Ecological Aspects of Artificial Water Provision in African Ecosystems

water holes ecological effect

Waterholes play an important role in regulating animal behaviour and they influence the functioning of ecosystems.  Some examples include:

  • Most conflicts between different species and between members of the same species occur when waterholes, water supplies or drinking space are limited.  Aggressive animals such as elephant, rhinoceros and buffalo have been known to kill and injure each other and other animals at waterholes.
  • The number and location of waterholes may control animal populations to some degree but the opposite may also be true.
  • Mortalities and injuries may result from the congregation of animals at a waterhole during peak drinking times when limited drinking space is available.  Young animals may also fall into troughs and drown.  Giraffe may slip on wet or smooth cement slabs and break their legs.
  • Water holes are focal points for animals in the dry season, and predators will lie in wait at such strategic places to obtain their prey more easily.
  • Diseases such as anthrax are spread by animals that contaminate waterholes after scavenging from diseased carcasses.  Vultures, in particular, bathe in shallow waterholes.  Consequently, when they have fed on the carcass of an animal that died of anthrax, they will contaminate the water hole.
  • High concentrations of salt in the drinking water may lead to chronic kidney damage.  When animals in such areas are herded for capture, capture Myopathy occurs more easily.  High fluorine content in boreholes in the Rust de Winter area north of Pretoria has also led to fractured legs in young buffalo bulls.
  • Veld pans fulfil a thermoregulatory function for animals such as elephant, warthog and buffalo, which enjoy rolling in the mud.  Mud pans that form as a result of such wallowing increase in size with time and serve as temporary water holes in the rainy season, easing grazing pressure around the permanent waterholes.
  • The incorrect location or placement of water holes can result in either over- or underutilization of grazing areas.  This may lead to management problems such as erosion and bush encroachment.  Another problem is a species-specific effect that could lead to undesirable ecological effects.  For example, when new water holes were opened up in parts of prime Roan Antelope habitat in the Kruger National Park, it also opened up those areas to large herds of plains ungulates such as zebra and blue wildebeest.  Roan Antelope are shy animals and will not drink in the presence of other animals.  In this case, the new waterholes probably contributed to the decline in the Roan Antelope population.  Closing such waterholes therefore yields better ecological results than establishing them.  Also, in the Kruger National Park, the establishment of artificial waterholes in large areas devoid of natural waterholes led to an influx of the more water-dependent Spotted Hyaenas at the cost of water-independent Brown Hyaenas.

Source: Game Ranch Management (4th Edition), Drinking patterns and drinking behaviour (J.G. Du Toit & H. Ebedes).

elephant ecology

One of the last remaining large Marula trees in Klaserie PNR destroyed by elephants. Too many artificial water points are part of the problem.

Artificial waterholes in many wildlife areas have caused more damage than good.  An example is in Klaserie Private Nature Reserve where landowners have established multiple waterholes on their properties, mainly for game-viewing purposes and ignorant of the many negative ecological effects these have caused.  Elephant and impala overpopulation and widespread distribution in these areas can, to a certain extent, be attributed to excessive artificial water points.  High elephant and impala concentrations may be leading to local extinction of many important tree species such the Marula (Sclerocarya birrea, subspecies caffra); the elephant destroy the adult trees while the impala kill the marula seedlings.  Ironically, germination success rates of marulas are drastically increased when passed through an elephant’s digestive system.  The balance of species composition and numbers is critical to continued healthy functioning of ecosystems.  In the case of Klaserie Private Nature Reserve and even the Kruger National Park, the high elephant concentrations are negatively impacting on lesser, but no less important,  fauna and flora.  Even birds from the tiniest warbler to the great Martial Eagle are being affected by changes in vegetation structure.  Martial Eagles and many other raptors, including most vulture species, require large trees for nesting purposes.  Other birds such as Ground Hornbills nest inside holes in big trees.  As the elephant destroy the last of the big trees, so will we see birds such as these disappearing from the area. Humans have created these ecological problems and now it is our responsibility to actively manage most of our wilderness areas to preserve biodiversity for future generations.

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