Diversity and endemism in cold waters of the South Atlantic: contrasting patterns in the plankton and the benthos.

BOLTOVSKOY DEMETRIO; CORREA NANCY; BOLTOVSKOY ANDRES

SCIENTIA MARINA

Instituto de Ciencias del Mar - Centro Mediterráneo de Estudios Marinos y Ambientales (CSIC)

Lugar: Madrid; Año: 2005 vol. 69 p. 17 - 26

0214-8358

In total, ca. 7000 zooplanktonic species have been described for the World Ocean. This figure represents less than 4% of the overall number of marine organisms known, and is likely to decrese with additional surveys. Of the 7000 zooplanktonic species world wide, some 60% are present in the South Atlantic; about one third of the latter have been recorded in its Subantarctic waters, and ca. 20% south of the Polar Front. When compared with benthic animals, these figures indicate that proportions of the overall inventories that are present in the cold waters are almost two times higher among the zooplankton. In agreement with this pattern, the proportions of Antarctic endemics in the benthos are very significantly higher than those in the plankton. For the water-column dwelling animals the Polar Front boundary is more important than the Tropical-Subtropical limit, but almost equivalent to the Subtropical-Transitional limit, and weaker in biogeographic terms than the Transitional-Subantarctic boundary. Some of the implications of these dissimilarities, both for ecological theory and for resource allocation strategies, are discussed.