An Updated Checklist of the Phytoplankton of the Blue Nile at Khartoum

Abstract

The phytoplankton of the Blue Nile at Khartoum was investigated during May 2000 to February 2002. Brook (1954) and Sinada (1972) presented similar data collected during 1949-1952 and during 1968-1970 respectively. A total of 225 species and varieties belonging to 75 genera was compiled as the algal flora of the Blue Nile at Khartoum. In terms of number of species Chlorophyta formed the most abundant group (118 species, 36 genera) followed by Bacillariophyta and Cyanobacteria. The contribution of Euglenophyta, Pyrrhophyta and Xanthophyta was negligible. Phytoplankton diversity, biomass and chemical analyses revealed no indication that the Blue Nile at Khartoum suffers from any degree of pollution. However, major changes occurred in the algal species composition when certain taxa which dominated the phytoplankton in the 1950s disappeared and new species appeared in appreciable numbers in early 1970s and during the present study. These changes may be influenced by changes in hydrological regime of the Blue Nile following the construction of the Roseires dam in 1966, and possibly incipient eutrophication resulting from agrochemicals and industrial wastewaters reaching the Blue Nile during the latter decades of the 20th century.