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What is plankton?

Organisms that drift with the currents

Mostly very small (1/1000 mm to 10 mm)

Plants of the plankton are single-celled algae (phytoplankton)

hair50 µm

chain of algae cells (diatom)

flagellate algae

Large phytoplankton

Tiny phytoplankton

Microzooplankton

Larger zooplankton

Ware & Thomson 2005 Science 308

B. Anderson and D.J. Patterson

Prochlorococcus

Lalli and Parsons

What is the amount (and rate) of production?

What types of organisms are being produced?

Why?

What is the amount (and rate) of production?

What types of organisms are being produced?

Why?

Amount (and rate) of production affected by:

Resources: light, nutrientsConsumption: removal by grazers

PSi

NP

N Si

LIGHT

NUTRIENTS

Phytoplankton resources are partitioned by depth:

N

Fe

PSi

NP

N Si

LIGHT

NUTRIENTS

Phytoplankton resources are partitioned by depth:

N

Fe

Phyto can only growwhere there is light

PSi

NP

N Si

LIGHT

NUTRIENTS

Phytoplankton resources are partitioned by depth:

N

Fe

Phyto can only growwhere there is light

Deep waters becomeenriched throughsinking and decompositionof material produced at surface

Si

SiP

P

N

N

Mixing changes availability of resources to phytoplankton:

LIGHT

NUTRIENTS

N

Fe

Lower density(warmer, fresher)

Layering due to density differences (stratification) opposes mixing

Higher density(colder, saltier)

Lower density(warmer, fresher)

Layering due to density differences (stratification) opposes mixing

Higher density(colder, saltier)

Lower density(warmer, fresher)

Heating, precipitation, and runoff all contribute to lower density surface waters

Higher density(colder, saltier)

Is mixing a good thing for phytoplankton?

(Does it increase resource availability and growth rate?)

?

It depends...

Amount (and rate) of production affected by:

Resources: light, nutrientsConsumption: removal by grazers

Day 1

Daily production

Day 1

Daily production

Daily consumption

Day 2

What is the amount (and rate) of production?

What types of organisms are being produced?

Why?

Species produced are also affected by:

Resources: light, nutrientsConsumption: removal by grazers

SiO4

NO3Nutrients:amount and ratios

SiO4

NO3

Nutrients:amount and ratios

Grazers:selective feeding

Larger cells become dominant

Oceanographic processes affecting resource availability (and thus production) in our region:

1. Tides2. Upwelling3. River plumes4. Estuarine circulation

Oceanographic processes: TIDES

Oceanographic processes: TIDES

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Oceanographic processes: TIDES

Oceanographic processes: TIDES

Oceanographic processes: TIDES

Oceanographic processes: UPWELLING

Oceanographic processes: UPWELLING

Oceanographic processes: UPWELLING

Brings deep nutrients to surface

Oceanographic processes: UPWELLING

Strongest in summer

Oceanographic processes: RIVER PLUMES

Fraser

Oceanographic processes: RIVER PLUMES--suspended sediments can block light

Fraser suspended sediments

Mississippi plume

Oceanographic processes: RIVER PLUMES--fresh water reduces surface salinity, promotes stratification

Oceanographic processes: RIVER PLUMES--can bring nutrients into coastal ocean…

Oceanographic processes: RIVER PLUMES--but this depends on the watershed

Oceanographic processes: RIVER PLUMES--but this depends on the watershed

Can have nutrient depletion in bays and inlets with restricted flow: vulnerable to human inputs (sewage, fertilizer)

Saanich Inlet, Vancouver Island

Estuarine circulation in the Salish Sea brings it all together

Estuarine circulation in the Salish Sea brings it all together

River discharge drives surface outflow

Estuarine circulation in the Salish Sea brings it all together

Subsurface nutrients mixed up to surface at plume interface

Estuarine circulation in the Salish Sea brings it all together

Inflow of nutrient-rich water from coastal upwelling

Estuarine circulation in the Salish Sea brings it all together

Tides promote mixing over sills

Combined with seasonal increases in light, these sources of nutrients MAKE OUR WATERS

GREEN