DIEL VERTICAL MIGRATION OF DAPHNI/l BARBATA IN A SHALLOW TROPICAL LAKE, ETHiOPIA

Abstract

Diel vertical migration (DVM) has rarely been studied in tropical fresh waters such as in
Ethiopia, East Africa. However, its understanding is pivotal in lake ~cosystem management as fresh
waters are the means of all sorts of livelihood for populations in the tropics. It was therefore necessary
to study various aspects of the ecology of these waters where zooplankton take their share. As Ii result
DVM of Daphnia barbata was studied in two consecutive years to reflect on the tropical DVM scenario by
sampling the lake by daylight and darkness using traps to collect water from various depths. The
results showed that normal DVM t;akes place in Lake Kuriftu with ascent of D. :barbata at dusk and
descent at dawn. This behavior is discussed in light of tropical high water temperatures from top to
bottom, dissolved oxygen stratification and other related parameters and comparisons have also been
made with classical temperate lake scenarios with recommendations for future work for the sake of
sustainable use of tropical freshwater ecosystems.