Research Projects

To relate the cycling of organic pollutants in Chesapeake Bay to seasonal changes in organic matter cycling and sediment transport. We will link compound-specific settling velocities, burial rates, resuspension fluxes, and benthic recycling rates to contaminant sorption and particle characteristics.

The objectives of the proposed study are: 1) To investigate the resuspension and transport of fine sediments in the northern Chesapeake Bay, characterizing temporal and spatial variability in resuspension processes 2) To investigate the influence resuspension on the time varying flux of toxics across the sediment-water interface, and to examine how resuspension affects partitioning of toxics between continuously suspended particulates, tidally resuspended particulates, bottom sediments, and dissolution; 3) To relate resuspension and transport of sediment associated toxics to more easily measureable or predictable sediment and physical forcing characteristics.

The production of cytotoxic oxygen metabolites by oyster blood cells will be quantified by state-of-the-art assays measuring biochemical events associated with hemocyte-mediated destruction of pathogens. Hemocytes from oysters exposed to sub-lethal concentrations of model pollutants will also be studied to identify immunotoxicological responses. Our data will define mechanisms of disease resistance, as well as unique biomarker assays for chemical stress.

We hypothesize that abundant pelagic fishes, principally the bay anchovy and menhaden, are the major consumers of plankton production in the Chesapeake Bay, forming a key link in the pathway from primary production to harvestable fish resources. To test this hypothesis and to compare/contrast the ecology of the two species in the Maryland portion of the Bay, we will estimate seasonal biomasses and abundances of anchovy and menhaden, and define their trophic relationships, growth statistics and production in relation to the physical structure of the environment. Schooling pelagic fishes, principally bay anchovy and menhaden, are hypothesized to be major consumers of plankton production in the Chesapeake Bay and form a key link in the pathway from primary production to harvestable fish.

In field collections of surficial sediments, sediment traps material and 4 size fractions of suspended particles, the concentration and distribution of hydrophobic organic contaminants (HOC) will be quantified. Parallel laboratory studies will examine the speciation and binding of contaminants to phytoplankton and the role of specific organic pools (lipids and pigments) in HOC movement.

The proposed research will provide data on behavior, growth and survival needed to assess the impact of anoxic and hypoxic waters in the Chesapeake Bay on mortality of larval fishes. We will determine whether larvae of two important forage species avoid oxygen-poor water in a stratified water column, as well as effects of low DO on growth, survival, swimming behavior and susceptibility to predation -- factors likely to influence larval mortality when hypoxic waters are not avoided. In addition, we will compare results of laboratory experiments with samples collected to examine the relationship between DO and larval distributions in the field.

The objectives of this project are: to establish mass-balance constraints on planktonic trophuc fluxes through simulation studies and measures of net community metabolism (NCM); to calculate nutrient export/input for Bay regions and seasons in relation to NCM; to estimate particulate organic (POM) deposition for specific seasons and Bay regions; to relate spatial/temporal variations in NCM and POM deposition to changes in plankton trophic dynamics.

This proposal seeks funds for participation in a multidisciplinary investigation of the transport of hydrophobic organic contaminants (HOCS) in Chesapeake Bay. This component of the project will focus on how zooplankton feeding and excretion alter the size distribution of suspended matter and thus affect the fact of particle-associated HOCS.

Determine the effects of dietary HUFA supplement on production and performance of hybrid striped bass. Determine the function of 20:5 (n-3) and 22:6 (n-3) in the diets of hybrid striped bass with respect to growth. Determine the requirements (by weight) of (n-3) fatty acids for hybrid striped bass.

The general objective of the proposed research is to apply economic analysis to the problem of changing people's behavior concerning the* disposal of marine debris. There are three specific objectives: 1)to prepare a comprehensive state~nt of the economic dimensions of the marine debris policy problem; 2)to review and evaluate the available theory and evidence on the effectiveness of policies used in other related pollution contml programs; and 3)to conduct an empirical study of the marine debris problem in the commercial fishing and recreational boating sectors.-

The objective of this study is to deploy NASA's Ocean Data Acquisition System (ODAS) in the Chesapeake Bay during successive winter-spring transitions in 1990 and 1991 to produce fine-scale maps of phytoplankton biomass. ODAS is an aircraft borne ocean color instrument that is used to detect chlorophyll concentrations. We propose to track event-scale changes in phytoplankton distributions during the diatom blooms that develop annually in the mesohaline to polyhaline part of the Bay.

To study the sequential pathological and microbiological changes occurring in striped bass experimentally infected with selected microbial pathogens, to study virulence mechanisms of those pathogens, and to develop rapid and sensitive methods for their detection.