M6 AM Suspended and Bedded Sediments and Nutrients: Exposure-response Relationships
Monday, 14 November 2005: 8:00 AM - 11:40 AM in 324-326

(PAR-1117-751509) Modeling sediment and nutrient stressor interactions with AQUATOX.

Park, R¹, Wellman, M², Carleton, J², Clough, J³, ¹ Eco Modeling, Diamondhead, MS, USA² US Environmental Protection Agency, Washington, DC, USA³ Warren Pinnacle Consulting, Inc., Warren, VT, USA

ABSTRACT- AQUATOX, a mechanistic fate and effects model, simulates the significant physical, chemical, and biological processes affecting aquatic biota. It can model multiple species of periphyton, phytoplankton, macrophytes, invertebrates, and fish as well as nutrients, sediments, and pesticides. The same parameterization has been used to simulate the nutrient-rich, turbid Blue Earth River and the nutrient-poor, clear Crow Wing River, as well as the Rum River, which has intermediate nutrient conditions and low total suspended solids. These rivers span four ecoregions in MN. It has also provided a good fit to data from the nutrient-rich, sporadically turbid Cahaba River in AL with minimal changes in parameters. Model experimentation has shown that reduction in sediments without a corresponding reduction in nutrients results in increased periphytic and phytoplanktonic biomass but also can increase biomass of desirable invertebrates such as mussels. Compositional shifts are predicted for periphyton, phytoplankton, invertebrates, and fish with changes in N, P, and sediment loadings. Sensitivity analysis provides quantitative estimates of optimal levels of nutrients and sediments to sustain a diverse riverine community.

Key words: model, aquatic, ecosystem, river