The origin and structure of Tutia Reef, a coral reef off the Tanganyika coast, is described. It is concluded that the reef is formed in part from the cutting back flat of the older reef 14 ft above the level of the present reef, and in part from seaward growth of the reef.
Based on lines of quadrats down three sides of the reef an assessment of the cover of living coral on the reef is made, and the distribution of the dominant corals of the reef described. It is suggested that, contrary to the views of Crossland (1902, 1903), many East African coral reefs are undergoing seaward growth.
The distribution of the fishes on the reef is described, and a correlation is shown with the distribution of living coral on the reef. Many species of fishes have restricted distribution on the reef.
The feeding relationships of the fishes are discussed, and the total fish biomass divided into separate feeding categories. Tutia Reef has a low biomass of herbivorous fishes compared with the results from Eniwetok Atoll obtained by Odum & Odum (1955). This is considered to be due to the fact that Tutia Reef exhibits characteristics of an outer reef, deriving much of its energy from plankton, not those of an enclosed and almost autotrophic logoon.