Use the biological diversity indexes for the following streams.
Data for stream #1: 30 leeches, 1 crayfish, 30 left snails, 10 right snails,
1 caddisfly, 10 blackflies, and 10 scuds.
Data for stream #2: 30 caddisflies, 20 mayflies, 1 leech, 2 scuds, 3 blackflies,
1 blood worm midges, and 5 right handed snails.
The dissolved oxygen taken at 12:00 noon was
12mg/L and 5 days later it was 6mg/L.
Data for stream #3: 5 crayfish, 10 mayflies, 15 stoneflies, 5 dragonflies,
30 alderflies, 10 caddisflies, and 20 dobsonflies.
The dissolved oxygen taken at 12:00 noon was
20mg/L and 5 days later it was 15mg/L.
Questions:
1. Why is the water sample kept in a dark room for 5 days? Why does some of
the oxygen disappear when the D.O. test is completed again?
2. Which site has the greatest demand for oxygen? How do you find this B.O.D.?
3. When would you expect the dissolved oxygen to be at its highest: first thing in
the morning, 12:00 noon, late afternoon, or midnight? Explain why?
4. Which stream probably has the highest number of producers in it? Why do you
think so? Support this with some proof.
5. Write a 5 paragraph essay with simple support and proof for the following:
Which of the three streams has the highest level of water quality?
** Make sure that you show all of your work for each of the three streams when you
are fining the biological and diversity indexes.
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© 1998 Elmwood Jr/Sr High School