Master of Arts (M.A.)
Virginia Institute of Marine Science
Muscle and hepatopancreas of blue crabs (Callinectes sapidus), collected from the Elizabeth River, Virginia, contained residues of polycyclic aromatic hydrocarbon (PAHs}, polychlorinated biphenyls (PCBs) and organochlorine pesticides. Analytical procedures involved dichloromethane extraction of lyophilized tissue, followed by molecular size and polarity-based purification of the extract. capillary gas chromatography with flame ionization detection and electrolytic conductivity detection was used for quantitation and tentative identification of the xenobiotic compounds. Mass spectrometry was used for confirmation of these identities. Contaminant concentrations were greater in hepatopancreas than in muscle in crabs from every site examined. Hepatopancreas PAH burdens were as high as 11 mg/kg dry weight, with an accompanying muscle level of 3.1 mg/kg. The PAHs present consisted mainly of alkylated low molecular weight compounds (e.g., acenaphthenes and naphthalenes), except near a creosote-impacted site. At the latter location, unsubstituted, higher molecular weight PAHs (e.g., pyrene and chrysene) dominated. Organochlorines, which included PCBs, 4,4'-DDE, and chlordane were found in lower concentrations.
The effect of molting on xenobiotic accumulation in Crustacea was also examined. Molting is essential for crustacean growth and is integral to the reproductive process in some species. Molting and intermolt blue crabs were maintained in cages at the creosoted-impacted Elizabeth River site mentioned above. PAH concentration in muscle and hepatopancreas was measured for both molt groups. Newly molted blue crabs possessed statistically higher tissue burdens than intermolt crabs of three unsubstituted PAHs (cyclopenta(def)phenanthrene, fluoranthene, and pyrene) characteristic of the creosote-contaminated exposure site. Mean concentration of the three PAHs in hepatopancreas was 9560 μg/kg in newly molted crabs and 3360 μg/kg in intermolt crabs. Mean PAH concentration in muscle was 1380 μg/kg in new-molts and 498 μg/kg in intermolts. The elevated tissue burdens may be due to increased water uptake and shell permeability at ecdysis or decreased metabolism of PAH during the molt process. Newly molted blue crabs are regarded as a seafood delicacy and tissue burdens of xenobiotics, such as PAHs, may be of human health concern.
© The Author
Mothershead, Robert F., "Contaminant Accumulation in Hard and Soft Shell Blue Crabs from an Urban Subestuary" (1991). Dissertations, Theses, and Masters Projects. Paper 1539617623.