IMPACT OF SEDIMENT IN AQUATIC ECOSYSTEMS

Authors: Knight, Scott; Cooper, Charles; Shields Jr, Fletcher

Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Proceedings
Publication Acceptance Date: 7/1/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Erosion and the offsite damage of the resulting sediment is a serious national problem. Not only does sediment clog rivers and streams it also effects the ecological health of all bodies of water. Several years of research have examined the bad effects of sediment on aquatic life. This research demonstrates that sediment blocks the sunlight necessary for aquatic life in lakes and ponds and destroys fish habitat in streams. Research at the National Sedimentation Laboratory shows that sediment harms aquatic animals in different ways. Sediments can prevent some animals from eating. Sediments are also often contaminated with such pollutants as pesticides and heavy metals that can harm wildlife. This research provides insight into the question of 'how much sediment is too much?' and provides the information needed to set goals for reducing erosion and sedimentation.

Technical Abstract: Soil erosion and deposition of resulting sediment is a major problem nationally. Poor conservation practices and natural processes have resulted in the deposition of approximately 3 billion tons of sediment per year in U.S. waterways. An estimated 60% of these sediments originated from agricultural lands. Suspended sediments may profoundly impact aquatic ecosystems by reducing or eliminating sunlight that is the primary source of energy in lentic systems. Suspended sediments may interfere with the feeding ecology of aquatic organisms by making prey items more difficult to locate or by directly affecting the feeding structures as in the case of bryozoa. Contaminants such as metals and pesticides are often associated with suspended sediments. Persistent pesticides such as DDT have been recovered from sediment cores from lakes and rivers for more than twenty years following their discontinued use. Stream sediments have been shown to contain significantly higher concentrations of metals such as arsenic than other watershed components. Declines in fisheries, water quality and recreational value of lakes have been documented and attributed to increases in suspended sediments. In addition to and perhaps more importantly than declines in water quality and direct impact on aquatic organisms, sediments alter and destroy both aquatic and terrestrial habitats.