(also called Antiboreal, Australian, South Temperate, or Subantarctic region), a zoogeographical region of the ocean, lying between the Tropical Realm and the Antarctic region. In the pelagic zone the Notalian region stretches from the southern subtropical latitudes to the antarctic latitudes, from about 40° to about 50°–60° S lat. Its benthic zone (on the shelf) encompasses the southern part of South America, Tierra del Fuego, the Falkland Islands, the Prince Edward Islands, the Crozet Islands, Kerguelen Island, Heard Island, Mac-quarie Island, and the southern islands of New Zealand. Along the western coast of South America and along the coast of South Africa, southeastern Australia, and Tasmania organisms typical of the Notalian region are found in areas that have predominantly subtropical fauna.
Within the Notalian region the pelagic fauna is homogeneous; biological productivity is high, especially in the southern part of the region; and plankton and benthos are abundant. In addition to endemic Notalian species, the pelagic zone has a large number of forms that are also encountered in the tropics or in Antarctica, so that some scientists regard the Notalian region as a transitional zone. Endemic species predominate among the floor fauna of the shelf, but since various parts of the shelf are separated by thousands of miles of deep-water ocean, the fauna of the different parts varies significantly. Consequently, many scientists subdivide the Notalian region into the Patagonian region and the Kerguelen region; the latter is sometimes also classified as a subregion of the Antarctic region.
K. N. NESIS