Assessing the impact of heatwave exposure on the swimming performance, kinematics, and metabolism of a nearshore marine fish, Cymatogaster aggregata

Abstract

The severity and frequency of marine heatwaves (MHWs) have increased drastically across the globe, with some of the most intense heatwaves happening within the last decade. The consequences of MHWs vary in severity and include range shifts and diet changes as well as mortality events in marine species. In fishes, elevated temperatures can lead to changes in whole-animal metabolism and performance metrics. However, the impact of temperature on a key performance metric, optimal swim speed (Uopt) is not fully understood. Here, we investigate how heatwave exposure (I.e., +2°C and +4°C) over a five-day period affects the metabolic rate and swimming performance of the shiner perch (Cymatogaster aggregata) using a swimming respirometer. Preliminary findings demonstrated that Uopt slightly increased following moderate MHW exposure (+2°C) and plateaued at higher MHW exposure (+4°C). However, metabolic costs and maximum swimming speed peaked following moderate MHW exposure and declined under more intense MHWs. Not only does this provide more information on the swimming energetics and performance of a common nearshore species, but it also provides insight into heat tolerance and how this species may respond to future projected marine heatwaves.