Distribution and Environmental Determinants of Chironomids (Diptera, Chironomidae) in Sphagnum Microhabitats

Our study investigates the role of Sphagnum mosses as habitat for chironomid larvae with regard to peatbog type (raised bog, transitional bog, fen). Samples were collected within Roztocze National Park (eastern Poland) from May to October 2012 with two monthly intervals. Studied peatbog types differ significantly in terms of density and domination structure of Sphagnum-associated chironomids. The results of CCA analysis indicated that pH, N-NO3, and chlorophyll-a are significant for chironomid distribution between peatbog types. Moreover, chironomid assemblages were affected by environmental factors specific for a given peatbog type. Temperature and chlorophyll-a determined the chironomid assemblage in raised bogs. Water level, temperature, and total phosphorous were significant for chironomid structure in transitional bogs, whereas conductivity affected chironomids associated with Sphagnum in fens. Sphagnum mosses in transitional bogs were the preferred habitat for larval chironomids in this study. In transitional bogs chironomid density was the highest and typical, macrophyte-associated taxa, larvae of Psectrocladius sordidellus gr. (Zetterstedt, 1838), Cricotopus sylvestris gr. (Fabricius, 1794), and Glyptotendipes sp., were dominant. In raised bogs and fens, pelophilous taxa, larvae of Chironomus sp., and Procladius sp. showed higher abundances.