Study of flow effects on aquatic insect populations at a beaver dam.

Abstract

This is a study conducted on both sides of a beaver dam. The three sites include: site 1, above the dam, 0 cm/sec flow, 100 cm depth, and a silt bottom; site 2, below the dam, 8.5 cm/sec, cobble; site 3, below the dam, 4.0 cm/sec, sand. Site 2 was 22 cm, site 3 was 46 cm deep. The study looked for significant changes of insect populations due to flow. These include: total number of insects, species richness, and percentages of trophic relationship groups. Significant change occurred with increased flow and increased number of insects. Also the occurrence of no (or unmeasureable) flow, halved the species richness of the stream. When insects were grouped into trophic relationships, and the flow was changed, no signficant increase or decreases could be found.