244
Exercise 17
Table 17.1. Predation of a bluegill sunfish and a dragonfly nymph on Daphnia.
Prey density per 500 ml
- - - - - - _ .. -
- - - _ .
--~----- - -
- -
- _ . _ -
Bluegill as predator
Odonate as predator
- - - - _ . . -
- - - - - -
Trial
15L
15D
30L
50L
80L
15L
150
30L
50L
80L
10
0
22
20
9
8
7
4
12
6
2
5
5
20
39
10
4
1
2
4
16
3
15
0
19
38
3
2
3
0
8
7
4
13
6
23
15
12
9
7
9
23
3
5
11
I
29
16
3
4
9
9
10
19
6
14
0
0
16
15
5
2
12
4
7
7
15
10
0
9
8
15
3
0
5
9
13
4
2
12
10
4
8
4
5
11
14
11
2
5
12
15
4
3
5
13
15
4
6
I
14
12
1
5
6
15
7
5
0
9
16
3
4
9
8
17
11
5
2
I
18
0
0
0
19
15
14
3
4
20
2
7
6
Mean
10.5
4.4
18.8
24.0
8.7
3.8
5.3
6.0
10.2
9.7
S
5.0
3.4
9.9
4.9
4.8
2.9
3.3
4.7
7.1
6.3
CV(%) 48
77
53
20
55
76
62
78
70
65
SE
1.1
0.8
4.0
2.0
2.0
0.6
0.7
1.9
2.9
2.6
Equipment and Supplies
1. Beakers, 50-ml and 500-m1.
2. Wide-bore pipets.
3. Finger bowls.
4. Test tubes with caps.
5. Wide, flexible forceps.
6. Fine meshed net, < 80-{1m mesh size.
7. Stream or nonchlorinated well water.
8. Dispensing flasks, 4-1.
9. Stopwatch.
10. Nitex net/filter apparatus to separate predators from prey at the end of the
feeding period and for counting remaining prey.
11. Darkroom or darkened chamber.
12. Organisms:
a. Bluegill, or equivalent, of similar size.
b. Odonate nymphs (e.g., Tetragoneuria or Anax).
c. Daphnia (intermediate to large size).