Date Awarded

2001

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Virginia Institute of Marine Science

Advisor

Fu-Lin E. Chu

Abstract

The stress protein response has been proposed as a general indicator of exposure to stress as their expression might integrate overall biological impact and interactions among multiple stressors. as a marker of contaminant effects, a major advantage is the premise of higher sensitivity over other indices such as condition index, scope for growth and survival. Laboratory exposure to suspended field contaminated sediments (SFCS) elicited a stress protein response (HSP70) in the eastern oyster, ( Crassostrea virginica). The stress response probably resulted from the combined effect of various contaminants including PAHs, metals and PCBs. Exposure to 1--2g suspended clay particles spiked with PAHs (Fluoranthene, Pyrene, Benzo(e)Pyrene and Benzo(a)Pyrene) caused an increase in the levels of HSP70. No changes in the condition index or mortality were observed. B(e)P accumulated at a higher level compared to other PAHs. This study appears to indicate that the HSP70 provides a sensitive indicator of exposure to PAHs. The effect of PCBs (Aroclor 1242, 1254 and 1260) on the HSP70 was investigated in sexually mature oysters fed algal paste containing 0, 0.10 or 1.00 mug PCBs daily for 15 and 30 days and immature oysters fed algal paste containing 0, 0.35 or 3.50 mug PCBs daily for 56 days. Exposure to PCBs did not produce significant changes in the HSP70 levels. Exposure to 15--30ppb Cd sorbed to algal food and 1--2g suspended clay particles for 40 days generally did not cause changes in HSP70 levels in oysters. Oysters seem to have a high tolerance for Cd toxicity without eliciting a stress protein response. Oysters collected form Point of Shoals in the James River, Virginia, exhibited variation in the HSP70 levels probably related to water temperature. There seems to be an inverse relation between ambient water temperature and levels of stress protein (i.e. low temperature related to high levels of stress protein). The stress protein response has potential as a biomarker of exposure to contaminants. However, the target of the contaminant, mechanisms of coping with exposure, synergistic interactions of contaminants, endogenous factors, and adaptations and life history traits of organisms may influence the stress protein response.

DOI

https://dx.doi.org/doi:10.25773/v5-dwj4-r408

Rights

© The Author

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