SS3.10 Ecological Implications of Terrestrial Inputs into Lakes and Ponds
Date: Tuesday, June 11, 2002
Location: Poster Session - VCC
 
GutseitKC, Lund University, Lund, Sweden, kelly-c.gutseit.171@student.lu.se
Daniel, C, B, Lund University, Lund, Sweden, Cesar.Daniel@limnol.lu.se
Anesio, A, M, Lund University, Lund, Sweden, Alexandre.Anesio@limnol.lu.se
Graneli, W, , Lund University, Lund, Sweden, Wilhelm.Graneli@limnol.lu.se
 
DARK LIMNOLOGY II ZOOPLANKTON PRODUCTION BASED ON AGED VERSUS RECENTLY PRODUCED ORGANIC MATTER
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The development of a heterotrophic plankton food web based either on new inputs of POM and DOM, or on utilization of aged DOM was tested. Water from three lakes (humic, clearwater oligotrophic and clearwater hypertrophic), was exposed to low light or kept in darkness in triplicated 100L cylinders. Biomasses of monads (smaller than 5 micrometers), heterotrophic nanoflagellates (HNF) and ciliates, and numbers of bacteria and metazoans (rotifers, copepods and cladocerans) were estimated during one year. No primary production was detected in the dark treatments and DOC concentrations were lower in the dark compared to the light. Bacterial numbers and biomasses of monads, HNF and ciliates were lower in the dark treatments, probably due to a microbial loop based only on relatively aged OM. Metazoans were found in both light and dark treatments during the experiment, except for copepods and cladocerans in the oligotrophic clearwater lake. This study shows that, even in total absence of new inputs of OM, a complete plankton food chain can develop based on dissolved humic matter of terrestrial origin or on aged DOM of phytoplankton origin.