A Paleoecological History of the Late Precolonial

Authors: Angela A Sowers Grace S Brush

Publish Date: 2014/03/06

Volume: 37, Issue: 6, Pages: 1506-1515

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Abstract

Geochemical total nitrogen total organic carbon total phosphorus total sulfur and carbon and nitrogen stable isotopes and selected biotic diatom foraminifera polychaete indicators preserved in two estuarine sediment cores from the mesohaline Chesapeake Bay provide a history of alterations in the food web associated with landuse change One core from the mouth of the Chester River CR collected in 2000 represents a 1000year record The second core collected in 1999 from the Chesapeake Bay’s main stem opposite the Choptank River MD represents a 500year record As European settlers converted a primarily forested landscape to agriculture sedimentation rates increased water clarity decreased salinity decreased in some areas and the estuarine food web changed into a predominantly planktonic system Representatives of the benthic macrofaunal community foraminifera and the polychaetes Nereis spp were affected by local changes before there were widespread landscape alterations Nitrogen stable isotope records indicated that landuse changes affected nitrogen cycling beginning in the early 1700s Extreme changes were evident in the midnineteenth century following widespread deforestation and since the midtwentieth century reflecting heightened eutrophication as development increased in the Chesapeake Bay watershed Results also demonstrate how paleoecological records vary due to the degree of terrestrial inputs of freshwater runoff and nutrients at core locations within the Chesapeake BaySupport for this research was provided by Maryland Sea Grant cooperative agreement 00–21 the Johns Hopkins University’s Center for a Livable Future and the Marine Conservation Biology Institute Mia J Tegner Memorial Award We thank J Halka for collecting core CR22000 T Cronin for providing MD992205 sediment samples core stratigraphy MD992205 foraminifera counts and radiocarbon dates WW2719 WW2722 J Cornwell for performing 210Pb analyses plus technical assistance and R Hatfield for assistance with calibration of radiocarbon dates We thank the following for helping with microfossil identification J Cann foraminifera K Fauchald polychaetes and S Cooper diatoms We acknowledge the following laboratories for performing geochemical analyses Maryland Cooperative Extension sulfur and phosphorus the University of California Davis—Stable Isotope Facility carbon nitrogen and carbon and nitrogen stable isotopes and Beta Analytic radiocarbon dating Beta 162639 We thank Hilary Collier for assistance with the figures We also thank Dr Denise Breitburg for a prior manuscript review and Sandy Rodgers of Maryland Sea Grant for assistance with copyediting

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