bound; ill., maps; Thesis (Ph. D.)--Oregon State University, 1970; Includes bibliographical references (leaves 132-145)
AN ABSTRACT OF THE THESIS OF DOUGLAS WILLIAM LARSON for the DOCTOR OF PHILOSOPHY (Name) (Degree) Limnological data were collected from studies of four Oregon lakes that are classified as oligotrophic--Crater, Odell, Waldo, and Woahink. Phytoplankton primary production was estimated periodically using a standard carbon-14 in situ method. Bioassay experiments were conducted to determine whether water samples, treated with various kinds and concentrations of inorganic nutrients, might stimulate carbon uptake by phytoplankton. Chlorophyll a measurements complemented production estimates made with carbon-14. In comparing the lakes, differences were noted concerning lake origin, watershed features, basin morphometry, surface elevation, optical and thermal properties, and water chemistry. More notable, however, was the significant difference in phytoplankton primary production and biomass among the four lakes. During July and August, 1969, productivity averaged 25 3. 1 (Crater), 15 33. 2 (Odell), 35.5 (Waldo), and 301. 1 (Woahink) mgC/m day. For the same period, concentrations of chlorophyll a. averaged 34.4 (Crater), 99.03 (Odell), 4. 7 (Waldo), and 24. 7 (Woahink) mg/m . This resulted from the different uses each lake received. It is suggested that, on the basis of productivity, lakes are unique environments and are evolving at different rates in response to natural and artificial (cultural use) enrich*-ment. The need for an adaptable classification system that would take into account the continuous process of lake evolution was emphasized. Such a system, based on the relationship between phytoplankton pri- 2 mary productivity (mg C/m /hr) and light energy absorbed by phytoplankton for photosynthesis (coefficient K which represents the ratio of production to radiation at any depth; Platt, 1969), was proposed. The system will serve to diagnose, to a degree, the causes of lake eutrophication, will continue to provide an instantaneous assessment of lake productivity, and will have predictive power in determining lake evolution.
AN ABSTRACT OF THE THESIS OF DOUGLAS WILLIAM LARSON for the DOCTOR OF PHILOSOPHY (Name) (Degree) Limnological data were collected from studies of four Oregon lakes that are classified as oligotrophic--Crater, Odell, Waldo, and Woahink. Phytoplankton primary production was estimated periodically using a standard carbon-14 in situ method. Bioassay experiments were conducted to determine whether water samples, treated with various kinds and concentrations of inorganic nutrients, might stimulate carbon uptake by phytoplankton. Chlorophyll a measurements complemented production estimates made with carbon-14. In comparing the lakes, differences were noted concerning lake origin, watershed features, basin morphometry, surface elevation, optical and thermal properties, and water chemistry. More notable, however, was the significant difference in phytoplankton primary production and biomass among the four lakes. During July and August, 1969, productivity averaged 25 3. 1 (Crater), 15 33. 2 (Odell), 35.5 (Waldo), and 301. 1 (Woahink) mgC/m day. For the same period, concentrations of chlorophyll a. averaged 34.4 (Crater), 99.03 (Odell), 4. 7 (Waldo), and 24. 7 (Woahink) mg/m . This resulted from the different uses each lake received. It is suggested that, on the basis of productivity, lakes are unique environments and are evolving at different rates in response to natural and artificial (cultural use) enrich*-ment. The need for an adaptable classification system that would take into account the continuous process of lake evolution was emphasized. Such a system, based on the relationship between phytoplankton pri- 2 mary productivity (mg C/m /hr) and light energy absorbed by phytoplankton for photosynthesis (coefficient K which represents the ratio of production to radiation at any depth; Platt, 1969), was proposed. The system will serve to diagnose, to a degree, the causes of lake eutrophication, will continue to provide an instantaneous assessment of lake productivity, and will have predictive power in determining lake evolution.