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Uptake and release of phosphorus by representatives of a coastal marine ecosystem
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|Title:||Uptake and release of phosphorus by representatives of a coastal marine ecosystem|
|Authors:||Johannes, R. E (Robert Earle), 1936-2002|
Marine animals -- Hawaii
Marine plants -- Hawaii
|Abstract:||The supply of phosphorus limits the production of plants over wide areas of the sea (Harvey, 1955). It thus constitutes a limiting factor at the base of the food chain and its availability may strongly influence the entire economy of the sea. The study of the dynamics of phosphorus is therefore an important approach to a better understanding of the dynamics of marine production. There are many cycles of phosphorus in the sea. They can be classed in three principal interlocking groups, each on a different level of organization: biochemical, ecological and geochemical (Pomeroy, 1962). This thesis is an exploration of some of the aspects of the ecological cycle. The numerous pathways in this cycle (Figure 1.) have been discussed by Harvey (1955) and others. Summarizing briefly: dissolved inorganic phosphate, the only dissolved inorganic form of phosphorus in the sea, is utilized by marine plants and bacteria. Soluble organic phosphorus is also present in the sea; its constituent compounds are unknown. It is utilized by marine bacteria and is thought to be utilized to some extent by plants. Phosphorus contained in marine plants, bacteria and animals is passed through the food web and released when organisms die, as soluble organic, dissolved inorganic and detrital phosphorus. Soluble organic, dissolved inorganic and detrital phosphorus are also released by marine animals. Detrital phosphorus, composed of dead organisms and animal feces, may be assimilated by bacteria and animals, or even plants (Harvey, 1937). Detrital organic phosphorus and soluble organic phosphorus may be mineralized by alkaline phosphatase present in decaying organisms and in solution in the water (Goldschmidt, Mettenleiter and Borchardt, 1958; Goldschmidt, 1959). Detrital phosphorus may also be solubilized by certain free organic compounds (Neuberg, Grauer, Kreidl and Lowy, 1957). There have been numerous studies, both in the sea and in the laboratory of the dynamics of dissolved inorganic phosphate. Detrital phosphorus and dissolved organic phosphorus, on the other hand, have received little attention. This disparity reflects not so much the relative importance of these fractions in the phosphorus cycle as it does the relative difficulties of studying them. Dissolved inorganic phosphate determinations are a rapid and routine oceanographic measurement. The measurement of soluble organic phosphorus, however, is tedious and imprecise (Strickland and Austin, 1960) and is carried out much less often. A few studies do indicate that it exists in the sea in concentrations comparable to and sometimes exceeding those of dissolved inorganic phosphate (Redfield, Smith and Ketchum, 1937; Armstrong and Harvey, 1951; Ketchum, Corwin and Keen, 1955; Strickland and Austin, 1960; Duursma, 1960; El Wardani, 1960 and others). The problem of separating living from non-living particles in the sea has prevented even the order of magnitude of detrital phosphorus from being known. Some aspects of the ecological significance of these fractions are considered in this study. Representatives of the major trophic levels were used: a diatom, representing producers; an amphipod crustacean, representing consumers; and mixed species of marine bacteria, representing transformers (Zobell, 1946). The relative importance of these organisms, when living and when dead, in the production and utilization of dissolved inorganic phosphate, soluble organic phosphorus and detrital phosphorus was studied. In addition, some possible origins of free alkaline phosphatase in the sea were examined and the significance of this enzyme in the phosphorus cycle was considered. Chemical analyses were replaced where possible with radiometric analyses using the radionuclide p32. The greater sensitivity and relative ease of p32 analyses facilitated measurements of phosphorus in cultures where it was present in concentrations below the sensitivity of published chemical analyses (Strickland and Parsons, 1960) and/or in forms where the chemical analyses would have been too time consuming.|
Thesis--University of Hawaii, 1963.
Bibliography: leaves -86.
iii, 86 leaves mount. illus., diagrs. (part fold.) tables
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|Appears in Collections:||Ph.D. - Zoology|
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