Analysis of the structure of the immature insect segment of a stream riffle community

Abstract

Samples were collected monthly from July, 1972 through June 1973 using 1m² bottom sampler from a rifle in Sinking Creek in Giles County, Virginia to analyze the structure of the immature insect segment of the community. The following characteristics of the insect segment of the community were examined: life histories of the major species; total numbers; total biomass; species diversity; and energy distribution.

Four types of insect life histories were observed which differed in the length of time required for development of individuals. The life histories of closely related species were found to be synchronized so that hatching times were staggered. Seasonal fluctuations in the insect segment of the community were illustrated by changes in the total number of individuals and total biomass. The fluctuation were attributed primarily to the life histories of the component species. Species diversity was calculated with numbers showed little difference than diversity calculated with biomass. Diversity calculated both ways reflected seasonal changes and indicated a rich insect fauna. There was not significant seasonal variation in energy distribution examine but this could possibly be due to calorimetry methods. Investigation of the above parameters enable one to assess the insect segment of the community as dynamic yet containing structures and functions, such as relationships between populations, which can be described.