Geographic distribution of bryozoans in the Argentine Sea (South-Western Atlantic)

LÓPEZ GAPPA, J.; LICHTSCHEIN, V.

OCEANOLOGICA ACTA

Gauthiers-Villars

Año: 1988 vol. 11 p. 89 - 99

0399-1784

On the basis of benthos dredgings carried out by the R.V. Shinkai Maru on the Argentine continental shelf, the bryozoans associations on their areas of distribution were analysed. Presence/absence data of 95 species at 58 stations were processed using correspondence analyses. The area analyses confirms the classical zoogeographic scheme proposed by various authors for our coasts: a Magellanic group occupying most of the studied area an another composed of stations from the Argentine biogeographic province, occupying the inner shelf off Buenos Aires and north Patagonian gulfs. According to our results, the limit of both assemblages is situated near the coast at approximately 43ºS and offshore, at depths of 60-72 m following a SW-NE direction. A gradual and progressive impoverishment in species number towards the north and towards inner sectors of the shelf is observed off Chubut and Buenos Aires. The transitional zone between both zoogeographic provinces is inhabited by species of wide distribution, adapted to support the fluctuating hydrological conditions that characterize this area. Even though the results of this study have shown a higher number of species in the Magellanic group, a comparison between the Magellanic and Argentine provinces cannot yet be made, since the Uruguayan and south Brazilian bryozoan fauna, also included in the latter, is mostly unknown.