Estuaries and Coasts

, Volume 33, Issue 5, pp 1144–1163 | Cite as

Long-Term Trends in Submersed Aquatic Vegetation (SAV) in Chesapeake Bay, USA, Related to Water Quality

  • Robert J. OrthEmail author
  • Michael R. Williams
  • Scott R. Marion
  • David J. Wilcox
  • Tim J. B. Carruthers
  • Kenneth A. Moore
  • W. Michael Kemp
  • William C. Dennison
  • Nancy Rybicki
  • Peter Bergstrom
  • Richard A. Batiuk


Chesapeake Bay supports a diverse assemblage of marine and freshwater species of submersed aquatic vegetation (SAV) whose broad distributions are generally constrained by salinity. An annual aerial SAV monitoring program and a bi-monthly to monthly water quality monitoring program have been conducted throughout Chesapeake Bay since 1984. We performed an analysis of SAV abundance and up to 22 environmental variables potentially influencing SAV growth and abundance (1984–2006). Historically, SAV abundance has changed dramatically in Chesapeake Bay, and since 1984, when SAV abundance was at historic low levels, SAV has exhibited complex changes including long-term (decadal) increases and decreases, as well as some large, single-year changes. Chesapeake Bay SAV was grouped into three broad-scale community-types based on salinity regime, each with their own distinct group of species, and detailed analyses were conducted on these three community-types as well as on seven distinct case-study areas spanning the three salinity regimes. Different trends in SAV abundance were evident in the different salinity regimes. SAV abundance has (a) continually increased in the low-salinity region; (b) increased initially in the medium-salinity region, followed by fluctuating abundances; and (c) increased initially in the high-salinity region, followed by a subsequent decline. In all areas, consistent negative correlations between measures of SAV abundance and nitrogen loads or concentrations suggest that meadows are responsive to changes in inputs of nitrogen. For smaller case-study areas, different trends in SAV abundance were also noted including correlations to water clarity in high-salinity case-study areas, but nitrogen was highly correlated in all areas. Current maximum SAV coverage for almost all areas remain below restoration targets, indicating that SAV abundance and associated ecosystem services are currently limited by continued poor water quality, and specifically high nutrient concentrations, within Chesapeake Bay. The nutrient reductions noted in some tributaries, which were highly correlated to increases in SAV abundance, suggest management activities have already contributed to SAV increases in some areas, but the strong negative correlation throughout the Chesapeake Bay between nitrogen and SAV abundance also suggests that further nutrient reductions will be necessary for SAV to attain or exceed restoration targets throughout the bay.


Submersed aquatic vegetation Salinity community-types Chesapeake Bay Abundance Nutrients Nitrogen Water quality 



Funding for much of the monitoring were from the following sources: US Environmental Protection Agency’s Chesapeake Bay Program Office; the Coastal Programs of the Virginia Department of Environmental Quality and Maryland Department of Natural Resources funded by Coastal Zone Management Act of 1972, as amended, administered by the Office of Ocean and Coastal Resource Management; National Oceanic and Atmospheric Administration; US Fish and Wildlife Service; School of Marine Science, Virginia Institute of Marine Science, College of William and Mary; private grants from the Allied-Signal Foundation, Norfolk-Southern, and the Keith Campbell Foundation. WMK acknowledges funding from NOAA Maryland Sea Grant and the Army Corps of Engineers ERDC. We thank Kris Beckert for assistance with figures. We appreciate the thoughtful comments of the anonymous reviewers. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the US Government. Contribution no. 3091 from the Virginia Institute of Marine Science, College of William and Mary; 4412 from University of Maryland Center for Environmental Science.


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© Coastal and Estuarine Research Federation 2010

Authors and Affiliations

  • Robert J. Orth
    • 1
    Email author
  • Michael R. Williams
    • 2
  • Scott R. Marion
    • 1
  • David J. Wilcox
    • 1
  • Tim J. B. Carruthers
    • 2
    • 3
  • Kenneth A. Moore
    • 1
  • W. Michael Kemp
    • 3
  • William C. Dennison
    • 2
    • 3
  • Nancy Rybicki
    • 4
  • Peter Bergstrom
    • 5
  • Richard A. Batiuk
    • 6
  1. 1.Virginia Institute of Marine ScienceGloucester PointUSA
  2. 2.Center for Environmental Sciences, Integration Application NetworkUniversity of MarylandAnnapolisUSA
  3. 3.Center for Environmental Sciences, Horn Point LaboratoryUniversity of MarylandCambridgeUSA
  4. 4.US Geological SurveyRestonUSA
  5. 5.National Oceanic and Atmospheric AdministrationAnnapolisUSA
  6. 6.US Environmental Protection AgencyChesapeake Bay ProgramAnnapolisUSA

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