Pests or invasive
species are usually introduced by humans. They threaten the survival
of native plants and animals, and can also damage valuable agricultural
and personal resources.
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| Photo:
Waterwatch SA |
Terrestrial and aquatic pests affect the health of our waterways
as well as native animals and plants. For example, the mosquito
fish (Gambusia holbrooki) was introduced from the USA to
control mosquitoes. However, it now outnumbers native fish in
many parts of south eastern Australia, as they out compete indigenous
species for food.
Exotic trees such as willows (Salix sp.) are another problem.
Willows produce dense shade, suppressing understorey growth, resulting
in bare banks that are susceptible to erosion. The trees are a
poor habitat for land animals, and the population and diversity
of aquatic invertebrates and native fish is greatly reduced under
their canopy.
