Due to topography, as we have seen, pollution levels can be changed due to different topographical landscapes. Because of this, the macro-invertebrate life present in the stream also may change. Different organisms are more or less tolerant to pollution and provide good indications to the pollution levels of a water body. When the pollution levels raise, Taxa #3 (pollution tolerant) organisms will begin to be more populated in the stream, while Taxa #1 creature populations will begin to decrease. Furthermore, if the pollution levels are low, the macro-invertebrate life will more likely favor Taxa #1.
Many creatures from each of the three Taxa are pictured in the link provided below. These organisms give excellent indications of pollution levels, and their populations will surely change with different topographical features. As you can see, due to the influence of topography on pollution, the types of organisms present in a body of water will also change.