Interactions of Bacterio- and Phyto-Plankton in Nutrient Cycling Within Eutrophic Heywood Lake, Signy Island
Recent estimates of whole lake carbon budgets within eutrophic Heywood Lake and oligotrophic Sombre Lake, have revealed a significant disparity between production (as measured by 14C) and turnover values in the eutrophie system. Whereas the turnover of photosynthetically fixed C in Sombre Lake could be adequately explained in terms of bacterial decomposition, grazing, sedimentation and loss to the outflow, up to 70% of Heywood Lake production remained unexplained by the above processes. In Heywood Lake, carbon dioxide can become limiting to phytoplankton populations at certain periods of the production season. Bacterial breakdown of algal debris and extra-cellular products of photosynthesis (detected by 14C method) is too slow to generate the necessary levels of carbon dioxide, so a second extra-cellular DOC pool comprising small readily assimilable substrates was postulated. Using a variety of techniques, evidence was found to support this proposal. The possibility that N and P are also rapidly recycled was investigated using axenic algal cultures. Preliminary experiments indicated that bacteria were having a beneficial effect on algal production in both N and P-depleted environments. It is suggested that such mechanisms could explain the high production values recorded from enriched Antarctic lakes.
KeywordsBiomass Dioxide Filtration Urea Phytoplankton
Unable to display preview. Download preview PDF.
- Ellis-Evans JC (1981a) Freshwater microbiology in the Antarctic. 1. Microbial numbers and activity in oligotrophic Moss Lake. Bull Br Antarct Sury 54: 85–104Google Scholar
- Ellis-Evans JC (1981b) Freshwater microbiology in the Antarctic. 2. Microbial numbers and activity in nutrient-enriched Heywood Lake. Bull Br Antarct Sury 54: 105–121Google Scholar
- Hawes I (1983a) Turbulent mixing and its consequences for phytoplankton development in two ice-covered Antarctic lakes. Bull Br Antarct Sury 60: 69–82Google Scholar
- Hoppe H-G (1977) Analysis of actively metabolising bacterial populations with the autoradiographic technique. In: Microbial Ecology of a Brackish Water Enviroment (Rheinheimer G., ed):171–196 Springer, Berlin Heidelberg New YorkGoogle Scholar