Long-Term Trends in Chesapeake Bay Seasonal Hypoxia, Stratification, and Nutrient Loading
A previously observed shift in the relationship between Chesapeake Bay hypoxia and nitrogen loading has pressing implications on the efficacy of nutrient management. Detailed temporal analyses of long-term hypoxia, nitrogen loads, and stratification were conducted to reveal different within-summer trends and understand more clearly the relative role of physical conditions. Evaluation of a 60-year record of hypoxic volumes demonstrated significant increases in early summer hypoxia, but a slight decrease in late summer hypoxia. The early summer hypoxia trend is related to an increase in Bay stratification strength during June from 1985 to 2009, while the late summer hypoxia trend matches the recently decreasing nitrogen loads. Additional results show how the duration of summertime hypoxia is significantly related to nitrogen loading, and how large-scale climatic forces may be responsible for the early summer increases. Thus, despite intra-summer differences in primary controls on hypoxia, continuing nutrient reduction remains critically important for achieving improvements in Bay water quality.
KeywordsHypoxia Stratification Nutrients Chesapeake Bay Kriging Long-term trends
- Bahner, L. 2006. User guide for the Chesapeake Bay and tidal tributary interpolator. NOAA Chesapeake Bay Office, Annapolis, MD. http://noaa.chesapeakebay.net/Interpolator.aspx.
- Boesch, D.F., V.J. Coles, D.G. Kimmel, and W.D. Miller. 2007. Coastal dead zones & global climate change: Ramifications of climate change for Chesapeake Bay hypoxia. Pew Center on Global Climate Change. http://www.pewclimate.org/regional_impacts.
- Boicourt, W.C. 1992. Influences of circulation processes on dissolved oxygen in the Chesapeake Bay. In Oxygen dynamics in the Chesapeake Bay: A synthesis of recent research, ed. D.E. Smith et al., 7–59. College Park: Maryland Sea Grant Publication.Google Scholar
- Box, G.E.P., and D.R. Cox. 1964. An analysis of transformations. Journal of the Royal Statistical Society: Series B: Methodological 26: 211–252.Google Scholar
- Boynton, W.R., and W.M. Kemp. 2000. Influence of river flow and nutrient loads on selected ecosystem processes. In Estuarine science: A synthetic approach to research and practice, ed. J.E. Hobbie, 269–298. Washington: Island.Google Scholar
- CBEO Project Team (Ball, W., D. Brady, M. Brooks, R. Burns, B. Cuker, D. DiToro, T. Gross, W.M. Kemp, L. Murray, R. Murphy, E. Perlman, M. Piasecki, J. Testa, I. Zaslavsky). 2008. Prototype system for multidisciplinary shared cyberinfrastructure: Chesapeake Bay Environmental Observatory. Journal of Hydrologic Engineering 13: 960–970. doi:10.1061/(ASCE)1084-0699(2008)13:10(960).CrossRefGoogle Scholar
- Chesapeake Bay Program. 1993. Guide to using Chesapeake Bay Program water quality monitoring data. CBP/TRS 78/92, Annapolis, MD.Google Scholar
- Chesapeake Bay Program. 2008. Chesapeake Bay historical data sets. http://archive.chesapeakebay.net/data/historicaldb/historicalmain.htm. Accessed 8 Oct 2008.
- Chesapeake Bay Program. 2010. CBP Water Quality Database (1984–present). http://www.chesapeakebay.net/data_waterquality.aspx. Accessed 20 Jul 2010.
- Codiga, D.L., H.E. Stoffel, C.F. Deacutis, S. Kiernan, and C.A. Oviatt. 2009. Narragansett Bay hypoxic event characteristics based on fixed-site monitoring network time series: Intermittency, geographic distribution, spatial synchronicity, and interannual variability. Estuaries and Coasts 32: 621–641. doi:10.1007/s12237-009-9165-9.CrossRefGoogle Scholar
- Coma, R., M. Ribes, E. Serrano, E. Jimenez, J. Salat, and J. Pascual. 2008. Global warming-enhanced stratification and mass mortality events in the Mediterranean. Proceedings of the National Academy of Sciences of the United States of America (PNAS) 106: 6176–6181. doi:10.1073/pnas.0805801106.CrossRefGoogle Scholar
- Cressie, N.A.C. 1993. Statistics for Spatial Data, Revised ed. New York: Wiley.Google Scholar
- Cronin, W.B., and D.W. Pritchard. 1975. Additional statistics on the dimensions of Chesapeake Bay and its tributaries: Cross-section widths and segment volumes per meter depth. Reference 75–3. Special Report 42. Baltimore: Chesapeake Bay Institute, The Johns Hopkins University.Google Scholar
- Diggle, P.J., and P.J. Ribeiro. 2007. Modeled-based geostatistics. New York: Springer.Google Scholar
- Jolliffe, I.T. 2002. Principal component analysis, 2nd ed. New York: Springer.Google Scholar
- Kemp, W.M., and W.R. Boynton. 1984. Spatial and temporal coupling of nutrient inputs to estuarine primary production: The role of particulate transport and decomposition. Bulletin of Marine Science 35: 522–535.Google Scholar
- Kemp, W.M., W.R. Boynton, J.E. Adolf, D.F. Boesch, W.C. Boicourt, G. Brush, J.C. Cornwell, T.R. Fisher, P.M. Glibert, J.D. Hagy, L.W. Harding, E.D. Houde, D.G. Kimmel, W.D. Miller, R.I.E. Newell, M.R. Roman, E.M. Smith, and J.C. Stevenson. 2005. Eutrophication of Chesapeake Bay: Historical trends and ecological interactions. Marine Ecology Progress Series 303: 1–29.CrossRefGoogle Scholar
- Knauss, J.A. 1997. Introduction to physical oceanography, 2nd ed. Upper Saddle River: Prentice Hall.Google Scholar
- Langland, M.J., D.L. Moyer, and J. Blomquist. 2007. Changes in streamflow, concentrations, and loads in selected nontidal basins in the Chesapeake Bay watershed, 1985–2006. Open File Report 2007-1372. U.S. Geological Survey. http://pubs.usgs.gov/of/2007/1372/.
- Li, M., L. Zhong, W.C. Boicourt, S. Zhang, and D.-L. Zhang. 2007. Hurricane-induced destratification and restratification in a partially-mixed estuary. Journal of Marine Research 65: 169–192.Google Scholar
- Ludsin, S.A., X. Zhang, S.B. Brandt, M.R. Roman, W.C. Boicourt, D.M. Mason, and M. Costantini. 2009. Hypoxia-avoidance by planktivorous fish in Chesapeake Bay: Implications for food web interactions and fish recruitment. Journal of Experimental Marine Biology and Ecology 381: S121–S131. doi:10.1016/j.jembe.2009.07.016.CrossRefGoogle Scholar
- Malone, T.C. 1992. Effects of water column processes on dissolved oxygen, nutrients, phytoplankton and zooplankton. In Oxygen dynamics in the Chesapeake Bay: A synthesis of recent research, ed. D.E. Smith et al., 61–112. College Park: Maryland Sea Grant Publication.Google Scholar
- Najjar, R.G., C.R. Pyke, M.B. Adams, D. Breitburg, C. Hershner, M. Kemp, R. Howarth, M.R. Mulholland, M. Paolisso, D. Secor, K. Sellner, D. Wardrop, and R. Woodm. 2010. Potential climate-change impacts on the Chesapeake Bay. Estuarine, Coastal and Shelf Science 86: 1–20. doi:10.1016/j.ecss.2009.09.026.CrossRefGoogle Scholar
- National Climatic Data Center. 2009. Global summary of the day, Patuxent Naval Air Station. http://www7.ncdc.noaa.gov/CDO/cdoselect.cmd. Accessed 12 Jul 2010.
- National Oceanic and Atmospheric Administration. 2010. Historic tide data. http://tidesandcurrents.noaa.gov/station_retrieve.shtml?type=Historic+Tide+Data. Accessed 17 Jul 2010.
- R Development Core Team. 2008. The R project for statistical computing. http://www.r-project.org/. Accessed 24 Aug 2008.
- Ribeiro, P.J., and P.J. Diggle. 2008. geoR: A package for geostatistical analysis using the R software. http://leg.ufpr.br/geoR/. Accessed 18 Aug 2008.
- Ripley, B.D., and M. Lapsley. 2008. RODBC: ODBC database access. http://cran.r-project.org/web/packages/RODBC/index.html. Accessed 22 May 2008.
- U.S. Geological Survey. 2010a. Chesapeake Bay river input monitoring program. http://va.water.usgs.gov/chesbay/RIMP/. Accessed 17 May 2010.
- U.S. Geological Survey. 2010b. Surface-water data for the nation. http://waterdata.usgs.gov/nwis/sw. Accessed 1 Dec 2010.
- Zervas, C. 2009. Sea level variations of the United States 1854–2006. Technical Report NOS CO-OPS 053. National Oceanic and Atmospheric Administration, National Ocean Service, Center for Operational Oceanographic Products and Services, Silver Spring, Maryland. http://tidesandcurrents.noaa.gov/pub.html#sltrends.