Controls on Primary Productivity in the Strait of Georgia

The Strait of Georgia, located between Vancouver Island and mainland British Columbia, is a 28 km wide, 250 km long fjord-like estuary that is home to a vibrant marine ecosystem. Observations showed that after diatoms, the mixotroph, Myrionecta rubra was the next most abundant primary producer by biomass. Therefore, in addition to diatoms, M. rubra and its cryptophyte prey are represented as functional groups in a biological model for the region. We will discuss the impact of representation of M. rubra on modeled primary productivity. In initial one-dimensional runs, productivity was too high in the summer; we will describe physical and biological causes of this bias and their resolution. Observations show strong seasonal and interannual spatial variability of primary productivity and nutrient distributions. Dynamic processes behind this variability include river outflow, wind and tidal mixing, exchange with continental shelf waters, and exchange with smaller adjacent fjords. We will present preliminary results from a three-dimensional implementation of the model.