Respirometry and environmental control in micro aquatic systems

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Animals consume oxygen in order to harvest energy from proteins, carbohydrates and fats obtained in food. The amount of oxygen an animal consumes changes with body size, exercise, stress, temperature, daily body rhythms, among other variables. Accurate measurement of oxygen uptake, a good proxy for metabolic rate provides fundamental information on an animal's physiological status. Oxygen uptake can be measured in aquatic breathers by measuring the amount of oxygen removed from the external water per unit time. In air breathers, the measurement can be complicated by the relatively high oxygen concentrations in air, especially if the organisms are relatively small. We are requesting funds to purchase state-of-the-art respirometry equipment to precisely measure resting oxygen consumption in small aquatic and amphibious fishes at all stages of development from individual embryos (1 mm) to adults (< 3 cm) in water or air. These resting measurements will be followed up by measurements of oxygen uptake in swimming or active fish using specialized micro swim tunnels to assess performance after previous exposure to environmental perturbations. Environmental perturbations include low oxygen (hypoxia) and elevated carbon dioxide levels (hypercapnia) in the environment. We request funds to purchase two independent systems, one for oxygen, the other for carbon dioxide to precisely regulate these parameters in fish tanks for short (eg. < 1 day) or long periods of time (eg. > 1 month). Data is collected and analyzed by a computer interface. The equipment requested is fundamental to four NSERC-funded research programs and will be used weekly.