Limnological characteristics of, and ecology and diversity of Chironomidae (Insecta: Diptera) from, high alpine lakes of the Sangre de Cristo Range, Colorado, USA.

Adult Chironomidae (Diptera) from 12 alpine lakes (>3200 m elevation) in the Great Sand Dunes National Park and Preserve (GRSA) and Sangre de Cristo Wilderness of Colorado, USA, were sampled multiple times from 1983 to 1994. Male adult chironomids were dissected and identified to the species level. The primary objective of this study was to make initial species-level contributions to the biodiversity, ecology, and distribution of Chironomidae occurring in 12 alpine lakes of south-central Colorado. Water temperature and specific conductivity were measured in the field, and water samples were collected and analyzed for ammonium, nitrate, pH, acid neutralizing capacity, major anions (sulfate and chloride), and major cations (calcium, magnesium, sodium, and potassium). A total of 42 species were recorded from the 12 lakes, with 19 being "new" undescribed species. The most widespread chironomid was Tanytarsus bathophilus, var. occurring in 7 of the 12 lakes. For each species, we included its known distribution from northern United States (including Alaska), Canada, Greenland, and northern Eurasia. West-North Colony Lake, also known as Bench Lake, had the greatest species diversity with 20 species and was selected for intensive limnological and environmental study. Of the 12 lakes, 11 appear to be nitrogen saturated. Hierarchical cluster analysis indicated that lakes formed groups linked primarily by species richness and gradients in elevation and nutrients. Multiple regression results showed that nitrate, surface water temperature, and sodium were strong predictors of variation in chironomid total species richness. Neither lake surface area nor elevation were strong or significant predictors of richness. We discuss how increased anthropogenic global warming, climatic variability, and associated stressors may affect chironomid assemblages in the future for our 12 alpine lakes. [ABSTRACT FROM AUTHOR]