Investigating the timing of Saanich Inlet's summer mini-blooms




Reyda-Molnar, Meghan

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Saanich Inlet is an inverse estuary located on the Saanich Peninsula which hosts different levels of primary production throughout the year, dependent on light and nutrient availability. The summer cycle of productivity has been investigated through modelling (Gargett et al., 2003) and shown to relate to spring tides which cause a fortnightly reversal in the direction of estuarine flow. This drives upwelling, bringing nutrient-rich water (of higher salinity) to the surface for phytoplankton to use. The goal of this project was to visualize this reversal process in order to draw conclusions about the timing of increased phytoplankton biomass after spring tidal events. Chlorophyll and salinity data taken in 2014, 2016 and 2022 from the Ocean Networks Canada Buoy Profiling System moored in Saanich Inlet was used, averaging casts over depth and through time. In conjunction with tidal height data from nearby Patricia Bay, the average time lag between spring/neap tidal events and max/min surface salinities was determined to be seven days. With increases in salinity taking around five days to lead to increased biomass, this showed the time lag between spring tidal events and increased biomass to be in the range of nine to fourteen days.



upwelling, seasonal variability, oceanography, tides, phytoplankton, saanich inlet