Stonefly life histories were studied March, 1987 through May, 1990 in the Rio Conejos, Colorado. Adult presence phenology and intensity were monitored daily in the summers of 1988 and 1989 and were coupled with monthly benthic samples to assess nymphal growth. Eggs of several species were reared. Thirty-one species were collected, with several multi-species assemblages occurring in Capnia, Utacapnia, Taenionema, Suwallia, Triznaka, Isogenoides and Isoperla. Sufficient data were obtained to reveal partial or complete life histories of 13 species, five of which have not been previously reported. New information included the 9- to 10-mo egg diapause and semivoltine life histories of Isogenoides zionensis Hanson, Pteronarcella badia (Hagen) and Pteronarcys californica Newport. Additionally, Isoperla phalerata (Smith) had univoltine-slow growth, and L quinquepunctata (Banks) was univoltine-fast. Previously unstudied emergence periods are presented for Triznaka signata (Banks), Suwallia wardi Kondratieff and Kirchner and S. pallidula (Banks). The later two species temporally segregated emergence in both years. Isoperla fulva Claassen emerged in June, and was temporally segregated from its congeners. Regression analysis of cumulative percentage catch revealed two adult presence patterns. Eight species had slopes <7%/d (extended pattern), and only two, I. zionensis and P. cal'fornica, had slopes >7 %/d (synchronous pattern). Several stoneflies were more abundant in Massey Creek, a tributary of the Rio Conejos. The emergence and diversity of mayflies, stoneflies and caddisflies was studied there. During May-August, 1989, 46 species were collected using sweepnetting and emergence traps. Chloroperlid stoneflies were abundant, with Suwallia nr. lineosa (Banks) contributing 37% of the total catch. Slopes of adult presence ranged from 1.7 %/d for Epeorus alberta (McDunnough) to 6.2%/d for Rhyacophila pellissa Ross. Separation of patterns was more difficult here, but < 4%/d was used as a criterion for extended emergers. A cluster analysis of 17 species produced three clusters that corresponded to stream temperature as a cue for emergence.
| Identifer | oai:union.ndltd.org:unt.edu/info:ark/67531/metadc798169 |
| Date | 05 1900 |
| Creators | DeWalt, Ralph Edward |
| Publisher | University of North Texas |
| Source Sets | University of North Texas |
| Language | English |
| Detected Language | English |
| Type | Thesis or Dissertation |
| Format | viii, 152 leaves : ill., Text |
| Coverage | United States - Colorado |
| Rights | Public, DeWalt, Ralph Edward, Copyright, Copyright is held by the author, unless otherwise noted. All rights |
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