Rapid Communication: Climatic Control on Eutrophication of the Hudson River Estuary |
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Authors: | Robert W Howarth Dennis P Swaney Thomas J Butler Roxanne Marino |
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Institution: | (1) Program in Biogeochemistry and Environmental Change, E309 Corson Hall, Cornell University, Ithaca, New York 14853, USA , US |
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Abstract: | Eutrophication is arguably the biggest pollution problem facing estuaries globally, with extensive consequences including
anoxic and hypoxic waters, reduced fishery harvests, toxic algal blooms, and loss of biotic diversity. However, estuaries
vary greatly in their susceptibility to eutrophication. The Hudson River estuary receives very high levels of nutrient inputs
yet in the past has shown relatively low rates of phytoplankton productivity and is generally considered to be only moderately
susceptible to eutrophication. Here, we show that eutrophication and primary production in the Hudson estuary can increase
dramatically in response to climatic variation and lowered freshwater discharge from the watershed. During dry summer periods
in 1995 and 1997, rates of primary production were substantially higher than those measured during the 1970s, when freshwater
discharge tended to be high. In the Hudson, low freshwater discharge increases waterresidence times and stratification and
deepens the photic zone, all of which (alone or in combination) could lead to the observed increase in primary production.
Our data, along with the prediction of most climate change models that freshwater discharge will be lower in the future during
the summer in the northeastern US, suggest that the Hudson will become more susceptible to eutrophication. Eutrophication
in an estuary is a complex process, and climate change is likely to affect each estuary differently due to interactions with
nutrient loadings and physical circulation. Hence, it is essential to consider the effects of climate change in the context
of individual estuarine functioning to successfully manage eutrophication in the future.
Received 22 December 1999; accepted 28 December 1999. |
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Keywords: | : primary production eutrophication estuary climate change watershed freshwater discharge light limitation photic zone water residence time |
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