Effect of sediment type, feeding level, and larval density on growth and development of a midge (Chironomus riparius)

Abstract

AbstractA 10‐d growth test and an emergence test were performed with Chironomus riparius Meigen in four unpolluted lake sediments (organic carbon content 0.5–57%) using different feeding levels (Tetramin® at 0.03, 0.06, 0.12, or 0.33 mg/larva/d in the growth test and 0, 0.15, or 0.30 mg/larva/d in the emergence test) to study how sediment type and feeding level affect larval growth. To examine effects of larval density on growth, another growth test was performed using densities of one larva per 24, 12, 4.8, or 2.4 cm2 and a feeding level of Tetramin at 0.12 mg/larva/d. Regardless of sediment type, feeding was necessary in the experiments started with first‐instar larvae. The effects of sediment physicochemical characteristics on larval growth and development could not be totally compensated for by food addition. When fed, larvae grew best in sandy sediment with low organic carbon content (0.5%). Acceptable survival was achieved with a very low food dose (0.03 mg/larva/d), but a somewhat higher dose (0.12 mg/larva/d) is recommended. Increment of feeding accelerated larval growth and development. Larval growth was correlated to the food dose per individual and to the density of food particles on the sediment surface.