Patterns in Water Quality and Fish Assemblages in Three Central Indiana Streams with Emphasis on Animal Feed Lot Operations
Concentration of animals on land causes direct and indirect effects on aquatic systems. Perhaps the most obvious impact is toxicity caused by increased runoff of animal waste into streams, especially ammonia and nitrite. These increases in ammonia and nitrite may be enhanced by changes in pH. These episodic events may cause degradation of water quality to the extent that fish kills are observed. However, such events are difficult to predict and may be due to a variety of causes including poor disposal practices, storm events, and differential densities of animal populations. Differences may also be attributed to the types of animals; however, this has not been well documented (Morris et al., Chapter 6, this volume). In addition, the land use associated with concentrations of animals typically results in channelization of streams and loss of riparian habitat. The increase of soil loss from animal movements and the sloughing of banks cause significant amounts of erodible soil movement through stream channels. This may often be a result of the need for access for animals but equally more likely is the encroachment of tillable acres.