2nd Reminder: Midterm 1 is this Friday February 1st2nd Reminder: Midterm 1 is this Friday February 1st

• Midterm 1 is 15% of your final gradeMidterm 1 is 15% of your final grade

• It covers all lectures through Monday January 28thIt covers all lectures through Monday January 28th

• It covers It covers ALL ALL reading assigned for weeks 1-4reading assigned for weeks 1-4 , including topics not covered in class , including topics not covered in class

Lecture related material is emphasized Lecture related material is emphasized butbut general reading is covered generally ( general reading is covered generally (optional study aidsoptional study aids are are available on website for early reading assignments)available on website for early reading assignments)

• It will be short answer comprehensive based upon understanding of content, not problem solving.It will be short answer comprehensive based upon understanding of content, not problem solving.

• Expect you to knowExpect you to know

a)a) Fundamental properties of seawater, major currents, lightFundamental properties of seawater, major currents, light

b)b) Chemotaxonomic pigmentsChemotaxonomic pigments

c)c) General properties of different phytoplankton groupsGeneral properties of different phytoplankton groups

d)d) PhotosynthesisPhotosynthesis

e)e) Primary production methods, formula and nomenclaturePrimary production methods, formula and nomenclature

e. g. Spectral estimates of PP, P-I curves and names/symbols of partse. g. Spectral estimates of PP, P-I curves and names/symbols of parts

e. g. Qpar, Qpar (e. g. Qpar, Qpar (), Pmax, Ik, aph(), Pmax, Ik, aph(),, alpha, beta, etc. ),, alpha, beta, etc.

f) f) Generalities about major case studies discussed in readings: spring blooms in lakes, along coasts, and over Generalities about major case studies discussed in readings: spring blooms in lakes, along coasts, and over the N. Atlanticthe N. Atlantic

Extended office hours todayExtended office hours todayWednesday 10AM-NOONWednesday 10AM-NOON

SBC resides in northern portion of the Southern SBC resides in northern portion of the Southern California Bight (not Bite) below Pt. ConceptionCalifornia Bight (not Bite) below Pt. Conception

California Current (CC):California Current (CC): cool (15C), nutrient rich, flows cool (15C), nutrient rich, flows south along the outer edge of the Continental Shelf (1000 m).south along the outer edge of the Continental Shelf (1000 m).

Southern California CounterCurrent (SCCC):Southern California CounterCurrent (SCCC): warmer, lower nutrient waters that turns from a southerly flow warmer, lower nutrient waters that turns from a southerly flow off shore to a northerly flow over the Continental Shelf until off shore to a northerly flow over the Continental Shelf until encountering the SBC which block much of the flow and encountering the SBC which block much of the flow and divert it seward to mix again with the CC. divert it seward to mix again with the CC.

Episodic upwelling north of Pt. Conception Episodic upwelling north of Pt. Conception brings brings very cold (13C<), nutrient rich water from deep waters to very cold (13C<), nutrient rich water from deep waters to surface, which mixes with the CC watersurface, which mixes with the CC water forming forming sharpsharp frontal boundariesfrontal boundaries as it encounters the SCCC. as it encounters the SCCC. Upwelling is Upwelling is the primary source of nutrients derived from the ocean near the primary source of nutrients derived from the ocean near the coast of central Californiathe coast of central California

Subtropical oligotrophic waters flow northSubtropical oligotrophic waters flow north along the along the coast in summer months, more so in coast in summer months, more so in El NinoEl Nino years. Very years. Very warm(>20 C), oligotrophic waters in relatively shallow surface warm(>20 C), oligotrophic waters in relatively shallow surface current. current.

The current dynamics of the SBC region generate marked The current dynamics of the SBC region generate marked gradients in the physical, chemical, biological and optical gradients in the physical, chemical, biological and optical properties of the upper water column (0 to 160 m) are properties of the upper water column (0 to 160 m) are observed across the SBC coastal region.observed across the SBC coastal region.SST

General Current patterns of the Southern California Bight

West-East Transect Line, showing 12 stations where vertical profiling of physical, West-East Transect Line, showing 12 stations where vertical profiling of physical, optical, chemical and biological properties were madeoptical, chemical and biological properties were made.

Working between dawn and dusk of a single day, transect Working between dawn and dusk of a single day, transect stations can sampled across the cold-front-warm stations can sampled across the cold-front-warm boundaries along the outer side of the SBC.boundaries along the outer side of the SBC.

Hydrographic conditions change between repeated transects at weekly intervals, e.g.Hydrographic conditions change between repeated transects at weekly intervals, e.g.

During strong upwelling No upwelling

SeaWifs Chl map SeaWifs Chl map

The abundance, composition and photosynthetic capabilities of phytoplankton The abundance, composition and photosynthetic capabilities of phytoplankton communities vary widely across the frontal boundaries in SBC regioncommunities vary widely across the frontal boundaries in SBC region

Surface Pmax/volSurface Pmax/vol

Surface Chl /volSurface Chl /vol

Surface water temperature, SSTco

ldco

ldco

ldco

ld

war

mw

arm

war

mw

armFR

ON

TA

L B

OU

ND

AR

YF

RO

NT

AL

BO

UN

DA

RY

SST = sea surface temperature

TEMP

DEPTH OF

EUPHOTIC

ZONE

TEMPTEMP

PROFILEPROFILE

MIXED LAYER DEPTH

Highly variable waters of the SBC region create a diverse spatial gradients in hydrographic propertiesHighly variable waters of the SBC region create a diverse spatial gradients in hydrographic properties

Nutrient-limitationCHLCHL

BIOMASSBIOMASS

PROFILEPROFILEUniform mixing

downwelling Subtropical oligotrophic

Note differences in pigment concentration range for cold, front, warm waters

HIGH BIOMASSHIGH BIOMASS

DOMINATED BY DOMINATED BY

LARGE DIATOMS LARGE DIATOMS

FOLLOWING FOLLOWING

UPWELLINGUPWELLING

MODERATE BIOMASSMODERATE BIOMASS

DOMINATED BY DOMINATED BY

MIXED COMMUNITY OF MIXED COMMUNITY OF

DIATOMS AND DIATOMS AND

MICROFLAGELLATESMICROFLAGELLATES

LOW BIOMASS;FEW SMALL LOW BIOMASS;FEW SMALL

DIATOMS; COMMUNITY DIATOMS; COMMUNITY

DOMINATED BY SMALLDOMINATED BY SMALL

MICROFLAGELLATES & PICO MICROFLAGELLATES & PICO

SIZE ‘RED’ CYANOBACTERIASIZE ‘RED’ CYANOBACTERIA

Chl-specific Pmax = photosynthetic potential

Chl-specific alpha ~ ~ relative quantum yield

Chl-specific P = (Pmax )(tanh I/Ik)Chl-specific P = (Pmax )(tanh I/Ik)

c

P

QPAR

cw

w

f

f

California CurrentCold, nutrient richDiatom-dominatedmicroplankton

Frontal baundaryFrontal baundary

Upwelling event at west end of SBCUpwelling event at west end of SBC

before upwelling at west end of SBC

Chl biomass

upwelling

Comment on phytoplankton size and food chain dynamics

Net phytoplanktonNet phytoplankton feed the linear food feed the linear food viavia larger zooplankton larger zooplankton

Nano- and pico-phytoplanktonNano- and pico-phytoplankton feed the microbial loop feed the microbial loop