Response of an algal assemblage to nutrient enrichment and shading in a Hawaiian stream

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To investigate the effects of nitrate enrichment, phosphate enrichment, and light availability on benthic algae, nutrient-diffusing clay flowerpots were colonized with algae at two sites in a Hawaiian stream during spring and autumn 2002 using a randomized factorial design. The algal assemblage that developed under the experimental conditions was investigated by determining biomass (ash-free dry mass and chlorophyll a concentrations) and composition of the diatom assemblage. In situ pulse amplitude-modulated fluorometry was also used to model photosynthetic rate of the algal assemblage. Algal biomass and maximum photosynthetic rate were significantly higher at the unshaded site than at the shaded site. These parameters were higher at the unshaded site with either nitrate, or to a lesser degree, nitrate plus phosphate enrichment. Analysis of similarity of diatom assemblages showed significant differences between shaded and unshaded sites, as well as between spring and autumn experiments, but not between nutrient treatments. However, several individual species of diatoms responded significantly to nitrate enrichment. These results demonstrate that light availability (shaded vs. unshaded) is the primary limiting factor to algal growth in this stream, with nitrogen as a secondary limiting factor. 

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Response of an algal assemblage to nutrient enrichment and shading in a Hawaiian stream
Series title Hydrobiologia
DOI 10.1007/s10750-011-0947-2
Volume 683
Issue 1
Year Published 2012
Language English
Publisher Springer
Contributing office(s) Utah Water Science Center
Description 16 p.
First page 135
Last page 150
Country United States
State Hawaii
Other Geospatial Oahu, Waihee Stream
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