Notes on the Community Structure and Biology of Fishes in the Okavango Delta

Abstract

The Okavango Delta (Delta) is a dynamic ecosystem constantly in motion. Each year the timing, magnitude,
and duration of the annual flood is dependent on rainfall levels in the southern Angolan highlands. The annual
floodwaters arrive in the northern Delta in January but do not reach the southern Delta and Thamalakane
River until approximately May. With the flood waters the Delta rapidly surges with biological productivity
as nutrients are quickly assimilated by aquatic plants, fish, and insects. Many of the 80 fish species undergo
annual migrations to spawning and feeding grounds throughout the myriad of waterways.
There are distinct fish communities in the Delta which can be separated from each other by the
physical characteristics of the different habitat types with which they co-evolved. An overview of the
community structure of the fishes and the environmental factors that limit their distribution is presented in
this piece. In the northern riverine floodplain and perennial swamp, a higher species richness was recorded
than in the seasonal swamp and drainage rivers.