Mechanisms for climate-induced mortality of fish populations in whole-lake experiments

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 104; no. 23; pp. 9715 - 9719
• Main Authors: Biro, Peter A, Post, John R, Booth, David J
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 05.06.2007; National Acad Sciences
• Subjects: Animal behavior; Animal populations; Animals; Biological Sciences; British Columbia; Climate change; Climate models; Energy Metabolism - physiology; Feeding Behavior - physiology; Fish; Food Chain; Fresh Water; Freshwater; Freshwater fishes; High temperature; Lakes; Mortality; Oncorhynchus mykiss; Oncorhynchus mykiss - physiology; Population Dynamics; Population growth; Population growth rate; Temperature; Trout; Water temperature; British Columbia
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0701638104

The effects of climate change on plant and animal populations are widespread and documented for many species in many areas of the world. However, projections of climate impacts will require a better mechanistic understanding of ecological and behavioral responses to climate change and climate variation. For vertebrate animals, there is an absence of whole-system manipulative experiments that express natural variation in predator and prey behaviors. Here we investigate the effect of elevated water temperature on the physiology, behavior, growth, and survival of fish populations in a multiple whole-lake experiment, by using 17 lake-years of data collected over 2 years with differing average temperatures. We found that elevated temperatures in excess of the optimum reduced the scope for growth through reduced maximum consumption and increased metabolism in young rainbow trout, Oncorhynchus mykiss. Increased metabolism at high temperatures resulted in increased feeding activity (consumption) by individuals to compensate and maintain growth rates similar to that observed at cooler (optimum) temperatures. However, greater feeding activity rates resulted in greater vulnerability to predators that reduced survival to only half that of the cooler year. Our work therefore identifies temperature-dependent physiology and compensatory feeding behavior as proximate mechanisms for substantial climate-induced mortality in fish populations at the scale of entire populations and waterbodies.