SS3.10 Ecological Implications of Terrestrial Inputs into Lakes and Ponds
Date: Tuesday, June 11, 2002
Location: Poster Session - VCC
 
DanielCB, Lund University, Lund, Sweden, Cesar.Daniel@limnol.lu.se
Gutseit, K, C, Lund University, Lund, Sweden, kelly-c.gutseit.171@student.lu.se
Anesio, A, M, Lund University, Lund, Sweden, Alexandre.Anesio@limnol.lu.se
Granéli, W, , Lund University, Lund, Sweden, Wilhelm.Graneli@limnol.lu.se
 
DARK LIMNOLOGY I – BACTERIAL UTILIZATION OF AGED VERSUS RECENTLY PRODUCED ORGANIC MATTER IN LAKES
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We investigated DOC dynamics and bacterial growth in a mesocosm experiment lasting for one year. Water was sampled in late winter from three lakes differing in color and trophy (humic, clearwater oligotrophic, clearwater hypertrophic) and was exposed to light or kept in darkness in triplicated 100L cylinders. After one year DOC concentrations in the dark were significantly lower than in the light for all lake water types. The largest difference in DOC between dark and light occurred in the humic lake. In this water, numbers and production of bacteria in the dark were similar to the values found in light, while for the oligotrophic and hypertrophic lakes bacterial numbers and production were significantly lower in darkness. These results are a direct experimental support for the hypothesis that in humic lakes bacterial production is relatively independent of phytoplankton, while in lakes lacking large inputs of allochthonous carbon, OM of recent phytoplankton origin supports a substantial fraction of the bacterial production. However, even in clearwater lakes, aged OM can support significant numbers and production of bacteria for extended periods.