Distribution and production of midges (Tendipedidae) in an alpine lake

Abstract

Larval populations and emergence of midges were sampled during the summer of 1966 in Emmaline Lake, Colorado. The fish population was removed from this alpine lake in 1964. Emergence was sampled using surface cone traps. Midge emergence was extremely variable in time and space; greatest numbers emerged in early summer over broken rock and sandy shoreline areas. Weight of emerging midges was often greatest over the mud lake bottom where it bordered rocky slopes. Taxonomic diversity was high; at least 10 species of midges occurred in emergence samples. Statistically, emergence counts followed the negative binomial distribution with ”k” usually in the range 0.1 to 0.2. Larval populations in mud bottoms were not clearly correlated with emergence over mud areas. Survival of preemergent larvae to adulthood was low, but 20 to 50 adults emerging per m2 in late July were apparently enough to yield larval populations of over 5000 per m2 by late September. Larval growth and net biomass production were greatest in early summer and fall. Detectable larval mortality occurred only in late fall.