The Role of Antifreeze Glycopeptides and Peptides in the Freezing Avoidance of Cold-Water Fish

Abstract

The Antarctic and Arctic oceans are perennially at about −1.9 °C, the freezing point of seawater, and ice-covered in their shallow waters (Littlepage 1965). The near-shore waters of the north temperate oceans reach this freezing temperature during the winter seasons. This is well below the freezing point of between −0.5 to −0.9 °C of a typical marine teleost (Black 1951). In the presence of ice, supercooling is impossible, and therefore a 1 °C difference between the freezing point of the fish’s body fluids and the environment would lead to freezing. Freezing or even partial freezing has been shown in all cases to result in death (Scholander et al. 1957). However, many fish living in these freezing environments frequently come into contact with ice (DeVries and Wohlschlag 1969; DeVries 1970, 1971, 1974), yet do not appear to freeze (Hargens 1972). In fact, some use the abundant ice crystal formations as a habitat and spend their entire lives there to forage for food and to escape predators (Andriashev 1970; DeVries and Lin 1977a). Freezing in these fish does not occur unless they are exposed to temperatures below −2.2 ° C in the presence of ice (Scholander et al. 1957; DeVries and Lin 1977a).