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Exercise 20
clean I-liter bottles in an ice chest and transport to the laboratory as rapidly as possible. Take
the water temperatures at meter intervals throughout the water column.
2. Determine the relative heterotrophic bacterial assimilation and mineralization rates of an
organic substrate such as glucose or acetate by the procedures outlined. Incubate the samples
as close to the in situ temperatures as possible.
3. Calculate the assimilation and mineralization parameters as outlined earlier. Compare
observed differences in the heterotrophic activity against depth.
4. Answer the questions following Option 6.
OPTION 2. SPATIAL DIFFERENCES IN ACTIVITY
1. Collect water samples from a depth of 2 m from the central area of a lake or reservoir, from the
littoral zone among emergent macrophytes near the sediments, and from the mouth of an inlet
stream. Place the samples into clean I-liter bottles in an ice chest and transport to the
laboratory as quickly as possible, after taking the water temperatures at the points of
collection.
2. Determine the relative bacterial assimilation and mineralization rates of an organic substrate
(e.g., glucose or acetate) by the procedures outlined. Incubate the samples as close as possible
to in situ temperatures.
3. Calculate the assimilation-mineralization parameters as outlined. Compare the spatial
differences in heterotrophic activity.
4. Answer the questions following Option 6.
OPTION 3. COMPARATIVE UTILIZATION OF SUBSTRATES
1. Collect a water sample of several liters from a depth of ca. 2 m from the central portion of a
lake or reservoir. Measure the water temperature at the point of collection.
2. Determine the relative bacterial assimilation and mineralization rates of several organic
substrates (e.g., glucose, acetate, or an amino acid) by the procedures outlined. Incubate the
samples at the temperature as close to in situ as possible.
3. Calculate the assimilation-mineralization rates of each substrate and compare the differences.
4. Answer the questions following Option 6.
OPTION 4. RELATIVE HETEROTROPHIC ACTIVITY IN WATERS
OF DIFFERING PRODUCTIVITY
1. Divide the class into teams and collect water samples from ca. 2 m or the epi- and hypolimnion
of an oligotrophic lake and from a eutrophic lake, reservoir, or pond. Place the samples into
clean I-liter bottles in an ice chest and transport to the laboratory as rapidly as possible.
Determine the water temperatures at the points of collection.
2. Determine the relative assimilation-mineralization rates of an organic substrate (e.g., glucose
or acetate) by the procedures outlined. Incubate the samples at in situ temperatures.
3. Calculate the rates of substrate utilization and mineralization as outlined and compare the
results for the lakes of differing productivity.
4. Answer the questions following Option 6.
OPTION 5. COMPARISON OF ACTIVITY OF WATER VERSUS SEDIMENTS
1. Collect water samples from the epi-, meta-, and hypolimnion at a central station of a lake or
reservoir. In addition, collect a sample of surface sediments with an Ekman grab or coring
Exercise 20
clean I-liter bottles in an ice chest and transport to the laboratory as rapidly as possible. Take
the water temperatures at meter intervals throughout the water column.
2. Determine the relative heterotrophic bacterial assimilation and mineralization rates of an
organic substrate such as glucose or acetate by the procedures outlined. Incubate the samples
as close to the in situ temperatures as possible.
3. Calculate the assimilation and mineralization parameters as outlined earlier. Compare
observed differences in the heterotrophic activity against depth.
4. Answer the questions following Option 6.
OPTION 2. SPATIAL DIFFERENCES IN ACTIVITY
1. Collect water samples from a depth of 2 m from the central area of a lake or reservoir, from the
littoral zone among emergent macrophytes near the sediments, and from the mouth of an inlet
stream. Place the samples into clean I-liter bottles in an ice chest and transport to the
laboratory as quickly as possible, after taking the water temperatures at the points of
collection.
2. Determine the relative bacterial assimilation and mineralization rates of an organic substrate
(e.g., glucose or acetate) by the procedures outlined. Incubate the samples as close as possible
to in situ temperatures.
3. Calculate the assimilation-mineralization parameters as outlined. Compare the spatial
differences in heterotrophic activity.
4. Answer the questions following Option 6.
OPTION 3. COMPARATIVE UTILIZATION OF SUBSTRATES
1. Collect a water sample of several liters from a depth of ca. 2 m from the central portion of a
lake or reservoir. Measure the water temperature at the point of collection.
2. Determine the relative bacterial assimilation and mineralization rates of several organic
substrates (e.g., glucose, acetate, or an amino acid) by the procedures outlined. Incubate the
samples at the temperature as close to in situ as possible.
3. Calculate the assimilation-mineralization rates of each substrate and compare the differences.
4. Answer the questions following Option 6.
OPTION 4. RELATIVE HETEROTROPHIC ACTIVITY IN WATERS
OF DIFFERING PRODUCTIVITY
1. Divide the class into teams and collect water samples from ca. 2 m or the epi- and hypolimnion
of an oligotrophic lake and from a eutrophic lake, reservoir, or pond. Place the samples into
clean I-liter bottles in an ice chest and transport to the laboratory as rapidly as possible.
Determine the water temperatures at the points of collection.
2. Determine the relative assimilation-mineralization rates of an organic substrate (e.g., glucose
or acetate) by the procedures outlined. Incubate the samples at in situ temperatures.
3. Calculate the rates of substrate utilization and mineralization as outlined and compare the
results for the lakes of differing productivity.
4. Answer the questions following Option 6.
OPTION 5. COMPARISON OF ACTIVITY OF WATER VERSUS SEDIMENTS
1. Collect water samples from the epi-, meta-, and hypolimnion at a central station of a lake or
reservoir. In addition, collect a sample of surface sediments with an Ekman grab or coring