The Effects of Environmental Variables on the Distribution of Immature Black Flies (Diptera, Simuliidae) in Various Streams of Northeastern Turkey

The Eastern Black Sea Region of Turkey is located in the Caucasus Ecoregion and is one of the richest regions of the world in terms of biodiversity. Black flies are an important part of the biodiversity of running waters in the region. To determine the Simuliidae fauna of this region and understand the relationships between species distribution and environmental variables, 41 sites, mostly unpolluted or slightly polluted, were sampled in July 2008 and June 2009. A total of 3309 simulids and 20 species were identified. The most frequent and the most abundant species were Simulium variegatum Meigen, 1818, Simulium bezzii Corti, 1914, and Simulium trifasciatum Curtis, 1839. Simulium costatum Friedrichs, 1920, Simulium argenteostriatum Strobl, 1898, Simulium angustipes Edwards, 1915, Simulium balcanicum Enderlein, 1924, and Simulium pseudequinum Seguy, 1921 were positively correlated with NO2–N, water temperature, and pH but negatively correlated with PO4–P and dissolved oxygen. Simulium argyreatum Meigen, 1838, S. variegatum, and S. trifasciatum were positively correlated with dissolved oxygen. Simulium ornatum Meigen, 1818 was negatively correlated with pH. Prosimulium tomosvaryi Enderlein, 1921, Simulium cryophilum Rubtsov, 1959, Simulium vernum Macquart, 1826, and Simulium hispaniola Grenier and Bertrand, 1954 were negatively correlated with electrical conductivity. The results indicate that black flies, like other benthic macroinvertebrates, also respond to changes in environmental conditions with changes in composition and distribution. We hope that our research will contribute to biomonitoring studies in the future.