Midges of the dipteran family Chironomidae are the most diverse and abundant insects in Lake Superior. Influences of sediment microbial respiration, organic matter content, particle size, depth, temperature, month, and infaunal interactions on chironomid midge abundance, diversity and taxonomic richness, productivity, and distribution were assessed. Monthly benthic dredge samples were taken from six sites in Marquette Bay ranging in depth from 1.5 to 100 meters, from July through October 2001. Forty-six genera of midges were collected, eleven of which were new to the Lake Superior faunal list. Chironomidae abundance was positively correlated to temperature and negatively correlated to sediment organic matter and depth (p ≤ 0.05). Chironomidae production estimates were negatively correlated with depth and organic matter, and positively correlated with temperature (p ≤ 0.05) and CO2 efflux (p ≤ 0.05). Canonical correspondence analysis revealed temperature, percent fine silt and clay, microbial activity, month, and depth as the important factors influencing the distributions of Lake Superior Chironomidae. The results of this study indicate that the Chironomidae vary in abundance in a predictable way from site to site and are major contributors to the bioenergetics and biodiversity of Lake Superior.
