ZOOGEOGRAPHY OF PACIFIC-OCEAN ISLANDS - A COMPARISON OF THE ROTIFER FAUNAS OF EASTER ISLAND AND THE GALAPAGOS ARCHIPELAGO

During September 1990, an extensive sampling of the freshwaters of Eas ter Island was conducted. The resulting list of rotifer species, suppl emented by taxa present in samples collected during a previous trip to the island, is compared with that of another oceanic island of volcan ic origin, namely Santa Cruz, Galapagos archipelago. In spite of less research, Santa Cruz has a richer rotifer fauna which, unlike Easter I sland, includes endemic species. Possible causes for the faunal povert y of Easter Island are: large source-to-target distance, small target size, uniformity of the target island's ecosystems and limited age of its aquatic biotopes.