PRIMARY PRODUCTION IN LABORATORY STREAMS 1,2

Abstract

Six laboratory streams are being used to study primary production and community respiration in simple communities under different environmental conditions. A photosynthesis‐respiration chamber has been developed to perform experiments relating primary production to different environmental conditions and to verify primary production measurements made directly in the laboratory streams or in natural streams. Gross primary production in the six streams under 6,000 lux of illumination ranged from 2.4 to 4.7 g of oxygen per m 2 per day. Community respiration ranged from 1.6 to 4.2 g of oxygen per m 2 per day. The P/R ratios usually varied between 1.0 and 2.0. The relationship between illumination intensity and primary production was approximately linear between zero and 4,000 lux, and maximum photosynthetic rates were obtained at about 21,000 lux.