ECOLOGY OF SOME ROCKY SHORES IN TROPICAL EAST-AFRICA

A quantitative survey was made of the communities on rocky shores at Dar es Salaam [Tanzania] (Latitude 7.degree. S) on the East African coast. These shores are of coral limestone and generally a wide flat erosion platform rises to the level of mean neap tides, backed by steep cliffs. Three zones are defined: a lower eulittoral rising to mean tide level, an upper eulittoral to about mean high water springs and a littoral fringe extending some 5 m or more above the latter level. The degree of wave exposure and the slope of the substrate both modify the abundance of a number of species. The results of this study are compared with those from other areas in the W Indian Ocean and the Red Sea. Within this region much of the fauna is widely distributed, and the basic zonation patterns are essentially similar to that at Dar es Salaam. The heights of the zones in this tropical area bear much the same relationship to the tidal constants as do the equivalent zones on temperate European shores.