Respiration in eutrophic lakes: the contribution of bacterioplankton and bacterial growth yield

Open Access
Publisher Website
Google Scholar
Abstract
The contribution of bacterioplankton to total plankton respiration was measured in two eutrophic Danish lakes and in experimental enclosures treated with planktivorous fish and nutrients. Bacterial respiration was calculated from measured oxygen uptake rates in particles passing a 1.0-μm pore size filter, the rates were then corrected for the size distribution of glucose uptake. During summer the respiration of the planktonic bacteria contributed ˜50% of the community respiration in the two lakes. Prolific phytoplankton growth induced by biomanipulation and nutrient addition created situations where the contribution of the bacteria decreased to 20%. High bacterial contributions to community respiration were found when the phytoplankton biomass decreased. Simultaneous measurements of bacterial respiration and production (by means of [3H]thymidine incorporation) allowed an estimation of bacterial growth yield, which ranged from 9 to 66%. In the two lakes the growth yield was constant with a mean of 29 ± 5% (±SD, RQ = 1). The variability of the growth yield was larger in the enclosures. The wide range (9–66%) was mainly caused by changes in bacterial net production without concomitant changes in respiration. The discussion includes an evaluation of the oxygen uptake method in size fractionated samples and the availability of labile organic substrates as a factor controlling bacterial growth yield.

This publication has 0 references indexed in Scilit: