considered to be aspects of altered habitat. Indirect effects on biota will occur as the fish, 
invertebrates, algae, amphibians, and birds that rely upon aquatic habitat for reproduction, 
feeding, and cover are adversely affected by habitat loss or degradation (Platts et al. 1983, 
Hawkins et al. 1983, Rinne 1988). 
Sea grasses and other SAV are considered “keystone” species in temperate and tropical coastal 
areas. These flora have a variety of beneficial attributes including providing food and shelter for 
many biotic species. There has been a worldwide decline in sea grasses including dramatic 
regional losses in the Gulf of Mexico. The reasons for the decline are unknown but reduction in 
light attenuation (quantity and spectral quality) is thought to be a major factor. The presence of 
suspended sediments is one factor that can impact water clarity; however, its significance to this 
effect and observed sea grass declines is relatively unknown. 
Ultimately, resolution of any problems associated with increases in suspended and bedded 
sediments will need to address the sources of the sediment. These influxes of sediments, in 
general, are associated with increased sediment delivery via soil erosion often caused by changes 
in landuse and landcover, and changes in flow regimes that effect in-channel sediment transport 
and loading. Recognition of the proximal and distal “causes” of suspended and bedded sediment 
problems will affect the classification scheme used and the development of the “expectation” for 
natural sediment loads. 
Goals 
The primary goal for NHEERL’s Suspended and Bedded Sediment program is to provide and 
demonstrate the approach for establishing sediment criteria that support aquatic life use in 
streams/rivers, lakes/reservoirs, wetlands, and estuaries. A necessary first step for achieving this 
goal is to assess the current knowledge and to report on the state of the science of this research 
area. A specific APG and APM for this assessment follows. Additional goals are proposed, but 
will depend on results from both EMAP research and the literature review. 
APG 1 FY02 Synthesize state of the science and remaining uncertainties for developing criteria 
for susp^ded and bedded sediments. 
APM 1A FY02 Report on the state of the science and progress for developing suspended 
and bedded sediment criteria (AED, MED). 
Provide summary of biological response profiles for suspended and bedded sediments in marine 
and freshwater systems. 
Develop models that predict and scale biological responses to suspended solids and sediment 
using assessment endpoints that support management decisions. 
Develop classification schemes to optimize efficiency in developing suspended and bedded 
sediment criteria. 
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