Page 117 - A Field Guide to Fairfax County's Plants and Wildlife
P. 117
Stream ecosystem challenge

Study the stream below: 1) Circle all the invertebrates, 2) place a triangle
over at least two producers, 3) place a square around all of the mammals,
4) Place an X over the animals that are not native and 5) draw an arrow
from a prey species to one or more of its predators.

Challenge yourself! Precipitation is crucial to keeping many small streams
wet and flowing. Some streams in Fairfax County are not as healthy as
they should be, though. Hard, nonporous surfaces like roads, sidewalks
and rooftops keep stormwater from soaking into the ground or moving
slowly across the land. Having more nonporous surfaces causes greater
amounts of stormwater to run off the land and into streams quickly.
Sometimes stormwater flows into underground pipes and comes out
the other end fast enough to cause erosion of the stream banks and
bottom. How might the organisms in the picture be affected if boulders in
the stream and soils along the stream banks were washed away during
heavy rains? Would some organisms tolerate the changes better than
others? Why?

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