Date of Award

11-1974

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

Supervisor

Dr. G. P. Harris

Abstract

During the period June, 1973 to May, 1974 limnological studies were carried out on the waters of Coote's Paradise, a marsh and wildlife sanctuary in Hamilton, Ontario. All of the indicles of eutrophication measured indicated that the marsh ranked among the most eutrophic of aquatic systems in temperate regions. The secondary treated sewage which was discharged into the western end of the marsh from the Dundas Sewage treatment plant was the primary source of nutrients.

The phytoplankton populations showed a prolonged summer bloom typical of aquatic systems polluted by sewage effluent. Chlorophyll a, used as an index of biomass, was highest during the spring and summer, and lowest during the fall and winter. The converse was true for the nutrients. Phytoplankton decreases and increases were correlated with changes in the light/temperature regimes during the fall and spring transition periods. Temperature had a pronounced effect upon chlorophyll variations between January and May 1974 in West Pond.

Weekly biomass variations during the summer at stations 4 and 12 were related to a complex of interactions involving eleven environmental parameters. Station 4 was located in the western end of the marsh and station 12 was in the eastern end. Nitrate-nitrogen was suspected to be the nutrient which was limiting algal growth in the western end of the marsh. Phosphorous mining in the sediments and nitrification of ammonia were observed in the Desjardins Canal and West Pond.

The west and east-end sample stations of the marsh were significantly different in phytoplankton composition and nutrient status when compared to each other. Algal genera and species typical of highly eutrophic waters were observed in West Pond and in the main open water area (station 12). Chlorophyta were the dominant group in West Pond, while Cyanophyta formed the dominant group in the main area during the summer of 1973. Species composition and dominance of major algal groups changed with the seasons at both station 4 and station 12.

During the summer, chlorophyll averaged 695 mg/M' in the West Pond stations and about 196 mg/M' in the main open water area stations. N/P ratios were lower in the west end stations than in the east end stations. Nutrients in the sewage effluent had a greater effect on algal activity at those stations near the point of discharge (stations 1 through 6). By the time the waters reached station 6, 80% of inorganic phosphate and about 90% of nitrate-nitrogen were removed. In this respect, the West Pond area (20 acres) can be regarded as a sewage lagoon performing further treatment on the incoming sewage effluent. As a result, a decreased nutrient loading was discharged into the main open water area. This may have been a significant factor in determining the different phytoplankton structure in the main open water area.

Diurnal studies indicated that observed variations of various parameters were not great enough to affect an interpretation of seasonal changes based on data, collected on a bi-weekly schedule (providing that sampling was consistent). Diurnal studies also suggested that wind speed, incident solar radiation, and previous light history may have been important in explaining chlorophyll variations.

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