Anthropogenic nitrogen contributes to water quality degradation, but it is difficult to distinguish sources once they are mixed in coastal ecosystems. Natural abundances of stable nitrogen isotopes (delta N-15) were measured in oyster (Crassostrea virginica) tissues (muscle, gills, and mantle) during summer 2006 to summer 2008 to identify nitrogen sources in Monie Bay (a subestuary of Chesapeake Bay) receiving freshwater inputs from three tributary creeks. The creeks (estimated flushing times:

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Long-term non-linear ecosystem-scale changes in water quality and biotic communities in coastal lagoons have been associated with intensification of anthropogenic pressures. In light of incipient changes in Johnson Bay (an embayment of Chincoteague Bay, Maryland-Virginia, USA), examination of nitrogen sources was conducted through synoptic water quality monitoring, stable nitrogen isotope signatures (deltaN-15) of in situ bioindicators, and denitrification estimates.

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Anthropogenic nitrogen contributes to water quality degradation, but it is difficult to distinguish sources once they are mixed in coastal ecosystems. Natural abundances of stable nitrogen isotopes (deltaN-15) were measured in oyster (Crassostrea virginica) tissues (muscle, gills, and mantle) during summer 2006 to summer 2008 to identify nitrogen sources in Monie Bay (a subestuary of Chesapeake Bay) receiving freshwater inputs from three tributary creeks. The creeks (estimated flushing times:

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Chapter 4 discussed how selecting an appropriate communication product can affect an audience and persuade opinions. This chapter discusses how using another tool, an indicator (Figure 5.1), not only can persuade opinions, but also can be used to evaluate the health of an ecosystem.

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One of the most important goals of a coastal assessment program is to increase the knowledge of individuals and agencies who make management decisions. Information must be presented in an easy-to-understand format and supported by quantitative analyses. Quantitative analyses often involve applying statistical techniques that are used to visualize, describe, and model data.

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Stable nitrogen isotopes ([delta]15N) in bioindicators are increasingly employed to identify nitrogen sources in many ecosystems and biological characteristics of the eastern oyster (Crassostrea virginica) make it an appropriate species for this purpose. To assess nitrogen isotopic fractionation associated with assimilation and baseline variations in oyster mantle, gill, and muscle tissue [delta]15N, manipulative fieldwork in Chesapeake Bay and corresponding modeling exercises were conducted.

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Coastal lagoon ecosystems across the Delmarva Peninsula are rapidly evolving due to changing land use patterns and shifts towards intensive agriculture, particularly poultry production, and intensive rural-resi­dential development. These changes in the coastal lagoon seascape are especially evident in the northern Coastal Bays watershed of St. Martin River.

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Intensive sampling of the Maryland Coastal Bays in May and July of 2007 served to further assess spatial patterns in nutrients, responses of biological indicators, seasons, land use, and nutrient cycling. Trends indicated degraded water quality, high tubidity, increasing total nitrogen and phosphorus concentrations, high natural isotope abundance (δ15N), and low dissolved oxygen. The abundance of crop agriculture and development of the St.

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To develop the native eastern oyster, Crassostrea virginica, as a biological indicator of nitrogen source, linkages between stable nitrogen isotopes in its tissues and land use adjacent to deployment stations were assessed. As part of a National Estuarine Research Reserve System Graduate Research Fellowship, this study focused on the Monie Bay component of Chesapeake Bay, MD Research Reserve, which includes Monie Bay and three similar tributary creeks which vary in their surrounding land use.

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Nutrient point sources such as wastewater treatment plants and non-point sources including agricultural runoff degrade the water quality of Maryland's Coastal Bays through excessive nutrient loading. Identifying specific sources is difficult due to their variety and mixture. Biological indicators can identify nitrogen sources, integrate nitrogen from these sources over time, and detect biologically important nutrients.

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