Northern Prairie Wildlife Research Center
The impact of suspended sediment and sedimentation on fish and aquatic life has been investigated in riverine systems (Newcombe and MacDonald 1991; Waters 1995), but few studies have adressed impacts of sedimentation in wetland ecosystems. Sedimentation impacts include increased turbidity that reduces the depth of the photic zone and increases sediment fallout which may cover primary producers and invertebrates. Excessive sediment input thus potentially alters aquatic food webs as well as basic wetland functions related to water quality improvement, nutrient cycling, and other biogenic processes that transform and sequester pollutants. Moreover, erosional sediment can fill wetlands either as a single catastrophic event or gradually; basins totally filled with sediment provide no natural wetland functions of benefit to society.
The primary source of sediments in prairie wetlands is wind and water erosion from agricultural fields (Gleason 1996). Agricultural research is replete with information on soil erosion and the detrimental effects of soil loss on agricultural production (e.g., Wischmeier and Smith 1978; Bills and Heimlich 1984; Lane and Nearing 1989; Moldenhauer and Black 1994). Agricultural research also has been instrumental in developing and implementing conservation practices on private lands that reduce soil erosion, maintain productivity of croplands, and improve soil and water quality (Cook 1988; Moldenhauer and Black 1994). However, the benefits of such consequences of implementing those conservation practices on most wetland functions have not been evaluated. Future research needs to examine the impact of sedimentation from an interdisciplinary platform. Integration of agricultural and wetland interests and expertise is critical to development of such research programs (Gleason and Euliss 1997).
This manuscript is a review of sedimentation in PPR wetlands. Its purpose is to (1) present an overview of sedimentation and identify potential impacts on wetland functions, (2) identify management strategies that reduce sediment inputs, and (3) highlight research needs of prairie wetlands relative to soil conservation issues.