Monteverde : Ecology and Conservation of a Tropical Cloud Forest

Table 12.4. Comparison of stream fauna in the Quebrada Guacimal during 10 years when invertebrates
were collected from upstream (Up) and downstream (Down) sites, relative to a point of discharge from the
lecheria.

1980

Odonata
Ephemeroptera
Plecoptera
Trichoptera
Coleoptera
Diptera
Chironomidae
Others
Planaria
Amphipoda

Up

4

30

nr

30

nr

19

nr

2

9

Down

0.9

23

nr

6

nr

63

nr

2

6

1982

Up

2

49

nr

7

nr

0

nr

nr

42

Down

1

8

nr

3

nr

80

nr

nr

8

1984

Up

5

24

7

12

4

0

nr

nr

2

Down

0.2

0.2

0

0

0

100

nr

nr

0

1985

Up

2

10

6 8 0 1 0 0

70

Down

0

l

0

1

0

98

0

0

0.1

1990

Up

0.3

15

2

8

9

1

64

0.6

0.3

Down

0

0

0

0

0

nr

nr

nr

0

Numbers are the percentage of total invertebrates based on morphospecies counts, nr = not reported.

positively to the 3-4% lactose in the discarded whey.
As a consequence, bacterial populations flourished
downstream as a result of the constant supply of their
limiting resource. The bacterial slimes that coated the
downstream rocks used up oxygen, created anoxic
conditions on those surfaces, and accounted for the
absence of high oxygen-demanding insects. Chirono-
mid larvae filter feed on the bacteria and thrive.

Studies by OTS highlighted an important environ-

mental problem in the Monteverde community and

helped redirect the management of the lecheria (see

Chap. 10 on conservation institutions). This research

also revealed that microbial components of fresh-

water ecosystems respond to direct organic carbon en-

richment, which contributes to our understanding of

ecosystem processes in tropical streams.

Table 12.5. Measures of water quality and results of light

bottle—dark bottle measures of primary productivity and

respiration in the Quebrada Guacimal during 5-7 August

1990.

Ammonia (mg/1)

CO 2 (mg/liter)

Chloride (mg/liter)

Dissolved O 2 (mg/liter)

Hardness (Ca^2 and Mg^2 ) (mg/liter)

Nitrite

PH

Temperature (°C)

Discharge (m^3 /s)

Oxygen light-dark bottle experiment

Rock-light

Rock-dark

Water-light

Water-dark

Gross primary production

Net primary production

Respiration

Upstream

0.35

8.0

3.3

9.1

110

0

7.0

14

0.16

9.8

8.3

8.7

8.6

1.5

0.7

0.8

Downstream

0.35

19.6

5.3

7.8

850

0

7.0

14

0.22

1.6

1.8

6.6

6.6

-0.2

-6.2

6.0

447 Conservation Biology