AQUATOX Release An Aquatic Ecosystem Model and Its Potential Applications

							AQUATOX Release 2: An Aquatic Ecosystem Model and Its Potential Applications

Author: Marjorie Coombs Wellman

Key Words: AQUATOX, model, water quality, ecosystem, eutrophication, bioaccumulation,
           ecotoxicology

AQUATOX is a process-based, time-varying, fate and effects simulation model that integrates
aquatic ecology, chemical dynamics, bioaccumulation, and ecotoxicology.
     AQUATOX can predict not only the environmental fate of nutrients, pesticides, and other
chemicals in aquatic ecosystems, but also their direct and indirect effects on the organisms. The
model can represent ponds, stratified and unstratified lakes and reservoirs, and streams and rivers
(including compartments for periphyton, moss, macrophytes, aquatic insects and mollusks, and
size or age classes of fish). Also, an estuarine version is being tested for later release.
     AQUATOX was first released by EPA in 2000, and Release 2 will be available in the spring
of 2003. The model has undergone outside peer review, and it has been favorably reviewed in
the open literature. Release 2 has many new features that facilitate its use: a Wizard with
context-sensitive help to lead users through model setup; capability for modeling multiple
stressors including nutrients, suspended sediments, temperature, discharge, and up to 20
chemicals simultaneously; and linkage to the BASINS GIS and modeling system.
     This poster will present an overview of Release 2 and provide examples of potential
applications, answering questions that water resource managers and ecological risk assessors
might ask. For example:

   •   How much reduction in nutrients is required to relieve or prevent excessive algae growth
       at a site? How much reduction in toxic pollutants is required to prevent biological
       impairment? Will desirable species of fish and other organisms reappear and replace
       pollutant tolerant species?
   •   What are the effects of land use, agricultural practices, industrial and stormwater
       discharges, or climate change on aquatic ecosystems? Where changes in land use are
       anticipated, how will the aquatic biota respond?
   •   Where there are multiple environmental stressors on a waterbody, which is the most
       important one to address first?
   •   Where there are organic pollutants, such as PCBs, that bioaccumulate in fish, how much
       remediation is necessary to reach safe levels in fish, and how long will recovery take?

Contact Information:      Marjorie Coombs Wellman
                          Environmental Protection Specialist
                          Office of Water/Office of Science & Technology
                          202-566-0407
                          wellman.marjorie@epa.gov