1. Reminder: Midterm 1 is one week from today on 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 (up to and including “Ecology of Water Columns) It covers all reading assigned for weeks 1-4 (up to and including “Ecology of Water Columns) 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. Extended office hours next week for Professor Prézelin Monday 11AM-1PM Wednesday 10AM-NOON Big!! Phyto Story: The monster diatom Coscinodiscus wailessi Regular sized diatoms Common Indo-Pacific Ocean species, invaded English Channel Common Indo-Pacific Ocean species, invaded English Channel in 1977 when likely introduced by ballast waters of ships or exotic shellfish (oysters) transplanted to European coastal mariculture facilities. Invasion spread rapidly to Atlantic coast of France by 1978 & Norway by 1979. Effects on the environment: Effects on the environment: They bloom & produce copious mucilage that glue particles in water together & sink to blanket the seabed in particulate mucilage, affecting gas & nutrient exchange at sediment/water column interface. Effects on commercial interests: Effects on commercial interests: Fishing trawls become clogged or broken by heavy grey slime. Fucoxanthin marker pigment

2. at ~60 % Pmax, cell division rates become maximal, eg.  =  max No PP, No growth, possible Senescence (decay, death, ), formation Resting stages, P max Light limited PP & Growth rates (  ) Light saturated PP and  Light saturated PP and  Light limited PP but Light saturated  Light-inhibited PP and 

3. slopes IkIkIkIk ItItItIt I k = Pmax/alpha I t = Pmax/beta without photoinhibition, Ps = Pmax. tanh (I/I k ) with photoinhibition, Ps = [Pmax. tanh (I/I k )] minus [ eq. describing shape of beta ] Beta varies from a linear to exponential decline Parameters of Photosynthesis-Irradiance curves , alpha , beta   = Ps rate/ PFD Indices of Photoadaptation Photoinhibition Indices of Photoadaptation Photoinhibition Chl-specific  relative quantum yield Photosynthetic potential

4. Comparison of P-I curves for different algae under different growth conditions Which has the highest P max ? Which has the highest P max ? Which has the highest alpha? Which has the highest alpha? Which has the lowest Ik? Which has the lowest Ik? At 50  Ein m -2 s -1, which has the greatest rates of Ps? At 50  Ein m -2 s -1, which has the greatest rates of Ps? At 200  Ein m -2 s -1, which has the greatest rates of Ps? At 200  Ein m -2 s -1, which has the greatest rates of Ps? Above what Q PAR does Ceratophylum Above what Q PAR does Ceratophylum Ps rates exceed those of Hydrilla? P-I relationships are a “signature” of the photo-physiological state of the phytoplankton cell, population, and mixed community One mole of hv = one Einstein of hv = one Ein = 6.02 x 10 23 molecules

5. P-I sampling strategies for determination of in situ rates of primary productivity, PP For determinations of instantaneous in situ PP at one place (z) and time (t) PPz,t, expressed as mg C/m3/hr or mgC/mg Chl/hr need to measure (Qpar)z,t and (Chl a)z,t and experimentally determine (P-I)z,t, using (P-I)z,t, could estimate PP for other conditions (Qpar)z,t and (Chl a)z,t although the accuracy would depend on the P-I response remaining constant i.e. Daily rates of PP at same location i.e. Daily rates of PP at same location (PP)z, expressed as mg C/m3/day or mgC/mg Chl/day (PP)z, expressed as mg C/m3/day or mgC/mg Chl/day i.e. Integrated water column PP i.e. Integrated water column PP (  PP)t, expressed as mg C/m2/hr or mgC/mg Chl/hr) (  PP)t, expressed as mg C/m2/hr or mgC/mg Chl/hr) i.e. Daily integrated water column PP  PP, expressed as mg C/m2/day or mgC/mg Chl/day)  PP, expressed as mg C/m2/day or mgC/mg Chl/day) Accuracy increases with knowledge of how P-I, Chl a, and Qpar vary as f(x) of t,z.

6. Case Study: Santa Barbara Channel (SBC) Pt. Conception, at the western boundary of the Santa Barbara Channel (SBC), is a major biogeographic and coastal oceanic boundary that strongly influences the physical and biological dynamics of the marine ecosystems within the Channel. SBC is considered a transition zone between cold water ecosystems to the north of Pt. Conception and the warm water ecosystems of Southern California. This is one reason why there is a rich diversity of animal and plant life within the SBC. A most excellent place for research!!

7. Before SBC, brief summary of various bio-optical approaches to estimate in situ PPz,t 1. Optical measurements of Q PAR( )z,t, measured or estimated a ph ( )z,t, assumed or estimated operational  ( ) z,t FULLY SPECTRAL APPROACH 1. Optical measurements of Q PAR( )z,t, measured or estimated a ph ( )z,t, assumed or estimated operational  ( ) z,t. FULLY SPECTRAL APPROACH PP z,t  PAR Q PAR( )z,t aph(  z,t  (  z,t PP z,t =  PAR  Q PAR( )z,t x aph(  z,t x  (  z,t  Field measurements will also include vertical profiles of [Chl a] for biomass estimates.  Field measurements will also include vertical profiles of [Chl a] for biomass estimates.  If accessory pigments also measured, could tell how phytoplankton community composition varied in space and time.  If temperature or density profiles measured, could tell how PP was distributed with respect to water mass type and potential vertical mixing.  If nutrients were measured, could tell if phytoplankton if productivity was likely to be nutrient-limited or nutrient-repleted 2. Gas Exchange Experiments ( hv-dependent rates of O2 evolution or inorganic carbon uptake) a) for O 2 gas exchange, bottle experiments in situ or O2 electrode experiments under simulated in situ (sis) conditions. b) for radiolabeled H 14 CO3/ 14 CO2 uptake experiments, bottle experiments in situ or photosynthetron experiments under sis conditions. In situ studies give rates of PPz.t whether or not Q PAR is known while sis studies of PP require knowledge of in situ depth profiles of Q PAR and [Chl]

8. P-I approach allows for estimating and predicting in situ PP for any t,z where light &Chl are known NB: this FW experiment measured O2 changes in bottles, which is why respiration values are reported NB: this FW experiment measured O2 changes in bottles, which is why respiration values are reported marine PP studies use C14 uptake bottles similarly deployed; do not get respiration rates and PP measurement is something between NPP and GPP marine PP studies use C14 uptake bottles similarly deployed; do not get respiration rates and PP measurement is something between NPP and GPP Problem with C14 bottles, Problem with C14 bottles, some of uptake C14 gets respired during long incubations & bacteria accumulate & community biology changes hv Chl biomass as f(x) of depth (z) PP Light-limited (alpha portion of P-I curve) Light saturated photosynthesis, Pmax Photoinhibition and/or photorespiration In situ bottle measurements provide estimtew ofin situ rates of PP for one t,z but has no predictive value IF water column was well mixed, Chl was constant as a function of depth, & just one P-I Curve could describe phytoplankton photophysiology throughout the water column, then the depth-dependent PP could be viewed as Can predict in situ Ps rates if Chl distribution or Q PAR profiles change

9. 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 of the northerly flow of the hugs the coastline until encountering the SBC which block much of the flow and divert it seward to mix 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 warmm (>20 C), oligotrophic 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

10. SUMMER in the SBC In situ photosynthetic quantum yield. Correspondance to hydrographic and optical variability within the Southern California Bight. Schofield et al 1993 In situ photosynthetic quantum yield. Correspondance to hydrographic and optical variability within the Southern California Bight. Marine Ecology Progress Series 93: 25-37 SST Very high Chl biomass at peak of Upwelling at west end of SBC Very low Chl biomass in warm oligotrophic waters At east end of SBC

11. The abundance, composition and photosynthetic capabilities of phytoplankton communities vary widely across the frontal boundaries in SBC and extending seaward Surface Pmax/vol Surface Chl /vol Surface water temperature, SST cold cold warm warm FRONTAL BOUNDARY

12. 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

13. TEMP DEPTH OF EUPHOTIC ZONE CHLBIOMASSPROFILE TEMPPROFILE MIXED LAYER DEPTH

14. California Current Cold, nutrient rich Diatom-dominated microplankton So. Califoria Counter Current, warmer, less nutrients, microflagellates, picophytoplankton (cyanobacteria & chlorophytes) Upwelling event at west end of SBC before upwelling at west end of SBC Chl biomass upwelling

15. Operational Quantum Yield for Carbon fixation, Carbon fixation,  c ( z,t) Cold side of front Warm side of front Before upwelling at west end of SBC After upwelling at west end of SBC

19. 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