Date of Award

12-1-1974

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

Abstract

Potamogeton pectinatus L., a submerged, marl forming macrophyte, grows as a natural monospecies community in Fox Lake, 16 km northeast of Devils Lake, North Dakota. The water, sediment, dissolved oxygen, temperature and productivity relationships were studied in this small (0.4 X 1.2 km), shallow (60-75 cm) lake. Five replicate samples of the macrophyte, sediment, water and dissolved oxygen were taken at two week intervals during the 1972 growing season. In August of 1973, seven P. pectinatus sites in North Dakota, from the Minnesota to the Montana borders, were sampled. The sediments were analyzed for pH (7.8), electrical conductivity (9.8 Mmhos/cm), organic matter (4.1%), particle size (44% sand, 31% silt, 25% clay), 14 cations and four anions. The waters were analyzed for dissolved oxygen at two depths (114% saturation at 10 cm and 98% saturation at 40 cm), pH (9.2), electrical conductivity (15.8 Mmhos/cm), 13 cations and five anions. The plant biomass (maximum 2 of 293 gm/m ) was determined and samples were analyzed for caloric content (2972 cal/gm), carbon (54.3% not corrected for marl), nitrogen (1.47%) and 13 cations. The values in parentheses are means for Fox Lake over the 1972 growing season.

The temperatures were found to decrease with depth. The dissolved oxygen was higher in the surface waters for all dates, except the earliest sampling periods, when the macrophytes were very short. The temporal trends of all parameters were determined and phenograms based on correlation matrices were used to group environmental variables according to similarities in their trends, principal components analysis showed the same groups, but interpretation of the factor matrix was found to be more difficult. The ions in the water formed three groups, those in the sediments formed four groups and those in the plants formed four groups.

The characteristics of aerobic and anaerobic sediments in Fox Lake and the North Dakota transect are discussed in terms of their effects on the nutrient concentrations. Chelation of cations by dissolved organic materials in the water and adsorbed on the marl was found to be a possibility, especially for trace elements. Carbonate (marl) formation and bicarbonate utilization were found to be of major importance in the maintenance and productivity of the monotypic pectinatus community in Fox Lake.

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