Marine Mammals of the Southern Ocean
Marine mammals are a conspicuous faunal element of the Southern Ocean ecosystem and have evolved specialized life history patterns to live there. Six species of pinnipeds inhabit the Southern Ocean, including five species of true seals (family Phocidae) and one species of eared seal (family Otariidae. It is a critical feeding ground for many cetaceans: 15 species of cetaceans, including 6 species of baleen whales, Mysticeti, and 8 species of toothed whales, Odontoceti, inhabit the Southern Ocean. Climate, substrate and prey availability are key factors controlling breeding distributions. A unique reproductive pattern has evolved in the true seals, Phocidae, that enables them to inhabit and breed in the extensive ice regions of the Southern Ocean. While exerting strong direct influences on distribution, changes in the physical properties of the environment, most likely have strong indirect effects on both quality and quantity of breeding substrate, the nature of foraging habitat, or on determining the abundance of potential prey. The occurrence and extent of seasonal ice also play a role in determining the distribution and abundance of marine mammals. This chapter provides an overview of the biology of marine mammals found in the Southern Ocean.