Ecological and regional zoogeography of the marine benthic fauna of Chile

Abstract

The zoogeographic analysis is based on 240 species of 13 taxa, mainly the many new records from the ‘Lund University Chile Expedition 1948-49’. The purpose has been to find out whether or not the new data confirm earlier conceptions of zoogeographic regions and borders in Chilean waters. The climatic conditions at the shore and the hydrography are described. The Chilean archipelago differs from the area north thereof both in topography, climate, and hydrography. The direction and extension of the currents and the small differences in salinity and also in temperature along the shore favour a wide distribution. Except for brackish-water areas in the archipelago the salinity is high. The sea off Chile is colder than at the same latitudes in other oceans, except for southern Chile, where the sea is a little warmer than normal. The local annual range in temperature is small. The vertical and horizontal distributions of the species are illustrated in tables and maps. There are few wide-spread and endemic species among those treated. Northern species dominate in the littoral and in shallow water, southern in deeper water, but the fauna in its entirety has a northern stamp. Northern species also have a wider distribution in Chilean waters than the southern ones. The changes in taxonomic composition with depth and latitude are described. The maps show a step-like distribution pattern. One step, at the northern end of Chiloe and in Seno Reloncavi, about 42° S, seems to be real. There 60 of the 219 non-widespread species have their southern or northern limit. The other steps are most likely only apparent, being the result of more intense investigations in the areas where the steps are found than in the areas in between. The results confirm those of earlier investigations. There are two temperate regions along the Chilean coast, a northern warm-temperate and a southern cold-temperate region. The border is found at about 42° S and coincides with the change there in topography and partly in climate and hydrography. Within the warm-temperate region there is a transitional area between 30(33) and 42(46)° S, in which many species from both regions coexist.