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Nitrogen regulation of algal biomass, productivity, and composition in shallow mountain lakes, Snowy Range, Wyoming, USA

Canadian Journal of Fisheries and Aquatic Sciences
By: , , , and 
https://doi.org/10.1139/f04-085

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Abstract

We investigated the effects of increased nitrate (NO3), alone and in combination with phosphorus (P), on phytoplankton, epilithon, and epipelon in shallow lakes of the Snowy Range, Wyoming, using two enclosure experiments during early and late summer. Phytoplankton responded strongly to N and N + P, but not to P, with increased cell density, chlorophyll a, and photosynthesis and shifts in composition from chrysophytes to cyanophytes, chlorophytes, and diatoms. Zooplankton density and biomass were unaltered despite the additional phytoplankton stock, probably as the result of poor food quality. In the late summer, algae on tiles responded to N and N + P additions with greater chlorophyll a and increases in cyanophyte and chlorophyte density. Algae on sediment dominated whole-enclosure algal biomass but were spatially variable and responded insignificantly to nutrients. Consequently, N controlled productivity and community composition of phytoplankton and algae on hard substrates but had less impact on ecosystem algal biomass because of the large pool of nutrient-sufficient sediment algae. Phytoplankton were more photosynthetically efficient than the benthos, however, such that primary productivity did shift more toward the water column.

Publication type Article
Publication Subtype Journal Article
Title Nitrogen regulation of algal biomass, productivity, and composition in shallow mountain lakes, Snowy Range, Wyoming, USA
Series title Canadian Journal of Fisheries and Aquatic Sciences
DOI 10.1139/f04-085
Volume 61
Issue 7
Year Published 2004
Language English
Publisher NRC Research Press
Contributing office(s) Fort Collins Science Center
Description 13 p.
First page 1256
Last page 1268
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