Page 108 - A Field Guide to Fairfax County's Plants and Wildlife

ivity: Where did the insects go?

During storm events, runoff will travel over land until it soaks into a porous
surface (like dirt) or reaches a body of water. In urban environments, storm
drains are installed along roadways to prevent flooding. These drains
send the water from the road directly to the closest stream through a
series of underground pipes. This water is not cleaned before it goes into
the stream. Runoff may pick up pollutants on nonporous surfaces (like
roads and parking lots) before reaching a stream or a storm drain.

The graphs below show the results from sampling the same stream for
the number of mayfly nymphs, worms and dragonfly nymphs in 2008 and
2012. Between 2008 and 2012, the forested watershed was developed
into an apartment complex. Using the description above and the
information from the graphs, answer the questions below:

2008 2012

20 20

# of Organisms15 15
# of Organisms
10 10

5 5

0 0

Mayfly Worm Dragonfly Mayfly Worm Dragonfly

Nymph Nymph Nymph Nymph

The above paragraph mentions how pollutants can be picked up by
runoff before it enters a stream. Using the 2012 graph, which species can
tolerate pollution the best? The least?__________________________
_______________________________________________________

Challenge yourself! Look for storm drains around your school. What can
you do to keep pollutants from going down the drains and reaching a
stream? _________________________________________________

_______________________________________________________

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