PRODUCTION AND BIOENERGETIC ROLE OF THE MIDGE GLYPTOTENDIPES BARBIPES (STAEGER) IN A WASTE STABILIZATION LAGOON1

Abstract

The bioenergctic role of a population of Glyptotendipes barbipes in the process of waste stabilization in two sewage lagoons was studied. Weekly production rates of the multivoltine midge were computed. Annual production of G. barbipes was 808 kcal/m 2 in a narrow band nearshore of the secondary lagoon containing 90% of the biomass. Biomass data from both lagoons in 1966 and 1967 were used to estimate production using a turnover ratio (TR) of 8.49 (ratio of production: mean biomass) from definitive data collected in 1967. Production in the secondary lagoon was 459 kcal/m 2 in 1966 and 37 in 1967; in the primary lagoon it was 165 and 18 respectively. The factors causing these differences in production were probably the dissolved oxygen concentrations during the growing season, percent of the total lagoon bottom inhabitable by midge larvae, and the condition of the sludge substrate. The total energy removed by emergence and respiration of G. barbipes was compared with the energy in other pathways in the lagoon: import of sewage, primary production, community respiration, storage, and export. In 1966, G. barbipes removed about 6.6% of the net primary production in the secondary lagoon and 0.5% in 1967.