Phosphorus and phytoplankton dynamics in freshwater are usually thought to be tightly coupled and interdependent, yet orthophosphate uptake in situ has been observed to be mediated largely by particles of bacterial size. The purpose of this thesis is to examine the general hypothesis that freshwater bacterioplankton are markedly superior competitors for phosphorus, relative to the phytoplankton. Using isolates of three species of pelagic bacteria, and two of algae, it was shown that the bacteria possess much higher affinity orthophosphate uptake kinetics than the algae. In a Monte Carlo simulation study, the accuracy and precision of these Michaelis-Menten parameter estimates were found to depend strongly upon the experimental design matrix. Bacterial superiority in uptake was also reflected in terms of growth, in chemostat competition experiments, which also showed algal and bacterial uptake of orthophosphate to be well correlated with their relative long-term phosphorus assimilation. In parallel experiments in situ, bacterioplankton were found invariably to be responsible for more than 97% of the orthophosphate uptake. In contrast, excreted organic phosphorus was utilised almost exclusively by the phytoplankton. There is little evidence as yet that excretion and reuptake of phosphorus is important in redistributing phosphorus among the plankton.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.71827 |
| Date | January 1983 |
| Creators | Currie, David J. (David John) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Biology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 000168587, proquestno: AAINK64516, Theses scanned by UMI/ProQuest. |
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