A majority of carbon in freshwater and marine ecosystems is in the form of ultraplankton, heterotrophic and autotrophic plankton &<&5 &\mu&m including heterotrophic bacteria, Prochlorococcus, cyanobacteria, and autotrophic eucaryotes. However, ultraplankton and subsequently microbial food webs have yet to be incorporated into models of benthic-pelagic coupling despite the preponderance of macroinvertebrates with the capacity to feed on ultraplankton. I have examined the role of microbial food webs in benthic-pelagic coupling in three ecosystems: Lake Baikal, Siberia, Russia; Gulf of Maine, Northwest Atlantic Ocean; and Conch Reef, Florida Keys, USA. Using sponges as a model organism and in situ measurements, I have quantified (1) suspension feeding on ultraplankton and (2) release of dissolved inorganic nitrogen (DIN) and phosphorus (DIP) resulting in direct evidence that benthic macroinvertebrates do occupy the level of primary consumer within the microbial food web. Dual-beam flow cytometry was employed to quantified sponge suspension feeding on five types of ultraplankton: heterotrophic bacteria, Synechococcus-type cyanobacteria, autotrophic picoplankton &<&3 &\mu&m, autotrophic eucaryotes 3-10 &\mu&m, and in marine ecosystems Prochlorococcus. Grazing by the freshwater sponges Baikalospongia intermedia and B. bacilliferia and the boreal marine sponge, Mycale lingua, was unselective for all types of ultraplankton with efficiencies ranging from 63-99%. This is the first time that grazing on Synechococcus-type cyanobacteria and Prochlorococcus by macroinvertebrates has been quantified in freshwater and marine ecosystems. Conversely, the coral reef sponges Ircinia felix and I. strobilina release significant amounts of DIN and DIP as a result of grazing on procaryotic plankton. Using a general model for organism-mediated fluxes, it is conservatively estimated that through active suspension feeding sponges in Lake Baikal retain 1.97 g C day&\sp{lcub}-1{rcub}& m&\sp{lcub}-2{rcub}& and M. lingua retains 29 mg C day&\sp{lcub}-1{rcub}& m&\sp{lcub}-2{rcub}& while at Conch Reef sponges released 204 &\mu&mol DIN day&\sp{lcub}-1{rcub}& m&\sp{lcub}-2{rcub}& and 48 &\mu&mol DIP day&\sp{lcub}-1{rcub}& m&\sp{lcub}-2{rcub}&. A majority of the carbon retained at all three locations was from procaryotic cell types suggesting that ultraplankton are an important overlooked component of benthic-pelagic coupling.

Community concerns regarding natural resource management may be addressed in several forms. The community may participate as part of the public in the management process; community concerns may be included in social impact assessment; and communities may directly participate as managers of resources whether on their own or in conjunction with higher levels of government. In fisheries, typically community concerns are addressed through social impact assessment which is perceived to be lacking in social theory, history, and often effect (Boggs 1994, Little and Krannich 1989). More recent activity and newer regulations show success with co-management, a management regime of shared responsibilities that is perceived to be based in social theory (McCay and Acheson 1987, Berkes et al 2001). Co-management requires specific situations to be in place for its institution, however (McCay 2002). This dissertation was undertaken to find a mechanism to assist communities in providing their concerns on management issues of area management and possible buybacks while meeting requirements of social theory and law. In the attempt, a social impact assessment based upon community-based co-management theory, an assessment of the potential of community-based co-management are generated.*. *This dissertation is a compound document (contains both a paper copy and a CD as part of the dissertation).

American oyster (Crassostrea virginica) stocks on the East Coast in general, and in Chesapeake Bay in particular, have been in decline over the past half-century in large part due to Dermo disease, caused by the protist parasite Perkinsus marinus. Efforts to restore oysters for their ecological and economic value have centered on the development and use of hatchery-based seed selectively bred for disease resistance. Selective breeding could benefit from the incorporation of oysters from wild stocks that have developed "natural Dermo resistance", but few such stocks have been identified and verified. This dissertation describes reciprocal common-garden experiments carried out at two sites in each of the Gulf of Mexico and the Chesapeake Bay between fall 1999 and winter 2001. The experiments compared growth, disease intensity, and survival of seed from putatively disease resistant and susceptible populations in both the Gulf of Mexico and Chesapeake Bay. In the Gulf experiment, oysters from Gulf stocks showed increased survival and decreased disease intensity, determined by body burden analysis of parasite cell counts, compared to Chesapeake stocks. Survival and disease intensities showed statistically significant, but slight differences among stocks of Gulf origin and among stocks of Chesapeake origin. There was no significant difference in growth over the eighteen months of the experiment. The Chesapeake study also showed lower infection intensity and decreases mortality attributable to Dermo disease in Gulf stocks. There were also significant differences in disease intensity and survival among Chesapeake stocks. Additionally, the stock from Rappahannock River, VA showed increased growth compared to other stocks. In an additional study, oysters from the Chesapeake Bay study were used to determine if an association existed between disease intensity (body burden) and host defense activity, as measured by a suite of assays, including hemocyte counts, granulocyte percentage, hemocyte killing ability, serum protein concentration, and serum lysozyme activity. Development of two new assays, serum inhibition of P. marinus protease, and serum inhibition of P. marinus activity, was begun, but require additional refinement. No strong correlation or association was found, but a seasonal component was apparent in several defense assays, as well as in disease intensity. This work has identified and verified wild stocks that have been incorporated into existing breeding programs for both restoration and the development of commercial aquaculture in Chesapeake Bay and the Gulf of Mexico. The existence of disease resistant wild stocks also suggests that the conservation of wild oysters is a viable alternative or addition to current hatchery-based restoration efforts.

Spot, Leiostomus xanthurus, were exposed to suspended sediments (&\approx&20 mg/L) contaminated with polycyclic aromatic hydrocarbons (PAH) in a laboratory flow-through system to evaluate the applicability of hepatic ethoxyresorufin O-deethylase (EROD) induction as an indicator of PAH exposure. PAH sources tested were coal-tar creosote (CTC), a low molecular weight fraction of creosote (LMWF), and a high molecular weight fraction of creosote (HMWF). A standard 96-h acute toxicity test was conducted to ensure that PAH concentrations tested in induction studies were sub-acutely toxic. The 96-h LC50 for spot was 1740 &\mu&g PAH/L (95% confidence interval = 1480-2060 &\mu&g PAH/L). The lowest concentration producing an observable effect in 96 h was 560 &\mu&g PAH/L; no effects were observed for spot exposed to 250 &\mu&g PAH/L for 96 h. Induction of hepatic EROD activity occurred rapidly in fish exposed to high environmentally realistic concentrations of CTC or the HMWF, but not the LMWF. Maximal induction (30-fold) occurred in fish exposed for 48 h to 150 &\mu&g PAH/L. Induction was concentration-dependent up to 150 &\mu&g PAH/L; at 320 &\mu&g PAH/L induction was 14-fold. EROD activity decreased upon further exposure; by day 7, EROD activity was not significantly different than that on day 0. EROD activity in fish exposed to 16 &\mu&g PAH/L was not consistently higher than that in control fish. Spot exposed to at least 70 &\mu&g PAH/L from CTC or the HMWF experienced severe fin erosion, epidermal lesions, and mortality beginning a few days after maximal EROD induction occurred. No relationship between EROD induction and whole animal responses is implied, only that EROD induction did precede any high order effects. These results indicate complications to the use of EROD activity as a sensitive, reliable indicator of PAH exposure. The toxicity of CTC may inhibit or interfere with continued induction of EROD activity, but neither the toxicity nor inducing capability is associated with the LMWF. The lack of exposure-dependent EROD induction indicate there could be difficulties in interpreting field studies, where fish have unknown exposure histories.

An ontogenetic series of nine species; Centrophorus granulosus, Centroscymnus coelolepis, Dalatias licha, Deania calcea, Echinorhinus cookei, Isistius brasiliensis, Oxynotus centrina and Squalus acanthias were studied to determine swimming capabilities, boundary-layer flow conditions and placoid scale functional morphologies. Body morphometric variables included the girth and the distance from snout to the orbitals, origin of the median and paired fins, and the caudal peduncle, body and fin surface area, fin aspect ratios and caudal fin angles. Placoid scales were sampled from sixteen regions across the body. Morphometric variables included the number of scales per area of integument, scale crown width, length and area, and scale weight. Body shape morphometry coupled with published natural histories suggest a majority of the species examined are probably capable of moderate to fast swimming speeds. There was a correlation between low fin aspect ratios and near neutral buoyancy among the species examined suggesting functions other than dynamic lift for the paired fins. Likewise, there was a trend for these fins to be reduced in size suggesting decreased drag. Freed from functioning in generating lift, the pectoral fins probably provide a high degree of vertical directional control. Larger fins with relatively high aspect ratios were correlated with negatively buoyant species suggesting a role in providing dynamic lift. These sharks were more typical in body form of coastal pelagic or benthic sharks of the order Carcharinidae. The squaloid sharks have been recognized to possess the most morphologically diverse placoid scales. Among the nine species examined, three general crown morphologies were distinguished; traditional plate-like crowns, spike or thorn-like crowns and concave trapezoidal crowns. Ontogenetic, sexual dimorphic, and spatial variability within a specimen was observed in all species and interspecific variability was observed in the trends of placoid scale variability. Placoid scale functional morphologies are hypothesised from intraspecific and interspecific variability, body shape morphologies and natural histories.

Cataract formation in the Elizabeth River (ER) has been reported since 1986. Previous studies have concentrated on describing cataract as a function of exposure to polluted sediments, especially polycyclic aromatic hydrocarbons (PAH). These studies, however, have not examined what processes might be involved in fish cataractogenesis. The overall objective of this research was to identify important processes associated with the early development of cataract in feral fish populations. Field studies were used to systematically examine cataract development. Cataract in sciaenids was not associated with previously described cataractogenic factors, but could be linked to contaminated sediments of the ER. Cataract was highly prevalent, first appeared at the visible center of the lens, varied in the degree opacification (&<&10-100%), could be classified into stages of development (stage 1-4), and inhibited lens growth. Furthermore, data showed that a positive association existed between bottom water temperatures (&\sp\circ&C) and cataract prevalence. Biochemical comparison of lenses revealed that the water content, cholesterol level, and free fatty acid composition were significantly elevated, total esters reduced, while no significant changes occurred in the protein composition of lenses with early cataract development. These data suggest that altered plasma membrane permeability might be involved in opacification. Investigations of cataract in fish at the cellular level have not been studied due to the absence of a reliable in vitro model. Protocols were established for the primary culture, successful passage (45 subcultures), and the long-term maintenance (54 months) of spot lens epithelial cells. Cells exhibited certain morphological characteristics, crystallin-protein composition, and chromosome complement indicative of epithelial cell differentiation and cell-line transformation. In vitro experiments indicated that both DNA and RNA indices were positively associated with cataract development in spot lenses. Results suggested that high molecular weight PAH may play a role in interfering with the mitotic cycle of epithelial cells. These results suggest that lens epithelial cells are disturbed and may be involved in the initial steps of cataractogenesis. In conclusion, results demonstrate that cataract development is associated with high levels of contamination found in the ER. Altered membrane permeability and epithelial cell function may play a key role in cataract initiation.

No description available.

No description available.

No description available.

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.