Additional studies involve the interaction between the various parameters of the carbon system, fractionation, and CCM induction. More specifically this project will determine the response of commercial fish and plankton populations off the western Canadian continental shelf and slope to variability of circulation and water properties at seasonal to decadal time scales. Variations in phytoplankton primary production, biomass and composition, as mediated by physical transport and nutrient supply and how these variations affect food availability for salmon will be examined. This model will be used to forecast ecosystem production trends based on physical forcing of the lower trophic levels, and natural and anthropogenic forcing of the higher trophic levels. Three cruises are scheduled for 1997 and for 1998 to study seasonal phytoplankton variations.
Preliminary results indicate that there is a trend toward higher bacterial viability with depth.
The decrease does not coincide directly with indicators of phytoplankton iron limitation. Bacterial respiration appears to decrease more quickly than productivity indicating higher carbon assimilation efficiency further from shore. Heterotrophic bacterial numbers do not correspond to productivity measurements. Bacterial production appears to be carbon limited and may respond negatively to the addition of iron. Photoacclimation is widely observed in oceanic phytoplankton and it allows algae to maintain fast rates of photosynthesis.