UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Factors controlling the winter dominance of nanoflagellates in Saanich Inlet, British Columbia Watanabe, Leslie N.


The alternation between a summer diatom population and a winter nanoflagellate population in Saanich Inlet is documented. Factors controlling the winter dominance by nanoflagellates, as well as the spring and fall transitions, are considered. Field monitoring of temperature, salinity, light, nitrate and silicate concentrations, and zooplankton size and abundance was conducted for the year November, 1975 to October, 1976 and compared with the pattern of phytoplankton succession during that time. This was supplemented with laboratory experimentation on the effects of light, temperature and photoperiod, as well as metabolic excretions and hydrocarbon pollution, on the growth of diatoms and nanoflagellates in unialgal culture and natural populations. Factors which were considered to be non-contributory to the winter dominance by flagellates included nutrient concentrations, grazing, excretions, and hydrocarbon pollution. Factors of some importance included temperature, photoperiod and water stability. The single factor of major importance was light intensity. Diatoms were found to be incapable of growth at winter light levels while flagellates were able to do so, due to their ability to maintain themselves high in the water column, and possibly due to a capacity for heterotrophy. A qualitative model is presented which relates the succession of phytoplankton in Saanich Inlet to temporal changes in various environmental parameters.

Item Media

Item Citations and Data


For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.