United States
              Environmental Protection
              Aaencv
Office of Water
(4305)
EPA-823-F-00-015
September 2000
              Fact Sheet
             AQUATOX RELEASE  1: A SIMULATION MODEL FOR
             AQUATIC ECOSYSTEMS
The U.S. Environmental Protection Agency announces the release of the freshwater ecosystem simulation
model AQUATOX.  AQUATOX predicts the fate of various pollutants, such as nutrients and organic
toxicants, and their effects on the ecosystem, including fish, invertebrates, and aquatic plants. AQUATOX
is a valuable tool for ecologists, biologists, water quality modelers, and anyone involved in performing
ecological risk assessments for aquatic ecosystems.
BACKGROUND
A primary goal of the Clean Water Act is "to restore
and maintain the chemical, physical and biological
integrity of the Nation's waters". One of the biggest
challenges   is  to   adequately  understand   the
interrelationships between the chemical and physical
environment and the aquatic life. In particular, water
quality analysts need tools to  predict the effects of
chemical pollutants and other stressors on aquatic
ecosystems.

AQUATOX  is a PC-based ecosystem  model that
simulates the transfer of biomass and chemicals from
one compartment of the ecosystem to another. It does
this by simultaneously computing important chemical
and biological processes over time. AQUATOX can predict not only the fate of chemicals in aquatic
ecosystems, but also their direct and indirect effects on the resident organisms. Therefore it has the potential
to help establish  the cause and effect relationships  between chemical water quality, the physical
environment,  and aquatic life.
WHA TAOUA TOX DOES
AQUA TOX simulates the behavior of numerous inter-related
components
   multiple algal species and submerged aquatic vegetation
•   benthic invertebrates, zooplankton and fish
•   nutrients and dissolved oxygen
•   sediments
•   toxic organic chemicals
           SYSTEM REQUIREMENTS
           Pentium PC, 16 MB RAM, 30 MB free
           disk space, Windows 95, 98, NT

           ACKNOWLEDGMENTS
           AQUATOX was developed by Richard
           A. Park and Jonathan S. Clough of
           Eco Modeling with EPA funding.

-------
 AQUA TOX can represent a variety of aquatic
 ecosystems
 •   vertically stratified lakes, reservoirs and ponds
     rivers and streams

 AQUA TOX simulates the fate and effects of
 multiple environmental stressors
 •    nutrients
 •    organic toxicants
     temperature and turbidity
 •    changing depths and flow regimes

 AQUA TOX simulates and integrates significant
 ecological processes
 Biological effects
 •    food consumption
 •    growth and reproduction
 •    natural mortality
 •    acute and chronic toxicity
 •    trophic interactions
                                                          AQUATOX MODEL STRUCTURE
                                      Outflow,
             . ''Inorganic Sediment'* ^
             -^ (streamsonlv)
Environmental fate
    nutrient cycling and oxygen dynamics
•   toxic organic chemical transformations
•   partitioning to water, biota and sediments
•   bioaccumulation through gills and diet
 POTENTIAL APPLICA TIONS FOR AQUA TOX
 AQUATOX has a myriad of potential applications to water management issues and programs, including
 water quality criteria and standards, TMDLs (Total Maximum Daily Loads), and ecological risk assessment.
 AQUATOX should be considered when the user needs to understand the processes relating the chemical
 and physical environment to the biological community. AQUATOX can be used to predict ecological
 responses to proposed management alternatives. It may also help to determine the most important of several
 environmental stressors, e.g. where there are both nutrients and toxic pollutants.

 Application to nutrient and eutropkication analysis
 •   Eutrophication endpoints: dissolved oxygen, chlorophyll, nitrogen, phosphorus, Secchi depth
 •   Suitable for stratified lakes and reservoirs,  ponds,
    streams and small rivers
Application to aquatic life uses
•   Direct and indirect effects throughout food web
*   Causes of biological impairment

Application to organic toxicants and bioaccumulation
    Partitioning to water, sediments and biota
•   Bioaccumulation factors
*   Direct and indirect effects of toxicants

A QUA TOX FEA TURES
•   User friendly design
    Automated uncertainty analysis
•   Constant or variable environmental loading
    How to obtain AQUA TOX
    The model, users guide, technical documentation and validation
    reports are available at www.epa.gov/ost/models/agualox.
    They will be available this tall on CD and in print from NSCEP
    (800-490-9198 or www.epa.aov/iicepihom.).
    Be siiru to include the document numbers, as follows:
    EPA-X23-C-00-001: AQUATOX: A Modular Fate & Effects
           Model for Aquatic Ecosystems-CD-ROM (model &
           supporting documents)
    EPA-N23-R-00-006: Volume 1: User's Manual
    EPA-X23-R-00-007: Volume 2: Technical Documentation
    EPA-X23-R-00-008: Volume 3: Model Validation Reports

    For additional information, contact Marjorie Coombs Wellman,
    Office  of Science  and  Technology, U.S.   EPA,  1200
    Pennsylvania Ave., NW (4305), Washington,  DC, 20460
    (telephone:   202-260-9821,  or  email:
    wcllimin.mariorie'«!epa.gov)

-------