Quantitative and qualitative aspects of bacterial distribution, with special reference to the genus Pseudomonas Migula, in a cold seas environment (Avalon Peninsula Newfoundland)

Noseworthy, Joyce Elizabeth (1975) Quantitative and qualitative aspects of bacterial distribution, with special reference to the genus Pseudomonas Migula, in a cold seas environment (Avalon Peninsula Newfoundland). Masters thesis, Memorial University of Newfoundland.

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Abstract

Both sea water and plankton tow samples were taken off Small Point, on the east coast of the Avalon Peninsula, Newfoundland, at intervals from September 12, 1971 to August 10, 1972. Samples were collected from the surface, bottom and middepth or thermocline. To determine total bacterial populations, the samples were plated onto YBP-SWA and incubated at 20C and 5C; there were no significant differences between counts made at these two temperatures. Total pseudomonads were determined both by spreading plates of 0.03% cetrimide agar and by replication of colonies from YBP-SWA onto the cetrimide plates. -- The pseudomonads were identified using a scheme devised for this study, since it was found that the schemes already in existence placed undue emphasis on motility and pigmentation. The fluorescent antibody technique was used in the differentiation of pseudomonads from non- pseudomonads and was found to be of value. -- Seventy-eight percent of the plates spread with sea water produced no colonies. Total numbers of bacteria ranged from 10 to 4,329 per liter of plankton tow; total pseudomonads ranged from 1 to 865 per liter. Numbers varied apparently randomly from trip to trip. No regular pattern of vertical bacterial distribution was detected and the thermocline apparently had no effect on vertical distribution. Bacterial and pseudomonad numbers seemed to be unrelated to either water temperatures or salinities. -- Phytoplankton samples were counted and numbers of diatoms, dinoflagellates, and silicoflagellates were recorded. This data indicated that a diatom bloom, caused mainly by Chaetoceros species, occurred from March to May or June. For all three sampling depths, bacterial and pseudomonad numbers were lowest when the diatoms were at their peak, but started to increase as the bloom declined.

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