 More runoff makes its way into streams since paved roads, cement, and other basic infrastructure do not absorb materials, and all the harmful pollutants go directly into rivers and streams.Fish are very sensitive to changes in water pH, salinity, hardness, and temperature which can all be affected by runoff pollutants and indirect changes from land use.An exotic (or non-native) species is defined as a species that does not naturally occur in a certain area or ecosystem.