A Population Study of the Chironomidae (Diptera) of Lough Neagh

Abstract

The larval chironomid populations of Lough Neagh [Ireland] were sampled from Aug. 1969-July 1971. In both years, the average 4th instar larval density was about 4000 m-2 in Sept./Oct., and decreased to about 2000 m-2 prior to emergence in the spring. Chironomus anthracinus Zett. was the most abundant species in deep water (> 6 m) with a density of 350 m-2 just before emergence. C. plumosus L. was also present in the same area but at only 10% of the numbers. C. cingulatus Meig., found inshore (< 6 m depth), had an average overwintering population of .apprx. 100 m-2. Glyptotendipes larvae formed the most numerous group during the period of study. Pre-emergence populations were 500 m-2 and 1000 m-2 in 1970 and 1971, respectively. The larvae were found in the intermediate zone, mean depth about 4 m. Stictochironomus and Microtendipes both had overwintering larval populations of 100-300 m-2. Stictochironomus larvae were found inshore (< 6 m depth), Microtendipes slightly deeper (< 9 m). Procladius crassinervis Zett., a deep water species, had an average 4th instar density of 300 m-2, but a more complicated population pattern than any of the other species.