications for the sustainability of coastal ecosystems worldwide. Some evidence suggests that climate change resilience can differ between populations within a species. B2 oysters represent a unique genetic resource because of their capacity to better withstand the impacts of elevated CO 2 at the physiological level, compared to non-selected oysters from the same species (Saccostrea glomerata). Here, we used proteomic and transcriptomic analysis of gill tissue to evaluate whether the differential response of B2 oysters to elevated CO 2 also extends to increased temperature. Substantial and distinctive effects on protein concentrations and gene expression were evident among B2 oysters responding to elevated CO 2 or elevated temperature. The combination of both stressors also altered oyster gill proteomes and gene expression. However, the impacts of elevated CO 2 and temperature were not additive or synergistic, and may be antagonistic. The data suggest that the simultaneous exposure of CO 2 -resilient oysters to near-future projected ocean pH and temperature results in complex changes in molecular processes in order to prevent stress-induced cellular damage. The differential response of B2 oysters to the combined stressors also indicates that the addition of thermal stress may impair the resilience of these oysters to decreased pH. Overall, this study reveals the intracellular mechanisms that might enable marine calcifiers to endure the emergent, adverse seawater conditions resulting from climate change.

The Antimicrobial Defense of the Pacific Oyster, Crassostrea gigas. How Diversity may Compensate for Scarcity in the Regulation of Resident/Pathogenic Microflora

PubMed Central

Schmitt, Paulina; Rosa, Rafael Diego; Duperthuy, Marylise; de Lorgeril, Julien; Bachère, Evelyne; Destoumieux-Garzón, Delphine

2012-01-01

Healthy oysters are inhabited by abundant microbial communities that vary with environmental conditions and coexist with immunocompetent cells in the circulatory system. In Crassostrea gigas oysters, the antimicrobial response, which is believed to control pathogens and commensals, relies on potent oxygen-dependent reactions and on antimicrobial peptides/proteins (AMPs) produced at low concentrations by epithelial cells and/or circulating hemocytes. In non-diseased oysters, hemocytes express basal levels of defensins (Cg-Defs) and proline-rich peptides (Cg-Prps). When the bacterial load dramatically increases in oyster tissues, both AMP families are driven to sites of infection by major hemocyte movements, together with bactericidal permeability/increasing proteins (Cg-BPIs) and given forms of big defensins (Cg-BigDef), whose expression in hemocytes is induced by infection. Co-localization of AMPs at sites of infection could be determinant in limiting invasion as synergies take place between peptide families, a phenomenon which is potentiated by the considerable diversity of AMP sequences. Besides, diversity occurs at the level of oyster AMP mechanisms of action, which range from membrane lysis for Cg-BPI to inhibition of metabolic pathways for Cg-Defs. The combination of such different mechanisms of action may account for the synergistic activities observed and compensate for the low peptide concentrations in C. gigas cells and tissues. To overcome the oyster antimicrobial response, oyster pathogens have developed subtle mechanisms of resistance and evasion. Thus, some Vibrio strains pathogenic for oysters are equipped with AMP-sensing systems that trigger resistance. More generally, the known oyster pathogenic vibrios have evolved strategies to evade intracellular killing through phagocytosis and the associated oxidative burst. PMID:22783227

Molecular analysis of an oyster-related norovirus outbreak.

PubMed

Nenonen, Nancy P; Hannoun, Charles; Olsson, Margareta B; Bergström, Tomas

2009-06-01

Contaminated raw oysters were implicated in a severe outbreak of norovirus (NoV) gastroenteritis affecting 30 restaurant guests. To define the outbreak source by using molecular methods to characterize NoV strains detected in patient and oyster samples. Molecular epidemiological studies based on nucleotide sequencing and phylogenetic analyses of patient and oyster NoV strains, and comparison to background dataset. NoV genotype (G) I.1 was detected in the one patient stool analyzed by in-house TaqMan real time RT-PCR and classical nested RT-PCR targeting NoV RNA-dependent polymerase (RdRp, 285 nt), and by nested RT-PCR targeting RdRp-capsid-poly(A)-3' (3085 nt). Patient strain showed >or=99% similarity (285 nt) with three NoV strains detected in two of five oysters examined by classical nested RT-PCR (RdRp). A third oyster tested positive for NoV GII.3. Phylogenetic analysis showed clustering of patient and oyster strains related to this outbreak with GI.1 strains from previous local outbreaks, and mussel studies. Sequence data revealed >or=99% similarity (285 nt) between NoV GI.1 strains detected in patient stool and suspect oysters, linking the contaminated oysters to the outbreak. Identification of human NoV GI and GII strains in oysters indicated contamination of human fecal origin, presumably from inappropriate storage in the harbor. Comparative long-fragment analysis of the patient strain revealed 99% similarity (3085 nt) with NoV GI.1 strains detected in previous outbreaks and environmental mussel studies from West Sweden, 87% with M87661 (Norwalk68) and 96% with L23828 (SRSV-KY-89/89/J). These results indicated considerable genomic stability of NoV GI.1 strains over time.

Development and validation of a predictive model for the growth of Vibrio parahaemolyticus in post-harvest shellstock oysters.

PubMed

Parveen, Salina; DaSilva, Ligia; DePaola, Angelo; Bowers, John; White, Chanelle; Munasinghe, Kumudini Apsara; Brohawn, Kathy; Mudoh, Meshack; Tamplin, Mark

2013-01-15

Information is limited about the growth and survival of naturally-occurring Vibrio parahaemolyticus in live oysters under commercially relevant storage conditions harvested from different regions and in different oyster species. This study produced a predictive model for the growth of naturally-occurring V. parahaemolyticus in live Eastern oysters (Crassostrea virginica) harvested from the Chesapeake Bay, MD, USA and stored at 5-30 °C until oysters gapped. The model was validated with model-independent data collected from Eastern oysters harvested from the Chesapeake Bay and Mobile Bay, AL, USA and Asian (C. ariakensis) oysters from the Chesapeake Bay, VA, USA. The effect of harvest season, region and water condition on growth rate (GR) was also tested. At each time interval, two samples consisting of six oysters each were analyzed by a direct-plating method for total V. parahaemolyticus. The Baranyi D-model was fitted to the total V. parahaemolyticus growth and survival data. A secondary model was produced using the square root model. V. parahaemolyticus slowly inactivated at 5 and 10 °C with average rates of -0.002 and -0.001 log cfu/h, respectively. The average GRs at 15, 20, 25, and 30 °C were 0.038, 0.082, 0.228, and 0.219 log cfu/h, respectively. The bias and accuracy factors of the secondary model for model-independent data were 1.36 and 1.46 for Eastern oysters from Mobile Bay and the Chesapeake Bay, respectively. V. parahaemolyticus GRs were markedly lower in Asian oysters. Harvest temperature, salinity, region and season had no effect on GRs. The observed GRs were less than those predicted by the U.S. Food and Drug Administration's V. parahaemolyticus quantitative risk assessment. Copyright © 2012 Elsevier B.V. All rights reserved.

Development and validation of a predictive model for the growth of Vibrio vulnificus in postharvest shellstock oysters.

PubMed

DaSilva, Ligia; Parveen, Salina; DePaola, Angelo; Bowers, John; Brohawn, Kathy; Tamplin, Mark L

2012-03-01

Postharvest growth of Vibrio vulnificus in oysters can increase risk of human infection. Unfortunately, limited information is available regarding V. vulnificus growth and survival patterns over a wide range of storage temperatures in oysters harvested from different estuaries and in different oyster species. In this study, we developed a predictive model for V. vulnificus growth in Eastern oysters (Crassostrea virginica) harvested from Chesapeake Bay, MD, over a temperature range of 5 to 30°C and then validated the model against V. vulnificus growth rates (GRs) in Eastern and Asian oysters (Crassostrea ariakensis) harvested from Mobile Bay, AL, and Chesapeake Bay, VA, respectively. In the model development studies, V. vulnificus was slowly inactivated at 5 and 10°C with average GRs of -0.0045 and -0.0043 log most probable number (MPN)/h, respectively. Estimated average growth rates at 15, 20, 25, and 30°C were 0.022, 0.042, 0.087, and 0.093 log MPN/h, respectively. With respect to Eastern oysters, bias (B(f)) and accuracy (A(f)) factors for model-dependent and -independent data were 1.02 and 1.25 and 1.67 and 1.98, respectively. For Asian oysters, B(f) and A(f) were 0.29 and 3.40. Residual variations in growth rate about the fitted model were not explained by season, region, water temperature, or salinity at harvest. Growth rate estimates for Chesapeake Bay and Mobile Bay oysters stored at 25 and 30°C showed relatively high variability and were lower than Food and Agricultural Organization (FAO)/WHO V. vulnificus quantitative risk assessment model predictions. The model provides an improved tool for designing and implementing food safety plans that minimize the risk associated with V. vulnificus in oysters.

[Comparison of two nucleic acid extraction methods for norovirus in oysters].

PubMed

Yuan, Qiao; Li, Hui; Deng, Xiaoling; Mo, Yanling; Fang, Ling; Ke, Changwen

2013-04-01

To explore a convenient and effective method for norovirus nucleic acid extraction from oysters suitable for long-term viral surveillance. Two methods, namely method A (glycine washing and polyethylene glycol precipitation of the virus followed by silica gel centrifugal column) and method B (protease K digestion followed by application of paramagnetic silicon) were compared for their performance in norovirus nucleic acid extraction from oysters. Real-time RT-PCR was used to detect norovirus in naturally infected oysters and in oysters with induced infection. The two methods yielded comparable positive detection rates for the samples, but the recovery rate of the virus was higher with method B than with method A. Method B is a more convenient and rapid method for norovirus nucleic acid extraction from oysters and suitable for long-term surveillance of norovirus.

Radiation resistances and decontamination of common pathogenic bacteria contaminated in white scar oyster ( Crassostrea belcheri) in Thailand

NASA Astrophysics Data System (ADS)

Thupila, Nunticha; Ratana-arporn, Pattama; Wilaipun, Pongtep

2011-07-01

In Thailand, white scar oyster ( Crassostrea belcheri) was ranked for premium quality, being most expensive and of high demand. This oyster is often eaten raw, hence it may pose health hazards to consumers when contaminated with food-borne pathogens. As limited alternative methods are available to sterilize the oyster while preserving the raw characteristic, irradiation may be considered as an effective method for decontamination. In this study, the radiation resistance of pathogenic bacteria commonly contaminating the oyster and the optimum irradiation doses for sterilization of the most radiation resistant bacteria were investigated. The radiation decimal reduction doses ( D10) of Salmonella Weltevreden DMST 33380, Vibrio parahaemolyticus ATCC 17802 and Vibrio vulnificus DMST 5852 were determined in broth culture and inoculated oyster homogenate. The D10 values of S. Weltevreden, V. parahaemolyticus and V. vulnificus in broth culture were 0.154, 0.132 and 0.059 kGy, while those of inoculated oyster homogenate were 0.330, 0.159 and 0.140 kGy, respectively. It was found that among the pathogens tested, S. Weltevreden was proved to be the most resistant species. An irradiation dose of 1.5 kGy reduced the counts of 10 5 CFU/g S. Weltevreden inoculated in oyster meat to an undetectable level. The present study indicated that a low-dose irradiation can improve the microbial quality of oyster and further reduce the risks from the food-borne pathogens without adversely affecting the sensory attributes.

Combined effects of temperature acclimation and cadmium exposure on mitochondrial function in eastern oysters Crassostrea virginica gmelin (Bivalvia: Ostreidae).

PubMed

Cherkasov, Anton S; Ringwood, Amy H; Sokolova, Inna M

2006-09-01

Cadmium and temperature have strong impacts on the metabolic physiology of aquatic organisms. To analyze the combined impact of these two stressors on aerobic capacity, effects of Cd exposure (50 microg/L) on mitochondrial function were studied in oysters (Crassostrea virginica) acclimated to 12 and 20 degrees C in winter and to 20 and 28 degrees C in fall. Cadmium exposure had different effects on mitochondrial bioenergetics of oysters depending on the acclimation temperature. In oysters acclimated to 12 degrees C, Cd exposure resulted in elevated intrinsic rates of mitochondrial oxidation, whereas at 28 degrees C, a rapid and pronounced decrease of mitochondrial oxidative capacity was found in Cd-exposed oysters. At the intermediate acclimation temperature (20 degrees C), effects of Cd exposure on intrinsic rates of mitochondrial oxidation were negligible. Degree of coupling significantly decreased in mitochondria from 28 degrees C-acclimated oysters but not in that from 12 degrees C- or 20 degrees C-acclimated oysters. Acclimation at elevated temperatures also increased sensitivity of oyster mitochondria to extramitochondrial Cd. Variation in mitochondrial membrane potential explained 41% of the observed variation in mitochondrial adenosine triphosphate synthesis and proton leak between different acclimation groups of oysters. Temperature-dependent sensitivity of metabolic physiology to Cd has significant implications for toxicity testing and for extrapolation of laboratory studies to field populations of aquatic poikilotherms, indicating the importance of taking into account the thermal regime of the environment.

Growth and yield performance of Pleurotus ostreatus (Jacq. Fr.) Kumm (oyster mushroom) on different substrates.

PubMed

Girmay, Zenebe; Gorems, Weldesemayat; Birhanu, Getachew; Zewdie, Solomon

2016-12-01

Mushroom cultivation is reported as an economically viable bio-technology process for conversion of various lignocellulosic wastes. Given the lack of technology know-how on the cultivation of mushroom, this study was conducted in Wondo Genet College of Forestry and Natural Resource, with the aim to assess the suitability of selected substrates (agricultural and/or forest wastes) for oyster mushroom cultivation. Accordingly, four substrates (cotton seed, paper waste, wheat straw, and sawdust) were tested for their efficacy in oyster mushroom production. Pure culture of oyster mushroom was obtained from Mycology laboratory, Department of Plant Biology and Biodiversity Management, Addis Ababa University. The pure culture was inoculated on potato dextrose agar for spawn preparation. Then, the spawn containing sorghum was inoculated with the fungal culture for the formation of fruiting bodies on the agricultural wastes. The oyster mushroom cultivation was undertaken under aseptic conditions, and the growth and development of mushroom were monitored daily. Results of the study revealed that oyster mushroom can grow on cotton seed, paper waste, sawdust and wheat straw, with varying growth performances. The highest biological and economic yield, as well as the highest percentage of biological efficiency of oyster mushroom was obtained from cotton seed, while the least was from sawdust. The study recommends cotton seed, followed by paper waste as suitable substrates for the cultivation of oyster mushroom. It also suggests that there is a need for further investigation on various aspects of oyster mushroom cultivation in Ethiopia to promote the industry.

Impacts of upstream drought and water withdrawals on the health and survival of downstream estuarine oyster populations

PubMed Central

Petes, Laura E; Brown, Alicia J; Knight, Carley R

2012-01-01

Increases in the frequency, duration, and severity of regional drought pose major threats to the health and integrity of downstream ecosystems. During 2007–2008, the U.S. southeast experienced one of the most severe droughts on record. Drought and water withdrawals in the upstream watershed led to decreased freshwater input to Apalachicola Bay, Florida, an estuary that is home to a diversity of commercially and ecologically important organisms. This study applied a combination of laboratory experiments and field observations to investigate the effects of reduced freshwater input on Apalachicola oysters. Oysters suffered significant disease-related mortality under high-salinity, drought conditions, particularly during the warm summer months. Mortality was size-specific, with large oysters of commercially harvestable size being more susceptible than small oysters. A potential salinity threshold was revealed between 17 and 25 ppt, where small oysters began to suffer mortality, and large oysters exhibited an increase in mortality. These findings have important implications for watershed management, because upstream freshwater releases could be carefully timed and allocated during stressful periods of the summer to reduce disease-related oyster mortality. Integrated, forward-looking water management is needed, particularly under future scenarios of climate change and human population growth, to sustain the valuable ecosystem services on which humans depend. PMID:22957175

Angiotensin I-Converting Enzyme Inhibitor Derived from Cross-Linked Oyster Protein

PubMed Central

Xie, Cheng-Liang; Kim, Jin-Soo; Ha, Jong-Myung; Choung, Se-Young

2014-01-01

Following cross-linking by microbial transglutaminase, modified oyster proteins were hydrolyzed to improve inhibitory activity against angiotensin-converting enzyme (ACE) inhibitory activity with the use of a single protease, or a combination of six proteases. The oyster hydrolysate with the lowest 50% ACE inhibitory concentration (IC50) of 0.40 mg/mL was obtained by two-step hydrolysis of the cross-linked oyster protein using Protamex and Neutrase. Five ACE inhibitory peptides were purified from the oyster hydrolysate using a multistep chromatographic procedure comprised of ion-exchange, size exclusion, and reversed-phase liquid chromatography. Their sequences were identified as TAY, VK, KY, FYN, and YA, using automated Edman degradation and mass spectrometry. These peptides were synthesized, and their IC50 values were measured to be 16.7, 29.0, 51.5, 68.2, and 93.9 μM, respectively. Toxicity of the peptides on the HepG2 cell line was not detected. The oyster hydrolysate also significantly decreased the systolic blood pressure of spontaneously hypertensive rats (SHR). The antihypertensive effect of the oyster hydrolysate on SHR was rapid and long-lasting, compared to commercially obtained sardine hydrolysate. These results suggest that the oyster hydrolysate could be a source of effective nutraceuticals against hypertension. PMID:25140307

A PCR-based diagnostic assay for the detection of Roseovarius crassostreae in Crassostrea virginica affected by juvenile oyster disease (JOD)

USGS Publications Warehouse

Maloy, A.P.; Barber, B.J.; Boettcher, K.J.

2005-01-01

We have developed a PCR-assay for the diagnosis of juvenile oyster disease (JOD) based on the detection of Roseovarius crassostreae directly from affected oysters. Species-specific primers are used to amplify the 16S-23S rDNA internal transcribed spacer (ITS) of R. crassostreae, and confirmation of product identity is accomplished by restriction enzyme analysis. No false positives were obtained with either closely related bacterial species or from other DNAs present in oyster samples. The assay has the potential to detect as few as 10 cells of R. crassostreae per oyster when samples are taken from the inner valve surfaces of the animal. Inclusion of material from soft body surfaces is not necessary, and may reduce sensitivity approximately 10-fold. In a JOD-affected population, a positive PCR result was obtained from all oysters from which these bacteria were subsequently cultured. The assay also detected the presence of R. crassostreae in 2 oysters from which no R. crassostreae isolates were recovered. No R. crassostreae was detected by either PCR or bacteriology in oysters from a population that was not exhibiting JOD-signs. This assay is expected to advance regional disease management efforts and provide valuable insights into the disease process and epizootiology of JOD. ?? Inter-Research 2005.

The role of tissue-specific microbiota in initial establishment success of Pacific oysters.

PubMed

Lokmer, Ana; Kuenzel, Sven; Baines, John F; Wegner, Karl Mathias

2016-03-01

Microbiota can have positive and negative effects on hosts depending on the environmental conditions. Therefore, it is important to decipher host-microbiota-environment interactions, especially under natural conditions exerting (a)biotic stress. Here, we assess the relative importance of microbiota in different tissues of Pacific oyster for its successful establishment in a new environment. We transplanted oysters from the Southern to the Northern Wadden Sea and controlled for the effects of resident microbiota by administering antibiotics to half of the oysters. We then followed survival and composition of haemolymph, mantle, gill and gut microbiota in local and translocated oysters over 5 days. High mortality was recorded only in non-antibiotic-treated translocated oysters, where high titres of active Vibrio sp. in solid tissues indicated systemic infections. Network analyses revealed the highest connectivity and a link to seawater communities in the haemolymph microbiota. Since antibiotics decreased modularity and increased connectivity of the haemolymph-based networks, we propose that community destabilization in non-treated translocated oysters could be attributed to interactions between resident and external microbiota, which in turn facilitated passage of vibrios into solid tissues and invoked disease. These interactions of haemolymph microbiota with the external and internal environment may thus represent an important component of oyster fitness. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Salinity Tolerance of Early-Stage Oyster Larvae in the Choptank River, Chesapeake Bay, USA

NASA Astrophysics Data System (ADS)

Scharping, R. J.; North, E. W.; Plough, L. V.

2016-02-01

The eastern oyster (Crassostrea virginica) is ecologically and economically important to the Chesapeake Bay, Maryland, USA. Its population, however, is currently estimated to be less than one percent of what it was historically. To restore oyster populations, techniques such as larval transport modeling are being implemented to aid the selection of sanctuary locations. These models can incorporate biological factors such as salinity-induced mortality, but no data from low-salinity areas such as the oligohaline Choptank River, a major focus of oyster restoration in the Chesapeake, exist. The purpose of our study was to generate salinity-induced mortality data for oyster larvae from the Choptank River and compare their tolerances to those of oysters from different salinity regimes. We performed three experiments looking at the effect of salinities from 3 to 26 on the survival of larvae from 4 to 48 hrs post-fertilization. While overall survival differed across experiments, we found a consistent minimum survival threshold between 5-7 and peak survival window between 9-16. These salinity values were about 7 lower than those of oysters from the polyhaline Long Island Sound (threshold: 12.5-15; peak: 17.5-27). This research has direct application to oyster restoration in the Choptank River and similar low-salinity areas by improving larval transport model predictions.

Persistence, Seasonal Dynamics and Pathogenic Potential of Vibrio Communities from Pacific Oyster Hemolymph

PubMed Central

Wendling, Carolin C.; Batista, Frederico M.; Wegner, K. Mathias

2014-01-01

Bacteria of the genus Vibrio occur at a continuum from free-living to symbiotic life forms, including opportunists and pathogens, that can contribute to severe diseases, for instance summer mortality events of Pacific oysters Crassostrea gigas. While most studies focused on Vibrio isolated from moribund oysters during mortality outbreaks, investigations of the Vibrio community in healthy oysters are rare. Therefore, we characterized the persistence, diversity, seasonal dynamics, and pathogenicity of the Vibrio community isolated from healthy Pacific oysters. In a reciprocal transplant experiment we repeatedly sampled hemolymph from adult Pacific oysters to differentiate population from site-specific effects during six months of in situ incubation in the field. We characterized virulence phenotypes and genomic diversity based on multilocus sequence typing in a total of 70 Vibrio strains. Based on controlled infection experiments we could show that strains with the ability to colonize healthy adult oysters can also have the potential to induce high mortality rates on larvae. Diversity and abundance of Vibrio varied significantly over time with highest values during and after spawning season. Vibrio communities from transplanted and stationary oysters converged over time, indicating that communities were not population specific, but rather assemble from the surrounding environment forming communities, some of which can persist over longer periods. PMID:24728233

Parasites infecting the cultured oyster Crassostrea gasar (Adanson, 1757) in Northeast Brazil.

PubMed

Queiroga, Fernando Ramos; Vianna, Rogério Tubino; Vieira, Cairé Barreto; Farias, Natanael Dantas; Da Silva, Patricia Mirella

2015-05-01

The oyster Crassostrea gasar is a species widely used as food and a source of income for the local population of the estuaries of Northeast Brazil. Perkinsus marinus and Perkinsus olseni are deleterious parasites for oyster farming and were recently detected in Brazil. In this study, a histopathologic survey of the oyster C. gasar cultured in the estuary of the River Mamanguape (Paraíba State) was performed. Adult oysters were collected in December 2011 and March, May, August and October 2012 and processed for histology and Perkinsus sp. identification by molecular analyses. Histopathological analysis revealed the presence of parasitic organisms including viral gametocytic hypertrophy, prokaryote-like colonies, protozoans (Perkinsus sp. and Nematopsis sp.) and metazoans (Tylocephalum sp. and cestodes). Other commensal organisms were also detected (the protozoan Ancistrocoma sp. and the turbellarian Urastoma sp.). The protozoan parasite Perkinsus sp. had the highest overall prevalence among the symbiotic organisms studied (48.9%), followed by Nematopsis sp. (36.3%). The other organisms were only sporadically observed. Only the protozoan Perkinsus sp. caused alterations in the oysters' infected organs. Molecular analyses confirmed the presence of P. marinus, P. olseni and Perkinsus beihaiensis infecting the oyster C. gasar. This is the first report of P. beihaiensis in this oyster species.

[Shellfish monitoring system for paralytic shellfish toxins using enzyme-linked immunosorbent assay].

PubMed

Shinozaki, Takashi; Watanabe, Ryuichi; Kawatsu, Kentaro; Sakurada, Kiyonari; Takahi, Shinya; Ueno, Ken-ichi; Matsushima, Ryoji; Suzuki, Toshiyuki

2013-01-01

We investigated the applicability of enzyme-linked immunosorbent assay (PSP-ELISA) using a monoclonal antibody against paralytic shellfish toxins (PST) for screening oysters collected at several coastal areas in Kumamoto prefecture, Japan. Oysters collected between 2007 and 2010 were analyzed by PSP-ELISA. As an alternative calibrant, a naturally contaminated oyster extract was used to quantify toxins in the oyster samples. The toxicity of the calibrant oyster extract determined by the official testing method, mouse bioassay (MBA), was 4 MU/g. Oyster samples collected over 3 years showed a similar toxin profile to the alternative standard, resulting in good agreement between the PSP-ELISA and the MBA. The PSP-ELISA method was better than the MBA in terms of sensitivity, indicating that it may be useful for earlier warning of contamination of oysters by PST in the distinct coastal areas. To use the PSP-ELISA as a screening method prior to MBA, we finally set a screening level at 2 MU/g PSP-ELISA for oyster monitoring in Kumamoto prefecture. We confirmed that there were on samples exceeding the quarantine level (4 MU/g) in MBA among samples quantified as below the screening level by the PSP-ELISA. It was concluded that the use of PSP-ELISA could reduce the numbers of animals needed for MBA testing.

Laboratory investigations of the effects of predator sex and size on prey selection by the Asian crab, Hemigrapsus sanguineus.

PubMed

Brousseau, D J.; Filipowicz, A; Baglivo, J A.

2001-07-30

Laboratory studies have shown that the nonindigenous Asian shore crab, Hemigrapsus sanguineus, readily consumes three species of commercial bivalves: blue mussels, Mytilus edulis, soft-shell clams, Mya arenaria, and oysters, Crassostrea virginica. Although crabs can eat bivalves of a wide size range, they preferred the smaller prey (

Spatial and Temporal Dynamics of Mass Mortalities in Oysters Is Influenced by Energetic Reserves and Food Quality

PubMed Central

Pernet, Fabrice; Lagarde, Franck; Jeannée, Nicolas; Daigle, Gaetan; Barret, Jean; Le Gall, Patrik; Quere, Claudie; D’orbcastel, Emmanuelle Roque

2014-01-01

Although spatial studies of diseases on land have a long history, far fewer have been made on aquatic diseases. Here, we present the first large-scale, high-resolution spatial and temporal representation of a mass mortality phenomenon cause by the Ostreid herpesvirus (OsHV-1) that has affected oysters (Crassostrea gigas) every year since 2008, in relation to their energetic reserves and the quality of their food. Disease mortality was investigated in healthy oysters deployed at 106 locations in the Thau Mediterranean lagoon before the start of the epizootic in spring 2011. We found that disease mortality of oysters showed strong spatial dependence clearly reflecting the epizootic process of local transmission. Disease initiated inside oyster farms spread rapidly beyond these areas. Local differences in energetic condition of oysters, partly driven by variation in food quality, played a significant role in the spatial and temporal dynamics of disease mortality. In particular, the relative contribution of diatoms to the diet of oysters was positively correlated with their energetic reserves, which in turn decreased the risk of disease mortality. PMID:24551106

Spatial and temporal dynamics of mass mortalities in oysters is influenced by energetic reserves and food quality.

PubMed

Pernet, Fabrice; Lagarde, Franck; Jeannée, Nicolas; Daigle, Gaetan; Barret, Jean; Le Gall, Patrik; Quere, Claudie; D'orbcastel, Emmanuelle Roque

2014-01-01

Although spatial studies of diseases on land have a long history, far fewer have been made on aquatic diseases. Here, we present the first large-scale, high-resolution spatial and temporal representation of a mass mortality phenomenon cause by the Ostreid herpesvirus (OsHV-1) that has affected oysters (Crassostrea gigas) every year since 2008, in relation to their energetic reserves and the quality of their food. Disease mortality was investigated in healthy oysters deployed at 106 locations in the Thau Mediterranean lagoon before the start of the epizootic in spring 2011. We found that disease mortality of oysters showed strong spatial dependence clearly reflecting the epizootic process of local transmission. Disease initiated inside oyster farms spread rapidly beyond these areas. Local differences in energetic condition of oysters, partly driven by variation in food quality, played a significant role in the spatial and temporal dynamics of disease mortality. In particular, the relative contribution of diatoms to the diet of oysters was positively correlated with their energetic reserves, which in turn decreased the risk of disease mortality.

INFLUENCE OF ALTERED FRESHWATER FLOWS ON EASTERN OYSTERS

EPA Science Inventory

Abstract for National Shellfisheries Association

Eastern oysters Crassostrea virginica are prominent in Gulf of Mexico estuaries. Valued both commercially and ecologically, oyster populations are threatened by human activity, including dredging, harvesting, and upstream al...

Calculation of Oyster Benefits with a Bioenergetics Model of the Virginia Oyster

DTIC Science & Technology

2014-11-01

White, M., Powell. E., and Ray, S. (1988). “Effects of parasitism by the pyramidellid gastropod Boonea impressa on the net productivity of oysters...Effects of parasitism by the pyramidellid gastropod Boonea impressa on the net productivity of oysters (Crassostrea viginica),” Estuarine Coastal...Wisconsin Fish Model (Hanson et al. 1997) and was adapted for a model of Atlantic menhaden in Chesapeake Bay (Dalyander and Cerco 2010). Subsequent

Bioaccumulation of heavy metals in oysters from the southern coast of Korea: assessment of potential risk to human health.

PubMed

Mok, Jong Soo; Yoo, Hyun Duk; Kim, Poong Ho; Yoon, Ho Dong; Park, Young Cheol; Lee, Tae Seek; Kwon, Ji Young; Son, Kwang Tae; Lee, Hee Jung; Ha, Kwang Soo; Shim, Kil Bo; Kim, Ji Hoe

2015-06-01

From 2009 to 2013, 80 oyster and 16 seawater samples were collected from the southern coast of Korea, including designated shellfish growing areas for export. The concentrations and bioaccumulation of heavy metals were determined, and a potential risk assessment was conducted to evaluate their hazards towards human consumption. The cadmium (Cd) concentration in oysters was the highest of three hazardous metals, including Cd, lead (Pb), and mercury (Hg), however, below the standards set by various countries. The metal bioaccumulation ratio in oysters was relatively high for zinc and Cd but low for Hg, Pb, arsenic, and chromium. The estimated dietary intakes of all heavy metals for oysters accounted for 0.02%-17.75% of provisional tolerable daily intake. The hazard index for all samples was far <1.0, which indicates that the oysters do not pose an appreciable hazard to humans for the metal pollutants of study.

An outbreak of norovirus infection associated with fermented oyster consumption in South Korea, 2013.

PubMed

Cho, H G; Lee, S G; Lee, M Y; Hur, E S; Lee, J S; Park, P H; Park, Y B; Yoon, M H; Paik, S Y

2016-10-01

An acute gastroenteritis (AGE) outbreak was reported in May 2013 in Gyeonggi Province, South Korea. Eight students who had eaten breakfast on 21 May 2013 at a high-school restaurant exhibited AGE symptoms. Our case-control study showed that a strong association was observed between AGE symptoms and fermented oyster consumption. Virological studies also indicated that noroviruses (NoVs) were detected from both clinical samples and fermented oyster samples, and multiple different genotypes (genogroups GII.4, GII.11 and GII.14) of NoVs were present in both samples. The nucleotide sequence similarity between the strains found in the clinical samples and those in the fermented oysters was more than 99·5%. Therefore, to prevent further outbreaks, proper management of raw oysters is necessary and the food industry should be aware of the risk of viral gastroenteritis posed by fermented oysters contaminated with NoVs.

Offshore suspension relaying to reduce levels of Vibrio vulnificus in oysters (Crassostrea virginica).

PubMed

Motes, M L; DePaola, A

1996-10-01

Oysters naturally contaminated with 10(3) to 10(4) most probable numbers (MPN) of Vibrio vulnificus per g were relayed to offshore waters (salinity, 30 to 34 ppt), where they were suspended in racks at a depth of 7.6 m. V. vulnificus counts in oysters were reduced to < 10 MPN/g within 7 to 17 days in five of the six studies. At the end of the studies (17 to 49 days), V. vulnificus levels were reduced further and ranged from a mean of 0.23 to 2.6 MPN/g. Oyster mortalities during relaying were < 6%. The reduction of V. vulnificus in relayed oysters is associated with exposure to high-salinity environments essentially devoid of V. vulnificus. Offshore suspension relaying may be a method that industry can employ to reduce V. vulnificus levels in raw Gulf Coast oysters.

Determination and Quantification of metals in the shells of Crassostrea virginica after the Deepwater Horizon oil spill utilizing Atomic Absorption Spectrometry.

NASA Astrophysics Data System (ADS)

Roopnarine, D.; Patel, S.; Roopnarine, P.; Giarikos, D.; Anderson, L. C.

2017-12-01

The Deepwater Horizon (DWH) oil rig explosion on April 20, 2010 resulted in the release of 685,000 tons of crude oil into the Gulf of Mexico (GOM) over a period of three months. There were obvious immediate effects, but the long-term ramifications are still being studied. The primary constituent of crude oil is hydrocarbons with other organic compounds containing nitrogen, oxygen and sulfur. There are also a number of trace metals with the most abundant frequently being iron, nickel, copper and vanadium. These do not degrade like organic materials. However, the exact composition varies among the production sites. The oil from the DWH rig was classified as light crude which is moderately volatile. Natural oil seeps occur in the environment, but the DWH spill represented an acute impact. Trace amounts of heavy metals are a normal part of the composition of marine organisms, but can be toxic in high concentrations. Bivalved molluscs bioaccumulate heavy metals in their tissues and shells, and are therefore often useful as monitors of environmental pollution. We thus used the Eastern oyster Crassostrea virginica to determine the impact of the spill by measuring the concentrations of metals in the shells utilizing flame emission atomic absorption spectrometry. We focused on the hypothesis that DWH spill exposure resulted in an increase in metal uptake into the shells. Specimens spanned the years 2010 to 2014 and ranged from Grand Isle, LA to Apalachicola Bay, Fl. Vanadium had the greatest concentration in the shells, and along with copper, cadmium, zinc and iron displayed an upward trend of increase from 2010 to 2013, with a decline in 2014. However there was unexpected variability, as the specimens from Apalachicola Bay, Fl had higher levels of vanadium when compared to those from Grand Isle, LA. Ongoing work includes an increase of sample sizes from the same geographic localities and time period.

Apparent Loss of Vibrio vulnificus from North Carolina Oysters Coincides with a Drought-Induced Increase in Salinity

PubMed Central

Froelich, Brett A.; Williams, Tiffany C.; Noble, Rachel T.

2012-01-01

Despite years of successful isolation of Vibrio vulnificus from estuarine waters, beginning in 2007, it was extremely difficult to culture V. vulnificus from either North Carolina estuarine water or oyster samples. After employing culture-based methods as well as PCR and quantitative PCR for the detection of V. 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 with V. vulnificus and performing the same tests as those previously conducted on unadulterated oysters. V. vulnificus was readily detected in the seeded oysters using both classes of methods. Furthermore, oysters were obtained from the Gulf of Mexico, and V. vulnificus was easily isolated, confirming that the methodology was sound but that the oysters and waters of North Carolina were lacking the V. vulnificus population studied for decades. Strikingly, the apparent loss of detectable V. vulnificus coincided 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 with V. vulnificus being nearly nonexistent. When salinities returned to normal after the drought abated in 2010, we were again able to routinely isolate V. vulnificus from 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 displaced V. vulnificus and may be preventing recolonization. PMID:22447591

Apparent loss of Vibrio vulnificus from North Carolina oysters coincides with a drought-induced increase in salinity.

PubMed

Froelich, Brett A; Williams, Tiffany C; Noble, Rachel T; Oliver, James D

2012-06-01

Despite years of successful isolation of Vibrio vulnificus from estuarine waters, beginning in 2007, it was extremely difficult to culture V. vulnificus from either North Carolina estuarine water or oyster samples. After employing culture-based methods as well as PCR and quantitative PCR for the detection of V. 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 with V. vulnificus and performing the same tests as those previously conducted on unadulterated oysters. V. vulnificus was readily detected in the seeded oysters using both classes of methods. Furthermore, oysters were obtained from the Gulf of Mexico, and V. vulnificus was easily isolated, confirming that the methodology was sound but that the oysters and waters of North Carolina were lacking the V. vulnificus population studied for decades. Strikingly, the apparent loss of detectable V. vulnificus coincided 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 with V. vulnificus being nearly nonexistent. When salinities returned to normal after the drought abated in 2010, we were again able to routinely isolate V. vulnificus from 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 displaced V. vulnificus and may be preventing recolonization.

Neuropeptides encoded by the genomes of the Akoya pearl oyster Pinctata fucata and Pacific oyster Crassostrea gigas: a bioinformatic and peptidomic survey.

PubMed

Stewart, Michael J; Favrel, Pascal; Rotgans, Bronwyn A; Wang, Tianfang; Zhao, Min; Sohail, Manzar; O'Connor, Wayne A; Elizur, Abigail; Henry, Joel; Cummins, Scott F

2014-10-02

Oysters impart significant socio-ecological benefits from primary production of food supply, to estuarine ecosystems via reduction of water column nutrients, plankton and seston biomass. Little though is known at the molecular level of what genes are responsible for how oysters reproduce, filter nutrients, survive stressful physiological events and form reef communities. Neuropeptides represent a diverse class of chemical messengers, instrumental in orchestrating these complex physiological events in other species. By a combination of in silico data mining and peptide analysis of ganglia, 74 putative neuropeptide genes were identified from genome and transcriptome databases of the Akoya pearl oyster, Pinctata fucata and the Pacific oyster, Crassostrea gigas, encoding precursors for over 300 predicted bioactive peptide products, including three newly identified neuropeptide precursors PFGx8amide, RxIamide and Wx3Yamide. Our findings also include a gene for the gonadotropin-releasing hormone (GnRH) and two egg-laying hormones (ELH) which were identified from both oysters. Multiple sequence alignments and phylogenetic analysis supports similar global organization of these mature peptides. Computer-based peptide modeling of the molecular tertiary structures of ELH highlights the structural homologies within ELH family, which may facilitate ELH activity leading to the release of gametes. Our analysis demonstrates that oysters possess conserved molluscan neuropeptide domains and overall precursor organization whilst highlighting many previously unrecognized bivalve idiosyncrasies. This genomic analysis provides a solid foundation from which further studies aimed at the functional characterization of these molluscan neuropeptides can be conducted to further stimulate advances in understanding the ecology and cultivation of oysters.

Assessing shoreline exposure and oyster habitat suitability maximizes potential success for sustainable shoreline protection using restored oyster reefs

USGS Publications Warehouse

LaPeyre, Megan K.; Serra, Kayla; Joyner, T. Andrew; Humphries, Austin T.

2015-01-01

Oyster reefs provide valuable ecosystem services that contribute to coastal resilience. Unfortunately, many reefs have been degraded or removed completely, and there are increased efforts to restore oysters in many coastal areas. In particular, much attention has recently been given to the restoration of shellfish reefs along eroding shorelines to reduce erosion. Such fringing reef approaches, however, often lack empirical data to identify locations where reefs are most effective in reducing marsh erosion, or fully take into account habitat suitability. Using monitoring data from 5 separate fringing reef projects across coastal Louisiana, we quantify shoreline exposure (fetch + wind direction + wind speed) and reef impacts on shoreline retreat. Our results indicate that fringing oyster reefs have a higher impact on shoreline retreat at higher exposure shorelines. At higher exposures, fringing reefs reduced marsh edge erosion an average of 1.0 m y−1. Using these data, we identify ranges of shoreline exposure values where oyster reefs are most effective at reducing marsh edge erosion and apply this knowledge to a case study within one Louisiana estuary. In Breton Sound estuary, we calculate shoreline exposure at 500 random points and then overlay a habitat suitability index for oysters. This method and the resulting visualization show areas most likely to support sustainable oyster populations as well as significantly reduce shoreline erosion. Our results demonstrate how site selection criteria, which include shoreline exposure and habitat suitability, are critical to ensuring greater positive impacts and longevity of oyster reef restoration projects.

Overview and comparison of lipid-containing semipermeable membrane devices and oysters (Crassostrea gigas) for assessing organic chemical exposure

USGS Publications Warehouse

Huckins, J.N.; Prest, H.F.; Petty, J.D.; Lebo, J.A.; Hodgins, M.M.; Clark, R.C.; Alvarez, D.A.; Gala, W.R.; Steen, A.; Gale, R.; Ingersoll, C.G.

2004-01-01

We performed 20-d, flow-through exposures of lipid-containing semipermeable membrane devices (SPMDs) and Pacific oysters (Crassostrea gigas) to three concentrations (nominally 10, 100, and 250 ng/L) of a diverse mixture of polycyclic aromatic hydrocarbons (PAHs). Exposure water was seawater free of particulates larger than 0.1 μm. The results of these controlled laboratory studies demonstrated that SPMDs and oysters concentrate the same chemicals but that the relative amounts accumulated are different. For oysters, the 20-d mean (across treatments) concentration factors (CFs) of test compounds with log Kow ≤ 4.8 were much lower (4.0- to 20-fold lower) than those of the same compounds in SPMDs. In contrast, the 20-d CFs of PAHs with log Kow ≥ 5.6 in oysters from the low-level treatment were higher than the corresponding CFs for SPMDs. The CFs of these compounds in oysters from the low-level treatment ranged from approximately 3.0- to 13-fold higher than those in oysters from the high-level treatment. This physiologically mediated difference in oyster CFs appears to be linked to active feeding in the low-level treatment and to apparent toxicity-induced cessation of feeding (i.e., valve closure) in the high-level treatment. Because CFs for these compounds in oysters were not independent of exposure concentrations, it follows that tissue levels were not proportional to exposure concentration. However, both sampling approaches have advantages and disadvantages, and the appropriateness of their use depends on the goals of a given study.

Expression Characterization of Stress Genes Under High and Low Temperature Stresses in the Pacific Oyster, Crassostrea gigas.

PubMed

Zhu, Qihui; Zhang, Linlin; Li, Li; Que, Huayong; Zhang, Guofan

2016-04-01

As a characteristic sessile inhabitant of the intertidal zone, the Pacific oyster Crassostrea gigas occupies one of the most physically stressful environments on earth. With high exposure to terrestrial conditions, oysters must tolerate broad fluctuations in temperature range. However, oysters' cellular and molecular responses to temperature stresses have not been fully characterized. Here, we analyzed oyster transcriptome data under high and low temperatures. We also identified over 30 key temperature stress-responsive candidate genes, which encoded stress proteins such as heat shock proteins and apoptosis-associated proteins. The expression characterization of these genes under short-term cold and hot environments (5 and 35 °C) and long-term cold environments (5 °C) was detected by quantitative real-time PCR. Most of these genes reached expression peaks during the recovery stage after 24 h of heat stress, and these genes were greatly induced around day 3 in long-term cold stress while responded little to short-term cold stress. In addition, in the second heat stress after 2 days of recovery, oysters showed milder expression in these genes and a lower mortality rate, which indicated the existence of plasticity in the oyster's response to heat stress. We confirmed that homeostatic flexibility and anti-apoptosis might be crucial centers of temperature stress responses in oysters. Furthermore, we analyzed stress gene families in 11 different species and found that the linage-specific expansion of stress genes might be implicated in adaptive evolution. These results indicated that both plasticity and evolution played an important role in the stress response adaptation of oysters.

Baseline data for evaluating development trajectory and provision of ecosystem services of created fringing oyster reefs in Vermilion Bay, Louisiana

USGS Publications Warehouse

La Peyre, Megan K.; Schwarting, Lindsay; Miller, Shea

2013-01-01

Understanding the time frame in which ecosystem services (that is, water quality maintenance, shoreline protection, habitat provision) are expected to be provided is important when restoration projects are being designed and implemented. Restoration of three-dimensional shell habitats in coastal Louisiana and elsewhere presents a valuable and potentially self-sustaining approach to providing shoreline protection, enhancing nekton habitat, and providing water quality maintenance. As with most restoration projects, the development of expected different ecosystem services often occurs over varying time frames, with some services provided immediately and others taking longer to develop. This project was designed initially to compare the provision and development of ecosystem services by created fringing shoreline reefs in subtidal and intertidal environments in Vermilion Bay, Louisiana. Specifically, the goal was to test the null hypothesis that over time, the oyster recruitment and development of a sustainable oyster reef community would be similar at both intertidal and subtidal reef bases, and these sustainable reefs would in time provide similar shoreline stabilization, nekton habitat, and water quality services over similar time frames. Because the ecosystem services hypothesized to be provided by oyster reefs reflect long-term processes, fully testing the above-stated null hypothesis requires a longer-time frame than this project allowed. As such, this project was designed to provide the initial data on reef development and provision of ecosystem services, to identify services that may develop immediately, and to provide baseline data to allow for longer-term follow up studies tracking reef development over time. Unfortunately, these initially created reef bases (subtidal, intertidal) were not constructed as planned because of the Deepwater Horizon oil spill in April 2010, which resulted in reef duplicates being created 6 months apart. Further confounding the project were additional construction and restoration projects along the same shorelines which occurred between 2011 and June 2012. Because of constant activity near and around the reefs and continuing construction, development trajectories could not be compared among reef types at this time. This report presents the data collected at the sites over 3 years (2010–2012), describing only conditions and trends. In addition, these data provide an extensive and detailed dataset documenting initial conditions and initial ecosystem changes which will prove valuable in future data collection and analyses of reef development at this site. Data collection characterized the local water quality conditions (salinity, temperature, total suspended sediments, dissolved oxygen, chlorophyll a), adjacent marsh vegetation, soils, and shoreline position along the project shoreline at Vermilion Bay. During the study, marsh vegetation and soil characteristics were similar across the study area and did not change over time. Shoreline movement indicated shoreline loss at all sites, which varied by reefs. Water quality conditions followed expected seasonal patterns for this region, and no significant nonseasonal changes were measured throughout the study period. Despite oyster recruitment in fall 2010 and 2011, few if any oysters survived from the 2010 year class to 2012. At the last sampling of this project, some oysters recruited in fall 2011 survived through 2012, resulting in an on-reef density of 18.3 ± 2.1 individuals per square meter (mean size: 85.6 ± 2.2 millimeters). Because project goals were to compare reef development and provision of ecosystem services over time, as well as many of the processes identified for monitoring reflect long-term processes, results and data are presented only qualitatively, and trends or observations should be interpreted cautiously at this point. Measurable system responses to reef establishment require more time than was available for this study. These data provide a valuable baseline that can be ultimately used to help inform site selections for future restoration projects as well to further investigate the development trajectories of ecosystem provision of created reefs in this region.

Intracellular pH Recovery Rates of Hemocytes from Estuarine and Open Ocean Bivalve Species Following In vitro Acid Challenge

NASA Astrophysics Data System (ADS)

Croxton, A.; Wikfors, G.

2013-12-01

Decreasing pH in estuarine systems is a growing concern for researchers studying mollusk species. Debates continue on whether estuarine bivalve species are more or less vulnerable to ocean acidification than marine species because estuaries can present multiple environmental stressors. The aim of this study is to understand the homeostatic mechanisms of bivalve hemocytes following exposure to extracellular acid treatment. Previous measurements using fluorescent SNARF probes and flow-cytometry have determined the intracellular pH of hemocytes from several bivalve species (eastern oyster, bay scallop, northern quahog, soft-shell clam, and blue mussel) to range between 7.0-7.4. In the present study of four bivalve species, recovery rate profiles were determined for intracellular hemocyte pH following addition of acid to hemolymph in vitro. These profiles indicate that soft-shell clams and bay scallops maintained homeostasis with very little change in intracellular pH. In contrast, an initial drop in intracellular pH in northern quahogs was followed by a steady recovery of intracellular pH. Contrasting results between species appear to be unrelated to mineral shell composition (aragonite vs. calcite) or habitat location (infaunal vs. epifaunal). The next phase of this study will be to determine if offshore species (surfclams and sea scallops) will have similar responses. Results from these studies will provide a better understanding of the physiological responses of estuarine and marine species exposed to acidified environments.

Identification of molecular and physiological responses to chronic environmental challenge in an invasive species: the Pacific oyster, Crassostrea gigas

PubMed Central

Clark, Melody S; Thorne, Michael A S; Amaral, Ana; Vieira, Florbela; Batista, Frederico M; Reis, João; Power, Deborah M

2013-01-01

Understanding the environmental responses of an invasive species is critical in predicting how ecosystem composition may be transformed in the future, especially under climate change. In this study, Crassostrea gigas, a species well adapted to the highly variable intertidal environment, was exposed to the chronic environmental challenges of temperature (19 and 24°C) and pH (ambient seawater and a reduction of 0.4 pH units) in an extended 3-month laboratory-based study. Physiological parameters were measured (condition index, shell growth, respiration, excretion rates, O:N ratios, and ability to repair shell damage) alongside molecular analyses. Temperature was by far the most important stressor, as demonstrated by reduced condition indexes and shell growth at 24°C, with relatively little effect detected for pH. Transcriptional profiling using candidate genes and SOLiD sequencing of mantle tissue revealed that classical “stress” genes, previously reported to be upregulated under acute temperature challenges, were not significantly expressed in any of the treatments, emphasizing the different response between acute and longer term chronic stress. The transcriptional profiling also elaborated on the cellular responses underpinning the physiological results, including the identification of the PI3K/AKT/mTOR pathway as a potentially novel marker for chronic environmental challenge. This study represents a first attempt to understand the energetic consequences of cumulative thermal stress on the intertidal C. gigas which could significantly impact on coastal ecosystem biodiversity and function in the future. PMID:24223268

Transmission of the haplosporidian parasite MSX Haplosporidium nelsoni to the eastern oyster Crassostrea virginica in an upweller system.

PubMed

Sunila, I; Karolus, J; Lang, E P; Mroczka, M E; Volk, J

2000-08-31

The haplosporidian oyster parasite MSX (Multinucleated Sphere X) Haplosporidium nelsoni was transmitted to eastern oysters Crassostrea virginica. Hatchery-raised, MSX-free juvenile oysters were placed in upweller tanks. Water to the tanks was filtered through a screen with 1 mm2 openings and originated from the water column overlaying naturally infected oysters beds (MSX prevalence 17 to 57%). MSX was diagnosed by histopathological analysis. MSX-disease (57% prevalence) with increased mortality (19%) was observed 11 wk after the beginning of the exposure and mortality of 80% after 16 wk. The study demonstrates transmission of MSX via water-borne infectious agents capable of passing through a 1 mm filter.

[Monitoring of trace elements in oysters marketed in Recife, Pernambuco, Brazil].

PubMed

Cavalcanti, André Dias

2003-01-01

Samples of oysters marketed in Recife, Pernambuco, Brazil, were monitored for the concentration of trace elements (Hg, Zn, Fe, Cu, and Mn) for one year (from March 2001 to February 2002). Mercury was the principal contaminant found in oysters and the element posing the greatest public health risk. Mercury levels in oysters reached 551.12 g/kg (wet weight). These values suggest that oyster consumption should be restricted, especially among communities that gather them as a subsistence activity, as well as by children and pregnant women. Evaluation of mercury concentration in seafood is an important factor for assessing the risk of contamination among individuals who are not occupationally exposed.

Species Profiles. Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Mid-Atlantic). American Oyster.

DTIC Science & Technology

1986-07-01

umbones are usually straight. extends to the Yucatan Peninsula Single oysters from hard substrates of Mexico and the West Indies to are rounded and...season (Merrill and Boss postulated that phytoplankton blooms 1966). Kennedy and Krantz (1982) and nutrition may be responsible for documented the... nutritional factors which affect tidal American oyster Crassostrea the growth and setting of the virygnica (Gmelin). Ph.D. Thesis. larvae of the oyster

Analysis of Stomach and Gut Microbiomes of the Eastern Oyster (Crassostrea virginica) from Coastal Louisiana, USA

PubMed Central

King, Gary M.; Judd, Craig; Kuske, Cheryl R.; Smith, Conor

2012-01-01

We used high throughput pyrosequencing to characterize stomach and gut content microbiomes of Crassostrea virginica, the Easter oyster, obtained from two sites, one in Barataria Bay (Hackberry Bay) and the other in Terrebonne Bay (Lake Caillou), Louisiana, USA. Stomach microbiomes in oysters from Hackberry Bay were overwhelmingly dominated by Mollicutes most closely related to Mycoplasma; a more rich community dominated by Planctomyctes occurred in Lake Caillou oyster stomachs. Gut communities for oysters from both sites differed from stomach communities, and harbored a relatively diverse assemblage of phylotypes. Phylotypes most closely related to Shewanella and a Chloroflexi strain dominated the Lake Caillou and Hackberry Bay gut microbiota, respectively. While many members of the stomach and gut microbiomes appeared to be transients or opportunists, a putative core microbiome was identified based on phylotypes that occurred in all stomach or gut samples only. The putative core stomach microbiome comprised 5 OTUs in 3 phyla, while the putative core gut microbiome contained 44 OTUs in 12 phyla. These results collectively revealed novel microbial communities within the oyster digestive system, the functions of the oyster microbiome are largely unknown. A comparison of microbiomes from Louisiana oysters with bacterial communities reported for other marine invertebrates and fish indicated that molluscan microbiomes were more similar to each other than to microbiomes of polychaetes, decapods and fish. PMID:23251548

Role and Value of Nitrogen Regulation Provided by Oysters (Crassostrea virginica) in the Mission-Aransas Estuary, Texas, USA

PubMed Central

Beseres Pollack, Jennifer; Yoskowitz, David; Kim, Hae-Cheol; Montagna, Paul A.

2013-01-01

Suspension-feeding activities of oysters impart a potentially significant benefit to estuarine ecosystems via reduction of water column nutrients, plankton and seston biomass, and primary productivity which can have a significant impact on human well-being. This study considered nitrogen regulation by eastern oysters Crassostrea virginica in the Mission-Aransas Estuary, Texas, USA, as a function of denitrification, burial, and physical transport from the system via harvest. Oyster reefs were estimated to remove 502.5 kg N km−2 through denitrification of biodeposits and 251.3 kg N km−2 in burial of biodeposits to sediments. Nitrogen is also physically transported out of the estuary via harvest of oysters. Commercial harvest of oysters in the Mission-Aransas Estuary can remove approximately 21,665 kg N per year via physical transport from the system. We developed a transferable method to value the service of nitrogen regulation by oysters, where the potential cost equivalent value of nitrogen regulation is quantified via cost estimates for a constructed biological nutrient removal (BNR) supplement to a wastewater treatment plant. The potential annual engineered cost equivalent of the service of nitrogen regulation and removal provided by reefs in the Mission-Aransas Estuary is $293,993 yr−1. Monetizing ecosystem services can help increase awareness at the stakeholder level of the importance of oysters beyond commercial fishery values alone. PMID:23762341

Predicting the effects of proposed Mississippi River diversions on oyster habitat quality; application of an oyster habitat suitability index model

USGS Publications Warehouse

Soniat, Thomas M.; Conzelmann, Craig P.; Byrd, Jason D.; Roszell, Dustin P.; Bridevaux, Joshua L.; Suir, Kevin J.; Colley, Susan B.

2013-01-01

In an attempt to decelerate the rate of coastal erosion and wetland loss, and protect human communities, the state of Louisiana developed its Comprehensive Master Plan for a Sustainable Coast. The master plan proposes a combination of restoration efforts including shoreline protection, marsh creation, sediment diversions, and ridge, barrier island, and hydrological restoration. Coastal restoration projects, particularly the large-scale diversions of fresh water from the Mississippi River, needed to supply sediment to an eroding coast potentially impact oyster populations and oyster habitat. An oyster habitat suitability index model is presented that evaluates the effects of a proposed sediment and freshwater diversion into Lower Breton Sound. Voluminous freshwater, needed to suspend and broadly distribute river sediment, will push optimal salinities for oysters seaward and beyond many of the existing reefs. Implementation and operation of the Lower Breton Sound diversion structure as proposed would render about 6,173 ha of hard bottom immediately east of the Mississippi River unsuitable for the sustained cultivation of oysters. If historical harvests are to be maintained in this region, a massive and unprecedented effort to relocate private leases and restore oyster bottoms would be required. Habitat suitability index model results indicate that the appropriate location for such efforts are to the east and north of the Mississippi River Gulf Outlet.

Analysis of Stomach and Gut Microbiomes of the Eastern Oyster (Crassostrea virginica) from Coastal Louisiana, USA

DOE PAGES

King, Gary M.; Judd, Craig; Kuske, Cheryl R.; ...

2012-12-12

In this paper, we used high throughput pyrosequencing to characterize stomach and gut content microbiomes of Crassostrea virginica, the Easter oyster, obtained from two sites, one in Barataria Bay (Hackberry Bay) and the other in Terrebonne Bay (Lake Caillou), Louisiana, USA. Stomach microbiomes in oysters from Hackberry Bay were overwhelmingly dominated by Mollicutes most closely related to Mycoplasma; a more rich community dominated by Planctomyctes occurred in Lake Caillou oyster stomachs. Gut communities for oysters from both sites differed from stomach communities, and harbored a relatively diverse assemblage of phylotypes. Phylotypes most closely related to Shewanella and a Chloroflexi strainmore » dominated the Lake Caillou and Hackberry Bay gut microbiota, respectively. While many members of the stomach and gut microbiomes appeared to be transients or opportunists, a putative core microbiome was identified based on phylotypes that occurred in all stomach or gut samples only. The putative core stomach microbiome comprised 5 OTUs in 3 phyla, while the putative core gut microbiome contained 44 OTUs in 12 phyla. These results collectively revealed novel microbial communities within the oyster digestive system, the functions of the oyster microbiome are largely unknown. Finally, a comparison of microbiomes from Louisiana oysters with bacterial communities reported for other marine invertebrates and fish indicated that molluscan microbiomes were more similar to each other than to microbiomes of polychaetes, decapods and fish.« less

Interactive effects of water temperature and salinity on growth and mortality of eastern oysters, Crassostrea virginica: A meta-analysis using 40 years of monitoring data

USGS Publications Warehouse

Lowe, Michael R.; Sehlinger, Troy; Soniat, Thomas M.; LaPeyre, Megan K.

2017-01-01

Despite nearly a century of exploitation and scientific study, predicting growth and mortality rates of the eastern oyster (Crassostrea virginica) as a means to inform local harvest and management activities remains difficult. Ensuring that models reflect local population responses to varying salinity and temperature combinations requires locally appropriate models. Using long-term (1988 to 2015) monitoring data from Louisiana's public oyster reefs, we develop regionally specific models of temperature- and salinity-driven mortality (sack oysters only) and growth for spat (<25 mm), seed (25–75 mm), and sack (>75 mm) oyster size classes. The results demonstrate that the optimal combination of temperature and salinity where Louisiana oysters experience reduced mortality and fast growth rates is skewed toward lower salinities and higher water temperatures than previous models have suggested. Outside of that optimal range, oysters are commonly exposed to combinations of temperature and salinity that are correlated with high mortality and reduced growth. How these combinations affect growth, and to a lesser degree mortality, appears to be size class dependent. Given current climate predictions for the region and ongoing large-scale restoration activities in coastal Louisiana, the growth and mortality models are a critical step toward ensuring sustainable oyster reefs for long-term harvest and continued delivery of the ecological services in a changing environment.

[Phylogenetic analysis of tyrosinase gene family in the Pacific oyster (Crassostrea gigas Thunberg)].

PubMed

Yu, Xue; Yu, Hong; Kong, Lingfeng; Li, Qi

2014-02-01

The deduced amino acid sequence characteristics, classification and phylogeny of tyrosinase gene family in the Pacific oyster (Crassostrea gigas Thunberg) were analyzed using bioinformatics methods. The results showed that gene duplication was the major cause of tyrosinase gene expansion in the Pacific oyster. The tyrosinase gene family in the Pacific oyster can be further classified into three types: secreted form (Type A), cytosolic form (Type B) and membrane-bound form (Type C). Based on the topology of the phylogenetic tree of the Pacific oyster tyrosinases, among Type A isoforms, tyr18 seemed divergent from other Type A tyrosinases early, while tyr2 and tyr9 appeared divergent early in Type B. In Type C tyrosinses, tyr8 was divergent early. The cluster of the Pacific oyster tyrosinasesis determined by their classifications and positions in the scaffolds. Further analysis suggested that Type A tyrosinases of C. gigas clustered with those from cephalopods and then with nematodes and cnidarians. Type B tyrosinases were generally clustered with the same type of tyrosinases from molluscas and nematodes, and then with those from platyhelminths, cnidarians and chordates. Type A tyrosinases in the Pacific oyster and the Pearl oyster expanded independently and were divergent from membrane-bound form of tyrosinases in chordata, platyhelminthes and annelida. These observations suggested that Type C tyrosinases in the bivalve had a distinct evolution direction.

Perkinsus beihaiensis (Perkinsozoa) in oysters of Bahia State, Brazil.

PubMed

Luz, M S A; Carvalho, F S; Oliveira, H C; Boehs, G

2018-05-01

This study reports the pathogen Perkinsus beihaiensis in oysters of the genus Crassostrea on the coast of the State of Bahia (Brazil), its prevalence, infection intensity and correlation with salinity. Oysters (n = 240) were collected between October and December 2014 at eight sampling stations between latitudes 13°55'S and 15°42'S. The laboratory procedures included macroscopic analysis, histology, culture in Ray's fluid thioglycollate medium (RFTM), Polymerase Chain Reaction (PCR) and DNA sequencing. PCR and sequencing have been used for the genetic identification of oysters as well. Two species of oysters have been identified: Crassostrea rhizophorae and C. brasiliana. In both oyster species P. beihaiensis was the only Perkinsus species detected. In C. rhizophorae, the average prevalence was 82.8% by histology and 65.2% by RFTM. In C. brasiliana, the prevalences were 70.5% and 35.7%, respectively. The higher prevalence of P. beihaiensis in C. rhizophorae was probably influenced by salinity, with which was positively correlated (r> 0.8). In both oysters, P. beihaiensis was located mainly in the gastric epithelium. The infection was generally mild or moderate, without apparent harm to the hosts, but in cases of severe infection, there was hemocytical reaction and tissue disorganization. The generally high prevalence in the region suggests that oysters should be monitored with respect to this pathogen, especially in growing areas.

Ostreid herpesvirus OsHV-1 μVar in Pacific oysters Crassostrea gigas (Thunberg 1793) of the Wadden Sea, a UNESCO world heritage site.

PubMed

Gittenberger, A; Voorbergen-Laarman, M A; Engelsma, M Y

2016-01-01

The Wadden Sea is an extensive wetland area, recognized as UNESCO world heritage site of international importance. Since the mid-1990s, the invasive Pacific oyster Crassostrea gigas (Thunberg 1793) population in the area has grown exponentially, having a distinct impact on the ecosystem. The recent spread of the emerging oyster pathogen Ostreid herpesvirus OsHV-1 μVar worldwide and specifically in the oyster culture areas in the south of the Netherlands raised the question whether the virus may also be present in the Wadden Sea. In the summer of 2012 juvenile Pacific oysters were collected from five locations in the Dutch Wadden Sea. The virus was shown to be present in three of the five locations by real-time PCR and sequencing. It was concluded that OsHV-1 μVar has settled itself in Pacific oyster reefs in the Wadden Sea. These results and the recent discoveries of OsHV-1 microvariants in Australia and Korea indicate that OsHV-1 μVar and related variants might be more widespread than can be deduced from current literature. In particular in regions with no commercial oyster culture, similar to the Wadden Sea, the virus may go undetected as wild beds with mixed age classes hamper the detection of mortality among juvenile oysters. © 2015 John Wiley & Sons Ltd.

Unusually abundant and large ciliate xenomas in oysters, Crassostrea virginica, from Great Bay, New Hampshire, USA.

PubMed

McGurk, Emily Scarpa; Ford, Susan; Bushek, David

2016-06-01

During routine histological examination of oysters (Crassostrea virginica) from Great Bay, New Hampshire, USA, a high prevalence and intensity of ciliate xenomas has been noted since sampling began in 1997. Xenomas are hypertrophic lesions on the gills of bivalve molluscs caused by intracellular ciliates, likely Sphenophrya sp. Although not known to cause mortality in oysters, xenomas have not previously been reported at this high abundance. The objectives of this study were to characterize the xenomas, describe the ciliates, and gather baseline epizootiological data with correlations to environmental and biological parameters. Upon gross examination, xenomas appeared as white nodules, up to 3mm in diameter, located in the gill tissue and occasionally fusing into large masses along the gill filaments. Light microscopy of histological sections revealed xenomas located in the gill water tubes, which they often completely blocked. Higher magnification revealed dual nuclei, eight kineties, and conjugation of the ciliates. Transmission electron microscopy revealed dual nuclei that varied in density, a maximum of twenty cilia in each kinety radiating from the oral apparatus to the posterior, and a 9+2 axoneme structure within the cilia. These traits place the ciliates into the Order Rhynchodida, but insufficient molecular data exist to confirm classification of this ciliate to the Genus Sphenophrya. Since 1997, xenoma prevalence has fluctuated with peaks in 2000, 2004, and 2011. Infected oysters generally contained <30 xenomas, but 2.1% contained >100, sharply contrasting the rare prevalence and low intensity reported elsewhere. Prevalence increased with oyster size, leveling off near 50% in oysters >60mm. Infection intensity peaked in 70-90mm oysters and declined in larger oysters. Individual oyster condition was not associated with xenoma intensity, but sites with oysters in higher condition generally had a greater prevalence and intensity of xenoma infections. Seasonal data indicated an infection cycle increasing from summer to fall, peaking at 55-65% in November and dropping to <10% by spring. The oyster population in Great Bay, NH warrants further examination to understand the mechanisms and conditions controlling xenoma formation. Copyright © 2016 Elsevier Inc. All rights reserved.

Influence of water temperature and salinity on Vibrio vulnificus in Northern Gulf and Atlantic Coast oysters (Crassostrea virginica).

PubMed

Motes, M L; DePaola, A; Cook, D W; Veazey, J E; Hunsucker, J C; Garthright, W E; Blodgett, R J; Chirtel, S J

1998-04-01

This study investigated the temperature and salinity parameters associated with waters and oysters linked to food-borne Vibrio vulnificus infections. V. vulnificus was enumerated in oysters collected at three northern Gulf Coast sites and two Atlantic Coast sites from July 1994 through September 1995. Two of these sites, Black Bay, La., and Apalachicola Bay, Fla., are the source of the majority of the oysters implicated in V. vulnificus cases. Oysters in all Gulf Coast sites exhibited a similar seasonal distribution of V. vulnificus: a consistently large number (median concentration, 2,300 organisms [most probable number] per g of oyster meat) from May through October followed by a gradual reduction during November and December to < or = 10 per g, where it remained from January through mid-March, and a sharp increase in late March and April to summer levels. V. vulnificus was undetectable (< 3 per g) in oysters from the North and South Carolina sites for most of the year. An exception occurred when a late-summer flood caused a drop in salinity in the North Carolina estuary, apparently causing V. vulnificus numbers to increase briefly to Gulf Coast levels. At Gulf Coast sites, V. vulnificus numbers increased with water temperatures up to 26 degrees C and were constant at higher temperatures. High V. vulnificus levels (> 10(3) per g) were typically found in oysters from intermediate salinities (5 to 25 ppt). Smaller V. vulnificus numbers (< 10(2) per g) were found at salinities above 28 ppt, typical of Atlantic Coast sites. On 11 occasions oysters were sampled at times and locations near the source of oysters implicated in 13 V. vulnificus cases; the V. vulnificus levels and environmental parameters associated with these samples were consistent with those of other study samples collected from the Gulf Coast from April through November. These findings suggest that the hazard of V. vulnificus infection is not limited to brief periods of unusual abundance of V. vulnificus in Gulf Coast oysters or to environmental conditions that are unusual to Gulf Coast estuaries.

Influence of Water Temperature and Salinity on Vibrio vulnificus in Northern Gulf and Atlantic Coast Oysters (Crassostrea virginica)

PubMed Central

Motes, M. L.; DePaola, A.; Cook, D. W.; Veazey, J. E.; Hunsucker, J. C.; Garthright, W. E.; Blodgett, R. J.; Chirtel, S. J.

1998-01-01

This study investigated the temperature and salinity parameters associated with waters and oysters linked to food-borne Vibrio vulnificus infections. V. vulnificus was enumerated in oysters collected at three northern Gulf Coast sites and two Atlantic Coast sites from July 1994 through September 1995. Two of these sites, Black Bay, La., and Apalachicola Bay, Fla., are the source of the majority of the oysters implicated in V. vulnificus cases. Oysters in all Gulf Coast sites exhibited a similar seasonal distribution of V. vulnificus: a consistently large number (median concentration, 2,300 organisms [most probable number] per g of oyster meat) from May through October followed by a gradual reduction during November and December to ≤10 per g, where it remained from January through mid-March, and a sharp increase in late March and April to summer levels. V. vulnificus was undetectable (<3 per g) in oysters from the North and South Carolina sites for most of the year. An exception occurred when a late-summer flood caused a drop in salinity in the North Carolina estuary, apparently causing V. vulnificus numbers to increase briefly to Gulf Coast levels. At Gulf Coast sites, V. vulnificus numbers increased with water temperatures up to 26°C and were constant at higher temperatures. High V. vulnificus levels (>103 per g) were typically found in oysters from intermediate salinities (5 to 25 ppt). Smaller V. vulnificus numbers (<102 per g) were found at salinities above 28 ppt, typical of Atlantic Coast sites. On 11 occasions oysters were sampled at times and locations near the source of oysters implicated in 13 V. vulnificus cases; the V. vulnificus levels and environmental parameters associated with these samples were consistent with those of other study samples collected from the Gulf Coast from April through November. These findings suggest that the hazard of V. vulnificus infection is not limited to brief periods of unusual abundance of V. vulnificus in Gulf Coast oysters or to environmental conditions that are unusual to Gulf Coast estuaries. PMID:9546182

RESPONSES OF OYSTER (CRASSOSTREA VIRGINICA) HEMOCYTES TO NONPATHOGENIC AND CLINICAL ISOLATES OF VIBRIO PARAHAEMOLYTICUS

EPA Science Inventory

Bacterial uptake by oysters (Crassostrea virginica) and bactericidal activity of oyster hemocytes were studied using four environmental isolates and three clinical isolates of Vibrio parahaemolyticus. Clinical isolates (2030, 2062, 2107) were obtained from gastroenteritis patien...

CAN OYSTERS PLAY A ROLE IN ENVIRONMENTAL MANAGEMENT?

EPA Science Inventory

The culinary and commercial value of oysters is widely recognized but, until recently, their ecological importance has been largely overlooked. Field and laboratory studies have begun to explore how filter-feeding and reef building by oysters can influence nutrient cycling, biodi...

Climate Change, Precipitation and Impacts on an Estuarine Refuge from Disease

PubMed Central

Levinton, Jeffrey; Doall, Michael; Ralston, David; Starke, Adam; Allam, Bassem

2011-01-01

Background Oysters play important roles in estuarine ecosystems but have suffered recently due to overfishing, pollution, and habitat loss. A tradeoff between growth rate and disease prevalence as a function of salinity makes the estuarine salinity transition of special concern for oyster survival and restoration. Estuarine salinity varies with discharge, so increases or decreases in precipitation with climate change may shift regions of low salinity and disease refuge away from optimal oyster bottom habitat, negatively impacting reproduction and survival. Temperature is an additional factor for oyster survival, and recent temperature increases have increased vulnerability to disease in higher salinity regions. Methodology/Principal Findings We examined growth, reproduction, and survival of oysters in the New York Harbor-Hudson River region, focusing on a low-salinity refuge in the estuary. Observations were during two years when rainfall was above average and comparable to projected future increases in precipitation in the region and a past period of about 15 years with high precipitation. We found a clear tradeoff between oyster growth and vulnerability to disease. Oysters survived well when exposed to intermediate salinities during two summers (2008, 2010) with moderate discharge conditions. However, increased precipitation and discharge in 2009 reduced salinities in the region with suitable benthic habitat, greatly increasing oyster mortality. To evaluate the estuarine conditions over longer periods, we applied a numerical model of the Hudson to simulate salinities over the past century. Model results suggest that much of the region with suitable benthic habitat that historically had been a low salinity refuge region may be vulnerable to higher mortality under projected increases in precipitation and discharge. Conclusions/Significance Predicted increases in precipitation in the northeastern United States due to climate change may lower salinities past important thresholds for oyster survival in estuarine regions with appropriate substrate, potentially disrupting metapopulation dynamics and impeding oyster restoration efforts, especially in the Hudson estuary where a large basin constitutes an excellent refuge from disease. PMID:21552552

Genome and Transcriptome Analyses Provide Insight into the Euryhaline Adaptation Mechanism of Crassostrea gigas

PubMed Central

Zhang, Linlin; Li, Chunyan; Li, Li; She, Zhicai; Huang, Baoyu; Zhang, Guofan

2013-01-01

Background The Pacific oyster, Crassostrea gigas, has developed special mechanisms to regulate its osmotic balance to adapt to fluctuations of salinities in coastal zones. To understand the oyster’s euryhaline adaptation, we analyzed salt stress effectors metabolism pathways under different salinities (salt 5, 10, 15, 20, 25, 30 and 40 for 7 days) using transcriptome data, physiology experiment and quantitative real-time PCR. Results Transcriptome data uncovered 189, 480, 207 and 80 marker genes for monitoring physiology status of oysters and the environment conditions. Three known salt stress effectors (involving ion channels, aquaporins and free amino acids) were examined. The analysis of ion channels and aquaporins indicated that 7 days long-term salt stress inhibited voltage-gated Na+/K+ channel and aquaporin but increased calcium-activated K+ channel and Ca2+ channel. As the most important category of osmotic stress effector, we analyzed the oyster FAAs metabolism pathways (including taurine, glycine, alanine, beta-alanine, proline and arginine) and explained FAAs functional mechanism for oyster low salinity adaptation. FAAs metabolism key enzyme genes displayed expression differentiation in low salinity adapted individuals comparing with control which further indicated that FAAs played important roles for oyster salinity adaptation. A global metabolic pathway analysis (iPath) of oyster expanded genes displayed a co-expansion of FAAs metabolism in C. gigas compared with seven other species, suggesting oyster’s powerful ability regarding FAAs metabolism, allowing it to adapt to fluctuating salinities, which may be one important mechanism underlying euryhaline adaption in oyster. Additionally, using transcriptome data analysis, we uncovered salt stress transduction networks in C. gigas. Conclusions Our results represented oyster salt stress effectors functional mechanisms under salt stress conditions and explained the expansion of FAAs metabolism pathways as the most important effectors for oyster euryhaline adaptation. This study was the first to explain oyster euryhaline adaptation at a genome-wide scale in C. gigas. PMID:23554902

Controlling Vibrio vulnificus and spoilage bacteria in fresh shucked oysters using natural antimicrobials.

PubMed

Mahmoud, B S M

2014-01-01

This study evaluated the efficacy of grape seed extract (GE), citric acid (CA) and lactic acid (LA) on the inactivation of Vibrio vulnificus and inherent microflora in fresh shucked oysters. The minimum inhibitory concentration (MIC) of GE, CA or LA against V. vulnificus was determined. Furthermore, the shucked oysters were artificially inoculated with V. vulnificus. The inoculated shucked oysters (25 g) were then dipped in 250 ml GE, CA or LA solutions for 10 min. The population of V. vulnificus in shucked oysters was determined. The effects of the treatments with GE, CA or LA solutions on the inherent microbiota in fresh shucked oysters during storage at 5°C for 20 days were also studied. The MICs of GE, CA or LA against V. vulnificus were 10.0, 5.0 or 1.0 mg ml(-1), respectively. The concentrations of 500, 300 or 150 mg ml(-1) GE, CA or LA solutions were needed to reduce the population of V. vulnificus to below the detection level (1.0 log g(-1)). Treatment with 500, 300, 150 mg ml(-1) GE, CA or LA significantly reduced the initial inherent microbiota in fresh shucked oysters, and inherent levels were significantly (P < 0.05) lower than the control sample throughout refrigerated storage for 20 days. Oysters filter large volume of seawater during their feeding activities that concentrate bacteria such as Vibrio vulnificus in their body. The presence of V. vulnificus in oysters has a serious impact on public health and international trade. There is increasing concern over the use of chemical preservatives. Furthermore, the food industry is looking for new natural preservation methods. This study indicated that lactic acid and citric acid wash solutions could offer an inexpensive, natural and strong approach to control V. vulnificus and spoilage bacteria in fresh shucked for the oyster industry. © 2013 The Society for Applied Microbiology.

High salinity relay as a post-harvest processing method for reducing Vibrio vulnificus levels in oysters (Crassostrea virginica).

PubMed

Audemard, Corinne; Kator, Howard I; Reece, Kimberly S

2018-08-20

High salinity relay of Eastern oysters (Crassostrea virginica) was evaluated as a post-harvest processing (PHP) method for reducing Vibrio vulnificus. This approach relies on the exposure of oysters to natural high salinity waters and preserves a live product compared to previously approved PHPs. Although results of prior studies evaluating high salinity relay as a means to decrease V. vulnificus levels were promising, validation of this method as a PHP following approved guidelines is required. This study was designed to provide data for validation of this method following Food and Drug Administration (FDA) PHP validation guidelines. During each of 3 relay experiments, oysters cultured from 3 different Chesapeake Bay sites of contrasting salinities (10-21 psu) were relayed without acclimation to high salinity waters (31-33 psu) for up to 28 days. Densities of V. vulnificus and densities of total and pathogenic Vibrio parahaemolyticus (as tdh positive strains) were measured using an MPN-quantitative PCR approach. Overall, 9 lots of oysters were relayed with 6 exhibiting initial V. vulnificus >10,000/g. As recommended by the FDA PHP validation guidelines, these lots reached both the 3.52 log reduction and the <30 MPN/g densities requirements for V. vulnificus after 14 to 28 days of relay. Densities of total and pathogenic V. parahaemolyticus in relayed oysters were significantly lower than densities at the sites of origin suggesting an additional benefit associated with high salinity relay. While relay did not have a detrimental effect on oyster condition, oyster mortality levels ranged from 2 to 61% after 28 days of relay. Although the identification of the factors implicated in oyster mortality will require further examination, this study strongly supports the validation of high salinity relay as an effective PHP method to reduce levels of V. vulnificus in oysters to endpoint levels approved for human consumption. Copyright © 2018 Elsevier B.V. All rights reserved.

The Effects of Storage Temperature on the Growth of Vibrio parahaemolyticus and Organoleptic Properties in Oysters.

PubMed

Mudoh, Meshack Fon; Parveen, Salina; Schwarz, Jurgen; Rippen, Tom; Chaudhuri, Anish

2014-01-01

During harvesting and storage, microbial pathogens and natural spoilage flora may grow, negatively affecting the composition and texture of oysters and posing a potential health threat to susceptible consumers. A solution to these problems would mitigate associated damaging effects on the seafood industry. The purpose of this study was to investigate the effects of storage temperature on growth of vibrios as well as other microbial, sensory, and textural characteristics of post-harvest shellstock Eastern oysters (Crassostrea virginica). Oysters harvested from the Chesapeake Bay, Maryland, during summer months (June, July, and August, 2010) were subjected to three storage temperatures (5, 10, and 20°C) over a 10-day period. At selected time intervals (0, 1, 3, 7, and 10 days), two separate samples of six oysters each were homogenated and analyzed for pH, halophilic plate counts (HPC), total vibrios, and Vibrio parahaemolyticus (Vp). Oyster meats shucked after storage were also organoleptically evaluated (acceptability, appearance, and odor). Texture analysis was performed using a texture analyzer on meats shucked from oysters held under the same conditions. The pH of the oyster homogenates showed no consistent pattern with storage time and temperature. The HPC (4.5-9.4 log CFU/g) were highest on day 7 at 20°C while olfactory acceptance reduced with time and increasing storage temperatures. The Vp counts increased over time from 3.5 to 7.5 log MPN/g by day 10. Loss of freshness as judged by appearance and odor was significant over time (p < 0.05). Toughness of oysters increased with storage time at 5 and 10°C from days 1 to 3 but was inconsistent after day 7. The results indicate that the length of storage and temperature had a significant effect on bacterial counts and olfactory acceptance of oysters but had an inconsistent effect on texture.

The modulation role of serotonin in Pacific oyster Crassostrea gigas in response to air exposure.

PubMed

Dong, Wenjing; Liu, Zhaoqun; Qiu, Limei; Wang, Weilin; Song, Xiaorui; Wang, Xiudan; Li, Yiqun; Xin, Lusheng; Wang, Lingling; Song, Linsheng

2017-03-01

Serotonin, also known as 5-hydroxytryptamine (5-HT), is a critical neurotransmitter in the neuroendocrine-immune regulatory network and involved in regulation of the stress response in vertebrates and invertebrates. In the present study, serotonin was found to be widely distributed in the tissues of Pacific oyster Crassostrea gigas, including haemolymph, gonad, visceral ganglion, mantle, gill, labial palps and hepatopancreas, and its concentration increased significantly in haemolymph and mantle after the oysters were exposed to air for 1 d. The apoptosis rate of haemocytes was significantly declined after the oysters received an injection of extra serotonin, while the activity of superoxide dismutase (SOD) in haemolymph increased significantly. After the stimulation of serotonin during air exposure, the apoptosis rate of oyster haemocytes and the concentration of H 2 O 2 in haemolymph were significantly decreased, while the SOD activity was significantly elevated. Furthermore, the survival rate of oysters from 4 th to 6 th d after injection of serotonin was higher than that of FSSW group and air exposure group. The results clearly indicated that serotonin could modulate apoptotic effect and redox during air exposure to protect oysters from stress. Copyright © 2017 Elsevier Ltd. All rights reserved.

Copper and zinc contamination in oysters: subcellular distribution and detoxification.

PubMed

Wang, Wen-Xiong; Yang, Yubo; Guo, Xiaoyu; He, Mei; Guo, Feng; Ke, Caihuan

2011-08-01

Metal pollution levels in estuarine and coastal environments have been widely reported, but few documented reports exist of severe contamination in specific environments. Here, we report on a metal-contaminated estuary in Fujian Province, China, in which blue oysters (Crassostrea hongkongensis) and green oysters (Crassostrea angulata) were discovered to be contaminated with Cu and other metals. Extraordinarily high metal concentrations were found in the oysters collected from the estuary. Comparison with historical data suggests that the estuary has recently been contaminated with Cr, Cu, Ni, and Zn. Metal concentrations in blue oysters were as high as 1.4 and 2.4% of whole-body tissue dry wt for Cu and Zn, respectively. Cellular debris was the main subcellular fraction binding the metals, but metal-rich granules were important for Cr, Ni, and Pb. With increasing Cu accumulation, its partitioning into the cytosolic proteins decreased. In contrast, metallothionein-like proteins increased their importance in binding with Zn as tissue concentrations of Zn increased. In the most severely contaminated oysters, only a negligible fraction of their Cu and Zn was bound with the metal-sensitive fraction, which may explain the survival of oysters in such contaminated environments. Copyright © 2011 SETAC.

Preliminary stochastic model for managing Vibrio parahaemolyticus and total viable bacterial counts in a Pacific oyster (Crassostrea gigas) supply chain.

PubMed

Fernandez-Piquer, Judith; Bowman, John P; Ross, Tom; Estrada-Flores, Silvia; Tamplin, Mark L

2013-07-01

Vibrio parahaemolyticus can accumulate and grow in oysters stored without refrigeration, representing a potential food safety risk. High temperatures during oyster storage can lead to an increase in total viable bacteria counts, decreasing product shelf life. Therefore, a predictive tool that allows the estimation of both V. parahaemolyticus populations and total viable bacteria counts in parallel is needed. A stochastic model was developed to quantitatively assess the populations of V. parahaemolyticus and total viable bacteria in Pacific oysters for six different supply chain scenarios. The stochastic model encompassed operations from oyster farms through consumers and was built using risk analysis software. Probabilistic distributions and predictions for the percentage of Pacific oysters containing V. parahaemolyticus and high levels of viable bacteria at the point of consumption were generated for each simulated scenario. This tool can provide valuable information about V. parahaemolyticus exposure and potential control measures and can help oyster companies and regulatory agencies evaluate the impact of product quality and safety during cold chain management. If coupled with suitable monitoring systems, such models could enable preemptive action to be taken to counteract unfavorable supply chain conditions.

The simple neuroendocrine-immune regulatory network in oyster Crassostrea gigas mediates complex functions.

PubMed

Liu, Zhaoqun; Wang, Lingling; Zhou, Zhi; Sun, Ying; Wang, Mengqiang; Wang, Hao; Hou, Zhanhui; Gao, Dahai; Gao, Qiang; Song, Linsheng

2016-05-19

The neuroendocrine-immune (NEI) regulatory network is a complex system, which plays an indispensable role in the immunity of the host. In the present study, the bioinformatical analysis of the transcriptomic data from oyster Crassostrea gigas and further biological validation revealed that oyster TNF (CgTNF-1 CGI_10018786) could activate the transcription factors NF-κB and HSF (heat shock transcription factor) through MAPK signaling pathway, and then regulate apoptosis, redox reaction, neuro-regulation and protein folding in oyster haemocytes. The activated immune cells then released neurotransmitters including acetylcholine, norepinephrine and [Met(5)]-enkephalin to regulate the immune response by arising the expression of three TNF (CGI_10005109, CGI_10005110 and CGI_10006440) and translocating two NF-κB (Cgp65, CGI_10018142 and CgRel, CGI_10021567) between the cytoplasm and nuclei of haemocytes. Neurotransmitters exhibited the immunomodulation effects by influencing apoptosis and phagocytosis of oyster haemocytes. Acetylcholine and norepinephrine could down-regulate the immune response, while [Met(5)]-enkephalin up-regulate the immune response. These results suggested that the simple neuroendocrine-immune regulatory network in oyster might be activated by oyster TNF and then regulate the immune response by virtue of neurotransmitters, cytokines and transcription factors.

A Rhodopsin-Like Gene May Be Associated With the Light-Sensitivity of Adult Pacific Oyster Crassostrea gigas

PubMed Central

Wu, Changlu; Jiang, Qiuyun; Wei, Lei; Cai, Zhongqiang; Chen, Jun; Yu, Wenchao; He, Cheng; Wang, Jiao; Guo, Wen; Wang, Xiaotong

2018-01-01

Light-sensitivity is important for mollusc survival, as it plays a vital role in reproduction and predator avoidance. Light-sensitivity has been demonstrated in the adult Pacific oyster Crassostrea gigas, but the genes associated with light-sensitivity remain unclear. In the present study, we designed experiments to identify the genes associated with light-sensitivity in adult oysters. First, we assessed the Pacific oyster genome and identified 368 genes annotated with the terms associated with light-sensitivity. Second, the function of the four rhodopsin-like superfamily member genes was tested by using RNAi. The results showed that the highest level of mRNA expression of the vision-related genes was in the mantle; however, this finding is not true for all oyster genes. Interestingly, we also found four rhodopsin-like superfamily member genes expressed at an very high level in the mantle tissue. In the RNAi experiment, when one of rhodopsin-like superfamily member genes (CGI_1001253) was inhibited, the light-sensitivity capacity of the injected oysters was significantly reduced, suggesting that CGI_10012534 may be associated with light-sensitivity in the adult Pacific oyster. PMID:29615921

The simple neuroendocrine-immune regulatory network in oyster Crassostrea gigas mediates complex functions

NASA Astrophysics Data System (ADS)

Liu, Zhaoqun; Wang, Lingling; Zhou, Zhi; Sun, Ying; Wang, Mengqiang; Wang, Hao; Hou, Zhanhui; Gao, Dahai; Gao, Qiang; Song, Linsheng

2016-05-01

The neuroendocrine-immune (NEI) regulatory network is a complex system, which plays an indispensable role in the immunity of the host. In the present study, the bioinformatical analysis of the transcriptomic data from oyster Crassostrea gigas and further biological validation revealed that oyster TNF (CgTNF-1 CGI_10018786) could activate the transcription factors NF-κB and HSF (heat shock transcription factor) through MAPK signaling pathway, and then regulate apoptosis, redox reaction, neuro-regulation and protein folding in oyster haemocytes. The activated immune cells then released neurotransmitters including acetylcholine, norepinephrine and [Met5]-enkephalin to regulate the immune response by arising the expression of three TNF (CGI_10005109, CGI_10005110 and CGI_10006440) and translocating two NF-κB (Cgp65, CGI_10018142 and CgRel, CGI_10021567) between the cytoplasm and nuclei of haemocytes. Neurotransmitters exhibited the immunomodulation effects by influencing apoptosis and phagocytosis of oyster haemocytes. Acetylcholine and norepinephrine could down-regulate the immune response, while [Met5]-enkephalin up-regulate the immune response. These results suggested that the simple neuroendocrine-immune regulatory network in oyster might be activated by oyster TNF and then regulate the immune response by virtue of neurotransmitters, cytokines and transcription factors.

21 CFR 161.130 - Oysters.

Code of Federal Regulations, 2010 CFR

2010-04-01

... water. Before packing into the containers for shipment or other delivery for consumption the oysters are... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION FISH AND SHELLFISH Requirements for Specific Standardized Fish and Shellfish § 161.130 Oysters. (a...

High pressure-induced inactivation of Qbeta coliphage and c2 phage in oysters and in culture media.

PubMed

Smiddy, Mary; Kelly, Alan L; Patterson, Margaret F; Hill, Colin

2006-02-01

High pressure (HP) treatment inactivates bacteria in shellfish, but its effects on viruses in shellfish have not yet been determined, although viral illness is frequently associated with shellfish consumption. The aim of this study was to investigate the baroresistance of two bacteriophage viruses, Qbeta coliphage and c2 phage, in oysters and in culture media. High numbers (>or=10(7) ml(-1) or g(-1)) of both phages were obtained in culture media and in oysters. Samples were HP treated at 200-800 MPa at 20 degrees C for up to 30 min. Little or no inactivation of either phage was observed in oysters or in culture media after treatment at

Effects of High-Hydrostatic Pressure on Inactivation of Human Norovirus and Physical and Sensory Characteristics of Oysters.

PubMed

Ye, Mu; Lingham, Talaysha; Huang, Yaoxin; Ozbay, Gulnihal; Ji, Lin; Karwe, Mukund; Chen, Haiqiang

2015-06-01

The purpose of the study was to determine the effect of high-hydrostatic pressure (HHP) on inactivation of human norovirus (HuNoV) in oysters and to evaluate organoleptic characteristics of oysters treated at pressure levels required for HuNoV inactivation. Genogroup I.1 (GI.1) or Genogroup II.4 (GII.4) HuNoV was inoculated into oysters and treated at 300 to 600 MPa at 25 and 0 °C for 2 min. After HHP, viral particles were extracted by porcine gastric mucin-conjugated magnetic beads (PGM-MBs) and viral RNA was quantified by real-time RT-PCR. Lower initial temperature (0 °C) significantly enhanced HHP inactivation of HuNoV compared to ambient temperature (25 °C; P < 0.05). HHP at 350 and 500 MPa at 0 °C could achieve more than 4 log10 reduction of GII.4 and GI.1 HuNoV in oysters, respectively. HHP treatments did not significantly change color or texture of oyster tissue. A 1- to 5-scale hedonic sensory evaluation on appearance, aroma, color, and overall acceptability showed that pressure-treated oysters received significantly higher quality scores than the untreated control (P < 0.05). Elevated pressure levels at 450 and 500 MPa did not significantly affect scores compared to 300 MPa at 0 °C, indicating increasing pressure level did not affect sensory acceptability of oysters. Oysters treated at 0 °C had slightly lower acceptability than the group treated at room temperature on day 1 (P < 0.05), but after 1 wk storage, no significant difference in sensory attributes and consumer desirability was observed (P > 0.05). © 2015 Institute of Food Technologists®

Temporal variation in development of ecosystem services from oyster reef restoration

USGS Publications Warehouse

LaPeyre, Megan K.; Humphries, Austin T.; Casas, Sandra M.; La Peyre, Jerome F.

2014-01-01

Restoration ecology relies heavily on ecosystem development theories that generally assume development of fully functioning natural systems over time, but often fail to identify the time-frame required for provision of desired functions, or acknowledge different pathways of functional development. In estuaries, a decline of overall habitat quality and functioning has led to significant efforts to restore critical ecosystem services, recently through the creation and restoration of oyster reefs. Oyster reef restoration generally occurs with goals of (1) increasing water quality via filtration through sustainable oyster recruitment, (2) stabilizing shorelines, and (3) creating and enhancing critical estuarine habitat for fish and invertebrates. We restored over 260 m2 of oyster reef habitat in coastal Louisiana and followed the development and provision of these ecosystem services from 2009 through 2012. Oysters recruited to reefs immediately, with densities of oysters greater than 75 mm exceeding 80 ind m−2 after 3 years, and provision of filtration rates of 1002 ± 187 L h−1 m−2; shoreline stabilization effects of the created reefs were minimal over the three years of monitoring, with some evidence of positive shoreline stabilization during higher wind/energy events only; increased nekton abundance of resident, but not larger transient fish was immediately measurable at the reefs, however, this failed to increase through time. Our results provide critical insights into the development trajectories of ecosystem services provided by restored oyster reefs, as well as the mechanisms mediating these changes. This is critical both ecologically to understand how and where a reef thrives, and for policy and management to guide decision-making related to oyster reef restoration and the crediting and accounting of ecosystem services.

Extinction of a fast-growing oyster and changing ocean circulation in Pliocene tropical America

NASA Astrophysics Data System (ADS)

Kirby, Michael X.; Jackson, Jeremy B. C.

2004-12-01

Ocean circulation changed profoundly in the late Cenozoic around tropical America as a result of constriction and final closure of the Central American seaway. In response, regional planktonic productivity is thought to have decreased in the Caribbean Sea. Previous studies have shown that shallow-marine communities reflect these changes by reorganizing from a suspension-feeder dominated community to a more carbonate-rich, phototrophic-based community. Although changes in diversity, abundance, and body size of various shallow-marine invertebrates have previously been examined, no study has specifically used growth rate in suspension feeders to examine the effect that changes in ocean circulation may have had on shallow-marine communities. Here we show that a fast-growing oyster went extinct concurrently with changes in ocean circulation and planktonic productivity in the Pliocene. Faster-growing Crassostrea cahobasensis went extinct, whereas slower-growing Crassostrea virginica and columbiensis survived to the Holocene. Miocene Pliocene C. cahobasensis grew 522% faster in shell carbonate and 251% faster in biomass relative to Quaternary C. virginica and C. columbiensis. Although differences in growth are due to proximate differences in environment, the disappearance of faster-growing C. cahobasensis from shallow-marine environments and the continued survival of slower-growing C. virginica and C. columbiensis in marginal-marine environments (e.g., estuaries, lagoons) is consistent with the view that concurrent changes in ocean circulation and declining primary production resulted in the restriction of Crassostrea to marginal-marine environments.

Transcriptome and biomineralization responses of the pearl oyster Pinctada fucata to elevated CO2 and temperature

NASA Astrophysics Data System (ADS)

Li, Shiguo; Liu, Chuang; Huang, Jingliang; Liu, Yangjia; Zhang, Shuwen; Zheng, Guilan; Xie, Liping; Zhang, Rongqing

2016-01-01

Ocean acidification and global warming have been shown to significantly affect the physiological performances of marine calcifiers; however, the underlying mechanisms remain poorly understood. In this study, the transcriptome and biomineralization responses of Pinctada fucata to elevated CO2 (pH 7.8 and pH 7.5) and temperature (25 °C and 31 °C) are investigated. Increases in CO2 and temperature induced significant changes in gene expression, alkaline phosphatase activity, net calcification rates and relative calcium content, whereas no changes are observed in the shell ultrastructure. “Ion and acid-base regulation” related genes and “amino acid metabolism” pathway respond to the elevated CO2 (pH 7.8), suggesting that P. fucata implements a compensatory acid-base mechanism to mitigate the effects of low pH. Additionally, “anti-oxidation”-related genes and “Toll-like receptor signaling”, “arachidonic acid metabolism”, “lysosome” and “other glycan degradation” pathways exhibited responses to elevated temperature (25 °C and 31 °C), suggesting that P. fucata utilizes anti-oxidative and lysosome strategies to alleviate the effects of temperature stress. These responses are energy-consuming processes, which can lead to a decrease in biomineralization capacity. This study therefore is important for understanding the mechanisms by which pearl oysters respond to changing environments and predicting the effects of global climate change on pearl aquaculture.

Quantitative analysis of oyster larval proteome provides new insights into the effects of multiple climate change stressors.

PubMed

Dineshram, Ramadoss; Chandramouli, Kondethimmanahalli; Ko, Ginger Wai Kuen; Zhang, Huoming; Qian, Pei-Yuan; Ravasi, Timothy; Thiyagarajan, Vengatesen

2016-06-01

The metamorphosis of planktonic larvae of the Pacific oyster (Crassostrea gigas) underpins their complex life-history strategy by switching on the molecular machinery required for sessile life and building calcite shells. Metamorphosis becomes a survival bottleneck, which will be pressured by different anthropogenically induced climate change-related variables. Therefore, it is important to understand how metamorphosing larvae interact with emerging climate change stressors. To predict how larvae might be affected in a future ocean, we examined changes in the proteome of metamorphosing larvae under multiple stressors: decreased pH (pH 7.4), increased temperature (30 °C), and reduced salinity (15 psu). Quantitative protein expression profiling using iTRAQ-LC-MS/MS identified more than 1300 proteins. Decreased pH had a negative effect on metamorphosis by down-regulating several proteins involved in energy production, metabolism, and protein synthesis. However, warming switched on these down-regulated pathways at pH 7.4. Under multiple stressors, cell signaling, energy production, growth, and developmental pathways were up-regulated, although metamorphosis was still reduced. Despite the lack of lethal effects, significant physiological responses to both individual and interacting climate change related stressors were observed at proteome level. The metamorphosing larvae of the C. gigas population in the Yellow Sea appear to have adequate phenotypic plasticity at the proteome level to survive in future coastal oceans, but with developmental and physiological costs. © 2016 John Wiley & Sons Ltd.

Transcriptome and biomineralization responses of the pearl oyster Pinctada fucata to elevated CO2 and temperature

PubMed Central

Li, Shiguo; Liu, Chuang; Huang, Jingliang; Liu, Yangjia; Zhang, Shuwen; Zheng, Guilan; Xie, Liping; Zhang, Rongqing

2016-01-01

Ocean acidification and global warming have been shown to significantly affect the physiological performances of marine calcifiers; however, the underlying mechanisms remain poorly understood. In this study, the transcriptome and biomineralization responses of Pinctada fucata to elevated CO2 (pH 7.8 and pH 7.5) and temperature (25 °C and 31 °C) are investigated. Increases in CO2 and temperature induced significant changes in gene expression, alkaline phosphatase activity, net calcification rates and relative calcium content, whereas no changes are observed in the shell ultrastructure. “Ion and acid-base regulation” related genes and “amino acid metabolism” pathway respond to the elevated CO2 (pH 7.8), suggesting that P. fucata implements a compensatory acid-base mechanism to mitigate the effects of low pH. Additionally, “anti-oxidation”-related genes and “Toll-like receptor signaling”, “arachidonic acid metabolism”, “lysosome” and “other glycan degradation” pathways exhibited responses to elevated temperature (25 °C and 31 °C), suggesting that P. fucata utilizes anti-oxidative and lysosome strategies to alleviate the effects of temperature stress. These responses are energy-consuming processes, which can lead to a decrease in biomineralization capacity. This study therefore is important for understanding the mechanisms by which pearl oysters respond to changing environments and predicting the effects of global climate change on pearl aquaculture. PMID:26732540

Species profiles: Life histories and environmental requirements of coastal fishes and invertebrates (Pacific Northwest): Olympia oyster

DOE Office of Scientific and Technical Information (OSTI.GOV)

Couch, D.; Hassler, T.J.

Species profiles are literature summaries of the taxonomy, morphology, range, life history, and environmental requirements of coastal aquatic species. They are designed to assist in environmental impact assessments. Olympia oysters initially spawn as males then alternate their functional genders. Spawning begins at 13-16 {degree}C and occurs from spring to fall. After a short planktonic stage, larvae attach to the substrate. Olympia oysters thrive at salinities of 25 ppt or above; they are killed by freezing temperatures. Olympia oysters once supported large sustenance and commercial fisheries. Olympia oysters have not returned to pre-exploitation population levels which declined because of pollution andmore » loss of habitat. 32 refs., 2 figs.« less

DIFFERENTIAL EFFECTS OF OYSTER (CRASSOSTREA VIRGINICA) DEFENSES ON CLINICAL AND ENVIRONMENTAL ISOLATES OF VIBRIO PARAHEMOLYTICUS

EPA Science Inventory

Three clinical (2030, 2062, and 2107) and three environmental (1094, 1163, and ATCC 17802) isolates of Vibrio parahaemolyticus were exposed to hemocytes and plasma collected from oysters (Crassostrea virginica) to determine their susceptibility to putative oyster defenses. Clinic...

PERKINSUS-"CIDAL" ACTIVITY OF OYSTER HEMOCYTES USING A TETRAZOLIUM DYE REDUCTION ASSAY: OPTIMIZATION AND APPLICATIONS

EPA Science Inventory

A bactericidal assay developed to assess the ability of oyster (Crassostrea virginica) hemocytes to kill the human pathogen Vibrio parahaemolyticus was optimized to estimate killing of the oyster parasite Perkinsus marinus. Assay variables, temperature, hemocyte:parasite ratio, i...

ANTIMICROBIAL ACTIVITY OF COPPER AND ZINC ACCUMULATED BY EASTERN OYSTER AMEBOCYTES

EPA Science Inventory

Fisher, William S. Submitted. Antimicrobial Activity of Copper and Zinc Accumulated by Eastern Oyster Amebocytes. J. Shellfish Res. 54 p. (ERL,GB 1196).

The distribution of eastern oysters Crassostrea virginica near terrestrial watersheds has led to a general impression t...

Directly measured denitrification reveals oyster aquaculture and restored oyster reefs remove nitrogen at comparable high rates

EPA Science Inventory

Coastal systems are increasingly impacted by over-enrichment of nutrients, which has cascading effects for ecosystem functioning. Oyster restoration and aquaculture are both hypothesized to mitigate excessive nitrogen (N) loads via benthic denitrification (DNF). However, this has...

Thiabendazole uptake in shimeji, king oyster, and oyster mushrooms and its persistence in sterile and nonsterile substrates.

PubMed

Zhang, Zhiyong; Jiang, Wayne; Jian, Qiu; Song, Wencheng; Zheng, Zuntao; Ke, Changjie; Liu, Xianjin

2014-02-12

Thiabendazole in the substrates incurred from spraying and premixing was translocated to the pileus, stipe, and volva of selected mushrooms. The spraying on the substrates resulted in higher residues of thiabendazole in all three mushrooms than the premixing treatment. For premixing, in the five substrates, half-lives of thiabendazole were found to be 13.6 days for shimeji, 10.0 days for king oyster, 13.7 days for oyster, 19.1 days for sterilized substrate, and 8.4 days for nonsterilized substrate, respectively. For spraying, the longest and shortest half-lives were found to be 19.5 and 8.1 days for the nonsterilized and sterilized substrates, respectively. The residues of thiabendazole in three edible fungi were increased with the incubation days from 3 to 5 to 7. The residues of thiabendazole in king oyster were the highest among the three fungi while those in shimeji and oyster showed similar patterns.

Occurrence of Vibrio parahaemolyticus and Vibrio vulnificus in retail raw oysters from the eastern coast of Thailand.

PubMed

Changchai, Nuttawee; Saunjit, Sudarat

2014-05-01

Occurrence, population density and virulence of Vibrio parahaemolyticus and V. vulnificus in 240 retail raw oysters collected monthly between March 2010 and February 2011 from Ang Sila coast, Chon Buri Province, Thailand were determined using most probable number (MPN) multiplex PCR. Multiplex PCR detected V. parahaemolyticus in 219 raw oyster samples, of which 29 samples contained the virulence tdh. MPN values for V. parahaemolyticus and pathogenic strains in most samples ranged from 10 to 10(2) and from 3 to 10 MPN/g, respectively. The presence of V. vulnificus was found in 53 oyster samples in amounts between 10 and 10(2) MPN/g. Of 1,087 V. parahaemolyticus isolates, 14 and 2 isolates carried tdh and virulence trh, respectively but none with both genes. However, none of the presumptive isolates was shown to be V. vulnificus. The detection of pathogenic V. parahaemolyticus and V. vulnificus in raw oysters has rendered high awareness of risk in consumption of raw or undercooked oysters.

Oyster reproduction is compromised by acidification experienced seasonally in coastal regions.

PubMed

Boulais, Myrina; Chenevert, Kyle John; Demey, Ashley Taylor; Darrow, Elizabeth S; Robison, Madison Raine; Roberts, John Park; Volety, Aswani

2017-10-16

Atmospheric carbon dioxide concentrations have been rising during the past century, leading to ocean acidification (OA). Coastal and estuarine habitats experience annual pH variability that vastly exceeds the magnitude of long-term projections in open ocean regions. Eastern oyster (Crassostrea virginica) reproduction season coincides with periods of low pH occurrence in estuaries, thus we investigated effects of moderate (pH 7.5, pCO 2 2260 µatm) and severe OA (pH 7.1, pCO 2 5584 µatm; and 6.7, pCO 2 18480 µatm) on oyster gametogenesis, fertilization, and early larval development successes. Exposure at severe OA during gametogenesis caused disruption in oyster reproduction. Oogenesis appeared to be more sensitive compared to spermatogenesis. However, Eastern oyster reproduction was resilient to moderate OA projected for the near-future. In the context of projected climate change exacerbating seasonal acidification, OA of coastal habitats could represent a significant bottleneck for oyster reproduction which may have profound negative implications for coastal ecosystems reliant on this keystone species.

A 1-year investigation of the parasite Haplosporidium nelsoni (MSX) in the Pacific oyster Crassostrea gigas from Dayaowan Bay, China.

PubMed

Wang, Zhongwei; Lu, Xin; Liang, Yubo

2010-06-01

The infection prevalence of the protozoan parasite Haplosporidium nelsoni (MSX) in Pacific oysters (Crassostrea gigas), collected from Dayaowan Bay on the north coast of the Yellow Sea, China, was investigated in 2007. The traditional histological method of diagnosing H. nelsoni infection in oysters was compared to that of polymerase chain reaction (PCR). Histology and the first PCR analysis detected infection in 21 (a total of 240 oysters) (8.75%) oysters, and the second PCR revealed infection in 26 oysters (10.83%). Only local or epithelial infections were found; no systemic infections were detected. Infection by H. nelsoni mostly occurred from April through October, and the monthly prevalence ranged from 5% to 25%, with a peak in August. These results suggest that the prevalence of the parasite is low in Dayaowan Bay. The prevalence of H. nelsoni is thought to be controlled in some way by temperature and salinity.

Gauging state-level and user group views of oyster reef restoration activities in the northern Gulf of Mexico

USGS Publications Warehouse

LaPeyre, Megan K.; Nix, Ashby; Laborde, Luke; Piazza, Bryan P.

2012-01-01

Successful oyster reef restoration, like many conservation challenges, requires not only biological understanding of the resource, but also stakeholder cooperation and political support. To measure perceptions of oyster reef restoration activities and priorities for future restoration along the northern Gulf of Mexico coast, a survey of 1500 individuals representing 4 user groups (oyster harvesters, shrimpers, environmental organization members, professionals), across 5 states (Texas, Louisiana, Mississippi, Alabama, Florida) was conducted in 2011. All respondents highly supported reef restoration efforts, but there was a dichotomy in preferred restoration goals with commercial fishermen more likely to support oyster reef restoration for stock enhancement, while professionals and environmental organization members were more likely to support oyster reef restoration to enhance ecosystem services. All user groups identified enforcement, funding, and appropriate site selection as basic requirements for successful reef restoration. For management of restored oyster reefs, oyster harvesters and shrimpers were less likely to support options that restricted the use of reefs, including gear restrictions and permanent closures, but did support rotating annual reef closures, while other stakeholders were willing to consider all options, including annual reef closures and sanctuary reefs. Overall, there were clear differences in management and communication preferences across user groups, but few differences across states. Understanding these key differences in stakeholder support for, and willingness to accept specific management actions is critical in moving management and restoration forward while minimizing conflict.