Aspects of the limnology of Long Pond, St. John's, in relation to a changing environment

O'Connell, M. F. (1974) Aspects of the limnology of Long Pond, St. John's, in relation to a changing environment. Masters thesis, Memorial University of Newfoundland.

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Abstract

Certain physiocochemical parameters, benthos and plankton were examined on a seasonal basis in Long Pond, C. A. Pippy Park, St. John's. This pond receives both rural and urban runoff and is characterized by a high flushing rate. -- The physicochemical environment was studied from June 1971 to May 1973 at five stations. Of the parameters studied, concentrations of total suspended matter, BOD, total CO₂ and free CO₂ were significantly greater in a small pool prior to the main body of the pond near the entry of Learys Brook where current speed is noticeably reduced. Sedimentation rate was also greatest at this location. No significant differences were found between stations with respect to pH, dissolved O₂, TDS, total hardness, Ca hardness, alkalinity, ammonium-N, nitrite-N, nitrate-N, orthophosphate and polyphosphate. Water quality in Long Pond is compared with unpolluted lakes and streams in the area; nutrient levels are indicative of eutrophic conditions. -- Benthos was studied at the same station as above from June 1971 to August 1972. Adverse physicochemical conditions which prevailed near the point of entry of Learys Brook were reflected in the components comprising the benthos. Numbers of Tubifex tubifex (maximum: 720,000/m²) increased with time, which paralleled increases in BOD (maximum: 12.9 mg/1). Opposed to the almost monospecific nature of this station, diversity was greater at the other stations. Diversity index values were computed for all stations. -- Plankton was studied quantitatively at one station (mid-pond) from April 1972 to May 1973. A comparison is made with Clarkes Pond, Hogans Pond and Bauline Long Pond. Long Pond phytoplankton was characterized by nannoplankton (particularly phytoflagellates). The most important zooplankters were Bosmina coregoni and Daphina catawba. -- Significant negative correlations were obtained between total phytoplankton and nitrate-N and total phytoplankton and free CO₂. Significant positive correlations were obtained between total phytoplankton and temperature, total zooplankton and total phytoplankton and total zooplankton and temperature.

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