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LOGISTICS
Exercise 24
This exercise is designed to be done over a 24-h period, starting at midnight
(alternatively, sunrise or sunset). Students may choose to remain at the study site for the
entire 24 h or alternate on 4-h shifts. Establishing a field camp with tents facilitates the
collections and analysis of samples. If the class were large enough, several camps could
be set up at various locations along the stream to facilitate the study of spatial
variation. Since this exericse is designed to be an enjoyable outdoor experience as well
as a learning experience, it is important for each student to have adequate clothing,
boots, rain gear, and shelter.
SAMPLE AREAS
Select study areas along the stream that are relatively homogeneous, physically and
biologically. To accentuate response to environmental variables, it would be desirable
to select an open segment of stream after it flows out of or into a forested area.
Preferably, a biologically rich stream should be studied. It is advisable to avoid areas
immediately below waterfalls or very swift rapids, as high Oz-diffusion rates or
entrained air bubbles may interfere with some chemical analyses. When possible, select
study sites that are about I-h apart as determined by the flow rate of the stream (see
Exercise 5). These sites will be used for studies of changes in heat storage, nutrient flux,
and ecosystem metabolism.
GENERAL SAMPLING SCHEDULE
Measurements of solar radiation, temperature (water and air), dissolved oxygen, pH,
dissolved inorganic phosphorus, nitrate, total alkalinity, dissolved organic carbon,
particulate organic carbon, and flow should be made at 2400, 0300, 0600, 0900, 1200,
1500, 1800,2100, and 2400 h. Water samples should be taken from well-mixed parts of
the stream where stratification is minimal. Intially, samples should be obtained at
several locations across the stream channel and at different depths to delineate any
spatial patterns.
During this exercise it will become apparent how arbitrary field measurements can
be (especially at night!) unless they are done carefully and with replication. Make
measurements as precisely as possible and keep notes about any variation in procedure
or unusual circumstances. You will be attempting to integrate and evaluate, with a few
careful measurements, many of the complex interactions occurring within the entire
ecosystem.
If possible divide the laboratory into groups of students, each group having
responsibilities as listed below.
LOGISTICS
Exercise 24
This exercise is designed to be done over a 24-h period, starting at midnight
(alternatively, sunrise or sunset). Students may choose to remain at the study site for the
entire 24 h or alternate on 4-h shifts. Establishing a field camp with tents facilitates the
collections and analysis of samples. If the class were large enough, several camps could
be set up at various locations along the stream to facilitate the study of spatial
variation. Since this exericse is designed to be an enjoyable outdoor experience as well
as a learning experience, it is important for each student to have adequate clothing,
boots, rain gear, and shelter.
SAMPLE AREAS
Select study areas along the stream that are relatively homogeneous, physically and
biologically. To accentuate response to environmental variables, it would be desirable
to select an open segment of stream after it flows out of or into a forested area.
Preferably, a biologically rich stream should be studied. It is advisable to avoid areas
immediately below waterfalls or very swift rapids, as high Oz-diffusion rates or
entrained air bubbles may interfere with some chemical analyses. When possible, select
study sites that are about I-h apart as determined by the flow rate of the stream (see
Exercise 5). These sites will be used for studies of changes in heat storage, nutrient flux,
and ecosystem metabolism.
GENERAL SAMPLING SCHEDULE
Measurements of solar radiation, temperature (water and air), dissolved oxygen, pH,
dissolved inorganic phosphorus, nitrate, total alkalinity, dissolved organic carbon,
particulate organic carbon, and flow should be made at 2400, 0300, 0600, 0900, 1200,
1500, 1800,2100, and 2400 h. Water samples should be taken from well-mixed parts of
the stream where stratification is minimal. Intially, samples should be obtained at
several locations across the stream channel and at different depths to delineate any
spatial patterns.
During this exercise it will become apparent how arbitrary field measurements can
be (especially at night!) unless they are done carefully and with replication. Make
measurements as precisely as possible and keep notes about any variation in procedure
or unusual circumstances. You will be attempting to integrate and evaluate, with a few
careful measurements, many of the complex interactions occurring within the entire
ecosystem.
If possible divide the laboratory into groups of students, each group having
responsibilities as listed below.