Seasonal and interannual variability of primary and secondary productivity in a coastal fjord

The phytoplankton and zooplankton dynamics in a coastal fjord in British Columbia were monitored in spring and early summer 2006 and 2007 to assess the annual variability in primary and secondary productivity and some characteristics of subsequent production. Phytoplankton biomass increased dramatically in early spring (spring bloom), declined abruptly, and then increased to a smaller peak two weeks after the spring bloom. Mesozooplankton biomass peaked one month after the spring bloom. The timing of the spring bloom was 20 days later in 2007. It is hypothesized that higher freshwater discharge and more frequent wind events in early spring 2007 were the driving factors behind the observed shift in bloom timing. The delay of the phytoplankton bloom resulted in a later and lower zooplankton biomass peak, and in a shift in zooplankton species composition. The implications of these changes for the survival of juvenile sockeye salmon are also discussed.