Physiological attributes altering the distribution of fishes: an energetics perspective

Timothy D. Clark (1)

1 University of Tasmania and CSIRO Agriculture Flagship, Hobart, Tasmania, Australia 7000

Climate change is altering the distribution of many fish species, often as a consequence of structural habitat degradation but also through alterations in the properties of water (e.g., temperature, oxygen levels, water chemistry). Upper and lower environmental limits of a species are routinely assessed in the laboratory (e.g., critical thermal maximum), but such experiments rarely provide an integrated understanding of the array of challenges and trade-offs experienced by animals in the natural environment.  Fundamental to animal fitness  is  an appropriate  balance  between energy acquisition (food) and energy  expenditure  (growth, activity, digestion, reproduction), which are dependent on factors such as foraging success, digestive efficiency and activity levels. The capacity for energy usage is intimately linked with the capacity for oxygen transport, as oxygen is required by mitochondria for the aerobic synthesis of ATP. This presentation will discuss how environmental change can cause species-specific range shifts by impacting oxygen transport and energetics. Methods and technologies for investigating the energy usage of free-roaming animals will also be discussed.