A Comparison of the Strombus (Mollusca) Colonies of Trinidad and Grenada

Abstract

Underwater observations on the genus Strombus around the coasts of Trinidad and Grenada show that the same species are common to the two areas but that they are today living under very different conditions. Grenada is surrounded by clear, oceanic water which supports the growth of reef corals while Trinidad, being close to the South American continent and the mouths of the Orinoco River, is surrounded by continental water of variable salinity and carrying much suspended material. In addition, the water at 100 feet depth on the north coast of Trinidad was found to be some 15° F. colder than it is off Grenada due to cold up[1]welling in the former case. Deep water and strong ocean currents effectively separate Strombus colonies in the two islands which lie 90 miles apart. The ecological differences as they affect the five species involved include the discovery that there is a tendency for colonies to be found considerably deeper in Grenada where the higher water temperatures and better light penetration allow this. Habitat differences illustrated by this study of Strombus species point to the care necessary in drawing paleoecological conclusions by extrapolation from the Recent to fossil forms.