APPLICATION OF THE SEDIMENT CORE RECORD OF ENVIRONMENTAL CHANGE TO CHESAPEAKE BAY MANAGEMENT ISSUES

A key question for Chesapeake Bay restoration and management concerns the relative influences of climate and land use changes on water quality and bay ecosystems. Specific concerns for Chesapeake Bay revolve around the sources and fluxes of suspended sediment, and setting baseline dissolved oxygen levels for various habitats. We are using the paleoecological record preserved in sediment cores to reconstruct patterns of natural variability in dissolved oxygen, sedimentation, salinity, and temperature to evaluate the impacts of post-Colonial land-use changes and regional climate on the bay.

Stratigraphic and paleoecological analysis of sediment cores collected from the bay and its larger tributaries document increased post-colonial sediment rates. However, there is large spatial variability in the impact of land use change over interannual and decadal timescales. Climate and hydrological variability is the primary driver of sedimentation. A regional sediment budget, including estimates of carbon flux from terrestrial to estuarine sediments, will be presented for the northern bay integrating the sedimentary record with data from surface erosion, Fall Line suspended solids, and tributary sedimentation.

Paleoecological studies also suggest that the deep channel of the bay probably experienced limited oxygen depletion prior to colonial period, but land clearance and 20th century fertilizer application progressively led to more severe and geographically widespread hypoxia and anoxia.