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Thermal heterogeneity mediates the effects of pulsed subsidies across a landscape.

https://arctichealth.org/en/permalink/ahliterature96829
Source
Ecology. 2010 May;91(5):1445-54
Publication Type
Article
Date
May-2010
Author
Jonathan B Armstrong
Daniel E Schindler
Kristen L Omori
Casey P Ruff
Thomas P Quinn
Author Affiliation
School of Aquatic and Fishery Sciences, Box 355020, University of Washington, Seattle, Washington 98195, USA. jonny99@u.washington.edu
Source
Ecology. 2010 May;91(5):1445-54
Date
May-2010
Language
English
Publication Type
Article
Keywords
Animals
Body Size
Ecosystem
Feeding Behavior
Fishes - physiology
Rivers
Seasons
Temperature
Time Factors
Abstract
Spatial and temporal heterogeneity interact to make the foraging rates of individuals more variable than expected from models assuming that spatial and temporal dimensions of habitat conditions operate independently. For example, trophic resource pulses produce temporal patches of prey superabundance, yet little is known about how spatial heterogeneity in habitat conditions mediates the ability of consumers to exploit these high-quality foraging opportunities. We studied how spatial variation in water temperature regulates the potential for juvenile coho salmon to exploit a seasonal pulsed subsidy of eggs produced by anadromous sockeye salmon. Streams within the Wood River watershed, southwestern Alaska, USA, ranged in mean summer temperature from 3.6 degrees to 14.5 degrees C. Growth of juvenile coho prior to the arrival of the seasonal egg subsidy was positively related to water temperature among streams. An in situ experiment combined with field samples of diets revealed a size threshold for egg consumption; only individuals longer than approximately 70 mm could consume eggs due to gape limitation of smaller individuals. A bioenergetics simulation demonstrated that water temperature regulated whether age-0 coho salmon could grow large enough to exceed the size threshold for egg consumption. Coho salmon that consumed eggs had energy rations that were five times higher than fish that did not consume eggs, resulting in a positive feedback of water temperature on their integrated seasonal growth. Across this landscape, heterogeneity in water temperature mediates individual- and population-level responses to seasonally available resource pulses. Our study illustrates that ecological mechanisms, such as size-based foraging asymmetries, can magnify the effects of climate change compared to predictions based on physiology alone.
PubMed ID
20503876 View in PubMed
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