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Document Type:
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Journal Article
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Center:
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NWFSC
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Document ID:
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6816
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Author:
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M. J. Angilletta Jr., E. A. Steel, K. K. Bartz, J. G. Kingsolver, M. D. Scheuerell, B. R. Beckman, L. G. Crozier
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Year:
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2008
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Title:
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Big dams and salmon evolution: changes in thermal regimes and their potential evolutionary consequences
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Journal:
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Evolutionary Applications
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Volume:
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1
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Issue:
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2
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Pages:
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286299
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Date:
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04/28/2008
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Abstract:
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Dams designed for hydropower and other purposes alter the environments of
many economically important fishes, including Chinook salmon (Oncorhynchus
tshawytscha). We estimated that dams on the Rogue River, the Willamette
River, the Cowlitz River, and Fall Creek decreased water temperatures during
summer and increased water temperatures during fall and winter. These thermal
changes undoubtedly impact the behavior, physiology, and life histories of
Chinook salmon. For example, relatively high temperatures during the fall and
winter should speed growth and development, leading to early emergence of
fry. Evolutionary theory provides tools to predict selective pressures and genetic
responses caused by this environmental warming. Here, we illustrate this point
by conducting a sensitivity analysis of the fitness consequences of thermal
changes caused by dams, mediated by the thermal sensitivity of embryonic
development. Based on our model, we predict Chinook salmon likely suffered
a decrease in mean fitness after the construction of a dam in the Rogue River.
Nevertheless, these demographic impacts might have resulted in strong selection
for compensatory strategies, such as delayed spawning by adults or slowed
development by embryos. Because the thermal effects of dams vary throughout
the year, we predict dams impacted late spawners more than early spawners.
Similar analyses could shed light on the evolutionary consequences of other
environmental perturbations and their interactions.
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Divisions:
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CB
EC
FE
REUT
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Projects:
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