Date of Award


Thesis Date


Degree Type

Honors Thesis-Restricted

Degree Name



Biological Sciences

Degree Program

Biological Sciences


Bernard Rees


Metabolic rate is an essential feature of animal physiology and ecology. The rate of aerobic metabolism, as determined by oxygen consumption rate (MO2), is influenced by a variety of factors, including body size, temperature, and activity levels. Maximum aerobic metabolic rate (MMR) reflects the physiological capacity of an animal for oxygen extraction and utilization. As such, MMR is argued to be an important feature of an animal’s life history. For fish, MMR is frequently estimated as the peak MO2 immediately following an exhaustive chase, although several studies indicate that this value may underestimate MMR. Rather, MMR may be attained during sustained activity or following ingestion of a large meal. In this study, I used intermittent-flow respirometry to quantify MO2 by the Gulf killifish, Fundulus grandis, after chasing, after ingestion of a meal, or during swimming. MMR estimates obtained by the three techniques were repeatable over two trials (r ≥ 0.74). However, MMR estimates after chasing were significantly lower than those obtained during swimming (P = 0.001); MMR estimates after feeding were marginally (P = 0.06) higher than those obtained after chasing and significantly lower than those during swimming (P = 0.02). Additionally, the MMR estimates among methods were uncorrelated with one another (r ≤ 0.55). The results demonstrate that MO2 after an exhaustive chase or during digestion underestimate MMR in this species, and, importantly, such estimates may be poor predictors of inter-individual variation in maximum aerobic metabolism.


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