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|Title:||Effects of Black Rock Harbor dredged material on the histopathology of the blue mussel 'Mytilus Edulis' and polychaete worm 'Nephtys Incisa' after laboratory and field exposures|
|Authors:||Environmental Research Laboratory (Narragansett, R.I.)|
Science Applications International Corporation.
United States. Environmental Protection Agency.
Field Verification Program (Aquatic Disposal)
Yevich, Paul P.
Nelson, William G.
Black Rock Harbor
|Publisher:||Environmental Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
Abstract: A study was conducted to field verify histopathological changes in two aquatic species, Mytilus edulis and Nephtys incisa, by comparing histological changes under both laboratory and field exposures to contaminated dredged material. A second objective of the study was to determine the degree of correlation between tissue residues resulting from bioaccumulation of dredged material contaminants with histopathological changes. A laboratory dosing system was designed to deliver a constant exposure concentration of suspended sediment (both reference and contaminated dredged material from Black Rock Harbor (BRH)) to the blue mussel Mytilus edulis and the polychaete worm Nephtys incisa. Residue concentrations in both mussels and worms, particularly stable compounds such as polychlorinated biphenyls (PCBs), were found to be closely related to exposure concentrations. Histopathological changes included the female reproductive tract, gills, and gastrointestinal tract for M. edulis and the parapodial epidermis for N. incisa. Histopathological changes observed for specimens of both species following laboratory exposures were directly related to BRH exposure and subsequent tissue concentrations. There was a definite relationship between histopathological change and tissue residues in M. edulis in the laboratory for those BRH contaminants that were bioaccumulated. A residue-effect relationship was not evident for N. incisa in the laboratory, since a change in the parapodial epidermis was not considered to be a pathological condition and was the only response reported. Field exposure estimates of BRH suspended sediments at 1 m above the sediment-water interface indicated that maximum concentrations occurred during the disposal operation, after which exposure concentrations and tissue concentrations of BRH contaminants decreased to background within 1 to 2 months. The general lack of exposure to BRH sediments in the field resulted in no observed histopathological changes in M. edulis; consequently, no residue-effects relationships could be determined. The laboratory-field comparison for M. edulis is based upon a comparison of exposure conditions estimated from tissue residues and chemical data. Cluster analysis of the M. edulis residue data indicates that field residues are most similar to laboratory exposures to reference material. Field residues during disposal, though elevated, are less than those reported for the lowest laboratory exposure (1.5 mg/𝓁) to BRH sediment. The lack of histopathological responses in M. edulis exposed in the field is not unexpected, since field exposures reflect laboratory reference exposures that did not result in histological effects. There is, therefore, excellent agreement between the histopathological data from the lab and from the field. Laboratory results for N. incisa show significant increases in tissue residue values. The only histopathological observation was a darkening and thickening of the epidermal tissue of the parapodia. Field results failed to detect similar changes from N. incisa exposed on and around the disposal site. Laboratory and field exposures were analogous as estimated by tissue residues and physical models. Cluster analysis of the N. inaisa tissue residue data from the laboratory and field revealed no consistency of association; that is, there were no differences. Thus, exposures to N. incisa between the laboratory and field were analogous, as was the absence of histopathological changes. The only exception was the thickening and darkening of the parapodial epidermis observed from the laboratory studies. Because of the general lack of histopathological change, residue-effect relationships were not determined. NOTE: This file is large. Allow your browser several minutes to download the file.
|Appears in Collections:||Technical Report|