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 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.

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

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 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

6. 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.

7. Lecture 10: FYI for readings on waters in or near the Santa Barbara Channel (SBC) SBC resides in northern portion of the Southern California Bight (not Bite) California Current (CC): cool, 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 produces cold, nutrient rich water which mixes with the CC water forming sharp frontal boundaries as it encounters the SCCC. Subtropical oligotrophic waters flow north along the coast in summer months, more so in El Nino years 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

8. The abundance, composition and photosynthetic capabilities of phytoplankton communities vary widely across the frontal boundaries in SBC and extending seaward From your reading P et al 1987 Surface Pmax/vol Surface Chl /vol Surface water temperature, SST

9. Note differences in pigment concentration range for cold, front, warm waters SBC, fig. From P et al. 1987.

10. Diatom-dominated Synechococcus ?? expressed as mg C/m3/hr

11. 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