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Overview of Estuarine
(and Puget Sound)
Oceanography
PSO 2009
Drivers
• Geology: Glacial-Interglacial carve
channels, 200 m sea-level change
• Atmosphere: Weather, Climate
• Ocean: Nutrients in inflow (coastal
upwelling)
• Rivers: Storms, nutrients, sediment
• Tides: Sea-surface and currents, SpringNeap cycle
Physical & Chemical Habitat
• Circulation: The Exchange Flow
• Stratification: Increased by river, decreased by tidal
mixing
• Salinity: Huge along-channel gradient
• Temperature: surface warming
• Nutrients: Ocean or river sources, AND lots of internal
recycling (e.g. remineralization in the ETM)
• Residence Time = Volume/Flux, but be careful about
the definition of both
Ecosystem Fundamentals
• Primary Production: is high in estuaries,
needs nutrients and light (and
stratification), different bloom timing in
different basins.
• Zooplankton: like concentrated food
sources, populations lag phytoplankton,
behaviors (vertical distributions) affect
distribution/retention in sheared
currents.
Special Places
• ETM: Flocculation + deep inflow =
accumulation of sediment, detritus, bacteria,
zooplankton, larval fish
• Intertidal: episodic water exchange, waves
important, high benthic grazing
• Basins: Long residence time, hypoxia, daytime
predation refuge (e.g. krill)
• Sills: localized vertical turbulent mixing
• Headlands and braided channels: enhanced
lateral dispersion by eddies,
phytoplankton/zooplankton aggregation
Special Problems
• Hypoxia: Productivity + Stratification +
Long deep residence time. Big
biological consequences.
• HAB’s: causes debatable, different for
diatoms vs. dinoflagellates, increasing in
Sound?
• Invasive species: Asian zooplankton from
SF Bay ballast water, competition for
native species
Classification
• Well-mixed: Delaware Bay
• Well-mixed sometimes: Willapa Bay
• Partially-mixed: Hudson River, North SF Bay, James
River
• Partially-mixed with deep basins: Chesapeake, Long
Island Sound, Puget Sound
• Highly-stratified: Mississippi, Snohomish Rivers
• Intensely Variable: Skagit River
• Stagnant with episodic renewal: Baltic Sea