Anoxic degradation of organic matter in lakes: implications for carbon cycling and aquatic food webs
2002 (English)Doctoral thesis, comprehensive summary (Other academic)
Considerable evidence from laboratory studies and marine environments suggests that degradation of organic matter (OM) is restricted under anoxic conditions compared to when molecular oxygen (O2) is present. However, other studies contradict this view since they found similar OM degradation rates and bacterial growth rates under both oxic and anoxic conditions in aquatic environments. Studies from freshwater environments are rare, and have been primarily based on bacterial production estimates. Anoxic degradation of OM in lakes is commonly considered to be slow and of little importance for overall lake food webs compared to oxic degradation. The present thesis and the work it is based on challenge this view. First, the performance of a commonly used method to measure bacterial production was tested in both oxic and anoxic lake water. Then, the oxic and anoxic potentials of bacterial growth and OM mineralization were compared in lake water and sediment. In addition, I assessed the potential of carbon transfer from methane (CH4; i.e. an end-product of anoxic degradation) to pelagic food webs. Three methods for measuring water column methane oxidation were evaluated. Then, the potential transport of methane carbon into the microbial community via methane oxidation, and further -up the food web- into the zooplankton community was estimated. Results indicate 1) that OM degradation and bacterial growth may be similar in oxic and anoxic lake environments, 2) that OM characteristics may be more important for the mineralization than the O2 regime per se in the short term (daysweeks), and 3) that methane can be a significant source of carbon and energy for pelagic food webs. This suggests that the anoxic carbon metabolism may be extensive and potentially important for pelagic organisms in many lakes.
Place, publisher, year, edition, pages
Linköping: Linköpings universitet , 2002. , 55 p.
Linköping Studies in Arts and Science, ISSN 0282-9800 ; 262
Ekonsystem i vatten
Social Sciences Interdisciplinary
IdentifiersURN: urn:nbn:se:liu:diva-29575Local ID: 14951ISBN: 91-7373-436-5OAI: oai:DiVA.org:liu-29575DiVA: diva2:250391
2002-11-01, Sal Elysion, Hus-T, Universitetsområdet Valla, Linköping, 10:00 (Swedish)
Gasol, Joseph M, Dr
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