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Seasonal and interannual variation in nutrient fluxes from tributary inputs, consumer recycling and algal growth in a eutrophic river impoundment

Seasonal and interannual variation in nutrient fluxes from tributary inputs, consumer recycling... We measured tributary inputs, algal nutrient demand and excretion rates of consumers (gizzard shad and zooplankton) at a eutrophic river impoundment. During two summers with contrasting flow regimes, tributary inputs accounted for 38% (1998) and 3% (1999) of algal N demand and 95% (1998) and 17% (1999) of algal P demand. Gizzard shad contributions averaged 14% and 20% of algal demand for N whereas P contributions were 31% and 58% (1998, 1999; respectively). Zooplankton recycling accounted for a comparable fraction of algal P demand (47%) but a larger fraction of N demand (43%) because their excretia were N rich (N:P = 13:1) compared to fish (7:1). Nutrient release by one of the consumers (gizzard shad) was compared with tributary loading over a nine-year period to assess inter-annual variation in their relative importance. Historical records of inflow chemistry, discharge and gizzard shad biomass showed that variation in tributary inputs was the primary determinant of seasonal and inter-annual variation in nutrient loading. Consumer-derived nutrients were important in late-summer and during years when tributary inputs were low. We propose a conceptual model in which primary production is regulated by external nutrient loading and consumer recycling acts to stabilize and sustain production during periods of diminished external inputs. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Aquatic Ecology Springer Journals

Seasonal and interannual variation in nutrient fluxes from tributary inputs, consumer recycling and algal growth in a eutrophic river impoundment

Shostell, Joseph; Bukaveckas, Paul
Aquatic Ecology , Volume 38 (3) – Oct 2, 2004
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References (89)

Publisher
Springer Journals
Copyright
Copyright © 2004 by Kluwer Academic Publishers
Subject
Life Sciences; Freshwater & Marine Ecology; Ecosystems
ISSN
1386-2588
eISSN
1573-5125
DOI
10.1023/B:AECO.0000035167.67399.63
Publisher site
See Article on Publisher Site

Abstract

We measured tributary inputs, algal nutrient demand and excretion rates of consumers (gizzard shad and zooplankton) at a eutrophic river impoundment. During two summers with contrasting flow regimes, tributary inputs accounted for 38% (1998) and 3% (1999) of algal N demand and 95% (1998) and 17% (1999) of algal P demand. Gizzard shad contributions averaged 14% and 20% of algal demand for N whereas P contributions were 31% and 58% (1998, 1999; respectively). Zooplankton recycling accounted for a comparable fraction of algal P demand (47%) but a larger fraction of N demand (43%) because their excretia were N rich (N:P = 13:1) compared to fish (7:1). Nutrient release by one of the consumers (gizzard shad) was compared with tributary loading over a nine-year period to assess inter-annual variation in their relative importance. Historical records of inflow chemistry, discharge and gizzard shad biomass showed that variation in tributary inputs was the primary determinant of seasonal and inter-annual variation in nutrient loading. Consumer-derived nutrients were important in late-summer and during years when tributary inputs were low. We propose a conceptual model in which primary production is regulated by external nutrient loading and consumer recycling acts to stabilize and sustain production during periods of diminished external inputs.

Journal

Aquatic Ecology – Springer Journals

Published: Oct 2, 2004

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