Abstract
In the Gebel Aulia dam basin of the White Nile (Sudan) 3 sets of quantitative zooplankton samples were taken, within a year, at intervals of 3-5 hr. and several depths over a time of 21, 39 and 48 hr. The results show a strong patchiness of all components in a quick succession in time. There is no evidence of vertical migration in this lake-like, but slowly moving water-mass, but evidence exists of diurnal increases and falls of total densities. Histograms illustrate the changes in particular depth layers, linear curves show the succession of total densities. The data pose some problems for attempts at biomass assessments in moving water.

This publication has 2 references indexed in Scilit: