Bacterial Production and Abundance in Littoral Sediment of Oligotrophic Lakes: The Role of Benthic Primary Production and Allochthonous Carbon

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Much of what is known about bacterial dynamics in lakes has been derived from pelagic studies, while few studies investigate littoral bacteria. Littoral sediments in oligotrophic lakes range from sand to highly organic mud comprised of allochthonous carbon from exogenous sources or autochthonous benthic primary production. The ratio of benthic primary production to benthic OM content (BPPr:OM) provides an integrated index of the source and amount of benthic OM available for bacteria. We measured benthic bacterial production (BP) and abundance (BA) in the littoral zones of four oligotrophic NTL-LTER lakes with varying sediment types each season over the course of one year. Seasonal variation in bacterial production was driven by a positive relationship between BP and temperature (t =5.274 4, p<-.0001). Differences in source and amount of sediment organic matter drive among lake variation in BP and BA along a BPPr:OM gradient. Autochthonous organic matter content of littoral sediments could regulate bacterial dynamics and impact ecosystem processes such as nutrient recycling and trophic linkages to organic carbon pools.


Presented at the Joint Meeting with ASLO & NABS, Santa Fe, NM.