Sandy-beach fauna of the Pacific and Atlantic coasts of Costa Rica and Colombia

Abstract

The macroscopic infaunas of 18 tropical sandy beaches along both coast; of Costa Rica and Colombia were examined during the spring of 1971. The Pacific beaches averaged 7 times the density of individuals, had significantly larger numbers of species, and had significantly finer sand than the Atlantic beaches. The two most abundant species the isopods Cirolana salvadorensis and Exosphaeroma diminutum, occurred on both coasts. The polychaetes Scolelepis agilis and Hemipodus armatus were found on the majority of beaches on both coasts. In general, the faunas of the Pacific and Atlantic sandy beaches were composed of closely related species.