Diversity of Chironomidae (Diptera) in Lakes and Wetlands of the Nebraska Sandhills, USA

The Nebraska Sandhills is the largest grass stabilized sand dune region in the Western Hemisphere, and it is characterized by thousands of lake and wetland ecosystems (LWE), many of which are saline. These LWE are protected from row crop agriculture common in the Great Plains of North America due to the sandy substates that preclude tilling. Chironomidae (Insecta: Diptera) are common aquatic insects that inhabit LWE which exhibit a wide range of salinity in the Nebraska Sandhills. The goal of our study is to understand how salinity and other physical and habitat characters influence biodiversity of Chironomidae in freshwater to saline LWE in the Nebraska Sandhills. A total of 45 SFPE (surface floating pupal exuviae) samples were collected from 37 LWE between 2011 and 2015. Due to a strong relationship between chironomid diversity and salinity (R2 = 0.38, P ≤ 0.01), LWE were classified into three salinity categories: Freshwater, Subsaline, and Hyposaline. Results of the canonical correspondence analysis of the 12 landscape, LWE, and water quality variables analyzed in this study indicated that Freshwater LWE and Hyposaline LWE are clearly different, whereas Subsaline LWE overlapped with the other two LWE salinity categories. Chironomid communities, particularly the 18 indicator taxa identified by indictor taxa analysis, were strongly related to variation in conductivity and LWE circumference along the two CCA axes. Gamma (γ) diversity for the entire study was 53 and γ diversity was highest in Freshwater LWE and lowest in Hyposaline LWE. Median alpha (α) diversity varied significantly between the three LWE categories. Beta (βSor) was partitioned into turnover (ßSimp) and nestedness (ßnest). Both βSor and ßSimp varied significantly between the three LWE categories but ßnest did not vary significantly. Overall, chironomid communities in Nebraska Sandhills LWE are strongly shaped by salinity and LWE circumference. This study provides valuable information for use in conservation of the unique and important LWE of the Nebraska Sandhills.