United States
Environmental Protection
Agency
Environmental Research
Laboratory
Corvallis OR 97333
Research and Development
EPA-600/S3-83-006 Apr. 1983
Project Summary
Habitat Preservation for
Midwest Stream Fishes:
Principles and Guidelines
James R. Karr, Louis A. Toth, and Gayle D. Carman
Natural and man-induced events (e.g.,
changes in land-use and channel modi-
fications) exert major effects on biotic
components of streams and rivers.
Historically, man's efforts to reverse
water resource degradation have em-
phasized physical and chemical attri-
butes of water (water quality) while
ignoring other factors that determine
the quality of a water resource system.
One of the most neglected components
of water resource quality in stream
ecosystems is physical habitat. Indeed,
concern for in-stream/near-stream
physical habitat is as critical to restoring
a fishery as is water quality. Among the
primary man-induced stresses on fish
communities (sedimentation, nutrient
enrichment, navigation, impoundments
and levees, toxic substances, consump-
tion of water, altered hydrological re-
gimes, introduction of exotics), most
have major impacts on physical habitat
conditions. The trend toward declining
fish resources in running water eco-
systems will continue until effective
programs to improve physical habitat
are instituted.
The degradation of running water
resources is at least partly due to a lack
of understanding of the physical and
biological dynamics of stream and river
ecosystems and to the lack of a compre-
hensive, integrated approach to water-
shed management. In the final report
such an approach is outlined, physical
and biological dynamics are reviewed,
and a set of habitat preservation guide-
lines for maintaining ecological integrity
are presented, with emphasis on warm-
water fish communities. Also, present
programs dealing with water resource
problems in agricultural areas are ana-
lyzed and institutional approaches sug-
gested for halting and reversing stream
and river degradation.
This Project Summary was developed
by EPA's Environmental Research
Laboratory, Corvallis. OR. to announce
key findings of the research project that
is fully documented in a separate report
of the same title (see Project Report
ordering information at back).
Introduction
The surface waters of the United States
absorbed effluents as well as other
impacts of a developing society for several
centuries before signs of degradation
(e.g., grossly polluted water and associ-
ated losses of aquatic resources, particu-
larly fish) could no longer be ignored. By
the mid-twentieth century, early legisla-
tive efforts were initiated and water
quality planning addressed the objective
of halting and reversing this trend.
Formerly, however, water quality plan-
ners often lacked the interdisciplinary
perspective to consider the full array of
ecosystem functions and needs. Their
primary target was restoration of the
chemical quality of water; desirable bio-
logical quality, it was assumed, would
follow. In most cases, streams were
viewed only as conduits for the transport
of water. The fundamental biological
nature of aquatic systems and their
complex interrelationships with terrestrial
watersheds frequently went unrecog-
nized. As a result, habitat quality contin-
ued to become degraded, and improve-
ment from effluent control was
minimized.
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A multivariate complex of factors
determines the integrity of a water re-
source system (Figure 1). The attributes
of a running water ecosystem are ulti-
mately determined by characteristics of
the terrestrial environment. The physical
structure of stream channels and their
flow reflect climate as well as topography,
parent material, and land-use in the basin.
These factors interact to produce surface
and groundwater dynamics. The riparian
environment plays a major role in miti-
gating these influences at the land-water
interface. Within the stream itself, five
major sets of variables interact to affect
biotic integrity: water quality, flow regime,
physical habitat, energy source, and btotic
interactions (Figure 2).
Historically, water resource planners
have considered only water quality and,
to a lesser extent, flow regime when
analyzing streams and rivers. But protec-
tion of physical habitat is a prerequisite
for maintenance of biotic integrity, one
that requires knowledge of biological
dynamics as well as the hydrological
conditions that produce specific physical
habitat characteristics. Both biological
and hydrological background are recom-
mended in the final report. Biologists
should no more ignore the hydrological
underpinnings of the stream ecosystem
than should engineers and hydrologists
ignore the ecosystem's biological founda-
tions.
This project summary briefly reviews
the history and background of the problem
and the hydrological and biological foun-
dation of physical habitat in running water
ecosystems. Guidelines and recommen-
dations for preservation of physical habi-
tat characteristics of warm-water streams
and rivers in the Midwest are provided in
the report, which also includes a compre-
hensive review of ecological literature
dealing with relationships between phys-
ical parameters and stream fish commun-
ities.
History and Background
Water Resource Quality
The passage of the Federal Water
Pollution Control Act Amendments of
1972 (PL 92-500) stimulated many efforts
to improve water quality through estab-
lishment and enforcement of criteria and
standards for specific contaminants. The
use of these criteria has been attacked on
numerous grounds. For example, they did
not account for naturally occurring geo-
graphic variation of contaminants (e.g.,
copper, zinc), or consider the synergistic
External
Weather/.
Climate
Terrestrial ^\ _
Environment/
Land Use \
Integrity
of
* Aquatic
Biota
Biological
Integrity of
Aquatic Biota
Figure 2.
Primary variables that affect the
structural and functional inte-
grity of an aquatic biota.
Figure 1. Conceptual model showing the primary variables (and their interactions) external
and internal to the stream that govern the integrity of an aquatic biota.
and antagonistic effects of numerous
contaminants; nor did they consider
sublethal effects (e.g., reproduction,
growth, behavior) of most contaminants.
In addition, monitoring water quality
parameters, such as nutrients, pesticides,
dissolved oxygen, temperature, and heavy
metals may miss short-term events and
long-term patterns critical to assessment
of biotic impacts. Thus, the primary
dependence on a chemical-contaminants
approach is limited in attaining biotic
integrity in running water ecosystems.
An additional disadvantage of a chemical-
contaminants-defined water quality ap-
proach is the fact that several key deter-
minants of biotic integrity are not
evaluated. Chemical monitoring misses
many of the man-induced perturbations
which may impair use. For example,
chemical sampling does not detect flow
alterations or physical habitat degrada-
tion.
With passage of the Clean Water Act of
1977 (PL 95-217) a more comprehensive
societal objective became clear when
pollution was defined as "the man-made
or man-induced alteration of the chemi-
cal, physical, biological, and radiological
integrity of water." Despite this refine-
ment, regulatory agencies have been slow
to replace the classical approach (uniform
standards focusing on contaminant levels)
with a more comprehensive approach.
The holistic perspective of ecosystems
(and the values derived from them) as
integrated systems of land-water-biota-
human needs to be recognized.
Man's Influence on
Stream Habitat
Human population increases, and tech-
nological advances during the last 100
years, have helped speed the degradation
of water resources in the midwestern
United States. Agriculture, urbanization,
industrial development, navigation, hydro-
electric development, and recreation have
also made significant impacts on the
physical attributes of lotic environments.
Impacts of modifications such as dredg-
ing and dam construction are obvious,
while others are more indirect. Urbaniza-
tion, for example, alters watershed hydrol-
ogy which affects stream habitat condi-
tions by disrupting flow dynamics, and
channel equilibrium. The driving forces of
changing technologies, increasing popu-
lation, and variable economic pressures,
especially in the agricultural sector, dis-
rupt stream ecosystems.
The cumulative impacts of human
activities on midwestern stream fishes
since the historical era of settlement have
created a fauna of reduced harvestable
productivity (sport and commercial) and
have decreased species richness. Overall,
the trophic structure of fish communities
has been markedly altered. Species that
have increased in abundance are typically
those which are more tolerant of habitat
degradation and having more generalized
food habits. Because of extensive migra-
tion of fish among river reaches, the
range and magnitude of local impacts on
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fish communities is vastly extended. The
magnitude of the degradation of fish
resources can be seen in the Maumee
and Illinois River watersheds where 44%
and 67%, respectively, of the fish species
known from those watersheds have de-
clined in abundance or disappeared since
1850, mostly as a result of human
activities.
The factors with greatest impact on fish
communities seem to be:
Agriculture - changing land use and
resultant drainage, erosion, sedimen-
tation, and nutrient enrichment.
Navigation- maintenance of navigation
locks and channels, especially in
large rivers.
Impoundments and levees.
Toxics - from urban, industrial, and
agricultural sources.
Consumption of water.
Introduction of exotics.
Most of these (except toxics and exotics)
have major impacts on physical habitat
conditions although habitat has received
relatively little attention. In areas with
agricultural, industrial, and/or urban
perturbations that impact physical habi-
tat, the biotic integrity of the aquatic
ecosystem is degraded and there is little
chance for recovery without efforts to
restore degraded physical habitat. The
degree of recovery possible depends on
the degree of disruption, both local and
regional, and the approach used to re-
verse the dominant trend of the past
century. Without prompt treatment of
physical habitat degradation, fish re-
sources in many rivers will continue to
decline.
Existing Programs and
Stream Habitat
Although stream habitat degradation
results from a number of human activities,
agriculture, because it makes up most of
the watershed area, either directly or
indirectly impacts the largest portion of
midwestern streams. Several ongoing
agricultural programs have been used to
address water resource problems (e.g.,
SCS Conservation Farm Plans, Small
Watershed PL 566 Plans, Rural Clean
Water Program, etc.) but they have been
largely ineffective in restoring stream
habitat.
What is needed is an approach that
embodies environmental protection along
with agricultural production principles
and will, in the long term, serve the
interests of soil and water conservation
as well as for protection of physical habitat
in warm-water streams.
Development of Physical
Characteristics of
Stream Channels
The physical attributes of a natural
stream channel result from a complex of
physical processes mitigated by the biota
of the entire watershed. Biologists and
planners attempting to maintain or re-
create desirable habitat must be aware of
these dynamics or they may waste time
and resources attempting to maintain a
physical habitat incompatible with local
hydrologic conditions.
The end result of these processes is the
evolution of a "dynamic equilibrium"
characterized by a stream channel mor-
phology that efficiently distributes the
energy flux required by the basin's water-
sediment discharge regime. By disrupting
stream equilibrium, land-use modifica-
tions and/or direct alterations of channels
commonly result in marked changes in
the structure and stability of stream
habitats. These effects are further com-
pounded by inter-relationships among
stream habitat components and their
interacting effects on biotic integrity.
Biological Foundations of
Habitat Protection
Fish communities vary along the con-
tinuum from headwater streams to large
rivers. Fish distributions along this
stream-size gradient also vary with time
and/or changing environmental condi-
tions. Fish species in streams and rivers
are associated to various degrees with
distinct habitat types. These habitats form
primarily as a result of natural fluvial
processes and their characteristic phys-
ical and chemical attributes vary consider-
ably with discharge. Like their general
distribution patterns, the type of habitat
in which a stream fish species is found
may change with age, sex, reproductive
state, geographic area, and/or fluctuating
environmental conditions.
Pools, riffles, and raceways are the
primary habitat divisions for fishes in
small to medium-sized streams. In addi-
tion to these main channel habitats, large
river environments have a diverse array
of other habitat types (Figure 3) that are of
critical importance to fishes. Side-channel
and extra-channel habitats, for example,
provide feeding, spawning, nursery, and
overwintering areas for many fish species.
Due to the dynamic nature of stream and
river ecosystems, these main channel
and extra-channel habitats are continu-
ally being created and destroyed by fluvial
processes. However, under natural equi-
librium conditions, a full mosaic of neces-
sary habitats is maintained. All of these
stream attributes must be protected to
preserve high quality fish communities in
warm-water streams. Improvement of
fish communities and thus biotic integrity,
in previously degraded areas requires pro-
grams that will restore missing habitat
features that are essential to high quality
fish communities.
Expected Benefits
A more integrative approach to the
maintenance of physical habitat charac-
teristics in warm-water streams can be
expected to reverse the trend toward
degradation of water resources through:
a. Improved water quality and quantity,
b. Improved fishery systems- and other
aspects of biotic integrity, including
terrestrial wildlife associated with
riparian environments,
c. More effective and efficient processing
of natural and man-induced organic
inputs to running waters,
d. Reduced sedimentation of channels
and reservoirs from land and channel
sources,
e. Decreased cost of channel construc-
tion and maintenance activities,
f. Increased recreational opportunities,
g. More cost-effective attainment of leg-
islative mandates for water resource
systems.
Main Channel
Backwater,
Pond
Bar
Side
'Channel
1 Side
Streams
Figure 3.
Slough
Diagrammatic representation of
major habitats associated with
large river environments.
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James R. Karr, Louis A. Toth, and Gayle D. Garman are with the University of
Illinois, Champaign, IL 61820.
Gerald S. Schuytema is the EPA Project Officer (see below).
The complete report, entitled "Habitat Preservation for Midwest Stream Fishes:
Principles and Guidelines," (Order No. PB 83-167 650; Cost: $14.50, subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Research Laboratory
U.S. Environmental Protection Agency
Corvallis, OR 97333
S. Government Printing Office: 1983-659-017/7028
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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