African Wildlife & Environment Issue 83

CONSERVATION

internationally significant range of biodiversity in areas of measurable habitat loss and ecological degradation. The Okavango is bound

by tectonic activity, that is actively capturing rivers and diverting flows in a unique manner, ending in an inland sea that has now desiccated to the point where it is a massive sodic depression known as the Makgadikgadi. The uMzimkhulu is faster to react, because of the interaction between wind and water, as well as the chemistry and physics associated with the relative density of saline and freshwater. It is the quickness of this change, coupled with the size of the sediment and nutrient plume, that amplifies the impact of any alteration to streamflow something far bigger than merely the loss of estuarine functionality.

Umzimkhulu Estuary high flood with North Easterly cross shore wind

plumes impact on different Marine Protected Areas in different ways at different times. While it is difficult to compare a predominantly terrestrial ecosystem with an oceanic one, we can learn from the Okavango and uMzimkhulu Rivers that complex relationships arise from the interaction between just four variables – flood pulse, tidal pulse, nutrient load and wind direction/ intensity. This enables us to conclude that while each of these two river basins is unique, both sustain an

Prof Anthony Turton Centre for Environmental Management

University of the Free State tony@anthonyturton.com

16 | African Wildlife & Environment | Issue 83 (2023)