Seasonal Succession in the Aquatic Insect Community of an Ozark Stream

ABSTRACT

We studied the temporal pattern of the aquatic insect assemblage of an Ozark stream by sampling riffle areas every two weeks from early February through late July, 2002. Total richness of the assemblage, for the entire study, was 138 taxa, including 57 from the dipteran family Chironomidae. Richness levels, per sampling period, ranged from the low 40s to the high 50s and were highest in late March through mid-April. Assemblage composition shifted from one dominated by chironomids in the winter and spring to one dominated by mayflies in the late spring and early summer and by caddisflies in summer. EPT richness levels, diversity, biotic index values, and relative abundances of functional feeding groups varied substantially during the study, occasionally even between two-week sampling periods. The data suggested that, for this type of stream, winter and summer are the times of year that the insect assemblage is least dynamic. These periods, despite lower overall community richness, may therefore be more appropriate to compare samples from different locations or years.