Effects of Sewage Dumping on Macrobenthic Invertebrates in the Jordan Gulf of Aqaba, Red Sea

There are two sewage outfalls along the Jordanian coastline in the Gulf of Aqaba. During 1982 and 1983 a total of 328 core samples (0.01 m2 to a depth of 15 cm) were collected from the two outfalls, two control stations which resemble the outfalls in depth and sediment texture, and from two stations 100 m on both sides of each outfall. Faunal analysis revealed that the total number of individuals, number of species, species richness, and faunal similarities of macrobenthic invertebrates were lower at the sewage outfall near the phosphate loading port than the control station during both collections. At the 100 m stations, the numbers of individuals were generally higher than the sewage and control stations. The number of species, however, was highest at the control station and lowest at the sewage outfall. At the other sewage outfall, where the sewage effluent is discharged sporadically, no measurable effects on macrobenthic invertebrates were found.