Some estimates of carbon and nitrogen flux through pelagic communities in coastal waters
Newell, R.C.; Lucas, M.I.; Painting, S.J.; Field, J.G. (1985). Some estimates of carbon and nitrogen flux through pelagic communities in coastal waters, in: Gibbs, P.E. (Ed.) Proceedings of the 19th European Marine Biology Symposium, Plymouth, Devon, UK, 16-21 September 1984. pp. 51-59 In: Gibbs, P.E. (Ed.) (1985). Proceedings of the Nineteenth European Marine Biology Symposium, Plymouth, Devon, UK, 16-21 September 1984. European Marine Biology Symposia, 19. Cambridge University Press: Cambridge. ISBN 0-521-30294-3. 541 pp., more In: European Marine Biology Symposia., more |
| Authors | | Top | - Newell, R.C.
- Lucas, M.I.
- Painting, S.J.
- Field, J.G.
| | |
| Abstract | Evidence is presented which suggests that the microheterotrophic pathway in pelagic systems may differ significantly between poorly-productive systems and upwelling or decomposer-dominated nearshore areas. Carbon flow through the microheterotrophic community may also vary according to the stage of a phytoplankton bloom in nearshore eutrophic systems. The relative significance of phytoplankton primary production and bacterial production at the peak, during the decline, and following the subsequent recovery phase of a phytoplankton bloom in the Southern Benguela upwelling system is described. It is shown that bacterial production is sustained at 1000-2000 mg C .m-2 .d-1 despite a decline in primary production from approximately 5000 mg C. m-2 .d-1 to only 700 mg C .m-2 .d-1 during a survey between 15 March and 20 March 1983. Bacterial carbon consumption is estimated to account for approximately 75% of primary production at the peak of a bloom, much as reported for the Peruvian upwelling system, but appears to be sustained by utilisation of the biomass of senescent phytoplankton cells during the collapse phase of a bloom. Estimates of nitrogen flow based on carbon flux are in reasonable agreement with those based on the 15N-isotopic dilution technique. They suggest that, at the peak of a bloom, nitrogen regeneration through the bacterial community may account for approximately 40% of the nitrogen requirements of primary production. Following the collapse of the bloom, however, the community becomes a net mineraliser and may be responsible for the subsequent restoration of primary production by phytoflagellates. |
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