Environmental Management

, Volume 37, Issue 3, pp 422–436 | Cite as

Assessing the Effects of Nutrient Management in an Estuary Experiencing Climatic Change: The Neuse River Estuary, North Carolina

  • Hans W. PaerlEmail author
  • Lexia M. Valdes
  • Michael F. Piehler
  • Craig A. Stow


Eutrophication is a serious water quality problem in estuaries receiving increasing anthropogenic nutrient loads. Managers undertaking nutrient-reduction strategies aimed at controlling estuarine eutrophication are faced with the challenge that upstream freshwater segments often are phosphorus (P)-limited, whereas more saline downstream segments are nitrogen (N)-limited. Management also must consider climatic (hydrologic) variability, which affects nutrient delivery and processing. The interactive effects of selective nutrient input reductions and climatic perturbations were examined in the Neuse River Estuary (NRE), North Carolina, a shallow estuary with more than a 30-year history of accelerated nutrient loading and water quality decline. The NRE also has experienced a recent increase in Atlantic hurricanes and record flooding, which has affected hydrology and nutrient loadings. The authors examined the water quality consequences of selective nutrient (P but not N) reductions in the 1980s, followed by N reductions in the 1990s and an increase in hurricane frequency since the mid-1990s. Selective P reductions decreased upstream phytoplankton blooms, but increased downstream phytoplankton biomass. Storms modified these trends. In particular, upstream annual N and P concentrations have decreased during the elevated hurricane period. Increased flushing and scouring from storms and flooding appear to have enhanced nutrient retention capabilities of the NRE watershed. From a management perspective, one cannot rely on largely unpredictable changes in storm frequency and intensity to negate anthropogenic nutrient enrichment and eutrophication. To control eutrophication along the hydrologically variable freshwater–marine continuum, N and P reductions should be applied adaptively to reflect point-source–dominated drought and non–point-source–dominated flood conditions.


Climate change Estuaries Eutrophication Hurricanes Nitrogen Nutrient management Phosphorus Water quality 



The authors appreciate the technical assistance and input of A. Joyner, B. Peierls, and P. Wyrick. This work was supported by the National Science Foundation (DEB 9815495 and OCE 9905723), the St. Johns River Water Management District, the U.S. Department of Agriculture NRI Project 00−35101-9981, U.S. EPA STAR Projects R82-5243-010, R82867701, and R83-0652, the NOAA/North Carolina Sea Grant Program R/MER-43, and the North Carolina Department of Natural Resources and Community Development/UNC Water Resources Research Institute (Neuse River Estuary Monitoring and Modeling Project, ModMon).

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Copyright information

© Springer Science+Business Media, Inc. 2006

Authors and Affiliations

  • Hans W. Paerl
    • 1
    Email author
  • Lexia M. Valdes
    • 1
  • Michael F. Piehler
    • 1
  • Craig A. Stow
    • 2
  1. 1.Institute of Marine SciencesUniversity of North Carolina at Chapel HillMorehead CityUSA
  2. 2.Department of Environmental Health SciencesNorman J. Arnold School of Public Health University of South CarolinaColumbiaUSA

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