Muscle Metabolite Response to Exercise and Recovery in Yellow Perch (Perca flavescens): Comparison of Populations from Naturally Acidic and Neutral Waters

Abstract

To test whether energy metabolism is responsive to changes in the aquatic environment and to better understand the exercise physiology of acid-tolerant fish species and populations, I compared metabolic responses to exercise and recovery in a population of perch from a naturally acidic lake (acid-lake perch, ALP) and a circumneutral lake (neutral-lake perch, NLP). White muscle from the two populations was sampled after 16 h of acclimation in a swim flume to either pH 4.0 or pH 7.8 water, after exhaustion induced by a critical swimming speed protocol, or after 6-12 h of recovery from exhaustive exercise. Extracts were analyzed for nucleotides, phosphagens, and glycolytic intermediates. Acid-lake perch had less severe postexercise metabolite perturbations and poorer exercise performance in neutral water than NLP, which suggests that fish that fully activate anaerobic metabolism during exercise may have been selected against in this population. Populations differed most in lactate and pyruvate levels, with ALP accumulating more pyruvate and less lactate after exercise than NLP. There was some support for my hypothesis that ALP are selected for minimal proton accumulation during recovery from exercise. Acid water altered the postexercise metabolic profile in NLP only. The significantly lower lactate, AMP, and IMP levels in "acid-naive" NLP signaled an inability of these fish to fully use anaerobic sources of ATP in acid water.