Biogeographical affinities of polychaetes from Îles Crozet

Abstract

The study of polychaetes from the Marion Dufresne expedition to the Îles Crozet in 1982 provided 45 species from depths ranging from 50–1055 m. The most abundant was Eunice pennata, found at all depths and in all types of substratum in about 66% of the samples. This species with Laetmonice producta, Harmothoe spinosa and Lanice marionensis made up over 50% of all polychaete specimens. A homogenous polychaete assemblage dominated by the above mentioned group of species was encountered in the shallower stations (100–300 m). A mosaic-like and less abundant polychaete fauna with some characteristic, abundant species: Amage sculpta, Laetmonice wyvillei, Leanira quatrefagesi and Melinna cristata was encountered in the deeper stations (300–1055 m). Clear similarities between the polychaete fauna of Îles Crozet and soft-sediment polychaete assemblages of Marion and Prince Edward Islands were noticed. No such affinity was encountered with the polychaete fauna of Îles Kerguelen. Their position in relation to the Polar Front as well as possible differences in bottom deposits (calcareous versus siliceous) may in part explain these dissimilarities. The biogeographical status of Kerguelen Islands is also discussed.