SMRF: A MODELING APPROACH FOR SIMULATING METACOMMUNITIES
OF RIVERINE FISHES
&EPA
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INNOVATIVE RESEARCH FOR A SUSTAINABLE FUTURE
Problem
Fish in rivers provide valuable
benefits to people, including
food, recreation, and cultural
value. Fish are also visible
indicators of river health.
Riverine fish can be affected by
changes in habitat and water
quality resulting from land
development and human
activities m the watershed.
Stressors from these activities -
altered flow, temperature,
sediment, nutrients, and other
pollutions - can affect water
quality and habitat conditions for
fish. Understanding how
stressors affect fish is
complicated by interactions
among fish species, as well as
patterns of movement across
river networks.
Environmental managers are
working to best protect and
restore water quality and habitat
in watersheds that provide valued
fish populations. To best target
their activities, managers require
tools to help understand how fish
populations will respond to
management actions.
EPA's Approach
Modeling can be used to assess
the consequences of multiple
stressors to multiple populations
of one or more fish species
across a over network. Modeling
represents important processes in
order to assess scenarios.
The US Environmental
Protection Agency (EPA)
developed a model that simulates
multiple populations of one or
more fish species - a
metacommunity -in response to
multiple stressors across a river
network. The model is called
SMRF (Simulating
Metacommunities of Riverine
Fishes) It is spatially-explicit
and age-structured, with three
components: habitat suitability;
population dynamics, including
species interactions; and
movement across a spatial
network.
SMRF is designed to assist the
Agency's ability to ensure that
the nation's waters are fishable
and to assess whether water
quality standards are protective
of aquatic life. SMRF can also
support economic assessment of
the benefits of regulations. The
model was designed for use by
communities, land managers,
policy makers, scientists and
engineers.
SMRF can be downloaded from
https://cfpub.epa.gov/ncea/risk/
recordisplav.cfm?deid=346971
Model Structure
The SMRF model is typically set
up to run across a network of
connected river reaches. Fish
populations are simulated within
and among river reaches that can
vary in suitability.
Fish species in the model can be
input using PiSCES. an EPA tool
that estimates fish at unsampled
sites. Data collected through
EPA's National Aquatic
Resource Surveys can be used to
calibrate the model. SMRF
simulates survival and
reproduction of multiple age
classes, where survival is
affected by habitat, water quality,
competition, and predation.
River reaches support fish communities
in the SMRF model
1
U.S. Environmental Protection Agency
Office of Research and Development

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SMRF model input includes
measures of water quality and
habitat, which may change
through time. SMRF"s outputs
include relative numbers of
different species of fish within
watersheds, with the expectation
that abundances will capture
order-of-magnitude differences
among species and general
patterns of distribution
(presence/absence).
Example Applications
SMRF provides useful insights
into the net effects on fish
communities of stream network
habitat conditions (water
temperature, channel slope,
stream size), spatial
configuration (proximity of
seasonal habitats), and fish
species characteristics (fecundity,
survival, competition). Some
example applications are to:
•	Compare the effects of
watershed and water quality
management scenarios on
fish communities.
•	Communicate to landowners
how activities on their
property are connected to
fish in the larger context.
Learn More
EPA's research on Ecosystem
Services
PiSCES -
https://cfpub.epa.gov/si/si pub
lie record report.cfm?Lab=N
ERL&dirEntrvId=297970
National Aquatic Resource
Survey shttps://www.epa.gov/n
ati onal -aquati c-resource-
survevs
Integrated Environmental
Modeling -
https://www.epa.gov/measure
ments-modeling/integrated-
environmental-modeling-
general-information-and-
guidance
Figure of an example stream
network (Calapooia River, Oregon)
illustrating the distribution and
relative density of juvenile steelhead
trout (Oncorhynchus mvkiss) as
predicted by a SMRF model. Darker
colors indicate stream sections with
higher trout densities.
Integrated Modeling
Support assessment of
potential outcomes for biotic
integrity based on watershed
and water quality
improvements, habitat losses,
or other changes.
CONTACT:
Brenda Rashleigh,
Office of Research and
Development,
401-782-3014
SMRF can be incorporated into
an integrated modeling system
for watershed management and
prediction. Watershed models
can provide flow, temperature,
nutrients, and other habitat
varables to SMRF, which can
provide fish species abundance,
distribution, and diversity to
economic models.
Economic Valuation
•	Identify critical knowledge
gaps or refine assumptions
where data are currently
lacking.
•	Evaluate the expected
benefits to fish of spatially-
explicit habitat actions, such
as target areas for restoration,
which may be particularly
useful for foundations,
granting agencies, and tribes.
•	Provide input for valuation.
rashleigh .brenda@epa.gov
httos: //www. epa. gov/research
March, 2020
EPA/665/F-200/01
2
U.S. Environmental Protection Agency
Office of Research and Development

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