8201

• UCREFRP Catalog Number: 8201
• Author: Carter, J. and V. Lamarra.
• Title: An ecosystem approach to environmental management.
• USFW Year: 1983.
• USFW - Doc Type: 261-287
• Copyright Material: YES

ch as
light
also
abitat
ion of
sively
alized
r pool
ystems
y, are
urface
). It
ulence
thus
Ie of
1S and
1 the

velocity are important factors. It has been noted that
the faster the current, the more the loosely attached
species will be washed downstream. Velocities greater
than about 5 mlsec erode all but the most tenacious
periphyton. Depth is important as it interacts with
turbidity and available light to limit photosynthetically
active light at the stream bottom (Whitton, 1975). Some
benthic algae are very tolerant of shade. Whitton (1972)
found that a quarter of the species taken from the River
Wear, England, and incubated in the dark for two months,
were able to grow when given favorable conditions. On the
other hand, Whitton (1973) has shown some species to be
tolerant only of high light conditions. The shallow,
lower velocity, high light areas in the White River are
always higher in chlorophyll a than the deeper, faster
areas (Figure 10).

of
in
has
. . An
data
C\I
on ~
'-
Cl
~
~s . tal
!posi t
. .

the
on on
is a
lirect
'na11y
pool.
t may
off,
y as

t be
n the
and

TRANSECT 18

o

o

Figure 10. The temporal change in periphyton
biomass at a pool and a riffle transect in the
White River at Southam Canyon.

In preliminary experiments, oil shale leachate has
been experimentally introduced into p/R chambers in situ.
Low-level leachate additions either depressed or
stimulated the community responses depending upon the

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