2nd Reminder: Midterm 1 is this Friday February 1st. Extended office hours today Wednesday 10AM-NOON. Midterm 1 is 15% of your final grade It covers all lectures through Monday January 28th It covers ALL reading assigned for weeks 1-4 , including topics not covered in class
Extended office hours today
Lecture related material is emphasized but general reading is covered generally (optional study aids are available on website for early reading assignments)
e. g. Spectral estimates of PP, P-I curves and names/symbols of parts
e. g. Qpar, Qpar (l), Pmax, Ik, aph(l),, alpha, beta, etc.
f) Generalities about major case studies discussed in readings: spring blooms in lakes, along coasts, and over the N. Atlantic
SBC resides in northern portion of the Southern California Bight (not Bite) below Pt. Conception
California Current (CC):cool (15C), nutrient rich, flows south along the outer edge of the Continental Shelf (1000 m).
Southern California CounterCurrent (SCCC):warmer, lower nutrient waters that turns from a southerly flow off shore to a northerly flow over the Continental Shelf until encountering the SBC which block much of the flow and divert it seward to mix again with the CC.
Episodic upwelling north of Pt. Conception brings very cold (13C<), nutrient rich water from deep waters to surface, which mixes with the CC waterforming sharpfrontal boundariesas it encounters the SCCC. Upwelling is the primary source of nutrients derived from the ocean near the coast of central California
Subtropical oligotrophic waters flow northalong the coast in summer months, more so in El Nino years. Very warm(>20 C), oligotrophic waters in relatively shallow surface current.
The current dynamics of the SBC region generate marked gradients in the physical, chemical, biological and optical properties of the upper water column (0 to 160 m) are observed across the SBC coastal region.
West-East Transect Line, showing 12 stations where vertical profiling of physical, optical, chemical and biological properties were made.
Hydrographic conditions change between repeated transects at weekly intervals, e.g.
During strong upwelling
Working between dawn and dusk of a single day, transect stations can sampled across the cold-front-warm boundaries along the outer side of the SBC.
The abundance, composition and photosynthetic capabilities of phytoplankton communities vary widely across the frontal boundaries in SBC region
SST = sea surface temperature
Surface Chl /vol
SeaWifs Chl map
Surface water temperature, SST
Highly variable waters of the SBC region create a diverse spatial gradients in hydrographic properties
MIXED LAYER DEPTH
DEPTH OF EUPHOTIC ZONE
HIGH BIOMASS spatial gradients in hydrographic properties
LARGE DIATOMS FOLLOWING UPWELLING
MIXED COMMUNITY OF DIATOMS AND MICROFLAGELLATES
LOW BIOMASS;FEW SMALL DIATOMS; COMMUNITY DOMINATED BY SMALL
MICROFLAGELLATES & PICO SIZE ‘RED’ CYANOBACTERIA
Note differences in pigment concentration range for cold, front, warm waters
Chl-specific Pmax = photosynthetic potential spatial gradients in hydrographic properties
Chl-specific alpha ~ relative quantum yield
Chl-specific P = (Pmax )(tanh I/Ik)
upwelling spatial gradients in hydrographic properties
Cold, nutrient rich
Upwelling event at west end of SBC
before upwelling at west end of SBC
Net phytoplankton spatial gradients in hydrographic properties feed the linear food via larger zooplankton
Nano- and pico-phytoplankton feed the microbial loop
Comment on phytoplankton size and food chain dynamics