Distributional patterns of immature Simuliidae (Diptera) in northwestern North America

• Published in: Freshwater Biology
• Main Authors: CORKUM, LYNDA D., CURRIE, D. C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1987
• Subjects: Aquatic Science; Arctic; Yukon; Hudson Bay; Pacific; Hudson; Dyar; Alaska
• Online Access: http://dx.doi.org/10.1111/j.1365-2427.1987.tb01043.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1365-2427.1987.tb01043.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2427.1987.tb01043.x

SUMMARY. 1. Major landscape features and hydrological parameters indicative of black fly species assemblages were examined at 101 stream sites in Alberta, northern British Columbia, the Yukon and Alaska during the summer. Forty‐one black fly taxa were recorded at seventy‐ nine sites using qualitative sampling procedures. River sites lacking black flies had significantly higher conductivity, greater depth, shallower slope and were farther from the Pacific Ocean than sites with black flies. 2. Classification of sites by taxon occurrence using hierarchical cluster analysis suggested five groupings: A. Simulium tuberosum (Lundstrëm) complex + several taxa. B, S. venustum Saylverecundum Stone and Jamnback complexes + S, tuberosum complex; C. 5. arcticum Malloch complex + S. corbis Twinn complex; D, Gymnopais Stone/ Prosimulium Roubaud; and E. P. onychodactytum Dyar and Shannon complex + several taxa. 3. Multiple discriminant analysis (MDA) was used to predict group membership of the seventy‐nine sites using nineteen environmental variables; 71% of the sites were classified correctly. MDA identified latitude and distance from stream source as important factors separating group D from other groups. Stream width and drainage basins entering the Arctic Oeean and Hudson Bay delineated group B. There was no clear separation among groups A. C or E. The presence of sibling species probably accounts for the overlap of black fly assemblages. 4. Our findings are briefly discussed in the context of stream classification systems, notably the river continuum concept.