This paper summarizes observations performed during 1966, 1968, and 1972, on coral reef flats 7 km south of Eliat (Gulf of Aqaba, Red Sea). The aim of this research was to describe the change in numbers of living coral colonies found on the coral tables in connection with pollution occuring in this habitat. A transect technique, developed by Loya and Slobodkin (1971) was used in this research. 2. In each of the three years, 19 ten metre transects were performed in various directions, on the same coral tables. 3. In 1966, 541 living coral colonies were counted in a total of 190 m of transects. At the identical place, this number had decreased to only 195, in 1972. The decrease in corals was found to be accompanied by a prominant increase in algae growth, that expend and develop, thus covering the coral specimens. 4. Especially sensitive to algal development are the branching micropolypal, coral species, that are the representatives of the genera Acropora, Seriatopora, and Stylophora. Of the above three genera counted in 1966, only 10 out of 192 colonies were found intact, in 1972. 5. The high mortality of corals in this locality occured during the years in which an oil terminal plus a mineral and phosphate loading harbour were developed at Eilat. 6. The frequent oil spills, together with the phosphate dust that reaches the sea, seem to be the factors that cause eutrophication in the shallow lagoon waters of the coral region, and thus the development of algae on the coast of corals is stimulated.
