BIOLOGY AND ZOOGEOGRAPHY OF THE VEMA SEAMOUNT: A REPORT ON THE FIRST BIOLOGICAL COLLECTION MADE ON THE SUMMIT

Abstract

Summary A collection of marine organisms, made in 1964 on the summit region of the volcanic Vema Seamount, situated some 450 miles off the west coast of South Africa, is discussed. The general terrain of the summit was rocky, and kelp, lesser algae and encrusting animals were dominant. The collection consisted of some 22 species of algae and over 105 species of benthic invertebrates. The three largest zoogeographical groups of animals on the Seamount were (a) the endemic species (28%, of which the majority belonged to the little known Porifera and Ascidiacea), (b) the cosmopolitan, and those species with a scattered distribution (27%) and (c) those species found only on the Seamount and in South Africa (25%). Species found on the Seamount whose distribution was limited to the Indo-Pacific region, and to West Africa and Europe with some overlapping into South Africa, amounted each to about 10% of the fauna. Only one species, the rock lobster, Jasus tristani, is confined to the Seamount and the relatively close Tristan da Cunha group of islands.