People | Joanna York

• B.A., Environmental Science, University of Virginia, 1997.
• Ph.D., Biology, Boston University, 2006.

Estuarine nutrient cycling and biogeochemistry, applications of stable isotopes, bottom-up and top-down controls on phytoplankton, microzooplankton dynamics

I am currently accepting students for Fall 2012.

Tracing land-derived nutrients into Delaware’s Inland Bays
Using a suite of approaches, we are quantifying the major sources of nitrogen and phosphorus to the Inland Bays, and assessing the impact of these nutrient loads at the ecosystem level.  Our main focus is on groundwater nutrient delivery and impacts on estuarine primary producers.

Nutrient sources in suburbanizing watersheds
We are characterizing groundwater chemistry at a site in southern Delaware with land-use that has changed from agricultural to suburban over the last 30 years. This site is in the Inland Bays' watershed of the Inland Bays, which have significant problems associated with eutrophication driven by delivery of groundwater-borne nutrients.

Impacts of changing land use and climate change on Delmarva’s lagoons
We are modifying a Nitrogen Loading Model to determine nitrogen loads to coastal lagoons on Delmarva from watersheds with contrasting agricultural land-use and population sizes. One of the questions we are addressing concerns the losses of N that occur through a variety of processes during transit through the watershed. This natural remediation of N loading is a powerful “ecosystem service” that should be estimated and considered in management scenarios.

MAST 314 Comparative Terrestrial and Marine Ecology

MAST 100 Marine Science Colloquium I

MAST 101 Marine Science Colloquium II

York J.K., B.A. Costas, and G.B. McManus. 2010, Microzooplankton grazing in green water - results from two contrasting estuaries.  Estuaries and Coasts 34:373-385

York J.K., G. Tomasky, I. Valiela, and A.E. Giblin. 2010. Isotopic approach to determining the fate of ammonium regenerated from sediments in a eutrophic sub-estuary of Waquoit Bay, MA. Estuaries and Coasts 33:1069-1079

York J.K., G. Tomasky, I. Valiela, and D.J. Repeta. 2007. Stable isotopic detection of ammonium and nitrate assimilation by estuarine phytoplankton in the Waquoit Bay estuarine system. Limnology and Oceanography 52:144-155

Kroeger K.D., M.L. Cole, J.K. York, and I. Valiela. 2006. N transport to estuaries in wastewater plumes: Modeling and isotopic approaches. Ground Water 44:188-200