scholarly journals Molecular Epizootiology of Toxoplasma gondii and Cryptosporidium parvum in the Eastern Oyster (Crassostrea virginica) from Maine (USA)

Pathogens ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 125 ◽  
Author(s):  
Nicholas D. Marquis ◽  
Theodore J. Bishop ◽  
Nicholas R. Record ◽  
Peter D. Countway ◽  
José A. Fernández Robledo
Keyword(s):  
Toxoplasma Gondii ◽  
Crassostrea Virginica ◽  
Cryptosporidium Parvum ◽  
Eastern Oyster ◽  
Environmental Data ◽  
Future Research ◽  
Human Consumption ◽  
Current Direction ◽  
Significant Patterns ◽  
Oxygen Measurements

Shellfish are known as a potential source of Toxoplasma gondii (responsible for toxoplasmosis), and Cryptosporidium parvum, which is one of the major causes of gastroenteritis in the world. Here we performed a comprehensive qPCR-based monthly survey for T. gondii and C. parvum during 2016 and 2017 in oysters (Crassostrea virginica) (n = 1440) from all six sites along the coast of Maine (USA). Pooled samples (mantle, gills, and rectum) from individual oysters were used for DNA extraction and qPCR. Our study resulted in detections of qPCR positives oysters for T. gondii and C. parvum at each of the six sites sampled (in 31% and 10% of total oysters, respectively). The prevalence of T. gondii was low in 2016, and in September 2017 several sites peaked in prevalence with 100% of the samples testing positive. The prevalence of C. parvum was very low except in one estuarine location (Jack’s Point) in June 2016 (58%), and in October of 2016, when both prevalence and density of C. parvum at most of the sampling sites were among the highest values detected. Statistical analysis of environmental data did not identify clear drivers of retention, but there were some notable statistically significant patterns including current direction and nitrate along with the T. gondii prevalence. The major C. parvum retention event (in October 2016) corresponded with the month of highest dissolved oxygen measurements as well as a shift in the current direction revealed by nearby instrumentation. This study may guide future research to locate any contributing parasite reservoirs and evaluate the potential risk to human consumption.

scholarly journals Maximizing Recovery and Detection of Cryptosporidium parvum Oocysts from Spiked Eastern Oyster (Crassostrea virginica) Tissue Samples

2007 ◽  
Vol 73 (21) ◽  
pp. 6910-6915 ◽  
Author(s):  
Autumn S. Downey ◽  
Thaddeus K. Graczyk
Keyword(s):  
Crassostrea Virginica ◽  
Cryptosporidium Parvum ◽  
Environmental Protection Agency ◽  
Eastern Oyster ◽  
Tissue Homogenate ◽  
Human Consumption ◽  
Oyster Tissue ◽  
Recovery Efficiency ◽  
Tissue Samples ◽  
Contamination Levels

ABSTRACT Numerous studies have documented the presence of Cryptosporidium parvum, an anthropozoonotic enteric parasite, in molluscan shellfish harvested for commercial purposes. Getting accurate estimates of Cryptosporidium contamination levels in molluscan shellfish is difficult because recovery efficiencies are dependent on the isolation method used. Such estimates are important for determining the human health risks posed by consumption of contaminated shellfish. In the present study, oocyst recovery was compared for multiple methods used to isolate Cryptosporidium parvum oocysts from oysters (Crassostrea virginica) after exposure to contaminated water for 24 h. The immunomagnetic separation (IMS) and immunofluorescent antibody procedures from Environmental Protection Agency method 1623 were adapted for these purposes. Recovery efficiencies for the different methods were also determined using oyster tissue homogenate and hemolymph spiked with oocysts. There were significant differences in recovery efficiency among the different treatment groups (P < 0.05). We observed the highest recovery efficiency (i.e., 51%) from spiked samples when hemolymph was kept separate during the homogenization of the whole oyster meat but was then added to the pellet following diethyl ether extraction of the homogenate, prior to IMS. Using this processing method, as few as 10 oocysts could be detected in a spiked homogenate sample by nested PCR. In the absence of water quality indicators that correlate with Cryptosporidium contamination levels, assessment of shellfish safety may rely on accurate quantification of oocyst loads, necessitating the use of processing methods that maximize oocyst recovery. The results from this study have important implications for regulatory agencies charged with determining the safety of molluscan shellfish for human consumption.

Marine Reservoir Effects in Eastern Oyster (Crassostrea Virginica) from Southwestern Florida, USA

Radiocarbon ◽  
2019 ◽  
Vol 61 (5) ◽  
pp. 1501-1510 ◽  
Author(s):  
Carla S Hadden ◽  
Margo Schwadron
Keyword(s):  
Crassostrea Virginica ◽  
National Park ◽  
Archaeological Site ◽  
Eastern Oyster ◽  
Everglades National Park ◽  
Future Research ◽  
Southwest Florida ◽  
Functional Relationships ◽  
Best Estimate ◽  
Carbon Reservoir

ABSTRACTIn southwestern Florida, USA, terraformed landscapes built almost entirely of oyster shells (Crassostrea virginica) reflect a unique pre-Columbian tradition of shell-built architecture. The ability to reliably date oyster shells is essential to identifying spatial, temporal, and functional relationships among shellworks sites, yet to date there has been no systematic attempt to quantify or correct for carbon reservoir effects in this region. Here we present 14 radiocarbon (14C) ages for 5 known-age, pre-bomb oyster shells collected between AD 1932–1948, as well as 6 14C ages for archaeological oyster/charcoal pairs from the Turner River Mound Complex, Everglades National Park. We report our current best estimate of ΔR = 92 ± 74 yr for Greater Southwest Florida, and ΔR = –15 ± 42 yr for the Turner River archaeological site. Future research should focus on paired archaeological specimens to obtain spatially and temporally relevant estimates of ΔR.

Effects of resuspension of eastern oyster Crassostrea virginica biodeposits on phytoplankton community structure

2020 ◽  
Vol 640 ◽  
pp. 79-105
Author(s):  
ET Porter ◽  
E Robins ◽  
S Davis ◽  
R Lacouture ◽  
JC Cornwell
Keyword(s):  
Water Quality ◽  
Community Structure ◽  
Crassostrea Virginica ◽  
Skeletonema Costatum ◽  
Eastern Oyster ◽  
Energy Dissipation Rate ◽  
Negative Effects ◽  
Cell Densities ◽  
Sediment Bottom ◽  
Nitrite Nitrate

Anthropogenic disturbances in the Chesapeake Bay (USA) have depleted eastern oyster Crassostrea virginica abundance and altered the estuary’s environment and water quality. Efforts to rehabilitate oyster populations are underway; however, the effect of oyster biodeposits on water quality and plankton community structure are not clear. In July 2017, we used 6 shear turbulence resuspension mesocosms (STURMs) to determine differences in plankton composition with and without the daily addition of oyster biodeposits to a muddy sediment bottom. STURM systems had a volume-weighted root mean square turbulent velocity of 1.08 cm s-1, energy dissipation rate of ~0.08 cm2 s-3, and bottom shear stress of ~0.36-0.51 Pa during mixing-on periods during 4 wk of tidal resuspension. Phytoplankton increased their chlorophyll a content in their cells in response to low light in tanks with biodeposits. The diatom Skeletonema costatum bloomed and had significantly longer chains in tanks without biodeposits. These tanks also had significantly lower concentrations of total suspended solids, zooplankton carbon, and nitrite +nitrate, and higher phytoplankton carbon concentrations. Results suggest that the absence of biodeposit resuspension initiates nitrogen uptake for diatom reproduction, increasing the cell densities of S. costatum. The low abundance of the zooplankton population in non-biodeposit tanks suggests an inability of zooplankton to graze on S. costatum and negative effects of S. costatum on zooplankton. A high abundance of the copepod Acartia tonsa in biodeposit tanks may have reduced S. costatum chain length. Oyster biodeposit addition and resuspension efficiently transferred phytoplankton carbon to zooplankton carbon, thus supporting the food web in the estuary.

Transcriptomic signatures of temperature adaptation in the eastern oyster Crassostrea virginica

2021 ◽  
Author(s):  
Kevin M. Johnson ◽  
Hollis R. Jones ◽  
Sandra M. Casas ◽  
Jerome F. La Peyre ◽  
Morgan W. Kelly
Keyword(s):  
Crassostrea Virginica ◽  
Eastern Oyster ◽  
Temperature Adaptation

scholarly journals Heritability of acute low salinity survival in the Eastern oyster (Crassostrea virginica)

Aquaculture ◽  
2020 ◽  
Vol 529 ◽  
pp. 735649
Author(s):  
Alexandra J. McCarty ◽  
K. McFarland ◽  
J. Small ◽  
S.K. Allen ◽  
L.V. Plough
Keyword(s):  
Crassostrea Virginica ◽  
Eastern Oyster ◽  
Low Salinity

Elimination of Fecal Coliforms and F-Specific RNA Coliphage from Oysters (Crassostrea virginica) Relaid in Floating Containers†

2001 ◽  
Vol 64 (6) ◽  
pp. 796-801 ◽  
Author(s):  
HOWARD KATOR ◽  
MARTHA RHODES
Keyword(s):  
Public Health ◽  
Crassostrea Virginica ◽  
Fecal Coliforms ◽  
Future Research ◽  
York River ◽  
The Public ◽  
Bottom Culture ◽  
Commercial Scale ◽  
Mesh Bags ◽  
Rain Events

Declining oyster (Crassostrea virginica) production in the Chesapeake Bay has stimulated aquaculture based on floats for off-bottom culture. While advantages of off-bottom culture are significant, the increased use of floating containers raises public health and microbiological concerns, because oysters in floats may be more susceptible to fecal contamination from storm runoff compared to those cultured on-bottom. We conducted four commercial-scale studies with market-size oysters naturally contaminated with fecal coliforms (FC) and a candidate viral indicator, F-specific RNA (FRNA) coliphage. To facilitate sampling and to test for location effects, 12 replicate subsamples, each consisting of 15 to 20 randomly selected oysters in plastic mesh bags, were placed at four characteristic locations within a 0.6- by 3.0-m “Taylor” float, and the remaining oysters were added to a depth not exceeding 15.2 cm. The float containing approximately 3,000 oysters was relaid in the York River, Virginia, for 14 days. During relay, increases in shellfish FC densities followed rain events such that final mean levels exceeded initial levels or did not meet an arbitrary product end point of 50 FC/100 ml. FRNA coliphage densities decreased to undetectable levels within 14 days (16 to 28°C) in all but the last experiment, when temperatures fell between 12 and 16°C. Friedman (nonparametric analysis of variance) tests performed on FC/Escherichia coli and FRNA densities indicated no differences in counts as a function of location within the float. The public health consequences of these observations are discussed, and future research and educational needs are identified.

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