The University of British Columbia

• Physiological ecology of marine algae;
• Nutrient uptake and assimilation by phytoplankton and seaweeds;
• Algal nutrition, nitrogen, iron and light influences on phytoplankton physiology;
• Production of extracellular metabolites by phytoplankton.

Lab studies are focused on nutrient uptake and assimilation in algae and how nutrients (e.g. nitrogen and iron) and light interact and influence physiology, and species competition and succession. Since nitrogen is frequently the nutrient that limits primary productivity in the sea, uptake and assimilation of nitrate, ammonium and urea are being investigated during transients in batch and continuous cultures. The determination of time series of uptake rates, enzyme activities, and storage of nutrients in intracellular pools provides a physiological basis for understanding how ecologically important species adjust their carbon and nitrogen metabolism during nitrogen starvation and recovery.

In addition to the studies on nitrogen, the laboratory projects on the nutrition of marine phytoplankton have examined aspects of silicon, phosphorus, iron and selenium uptake and metabolism. A study on the effects of iron limitation on iron requirements and nitrogen utilization by oceanic phytoplankton from the NE Pacific is underway. Additional studies include the effects of nutrients and light on phytoplankton sinking rates. Our field investigations include iron limitation in the NE Pacific and in the Strait of Georgia we are examining interannual differences in phytoplankton and zooplankton production which may help to explain interannual differences in the return of salmon to the Fraser River. The magnitude and timing of the Fraser River discharge, winds and the timing of the spring phytoplankton bloom in relation to the peak in zooplankton abundance may affect the food availability for young salmon when they enter the Strait on their way to the sea.