This book IS an attempt to review the state-of-the-art in the fields of limnology and of marine biology in the Sudan. The need for it became apparent while we were doing some joint field work in the Nile Valley and along the Red Sea coast. We feel that several reasons justify its publication. Firstly, a vast amount of information is being gathered year after year by the staff of the Hydrobiological Research U nit of the University of Khartoum, in conjunction with the faculties of Medicine and Agriculture of this university; much of this information fails to find an outlet to the scientific...