Formation of reactive species and induction of antioxidant defence systems in polar and temperate marine invertebrates and fish.

High oxygen solubility at cold-water temperature is frequently considered to be responsible for an apparently elevated level of antioxidant protection in marine ectotherms from polar environments. However, tissue oxidative stress is in most cases a function of elevated or variable pO2, rather than of an elevated tissue oxygen concentration. This review summarizes current knowledge on pro- and antioxidant processes in marine invertebrates and fish, and relates reactive oxygen species (ROS) formation in polar ectotherms to homeoviscous adaptations of membrane and storage lipids, as well as to tissue hypoxia and re-oxygenation during physiological stress.