The Effects of Stream Order, Season, and Drainage On the Abundance of Two Caddisfly Families

Abstract

Rivers are constantly flowing and vary in different locations. Therefore, one area of a river or stream may differ from another in abundance of organisms. However, streams remain connected, as changes upstream may affect areas downstream. We hypothesized that stream order, season, and drainage would affect the abundance of two caddisfly families (Leptoceridae and Hydroptilidae). Species within each of these families have been identified as species of conservation concern by the Oklahoma Department of Wildlife and Conservation. We collected adult caddisflies in the Kiamichi River, Little River, and Spring Creek drainages using manned and unmanned light traps. Samples were collected during both spring and summer months. For both families, we found no difference in abundance between seasons or among drainages. We found that the abundance of leptocerids was significantly higher in third order streams than first or second order streams. However, stream order did not have a significant effect on hydroptilid abundance. We conclude that stream order affects the abundance of Leptoceridae in eastern Oklahoma streams. This information can be used to optimize sampling effort to detect species of conservation concern in this family of caddisflies.