5. Approaches toward modeling the effects of suspended solids and sediments on aquatic 
ecosystems. 
6. Progress to date in developing state. National, and international suspended and bedded 
sediment criteria. 
Products 
APG 1 FY02 Synthesize state of the science and remaining uncertainties for developing criteria 
for suspended and bedded sediments. 
APM 1A FY02 Report on the state of the science and progress for developing suspended 
and bedded sediment criteria (AED, MED). 
Benefits of Products 
An up-to-date summary of the state of the science review of suspended and bedded sediments 
information will be provided with recommendations of needed research to develop and validate 
suspended and bedded sediment criteria for OW. 
Proposed Research Projects 
Based on results from EMAP research and the literature review, the following general projects 
are proposed assuming resources are available: 
Stressor-Response Relationships 
Associations between biotic assemblages and/or key aquatic species or guilds and deviations of 
sediment from expected values should be examined. In most cases, our data sets will include 
sites affected by multiple stressors besides sediment that could potentially act upon these aquatic 
biota. After demonstration of a plausible causal mechanism (from detailed experimental studies) 
and elimination of other plausible explanations for these observations, we will use these kinds of 
associational data in a weight-of-evidence approach to support modeling the effects of suspended 
and bedded sediments on aquatic biota. 
Thresholds for Sediment Effects 
The technical information on stressor/response relationships can be used to generate thresholds 
for sediment effects. These thresholds can be used in the development of criteria for suspended 
and bedded sediments, and thresholds can serve as input to both the development of criteria and 
to the TMDL process. They will consider the effects of suspended and bedded sediments in a 
more holistic manner than the standard criteria do, taking into account effects on both benthic 
and water column organisms, and direct as well as indirect effects on aquatic life use. 
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