Page 10 - HydrographyReadMe

Mean Conditions in the Strait of

Georgia

Mean near-surface conditions for the Strait of Georgia
since 2015. This figure summarizes thousands of
stations, the combined efforts of dozens of people
over many years.

th
Note in particular the 5 row, which shows the
seasonal and interannual changes in the the biomass
of primary producers (phytoplankton) in the Strait, the
ultimate source of organic material for all animal life
in the Strait. Sometime during March/April in each
year the spring phytoplankton bloom occurs and the
biomass increases tremendously before exhausting
the immediately available nutrients. Since this very
important event sometimes occurs between sampling
times, or earlier than sampling occurred in some
years, red markers are show to indicate the bloom
a) Fraser River inflow b) surface temperature c)
surface salinity d) surface dissolved oxygen e) time as estimated from continuous measurements of
Chlorophyll biomass (vertical bars show spring near-surface Chlorophyll from BC ferries.
bloom timing from other programs) f) surface
nitrate g) surface silicate h) surface phosphate

This figure shows the anomalies around the seasonal
mean for salinity at various depths, and surface
nutrients. At the top, we have also shown the flow of
the Fraser River, as measured at Hope. The summer
influx of fresh water from the Fraser, with smaller
contributions from other rivers, is responsible for the
low summer salinities in the Strait.

However, although there is slight tendency for above-
average flows to result in lower-than-usual surface
salinities, the other year-to-year variations shown are
still a mystery.

Anomalies around the seasonal mean for salinity
at various depths, and surface nutrients.