Publications

Palaeoclimate records from late-Holocene sediments in Chesapeake Bay, the largest estuary in the USA, provide evidence that both decadal to centennial climate variability and European colonization had severe impacts on the watershed and estuary. Using pollen and dinoflagellate cysts as proxies for mid-Atlantic regional precipitation, estuarine salinity and dissolved oxygen (DO) during...

Over the past decade, destruction and degradation of wetland habitat has contributed to the decline of wading bird colonies on the Atlantic Coast. In 1998, an initial assessment of the possible contribution of metal pollution to declining heron populations in Chesapeake and Delaware Bays was conducted. Study sites included two heronries in industrialized locations (Pea Patch Island, DE...

In this study we present a method for the measurement of in vitro mitogenesis in fish leucocytes that is based on the incorporation of the thymidine analogue 5′-bromo-2′-deoxyuridine (BrdU) into the DNA of replicating cells, followed by ELISA-based detection. This technique, adapted from methods developed for mammalian cells, operates on a similar biological principle to 3H-thymidine...

Annual yields (fluxes per unit area) of Al, Mn, Fe, Ni, Cd, Pb, Zn, Cu, Cr, Co, As and Se were estimated for two small non-tidal stream catchments on the Eastern Shore of the Chesapeake Bay, United States - a poorly drained dissected-upland watershed in the Nanticoke River Basin, and a well-drained feeder tributary in the lower reaches of the Chester River Basin. Both watersheds are...

The use of airborne hyperspectral remote sensing imagery for automated mapping of submerged aquatic vegetation (SAV) in the tidal Potomac River was investigated for near to realtime resource assessment and monitoring. Airborne hyperspectral imagery and field spectrometer measurements were obtained in October of 2000. A spectral library database containing selected ground-based and...

Slowly growing, non-pigmented mycobacteria were isolated from striped bass (Morone saxatilis) during an epizootic of mycobacteriosis in the Chesapeake Bay. Growth characteristics, acid-fastness and results of 16S rRNA gene sequencing were consistent with those of the genus Mycobacterium. A unique profile of biochemical reactions was observed among the 21 isolates. A single cluster of...

We present paleoclimate evidence for rapid ( 100 years) shifts of ~2-4oC in Chesapeake Bay (CB) temperature ~2100, 1600, 950, 650, 400 and 150 years before present (years BP) reconstructed from magnesium/calcium (Mg/Ca) paleothermometry. These include large temperature excursions during the Little Ice Age (~1400-1900 AD) and the Medieval Warm Period (~800-1300 AD) possibly related to...

Fractured calcareous nannofossils of the genus Discoaster from synimpact sediments within the Chesapeake Bay impact crater demonstrate that other petrographic shock indicators exist for the cratering process in addition to quartz minerals. Evidence for shock-induced taphonomy includes marginal fracturing of rosette-shaped Discoaster species into pentagonal shapes and pressure- and...

To compare natural variability and trends in a developed estuary with human-influenced patterns, stable isotope ratios (δ13C and δ15N) were measured in sediments from five piston cores collected in Chesapeake Bay. Mixing of terrestrial and algal carbon sources primarily controls patterns of δ13Corg profiles, so this proxy shows changes in estuary productivity and in delivery of...

The U.S. Geological Survey has developed a methodology for statistically relating nutrient sources and land-surface characteristics to nutrient loads of streams. The methodology is referred to as SPAtially Referenced Regressions On Watershed attributes (SPARROW), and relates measured stream nutrient loads to nutrient sources using nonlinear statistical regression models. A spatially...

Concentrations of current-use pesticides, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine (OC) insecticides were determined above the reach of tide in the Chesterville Branch and Nanticoke River on the eastern shore of Chesapeake Bay during base-flow and storm-flow hydrologic regimes to evaluate mass transport to Chesapeake Bay. The two...

This paper describes a rapid procedure that allows precise analysis of Mo, Cd, U and Th in sediment samples as small as 10 mg by using a novel approach that utilizes a "pseudo" isotope dilution for Th and conventional isotope dilution for Mo, Cd and U by ICP-MS. Long-term reproducibility of the method is between 2.5 and 5% with an advantage of rapid analysis on a single digestion of...