Paleolimnological records of nitrogen deposition in shallow, high-elevation lakes of Grand Teton National Park, Wyoming, USA

Arctic, Antarctic, and Alpine Research
By: , and 

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Abstract

Reactive nitrogen (Nr) from anthropogenic sources has been altering ecosystem function in lakes of the Rocky Mountains, other regions of western North America, and the Arctic over recent decades. The response of biota in shallow lakes to atmospheric deposition of Nr, however, has not been considered. Benthic algae are dominant in shallow, high-elevation lakes and are less sensitive to nutrient inputs than planktonic algae. Because the benthos is typically more nutrient rich than the water column, shallow lakes are not expected to show evidence of anthropogenic Nr. In this study, we assessed sedimentary evidence for regional Nr deposition, sediment chronology, and the nature of algal community response in five shallow, high-elevation lakes in Grand Teton National Park (GRTE). Over 140 diatom taxa were identified from the sediments, with a relatively high species richness of taxa characteristic of oligotrophic conditions. The diatom assemblages were dominated by benthic taxa, especially motile taxa. The GRTE lakes demonstrate assemblage-wide shifts in diatoms, including 1) synchronous and significant assemblage changes centered on ~1960 AD; 2) pre-1960 assemblages differed significantly from post-1960 assemblages; 3) pre-1960 diatom assemblages fluctuated randomly, whereas post- 1960 assemblages showed directional change; 4) changes in δ15N signatures were correlated with diatom community composition. These results demonstrate recent changes in shallow high18 elevation lakes that are most correlated with anthropogenic Nr. It is also possible, however, that the combined effect of Nr deposition and warming is accelerating species shifts in benthic diatoms. While uncertainties remain about the potential synergy of Nr deposition and warming, this study adds shallow lakes to the growing list of impacted high-elevation localities in western North America.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Paleolimnological records of nitrogen deposition in shallow, high-elevation lakes of Grand Teton National Park, Wyoming, USA
Series title Arctic, Antarctic, and Alpine Research
DOI 10.1657/AAAR0015-008
Volume 47
Issue 4
Year Published 2015
Language English
Publisher Institute of Arctic and Alpine Research
Contributing office(s) National Water Quality Assessment Program
Description 15 p.
First page 703
Last page 717
Country United States
State Wyoming
Other Geospatial Grand Teton National Park
Online Only (Y/N) N
Additional Online Files (Y/N) N