Semi-annual averaged values of photosynthetic carbon fixation (PCF), community respiration (CR), bacterial productivity (BP) and zooplankton carbon biomass, measured biweekly or monthly, were used to obtain long-term estimates of bacterial respiration (BR) and bacterial growth efficiency (BGE) in Lake Kinneret from 2001 through 2007. We posited that CR=BR+phytoplankton respiration (PR)+zooplankton respiration (ZR). Based on the results of independent experimental series, PR was estimated as 0.3 × gross primary production (GPP) and GPP as 1.5 × PCF. ZR was determined by multiplying zooplankton carbon biomass, measured biweekly, with published respiration rates for major zooplankton groups. From these data, we calculated BR and consequently BGE, determined as BP/(BR+BP). Over the entire study period, BR averaged 49 (±10)% of CR and was consistently higher during the first half of the year. Semi-annual averaged BGE ranged from 26% to 53%, mean 39 (±9)%. Similar values of BGE were obtained if we did not use the measured values for ZR, but estimated BR+ZR from CR–PR and then assumed that BR ranged from two to three times ZR. The approach outlined in this paper can be useful for determining BGE in aquatic systems where long-term data sets of PCF, CR and BP are available.
Keywords: bacterial growth efficiency; respiration and production; carbon flux; Lake Kinneret
Journal Article. 7972 words. Illustrated.
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