caa a22 4500 467885540 CHVBK 20180406152733.0 cr unu---uuuuu 170328e20060401xx s 000 0 eng 10.1007/s10021-005-0115-5 doi (NATIONALLICENCE)springer-10.1007/s10021-005-0115-5 Bacterial Growth on Allochthonous Carbon in Humic and Nutrient-enriched Lakes: Results from Whole-Lake 13C Addition Experiments [Elektronische Daten] [Emma Kritzberg, Jonathan Cole, Michael Pace, Wilhelm Granéli] Organic carbon (C) in lakes originates from two distinct sources—primary production from within the lake itself (autochthonous supply) and importation of organic matter from the terrestrial watershed (allochthonous supply). By manipulating the 13C of dissolved inorganic C, thereby labeling within-lake primary production, we examined the relative importance of autochthonous and allochthonous C in supporting bacterial production. For 35 days, NaH13CO3 was added daily to two small, forested lakes. One of the lakes (Peter) was fertilized so that primary production exceeded total respiration in the epilimnion. The other lake (Tuesday), in contrast, was low in productivity and had high levels of colored dissolved organic C (DOC). To obtain bacterial C isotopes, bacteria were regrown in situ in particle-free lake water in dialysis tubes. The contribution of allochthonous C to bacterial biomass was calculated by applying a two-member mixing model. In the absence of a direct measurement, the isotopic signature of the autochthonous end-member was estimated indirectly by three different approaches. Although there was excess primary production in Peter Lake, bacterial biomass consisted of 43-46% allochthonous C. In Tuesday Lake more than 75% of bacterial growth was supported by allochthonous C. Although bacteria used autochthonous C preferentially over allochthonous C, DOC from the watershed contributed significantly to bacterial production. In combination with results from similar experiments in different lakes, our findings suggest that the contribution of allochthonous C to bacterial production can be predicted from ratios of chromophoric dissolved organic matter (a surrogate for allochthonous supply) and chlorophyll a (a surrogate for autochthonous supply). Springer Science+Business Media, Inc., 2006 lakes nationallicence bacteria nationallicence dissolved organic carbon nationallicence allochthonous carbon nationallicence autochthonous carbon nationallicence stable isotope nationallicence Kritzberg Emma Department of Ecology/Limnology, Lund University, Ecology Building, S-223 62, Lund, Sweden aut Cole Jonathan Institute of Ecosystem Studies, Box AB, 12545, Millbrook, New York, USA aut Pace Michael Institute of Ecosystem Studies, Box AB, 12545, Millbrook, New York, USA aut Granéli Wilhelm Department of Ecology/Limnology, Lund University, Ecology Building, S-223 62, Lund, Sweden aut Ecosystems Springer-Verlag; www.springer-ny.com 9/3(2006-04-01), 489-499 1432-9840 9:3<489 2006 9 10021 https://doi.org/10.1007/s10021-005-0115-5 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10021-005-0115-5 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Kritzberg Emma Department of Ecology/Limnology, Lund University, Ecology Building, S-223 62, Lund, Sweden aut NATIONALLICENCE 700 1- Cole Jonathan Institute of Ecosystem Studies, Box AB, 12545, Millbrook, New York, USA aut NATIONALLICENCE 700 1- Pace Michael Institute of Ecosystem Studies, Box AB, 12545, Millbrook, New York, USA aut NATIONALLICENCE 700 1- Granéli Wilhelm Department of Ecology/Limnology, Lund University, Ecology Building, S-223 62, Lund, Sweden aut NATIONALLICENCE 773 0- Ecosystems Springer-Verlag; www.springer-ny.com 9/3(2006-04-01), 489-499 1432-9840 9:3<489 2006 9 10021 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer