AQUATOX
AQUATOX is an aquatic simulation model that was developed for EPA by Richard A. Park and Jonathan S. Clough of EcoModeling. AQUATOX simulates the transfer of biomass, energy and chemicals from one compartment of the ecosystem to another. It does this by simultaneously computing each of the most important chemical or biological processes for each day of the simulation period; therefore it is known as a process-based or mechanistic model. AQUATOX can predict not only the environmental fate of chemicals in aquatic ecosystems, but also their direct and indirect effects on the resident organisms, such as fish, invertebrates, and aquatic plants. It has the potential to establish causal links between chemical water quality and biological response and aquatic life uses. AQUATOX differs from most water quality models in several ways. Most models include few if any biological components, whereas AQUATOX is an ecosystem model. It includes not only numerous types of plants, invertebrates and fish, it also treats the biota as interacting with the chemical/physical system. As mentioned above, AQUATOX is a process-based model, as opposed to an empirical model, which are often based on statistical relationships. Empirical models may establish that correlations between variables exist, but do not explain why, or explain the mechanisms of the relationship.
Ecological components, or state variables, simulated by AQUATOX:
- phytoplankton
- periphyton and submerged aquatic vegetation
- planktonic and benthic invertebrates
- forage, game and bottom fish
- nutrients and dissolved oxygen
- organic sediments
- toxic organic chemicals
AQUATOX has proven to be a valuable tool for performing ecological risk assessments for aquatic ecosystems. At ERD, it has been used to assess the effects of nonpoint source pollution, including nutrients, sediments, and temperature, on stream ecosystems of the North Carolina coastal plain.
More detailed information about the AQUATOX model is available here.
For additional modeling information, please go to the EPA's Council on Regulatory Environmental Modeling (CREM) site. CREM promotes consistency and consensus within the Agency on mathematical modeling issues including model guidance, development, and application, and enhances both internal and external communications on modeling activities. The CREM is the Agency's central point to address modeling issues.
For information on models distributed by EPA's Center for Exposure Assessment Modeling (CEAM), please go to http://www.epa.gov/ceampubl/.