Reminder: Midterm 1 is one week from today on Friday February 1stReminder: Midterm 1 is one week from today on 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 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 PrézelinExtended office hours next week for Professor PrézelinMonday 11AM-1PMMonday 11AM-1PMWednesday 10AM-NOONWednesday 10AM-NOON

Big!!Big!!

Phyto Story: The monster diatom Phyto Story: The monster diatom Coscinodiscus wailessiCoscinodiscus wailessi

Regular sized diatoms

Common Indo-Pacific Ocean species, invaded English ChannelCommon 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

at ~60 % Pmax, cell division rates

become maximal, eg. =max

No PP, No growth, possible Senescence No PP, No growth, possible Senescence (decay, death, ), formation Resting stages, (decay, death, ), formation Resting stages,

PPmaxmax

Light limited PP & Growth rates (Light limited PP & Growth rates ( ) )

Light saturated PP and Light saturated PP and

Light limited PP but Light saturated Light limited PP but Light saturated

Light-inhibited PP and Light-inhibited PP and

slopes

IIkk IItt

IIk k = = Pmax/alphaPmax/alpha IIt t = = Pmax/betaPmax/beta

without photoinhibition,without photoinhibition, Ps = Pmax Ps = Pmax .. tanh (I/I tanh (I/Ikk))

with photoinhibition,with photoinhibition, Ps = [Pmax Ps = [Pmax .. tanh (I/I tanh (I/Ikk)] minus [ eq. )] minus [ eq. describing shape of betadescribing shape of beta] ] Beta varies from a linear to exponential declineBeta varies from a linear to exponential decline

Parameters of Photosynthesis-Irradiance curves

, alpha , alpha , beta , beta

= Ps rate/ PFD

Indices of Photoadaptation PhotoinhibitionIndices of Photoadaptation PhotoinhibitionChl-specific Chl-specific relative quantum yield relative quantum yield

Photosynthetic potential

Comparison of P-I curves for different algae under different growth conditionsComparison of P-I curves for different algae under different growth conditions

• Which has the highest PWhich has the highest Pmaxmax??• Which has the highest alpha?Which has the highest alpha?• Which has the lowest Ik?Which has the lowest Ik?• At 50 At 50 Ein mEin m-2-2 s s-1-1, which has the greatest , which has the greatest

rates of Ps?rates of Ps?

• At 200 At 200 Ein mEin m-2-2 s s-1-1, which has the greatest , which has the greatest

rates of Ps?rates of Ps?

• Above what QAbove what QPARPAR does does CeratophylumCeratophylum

Ps rates exceed those of Ps rates exceed those of HydrillaHydrilla??

P-I relationships are a “signature” of theP-I relationships are a “signature” of thephoto-physiological state of the phytoplanktonphoto-physiological state of the phytoplanktoncell, population, and mixed communitycell, population, and mixed community

One mole of hv = one Einstein of hv = one EinOne mole of hv = one Einstein of hv = one Ein

= 6.02 x 10 = 6.02 x 10 23 23 moleculesmolecules

P-I sampling strategies for determination ofP-I sampling strategies for determination of in situ in situ rates of primary productivity, PP rates of primary productivity, PP

For determinations of For determinations of instantaneous in situ PPinstantaneous in situ PP at one place (z) and time (t) at one place (z) and time (t)PPz,t,PPz,t, expressed as mg C/m3/hr or mgC/mg Chl/hr 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,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 using (P-I)z,t, could estimate PP for other conditions (Qpar)z,t and (Chl a)z,t although although the accuracy would depend on the P-I response remaining constantthe accuracy would depend on the P-I response remaining constant

i.e. i.e. Daily rates of PP at same locationDaily rates of PP at same location ((PP)z,PP)z, expressed as mg C/m3/day or mgC/mg Chl/day expressed as mg C/m3/day or mgC/mg Chl/day

i.e. i.e. Integrated water column PPIntegrated water column PP

(( PP)t,PP)t, expressed as mg C/m2/hr or mgC/mg Chl/hr) expressed as mg C/m2/hr or mgC/mg Chl/hr)

i.e. i.e. Daily integrated water column PPDaily integrated water column PP PPPP,, expressed as mg C/m2/day or mgC/mg Chl/day) 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.Accuracy increases with knowledge of how P-I, Chl a, and Qpar vary as f(x) of t,z.

Case Study: Santa Barbara Channel (SBC)Case Study: Santa Barbara Channel (SBC)

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

Before SBC, brief summary of various bio-optical approaches to estimate in situ PPz,tBefore SBC, brief summary of various bio-optical approaches to estimate in situ PPz,t

1.1. Optical measurements of Optical measurements of QQPAR(PAR()z,t)z,t, measured or estimated , measured or estimated aaphph(()z,t)z,t, assumed or estimated , assumed or estimated

operationaloperational (() z,t) z,t. FULLY SPECTRAL APPROACHFULLY SPECTRAL APPROACH

PP PP z,tz,t = PARPAR QQPAR(PAR()z,t )z,t x aph(aph(z,tz,t x (( z,tz,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 If accessory pigments also measured, could tell how phytoplankton community composition varied in space and time. and time.

If temperature or density profiles measured, could tell how PP was distributed with respect to water mass If temperature or density profiles measured, could tell how PP was distributed with respect to water mass type and potential vertical mixing. type and potential vertical mixing.

If nutrients were measured, could tell if phytoplankton if productivity was likely to be nutrient-limited or If nutrients were measured, could tell if phytoplankton if productivity was likely to be nutrient-limited or nutrient-repletednutrient-repleted

2. Gas Exchange Experiments ( hv-dependent rates of 2. Gas Exchange Experiments ( hv-dependent rates of O2 evolution O2 evolution oror inorganic carbon uptake) inorganic carbon uptake)

a) a) for Ofor O2 gas exchange2 gas exchange, bottle experiments , bottle experiments in situin situ or O2 electrode experiments under or O2 electrode experiments under simulated in situ (simulated in situ (sissis) conditions.) conditions.

b) for b) for radiolabeled Hradiolabeled H1414CO3/CO3/1414CO2 uptake CO2 uptake experiments, bottle experiments experiments, bottle experiments in situin situ or or photosynthetron experiments under sis conditions.photosynthetron experiments under sis conditions.

In situ In situ studies give rates of PPz.t whether or not studies give rates of PPz.t whether or not QQPARPAR is known while sis studies of PP require is known while sis studies of PP require knowledge of in situ depth profiles of knowledge of in situ depth profiles of QQPARPAR and and [Chl][Chl]

P-I approach allows for estimating and predicting in situ PP for P-I approach allows for estimating and predicting in situ PP for anyany t,z where light &Chl are known t,z where light &Chl are known

• NB:NB: this FW experiment this FW experiment measured O2 changes in measured O2 changes in bottles, which is why bottles, which is why respiration values are respiration values are reportedreported

• marine PP studies use C14 marine PP studies use C14 uptake bottles similarly uptake bottles similarly deployed; do not get deployed; do not get respiration rates and PP respiration rates and PP measurement is something measurement is something between NPP and GPPbetween NPP and GPP

• Problem with C14 bottles, Problem with C14 bottles, some of uptake C14 gets some of uptake C14 gets respired during long respired during long incubations & bacteria incubations & bacteria accumulate & community accumulate & community biology changesbiology changes

hv

Chl biomass as f(x) of depth (z)Chl biomass as f(x) of depth (z)

PP

Light-limited (alpha Light-limited (alpha portion of P-I curveportion of P-I curve))

Light-limited (alpha Light-limited (alpha portion of P-I curveportion of P-I curve))

Light saturated Light saturated photosynthesis, Pmaxphotosynthesis, Pmax

Light saturated Light saturated photosynthesis, Pmaxphotosynthesis, Pmax

Photoinhibition and/or Photoinhibition and/or photorespirationphotorespiration

Photoinhibition and/or Photoinhibition and/or photorespirationphotorespiration

In situ bottle measurements provide estimtew ofin situ rates of PP for one t,z but has no predictive valueIn 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 IF water column was well mixed, Chl was constant as a function of depth, & just one P-I Curve could describe function of depth, & just one P-I Curve could describe phytoplankton photophysiology throughout the water phytoplankton photophysiology throughout the water column, then the depth-dependent PP could be viewed as column, then the depth-dependent PP could be viewed as

IF water column was well mixed, Chl was constant as a IF water column was well mixed, Chl was constant as a function of depth, & just one P-I Curve could describe function of depth, & just one P-I Curve could describe phytoplankton photophysiology throughout the water phytoplankton photophysiology throughout the water column, then the depth-dependent PP could be viewed as column, then the depth-dependent PP could be viewed as

Can predict in situ Ps rates if

Chl distribution or QPAR profiles change