Chapter 8: Respirometry
Timothy D. Clark
This chapter follows in the footsteps of that of the same name written by Joseph J. Cech, Jr. in the first version of this book (Cech 1990). The original chapter remains an excellent resource for understanding the methods involved in fish respirometry; here, I touch on some similar themes and provide updated information on the technological and methodological advances that have occurred over the past 30 years.
Given the critical importance of energy flow through individuals and ecosystems (Deutsch et al. 2020), and that metabolic rate has the potential to provide a holistic measure of an organism’s overall physiological status and performance, techniques for quantifying metabolic activity have continued to gain interest since the first edition of this book. Indeed, organismal metabolism sets the rate of resource uptake from the environment and resource allocation to survival, growth, and reproduction; therefore, it is argued to be a primary modulator of ecological processes at all levels of biological organization from individuals to the biosphere (Brown et al. 2004; but see Price et al. 2012).
Energy transduction in fishes and other organisms is thermodynamically inefficient. Thus, organisms are unable to extract work from some of the potential energy in the molecules undergoing reactions, and this energy is subsequently dissipated as heat energy (Nelson 2016). Direct calorimetry is the name given to the technique of measuring the dissipated heat for the purpose of quantifying metabolic activity. While direct calorimetry is considered the “gold standard” for measuring organismal metabolic rates (Kaiyala and Ramsay 2011), few studies have applied this technique to fishes because of their relatively low metabolic rate and heat production, among other challenges (van Waversveld et al. 1989; Regan et al. 2013).