1. 2nd Reminder: Midterm 1 is this Friday February 1st Midterm 1 is 15% of your final grade Midterm 1 is 15% of your final grade It covers all lectures through Monday January 28th It covers all lectures through Monday January 28th It covers ALL reading assigned for weeks 1-4, including topics not covered in class It covers ALL reading assigned for weeks 1-4, including topics not covered in class Lecture related material is emphasized but general reading is covered generally (optional study aids are 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 know Expect you to know a)Fundamental properties of seawater, major currents, light b)Chemotaxonomic pigments c)General properties of different phytoplankton groups d)Photosynthesis e)Primary production methods, formula and nomenclature e. g. Spectral estimates of PP, P-I curves and names/symbols of parts e. g. Qpar, Qpar ( ), Pmax, Ik, aph( ),, alpha, beta, etc. f) Generalities about major case studies discussed in readings: spring blooms in lakes, along coasts, and over the N. Atlantic Extended office hours today Wednesday 10AM-NOON

2. 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 water forming sharp frontal boundaries as 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 north along 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. SST General Current patterns of the Southern California Bight

3. West-East Transect Line, showing 12 stations where vertical profiling of physical, optical, chemical and biological properties were made West-East Transect Line, showing 12 stations where vertical profiling of physical, optical, chemical and biological properties were made. 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. Hydrographic conditions change between repeated transects at weekly intervals, e.g. During strong upwellingNo upwelling

4. SeaWifs Chl map The abundance, composition and photosynthetic capabilities of phytoplankton communities vary widely across the frontal boundaries in SBC region Surface Pmax/vol Surface Chl /vol Surface water temperature, SST cold cold warm warm FRONTAL BOUNDARY SST = sea surface temperature

5. TEMP DEPTH OF EUPHOTIC ZONE TEMPPROFILE MIXED LAYER DEPTH Highly variable waters of the SBC region create a diverse spatial gradients in hydrographic properties Nutrient-limitation CHLBIOMASSPROFILE Uniform mixing downwellingSubtropical oligotrophic

6. Note differences in pigment concentration range for cold, front, warm waters HIGH BIOMASS DOMINATED BY LARGE DIATOMS FOLLOWING UPWELLING MODERATE BIOMASS DOMINATED BY MIXED COMMUNITY OF DIATOMS AND MICROFLAGELLATES LOW BIOMASS;FEW SMALL DIATOMS; COMMUNITY DOMINATED BY SMALL MICROFLAGELLATES & PICO SIZE ‘RED’ CYANOBACTERIA

7. Chl-specific Pmax = photosynthetic potential ~ Chl-specific alpha ~ relative quantum yield Chl-specific P = (Pmax )(tanh I/Ik) c P Q PAR c w w f f

8. California Current Cold, nutrient rich Diatom-dominated microplankton Frontal baundary Upwelling event at west end of SBC before upwelling at west end of SBC Chl biomass upwelling

9. Comment on phytoplankton size and food chain dynamics Net phytoplankton feed the linear food via larger zooplankton Nano- and pico-phytoplankton feed the microbial loop