apparatus and hand vacuum pump, and (3) wrapping the filter
in aluminum foil, placing the foil into a pre-labeled
container, and transporting the container to the laboratory
on dry ice. Specific details of the filtration procedure
are discussed in the co llection procedures for microalgae.
Obtaining representative chlorophyll subsamples from samples
of macroalgae can be a challenge, particularly for
filamentous taxa such as Cladophora glomerata. The
recommended sample-processing method used will depend in
part on the capabilities of the analytical laboratory and on
recommendations from the regional biologist. Several
sample-processing methods are suggested below. The
analytical laboratory should be contacted p rior to the
collection of quantitative macroalgal samples for CHL
determinations, particularly if sample-processing methods
(2) or (3) are selected.
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1. Cut algal filaments into smaller lengths with
scissors; add sufficient stream water to constitute a
known volume (for example, 1 L) of algae-water
suspension; pour the suspension into a churn splitter
(Ward and Harr, 1990), and withdraw a subsample vo lume
(for example, 50 mL) for filtration. The specific
subsample volume withdrawn from the churn splitter is
related to the volume of algal biomass in the
algae-water suspension. Sufficient subsample volume
should be withdrawn to ensure that adequate algal
biomass (green or brown color) is retained on the
surface of the glass-fiber filter after the filtration
process. Include the following information on the field
data sheet (fig. 5) and on the sample label (fig. 3):
area of the macroalgal sample, volume of algae-water
suspension, and volume of subsample filtered.
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2. Collect and process a quantitative macroalgal sample
for DM and AFDM. Collect a smaller representative
amount of macroalgal biomass from the same general
stream location; place the biomass into an externally
labeled sample container, and transport the sample to
the laboratory on dry ice. Request that the laboratory
report the CHL concentration in relation to the biomass
of the sample, for example, milligrams of CHL per gram
of DM. Estimate the CHL concentration per unit area by
multiplying the labo ratory datum by the result of the
DM determination.
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3. Collect a quantitative macroalgal sample and submit
the entire sample to the laboratory for CHL analysis.
All samples for CHL analysis must be placed into
containers that prevent exposure to sunlight and must be
shipped to the laboratory on dry ice. Record the area of
the macroalgal sample on the field data sheet and on the
sample label.
Although depositional habitats may support fewer algal
species than erosional habitats, algal species diversity,
biomass, and primary production can be large in epipelic and
epipsammic periphyton microhabitats (Hickman and Round,
1970). Photosynthesis by benthic algae in depositional
habitats can contribute to oxygenation of streambed
sediments (Antoine and Benson-Evans, 1985; Baillie, 1986),
potentially influencing trace-element partitioning between
the sediment and water (Horowitz, 1991). Benthic algal
communities in depositional habitats also are likely to be
exposed to sediment-borne contaminants for extended periods
of time.
DTH's are typically dominated by epipelic or epipsammic
periphyton microhabitats. Although epipelic and epipsammic
microhabitats are relatively easy to sample