• John Mendelsohn

Waterholes in a semi-arid environment

Sources of water and hubs for interaction between pathogens, hosts, vectors, predators, prey, plants and people

Aside from perennial rivers along certain international borders, the only permanent sources of water in Namibia a hundred years ago were in springs, most of which were – and are – in rocky areas of western Namibia (see page 122 in www.atlasofnamibia.online). Many are dry for much of the time, however, and much of the rest of Namibia had no permanent natural supplies of drinking water.

Since then, tens of thousands of water points have been established across Namibia (see pages 129 and 139 www.atlasofnamibia.online). Most serve water to people and livestock on farms and communal land, but hundreds of other waterpoints have been placed in conservation areas and on farms for wildlife.

The provision of water in Namibia has thus changed a great deal, and the same is true throughout other semi-arid areas of Africa. Yet the wild mammals, birds, pathogens and disease vectors that require freshwater evolved in a very different environment. How then, has this relative plethora of water affected animals and microbes as well as the environments that surround waterholes?

That is a big question, aspects of which have indeed been answered generally. For example, we know that water does much to affect the distribution and abundance of wildlife; that congregations of herbivores can influence the soil and vegetation structure near waterholes, that pathogens and parasites use waterholes to infect new hosts; that predation and fear of predators increases around waterholes; and that animals respond to different qualities of water, often shunning more saline water or water with an abundance of pathogens.

Most of these answers have come from studies conducted at certain times and in certain places. But little information is available on how these effects interact and play out in different conditions, such as varying land uses, degrees of aridity, vegetation and soil types, water qualities, and water abundance, for example. And little is known of these effects in places where wildlife, livestock and people use the same water, and where wildlife is confined in small, fenced nature or game reserves.

Evidently, there is much more to waterholes than meets the eye.

And tell me why do some animals prefer to drink from the centre of Okaukuejo waterhole?

Ongava Research Centre is well-placed to facilitate investigations on the effects of waterholes both generally and in the many environmental and socio-economic conditions found in nearby Etosha National Park, communal land, and on freehold and resettlement farms (https://doi.org/10.1016/j.gecco.2022.e02221). These are ideal areas in which to compare the effects and functioning of waterholes under different conditions. There is also abundant scope for experimental testing of different effects in these areas. Moreover, technical advances in the development of monitoring tools such as satellite imagery, tracking devices, camera traps, water quality sensors and eDNA offer opportunities to gather knowledge and to experiment in new, exciting ways.

What we now seek are experts, students, institutions, and resources to collaborate with ORC in answering the many interesting questions to be seen around waterholes in semi-arid environments.

Much good information and understanding about waterholes and their users will come from these studies.