Oxygen, metabolism, and population growth across marine fishes

The maximum intrinsic rate of population increase (rmax) estimates population growth at low abundance, and varies with size, temperature, and depth, suggesting a metabolic basis for population dynamics. Additionally, recent advances in aquatic ecophysiology have highlighted that oxygen supply constrains metabolic traits. Yet, little is understood of how rmax relates to metabolic rate across fishes, and how both are shaped by environmental oxygen. In this thesis, I conducted a comparative analysis of metabolic rate, rmax, and environmental oxygen for sharks and teleosts. First, I investigated the relationship between metabolic rate and rmax, finding that species with lower metabolic rates also had lower rmax. Next, I tested how metabolic rate and rmax are related to environmental oxygen, and found that both increased with oxygen availability. My findings support that species with slower metabolism (e.g., sharks, or low-oxygen inhabitants) exhibit slower population growth, and hence are more intrinsically sensitive to overfishing.