Publications

The Chesapeake Bay, the Nation's largest estuary, has been degraded because of diminished water quality, loss of habitat, and over-harvesting of living resources. Consequently, the bay was listed as an impaired water body due to excess nutrients and sediment. The Chesapeake Bay Program (CBP), a multi-jurisdictional partnership, completed an agreement called "Chesapeake 2000" that revises...

Atlantic menhaden Brevoortia tyrannus develop characteristic skin ulcers in response to infection by the oomycete Aphanomyces invadans. To investigate pathogenicity, we conducted a dose response study. Juvenile menhaden were inoculated subcutaneously with 0, 1, 5, 10, 100, and 500 secondary zoospores per fish and monitored for 37 d post-injection (p.i.). Survival rates declined with...

Ulcers in Atlantic menhaden Brevoortia tyrannus (Latrobe) (Clupeidae), observed along the USA east coast, have been attributed to diverse etiologies including bacterial, fungal and, recently, harmful algal blooms. To understand the early pathogenesis of these lesions, we examined juvenile Atlantic menhaden collected during their seasonal presence in Chesapeake Bay tributaries from April...

No abstract available.

Calculations indicate that the impact of an asteroid or comet on the Atlantic Coastal Plain 35 million years ago created subsequent hydrothermal activity and conditions suitable for phase separation and the creation of the brine observed in the groundwater at the site today. A calculation of groundwater velocity using Darcy's law suggests flow rates are insufficient to have moved the...

Ecological and paleoecological studies from the Patuxent River mouth reveal dynamic variations in benthic ostracode assemblages over the past 600 years due to climatic and anthropogenic factors. Prior to the late 20th century, centennial-scale changes in species dominance were influenced by climatic and hydrological factors that primarily affected salinity and at times led to oxygen...

The Chesapeake Bay impact structure, formed by a comet or meteorite that struck the Virginia continental shelf about 35.5 million years ago, is the focus of an extensive coring project by the U.S. Geological Survey and its cooperators. Organic-walled dinocysts recovered from impact-generated deposits in a deep core inside the 85-90 km-wide crater include welded organic clumps and fused...

Seasonal and interannual controls of benthic sulfate reduction (SR) were examined at 3 sites (upper [UB], mid- [MB] and lower [LB] bay) along the Chesapeake Bay central channel, from early spring through fall, for 6 yr (1989 to 1994). The combined influences of temperature, sulfate, organic loading and bioturbation affected seasonal SR rates differently in the 3 regions. Consistently low...

No abstract available.

Two major pulses of sea-level rise are thought to have taken place since the last glacial maximum — meltwater pulses (mwp) 1A (12 cal ka) and 1B (9.5 cal ka). Between mwp 1B and about 6 cal ka, many of the complex coastal ecosystems which ring the world’s oceans began to form. Here we report data for rhenium, carbon isotopes, total organic carbon, and fossil oysters from Chesapeake Bay...

Sediment cores as long as 20 m, dated by 14C, 210Pb, and 137Cs methods and pollen stratigraphy, provide a history of diatom productivity and sediment-accumulation rates in Chesapeake Bay. We calculated the flux of biogenic silica and total sediment for the past 1500 yr for two high-sedimentation-rate sites in the mesohaline section of the bay. The data show that biogenic silica flux to...