The American oyster (Crassostrea virginica) as a bioindicator of trace organic contamination /
| Main Author: | |
|---|---|
| Other Authors: | , , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1993.
|
| Subjects: | |
| Online Access: | Link to ProQuest copy Link to OAKTrust copy ProQuest, Abstract |
| Abstract: | This study was designed to examine the uptake and depuration of trace organic contaminants, e.g. poly nuclear aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), including planar congeners, and butyltin species, by oysters (Crassostrea virginica) through transplantation experiments in Galveston Bay, Texas. PAHs, low molecular weight PCBs and tributyltin (TBT) were rapidly bioaccumulated by transplanted oysters and apparent equilibrium concentrations were reached after 20 to 30 days of exposure. In contrast, high molecular weight PCBs did not reached an equilibrium plateau at the end of the seven-week exposure period. When oysters were back-transplanted to their former location, PAHs, low molecular weight PCB congeners and TBT were depurated at similar rates while the high molecular weight PCBs were depurated at considerably slower rates. The original background concentrations were not reached after the 50-day depuration period. Chronically contaminated Ship Channel oysters, simultaneously transplanted to the uncontaminated area, showed lower clearance rates than those encountered for originally uncontaminated bivalves. Oysters exposed in the laboratory to PCBs and PAHs, preferentially bioaccumulated four to six chlorine-substituted PCBs and four- and five-ring PAHs. Oysters exposed simultaneously to PAHs plus PCBs depurated PAHs at a faster rate than oysters that were exposed solely to PAHs. The half-lives for individual PAHs encountered in the first group of oysters were similar to those found in the field. The present study presents evidence to substantiate the theory that bioconcentration and clearance of different PCB congeners by oysters appear to be more affected by molecular size than by hydrophobicity. The influence of the chlorine substitution patterns in the bioaccumulation of PCBs by oysters is particularly evident in the case of the highly toxic planar congeners. Indigenous oysters can be valuable bioindicators of environmental contamination by trace organic compounds only if their limitations are fully understood. Within these limitations, transplanted oysters can be succesfully used to monitor environmental contamination by PAHs and TBTs in areas lacking indigenous bivalves if deployed in-situ for a period of time of at least 30 days; for PCBs, however, a much longer time period, i.e over 6 months, may be required. |
|---|---|
| Item Description: | "Major subject: Oceanography." Vita. |
| Physical Description: | xix, 242 leaves : illustrations, maps ; 28 cm |
| Bibliography: | Includes bibliographical references. |