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Similar a Assessing Cumulative Risks to Eastern Oysters
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Assessing Cumulative Risks to Eastern Oysters
- 1. BY: VRUSHALI LELE THESIS DIRECTOR: DR. PETER DEFUR
- 9. FACTORS FOR DECLINE: Overfishing, Pollution, Disturbance in Habitat, Diseases like MSX and Dermo
- 12. IMPACT OF MULTIPLE STRESSORS TO OYSTERS
- 13. Agricultural/Industrial Runoff Point/Non Point Sources Eutrophi cation overharvesting of natural resources Sources Changes in Salinity, Temperature Hypoxia, Hypercapnia, Acidosis Vulnerability to infection Water quality deterioration, habitat alteration Physiological functions like reproduction, respiration Eastern Oysters Invertebrates depending on oyster reefs, fishes etc. Sea food consumers, economy Oxygen Uptake of Oysters Vulnerability to diseases Stressors Pathways Receptors Endpoints CONCEPTUAL MODEL FOR THE STUDY +
- 17. Map of monitoring stations used in the study
- 18. DO (Hypoxia) Calculated slope (m), intercept (c), and substituted salinity values (x) from dataset (y = mx+c) Multiplied Q 10 values from the study with O 2 uptake from step 1 Calculated relative change and multiplied with O 2 uptake values from step 2 SEQUENCE OF STEPS USED TO CALCULATE FINAL OXYGEN UPTAKE Temperature Salinity Shumway and Koehn, 1982 Salinity: 7-28ppt Temp: 10-30°C
- 19. Final O 2 uptake in ml/hr gm -1 wet weight Multiplied step 4 O 2 uptake by 0.0224 to convert µmol/hr to ml/hr and 14.8 to convert dry weight to wet weight Calculated the relative change and multiplied with O 2 uptake value from step 3 CO 2 (Hypercapnia) Willson and Burnett,2000 Salinity: 25 ppt Temp: 25°C
- 25. CUMULATIVE PROBABILITY DISTRIBUTION OF OXYGEN UPTAKE USING CRYSTAL BALL
- 26. SENSITIVITY ANALYSIS CHART GENERATED BY CRYSTAL BALL
- 33. ?
Notas del editor
- The species name, virginica, was assigned because of the oysters’ predominance in the Virginia waters of the Chesapeake. Abundant in the Long Island Sound, Chesapeake Bay and Gulf of Mexico The American oyster typically lives in shallow, well-mixed estuaries, lagoons, and oceanic bays where it tolerates widely fluctuating water Temperatures and salinities. Why are temperature and salinity important?
- Descriptions of the oyster beds have been found in writings dating back to 1642, demonstrating the social and economic significance of the resource to early European settlers.
- Filter feeding activity may enhance water clarity, increasing light penetration and trapping contaminants entering coastal waters. Ecosystem Engineers
- Oyster spat are the juvenile "young of year" or yearling stage. Spat data indicate that oysters are still able to spawn and have the potential for restoration. The data do not reflect survival to harvestable size, nor do they reflect population size in the Bay. Data are from the VIMS Fall Public Oyster Grounds Survey. Oyster spat per bushel of bottom cultch sampled are averaged from seven bars on the James River: Horsehead, Long Shoal, Wreck Shoals, Point of Shoals, Dry Shoal, Thomas Rock and Nansemond Ridge. The historical peak in the James is around 10 times that of the Maryland peak. Oyster spat set and growth to adult stages are affected by freshwater flows to the Bay. At lower salinities, although growth is slower and potential for spat set is lower, oyster diseases caused by MSX and Dermo are kept in check. However, extremely low salinities may result in high oyster mortality. At higher salinities, growth and spat set are generally higher, but the potential for diseases caused by MSX and Dermo is greater. Virginia waters are generally higher in salinity compared to Maryland waters. Although spat set is higher in VA (compared to MD), survivorship to market size is typically lower than in MD.
- Chesapeake bay- as a hypoxic body
- Amongst all the abiotic factors, synergistic effects of temperature and salinity probably have the most significant effects on C. virginica . As numerous researchers have pointed out “two or more environmental factors acting in concert have profound biological consequences than any one of those factors acting independently”.
- Integrating the concepts of CRA in this study by taking elements from CRA Anthropogenic activities like
- (mx+c) = equation for a straight line Q 10 = factor by which the reaction rate increases for every 10-degree rise O 2(S) = Salinity adjusted O2 uptake RC = Relative change calculated relative change for adjusting changing DO oxygen uptake adjusted to temperature in ml/hr gm wet weight RCʹ = calculated relative change for adjusting changing CO 2 levels W = weight constant for converting dry weight into wet weight of the organism G = gas constant for converting µmole/hr into ml/hr
- Sensitivity analysis calculated when multiple risks of two or more independent stressors act simultaneously and are presented as a probability, the risk is the product of individual risks, not the sum (S. Ferenc et al., 1999). In this study, in order to calculate the oxygen uptake of oysters, cumulative risks (salinity, temperature, hypoxia and hypercapnia) were sequentially multiplied to understand if there was “synergy” between the risks. Therefore, cumulative risks need to multiplied and not added.
- stressors are not limited to chemicals. They could be biological, physical, social, economical, psychological, behavioral stresses, or natural or anthropologic activities that could disturb the equilibrium of any system. The third feature calls for combining the risks from the multiple stressors.
- 0.8- Loose distribution, loose the tail-single estimate