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UBC Theses and Dissertations

Some relationships between phytoplankton populations and physical chemical factors in Ladysmith Harbour, British Columbia McAllister, Carey Douglas


The physical characteristics and distributions in space and time of salinity, temperature and phytoplankton in Ladysmith Harbour are described. It is shown that water exchange in Inner Ladysmith Harbour is the result of horizontal mixing and a two-layered circulation. The mean rate of water renewal in the Inner Harbour is calculated to be 32.2. percent of the mean volume per day. It is shown that four blooms of phytoplankton may occur in Ladysmith Harbour during the growing season, each having characteristic distributions. The distributions of phytoplankton during the first three blooms are discussed in relation to the physical characteristics and processes in and near Ladysmith Harbour. It is stated that the generic composition of the phytoplankton in Ladysmith Harbour varies in time and space. The rate of water exchange is shown to be such that endemic species of diatoms may develop in the Inner Harbour and that under certain conditions apparent endemism may occur. It is shown that both population succession and local sequence may be responsible for changes in the generic composition of the phytoplankton with time. Using the mean rate of water exchange and the assumption that renewal of water results entirely from the two-layer circulation, the net rates of advection of phytoplankton into Inner Ladysmith Harbour are calculated. It is shown that variations in the standing crop appear to be more closely related to changes in the rate of advection of phytoplankton than to changes in the rate of removal of cells by zooplankton. The rate of recruitment of phytoplankton by growth is calculated. It is computed that recruitment of cells by advection exceeds the recruitment by growth in Inner ladysmith Harbour.

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