PLEISTOZANE UND REZENTE MOLLUSKEN VON SAN ANDRÉS (KARIBISCHES MEER, KOLUMBIEN) MIT BEMERKUNGEN ZUR GEOLOGISCHEN ENTWICKLUNG DER INSEL

Abstract

Investigations in the Pleistocene and Recent reef complexes of San Andres Island yielded a collection of 38 Pleistocene and 121 Recent species of marine mollusks. Recent species collected show an ecological distribution according to the following major biotopes: rocky shore, coral, sand, mangrove, rocky flats, and deep water, each environment being populated by certain key species. Collecting in the Pleistocene was restricted to outcrops of fossil rocky shore, coral and sand environments, others being covered by vegetation or absent. This fact and the lack of very shallow water mollusks may explain the apparent poverty of the Pleistocene fauna. Quantitative collections in Pleistocene and Recent lagoonal environments show strongly divergent faunal spectra as might be expected for different water depths. The Pleistocene lagoon depth at collecting locality, as tentatively inferred from mollusk spectra, indicates a position of former sea level 6,5-8 m higher than the present one. This is in agreement with morphological and other evidence.