MEASUREMENT OF BACTERIAL PRODUCTION IN STREAM-BED SEDIMENTS VIA LEUCINE INCORPORATION

The leucine incorporation technique was evaluated and optimised for me asuring bacterial production in stream-bed sediments. The original pro cedure was modified in order to obtain reliable production estimates i n this habitat. This included the use of higher leucine concentrations (50 mu mol l(-1)) for obtaining substrate saturation, and an enhanced protein extraction procedure after sample fixation. The leucine metho d was combined with a perfused core technique. Water containing C-14-l abelled leucine was pet-fused up through sediment cores, enabling the measurement of bacterial production in an experimental situation resem bling natural conditions in the stream bed. Bacterial production in th e Breitenbach, a small upland stream in Central Germany, showed a high degree of spatial variability in the sandy stream bed. It was related closely to sediment organic matter content, whereas varying perfusion rates had less influence. Annual bacterial production was estimated a t about 200 g C m(-2), demonstrating the potential for bacteria to act as a food resource for benthic fauna in this stream.