7843

• UCREFRP Catalog Number: 7843
• Author: Stalnaker, C. B., et al.
• Title: The Instream Flow Incremental Methodology, A Primer for IFIM.
• USFW Year: 1995.
• USFW - Doc Type: Biological Report 29,
• Copyright Material: NO

26 BIOLOGICAL REPORT 29

Aggradation

.I~ ~ ~~~r;p

1970

1990

Degradation

.1~9!~ F

1970

1990

Fig. 4.2. Channel aggradation compared with
degradation.

meet chemical criteria and public health criteria;
little has been done to advance the state-of-the-art
in managing healthy and viable biotic communi-
ties within regulated rivers. Nonetheless, tem-
perature and DO can be modeled, and these ap-
proaches are useful in designing flow release
patterns timed to provide optimal conditions for
spawning and growth (Armour 1991, 1993a,
1993b). More must be accomplished in this arena.

Food Energy Source

Thus far, flow-related models for evaluating the
food base in stream systems have been predomi-
nantly restricted to habitat use by benthic
macroinvertebrates in streams inhabited by trout
and salmon. Such models are based on velocity
relations in the substrate material used by aquatic
insects (Gore and Judy 1981; Minshall 1984; Gore
1987), and were recently shown by Jowett (1993)
to account for a significant amount ofthe variation
in brown trout production among 89 trout streams
in New Zealand.

Biotic Interactions

Of the five areas, this one offers most promise
for a research breakthrough in the development of
management tools for application. Species compe-
tition as a consequence of flow management has
thus far taken the form of examining the amount
of usable habitat overlap among trout species (N e-
hring and Miller 1987; Loar and West 1992). Care-
ful examination of simulated historical tempera-
ture and flow patterns for a stream reach can
provide evidence for mechanisms supporting the
observed dominance of one trout species over an-
other in the reach. Unfavorable temperature dur-
ing spawning and incubation, unfavorably high
velocities during fry emergence, or large overlap in

,

preferred space during critical periods may tip the
balance in favor of one species over another. Fur-
ther research is needed for developing habitat
models based on community structure. Habitat
use guilds for fishes have been discussed by
Leonard and Orth (1988) and Bain and Boltz
(1989). There is ongoing research addressing
guilds in southeastern United States coastal and
piedmont warmwater stream systems (Bain and
Boltz 1989; Freeman and Crance 1993).

Stream Habitat as an Integrator of
Man's Influence on Stream Systems

The initial focus of instream flow studies using
IFIM models was on understanding habitat dy-
namics as simulated for recent historical flow con-
ditions in the stream system under study. Analyti-
cal procedures developed by scientists at the
Midcontinent Ecological Research Center (for-
merly the National Ecology Research Center) aid
the river analyst in examining the spatial and
temporal aspects of stream habitat integrity.
These procedures provide information compatible
with three current concepts of stream ecosystems
(Table 4.3): (1) longitudinal succession, starting
with the principles introduced in Chapter III and
expanded into the river continuum concept by Van-
note et al. (1980); (2) habitat segregation and the
importance of habitat patchiness and habitat
boundaries in resource partitioning; and (3) biotic
responses to stochastic processes such as weather
(Wiens 1977; Grossman et al. 1982; Schlosser
1982, 1987). In dynamic stream environments the
interaction of all three ideas into an integrated
analysis of the spatial and temporal aspects of the
environment is necessary to sort out the relative
importance of deterministic and stochastic proc-
esses to the community being studied (Schlosser
1982; Gelwick 1990; Strange et al. 1992).
It is possible to model the linear distribution of
temperature, dissolved oxygen, and important
chemical constituents and to compute the linear
extent of usable macrohabitat, the extent of optimal
microhabitat, or the position of threshold bounds
for limiting variables. Aquatic species distribution
along a river segment continuum can be deter-
mined for many well-known aquatic organisms.
Such analyses require adequate sampling of the
water column along the linear distribution of meso-
habitat types in the river segments of concern.
Within mesohabitat types, measurements of the
distribution of cover, substrate material, and water
depths and velocities, when linked with hydraulic