Bioenergetics

Abstract

The energy in the food ingested has one of two fates. Some is dissipated in the form of waste products or heat and some is incorporated as new tissue. The heat losses are generated by the metabolic processes through which the energy in the food is released to do useful work. This includes the work done in tissue function and repair, synthesizing new tissue and swimming. The processes which result in the dissipation of energy can be grouped together as maintenance. New tissue may take two forms: growth or gametes (Fig. 1.2). The income of energy (and nutrients) will be limited by time, the availability of food and the capacity of the gut to process food. How should this limited income be allocated among maintenance, growth and reproduction? What pattern of allocation will maximize the lifetime production of offspring? This chapter starts the discussion of these questions by first introducing the concept of an energy budget and then describing the effects of abiotic environmental factors on the maintenance item in the energy budget using a classification originally developed by Fry (1971). The succeeding three chapters examine the allocation of time and energy in relation to patterns of movement (Chapter 5), growth (Chapter 6) and reproduction (Chapter 7).