Effects of Temperature on Cardiac Function in Teleost Fish

Abstract

Changes of environmental temperatures immediately and substantially influence cardio-vascular function in teleost fish. In most species, the body temperature closely parallels that of the environment. Some species live at a nearly constant temperature, such as deep seas and polar oceans. On the other hand, subtropical and tropical environments expose fish to ever-changing temperatures, which provokes large adjustments of physiological and biochemical rate processes and behavioral patterns. Teleost fish display large differences in cardiac function, depending on adaptations to temperature, mode of life, and activity levels. Seasonal and acute environmental temperature fluctuations, and the temperature-dependent regulation of cardiac performance become crucial for ectothermic fish. This motivates a growing concern about the possible impacts of global warming, since it is associated with ever-changing temperatures and oxygen levels in aquatic ecosystems. Currently, there is a growing need to understand the physiological basis of biodiversity, and to evaluate the resistance of distinct species to cope with changing environments. On this background, this chapter reviews how ambient temperature changes cardiac function in teleost fish, emphasizing both in vivo (heart rate, stroke volume and cardiac output) and in vitro components (cardiac contractility).