The Nile Benthos

Abstract

Benthic macro and micro-invertebrates include those biota that spend a significant portion of their life on or in the bottom. Nile benthic macroinvertebrates (molluscs, worms and crustaceans) exhibit a marked variation in composition and abundance, reflecting a range of microhabitats but a comprehensive inventory of the taxa present is still lacking. Meiobenthos (nematodes, flatworms, and microcrustaceans) has to date remained almost unstudied. Macroinvertebrate species richness in Egypt amounts to about 7-31 species at individual bank-side sites of the river and delta and the macrobenthos of the White Nile and its lakes is represented by about the same number of species. The sandy bed of the White Nile is sparsely populated, with the larvae of small Chironomidae prominent. Information about the Blue Nile is scarce, but its benthos appears to be poor, because of torrential flow and drastic changes in water level. Generally, benthic invertebrates of the Nile lakes have low diversity compared with temperate lakes. Twelve species of molluscs, 14 species of insects and three species of oligochaetes are known from Lake Victoria. The benthic community of Lake Turkana includes a sponge, a bryozoan, 8 gastropods, 3 bivalves, 17 ostracods, 23 insects and several hydracarines and annelids. Caridina nilotica, Potamonautes niloticus (Crustacea), Limnodrilus hoffmeisteri, Branchiura sowerbyi (Oligochaeta), Corbicula fluminalis, Cleopatra bulimoides and Melanoides tuberculata (Mollusca) occur Nile-wide.