Costs of living for juvenile Chinook salmon (Oncorhynchus tshawytscha) in an increasingly warming and invaded world
Kuehne, L. M., Olden, J. D., & Duda, J. J. (2012). Costs of living for juvenile Chinook salmon (Oncorhynchus tshawytscha) in an increasingly warming and invaded world. Canadian journal of fisheries and aquatic sciences, 69(10), 1621-1630. PDF.
Summary
Non-native, invasive fish often prey upon native fish species, leading to population declines. Warming water temperatures can cause further stress to fish, but it is unclear how the additional stress of warming will influence interactions between predators and prey. Kuehne et al. (2012) investigated the response of Chinook salmon (Oncorhynchus tshawytscha), which are native to the Pacific northwest, to the combined stresses of a non-native predator (smallmouth bass; Micropterus dolomieu) and a 5 C rise in water temperature. There was no effect of warming temperature on predation rates. That is, salmon were eaten at the same rates regardless of temperature. However, warming and the presence of a predator had a synergistic effect on salmon behavior. Salmon showed no change in behavior with either one or the other stressor, but with both stressors combined they were more likely to spend time swimming and shoaling (grouping together with other fish). Possibly due to the behavioral change, warming and the presence of a predator had an additive negative effect on salmon growth rates. That is, the decline in growth rates with warming + predation was equal to the decline with warming + the decline with predation. This study suggests that non-lethal effects on growth due to changes in prey behavior could be exacerbated by warming waters.
Take home points
Although predation rates were not influenced, prey fish exhibited different behavior and had lower growth rates due to the combined effects of warming and the presence of a non-native predator.
Management implications
Warming temperatures are likely to differently favor fish of different sizes and growth stages (e.g., large predators may be more resilient than small prey).
Stress caused by warming could exacerbate the negative impacts of non-native predators on fish physiology and growth rate
Keywords
Impact Study; Experiment; Invasive Vertebrate; Aquatic Habitat; Micropterus dolomieu; Smallmouth Bass