Flow regime, temperature, and biotic interactions drive differential declines of trout species under climate change

Proceedings of the National Academy of Sciences of the United States of America
By: , and 

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Abstract

Broad-scale studies of climate change effects on freshwater species have focused mainly on temperature, ignoring critical drivers such as flow regime and biotic interactions. We use downscaled outputs from general circulation models coupled with a hydrologic model to forecast the effects of altered flows and increased temperatures on four interacting species of trout across the interior western United States (1.01 million km2), based on empirical statistical models built from fish surveys at 9,890 sites. Projections under the 2080s A1B emissions scenario forecast a mean 47% decline in total suitable habitat for all trout, a group of fishes of major socioeconomic and ecological significance. We project that native cutthroat trout Oncorhynchus clarkii, already excluded from much of its potential range by nonnative species, will lose a further 58% of habitat due to an increase in temperatures beyond the species' physiological optima and continued negative biotic interactions. Habitat for nonnative brook trout Salvelinus fontinalis and brown trout Salmo trutta is predicted to decline by 77% and 48%, respectively, driven by increases in temperature and winter flood frequency caused by warmer, rainier winters. Habitat for rainbow trout, Oncorhynchus mykiss, is projected to decline the least (35%) because negative temperature effects are partly offset by flow regime shifts that benefit the species. These results illustrate how drivers other than temperature influence species response to climate change. Despite some uncertainty, large declines in trout habitat are likely, but our findings point to opportunities for strategic targeting of mitigation efforts to appropriate stressors and locations.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Flow regime, temperature, and biotic interactions drive differential declines of trout species under climate change
Series title Proceedings of the National Academy of Sciences of the United States of America
DOI 10.1073/pnas.1103097108
Volume 108
Issue 34
Year Published 2011
Language English
Publisher National Academy of Sciences of the United States of America
Publisher location Washington, D.C.
Contributing office(s) Forest and Rangeland Ecosystem Science Center
Description 6 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Proceedings of the National Academy of Sciences of the United States of America
First page 14175
Last page 14180
Country United States