1. The Southern Ocean is characterized by the combination of a low but stable temperature with a markedly seasonal pattern of primary production. It therefore offers an environment where the annual variations in temperature and production are uncoupled and it is possible to distinguish the effects of one from the other.
2. The widely observed slow growth of polar marine ectotherms is not due to a direct limitation by the low temperature. Rather the seasonal pattern of growth in many species, together with the frequent limitation of reproduction to the summer months, indicate that many processes are regulated strictly by the availability of food (that is they are resource limited).
3. The degree of seasonality in the biology of polar marine organisms varies with their position in the food web. In general, herbivores have highly seasonal life-histories, whereas carnivores, scavengers and higher level predators show less seasonal patterns of growth or reproduction