What a month. Dr. Alex McInturf’s paper on the role of physiology and metabolism in trophic interactions has just been published in Ecosphere and is entitled In hot water? Assessing the link between fundamental thermal physiology and predation risk of juvenile Chinook salmon. Dr. McInturf and I collaborated on developing this project to assess how metabolic traits like Aerobic Scope inform community interactions between juvenile Chinook salmon and their predators. In doing so we developed a hypothesis of “Thermal Metabolic Advantage” which posits that in a competitive or trophic interaction the species which has a greater proportional aerobic capacity will be advantaged.
We tested this by measuring the aerobic scope of predator species (e.g., rainbow trout and largemouth bass) as well as juvenile Chinook salmon. We measured aerobic scope at temperatures ranging from 11 to 25C. We also measured these organisms burst swim performance (more on this later). We then conducted predation experiments between these predators and prey at the same temperatures used prior and assessed the rates of predation on juvenile salmon.
To measure burst performance, we designed and built a burst swim chamber which uses an array of lasers to measure the burst swim velocity of a fish. We were able to develop our burst tunnel in a mirrored design which enabled us to conduct rapidly repeated trials and assess a fish’s capacity for repeated burst events, which we envisioned were particularly relevant to the outcomes of predatory encounters. For more information about the burst tunnel, check out this summary of the system prepared for a Conference.
The results of this experiment indicate that the role of water temperature in structuring trophic interactions is dependent on the combination of predator and prey. We also found that our measures of burst performance were better predictors of predatory outcomes than measures of aerobic scope.