Ecophysiology of phyto- and bacterioplankton growth in the Southern Ocean
Lancelot, Ch.; Billen, G.; Mathot, S. (1989). Ecophysiology of phyto- and bacterioplankton growth in the Southern Ocean, in: Caschetto, S. (Ed.) Belgian scientific research programme on Antarctica: scientific results of phase I (10/1985-01/1989): 1. Plankton ecology. pp. 05/1-97 In: Caschetto, S. (Ed.) (1989). Belgian scientific research programme on Antarctica: scientific results of phase I (10/1985-01/1989): 1. Plankton ecology. Belgian scientific research programme on Antarctica. Science Policy Office of Belgium: Brussel. 158 pp., more In: Belgian scientific research programme on Antarctica. Belgian Science Policy Office: Brussel. , more |
| Authors | | Top | - Lancelot, Ch., more
- Billen, G., more
- Mathot, S.
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| Abstract | Understanding the overall functionning of the Antarctic marine ecosystem at the first levels of the trophic web is required to evaluate the potential primary resources available for herbivores grazing and thus to assess the potential for krill exploitation. An experimental approach has been developped for studying phyto- and bacterioplankton dynamics at a rather fine physiological level. The control of phytoplankton photosynthesis and growth by light and temperature has been studied in details for the open sea and marginal ice communities. A conceptual model has been developped which is able to predlct the major trends of variations of phytoplankton biomass and activity in Antarctic waters from the knowledge of the physical characteristics of the environment among which the stability of the water column was shown to be the most important factor. Application of this model to the different habitats of the Southern Ocean during late summer yields net primary production (phytoplankton growth) rates ranging between 20-25 mgC.m-2.d-1 in the open sea areas, and between 30-250mgC.m-2.d-1 in thc marginal ice zone. These are the first available estimations of net primary production in this ecosystem. The dynamics of the microbial loop has been experimentally studied according to a similar approach, and a model of bacterioplankton development in response to phytoplankton has been elaborated. Although a much longer delay (about one month) exists between phytoplanktonic and bacterial development, the role of bacterial activity in utilizing primary produced organic matter was proven quantitatively as important in the Southern Ocean as it is in temperate marine systems. |
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