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Abstract

Abstract: Bacterial production measurements were performed in the upper 7 cm of the Breitenbach streambed sediments by using the leucine uptake technique, to evaluate the importance of bacteria in the carbon flow of this first-order, central European upland stream. Mean daily production rates fluctuated between 190 mg C m⁻² d⁻¹ (January) and 670 mg C m⁻² d⁻¹ (June), with an annual average of 440 mg C m⁻² d⁻¹. These data are within the upper range of the few measurements available for running waters, especially from North America. Total annual production was 162 g C m⁻² d⁻¹, which is similar in magnitude to net primary production. The main source for bacterial production is dissolved and particulate organic matter of allochthonous origin. The high rate of production indicates the potential for bacteria to act as a food resource for the benthic fauna in the Breitenbach and similar streams.