Chapter 10: Respirometry
Joseph J. Cech, Jr.
Respiration by fish includes the uptake of oxygen from the environment at sites of gas exchange (typically the gills), the use of oxygen at mitochondria within individual cells, and the excretion of waste gases to the environment. Respiration provides oxygen for aerobic conversion of the energy contained in food to high-energy chemical bonds, such as those formed when adenosine diphosphate (ADP) is changed to adenosine triphosphate (ATP). The energy thus stored is then used to keep fish alive (maintenance) and to allow fish to move, digest food, grow, reproduce, and carry out all other energy-requiring functions (see the review by Eckert and Randall 1983). In this chapter, the methods of measuring fish respiration are surveyed and evaluated.
Measurements of respiration often can tell us how a fish is responding to environmental conditions and what its physiological state may be. Respirometry gives quantitative measures of how rapidly energy and oxygen are used. Respiratory data are important in the construction of bioenergetic models (Chapter 12) that can be used, for example, to calculate capacities for growth and reproduction (Ware 1982). Respiration rates and gill ventilatory rhythms can be sensitive indicators of altered environmental conditions or physiological states, and thus can reveal much about a fish’s recent and current activity, acclimation, and stress.
The scope of this chapter is limited to measurements of respiratory (aerobic) metabolism and gill ventilation. Published techniques used with several species are reviewed, and some helpful details and expected advances are presented. Kaufmann et al. (1989) presented another interesting discussion on the subject.