PLANKTONIC RESPIRATION THE DARK SIDE OF THE MOON

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1 Agouron_PW_lecture_4 1/1 PLANKTONIC RESPIRATION THE DARK SIDE OF THE MOON A) WHAT IS RESPIRATION [CH 2 O] + C + H 2 O [CH 2 O] + NO 3 - C + N - + H 2 O H 2 S / 2 H 2 SO 4 + H 2 O (note no consumed) (note no C produced) Definition of Respiration: Respiration is a catabolic reaction involving the transfer of protons (and electrons) between a proton donor and a proton acceptor Respiration - fundamental reaction Proton donor e.g. H + + e - Proton acceptor Respiration end products H 2 O Respiration byproducts e.g. C Photosynthesis - fundamental reaction Proton donor H 2 O Proton acceptor C H + + e - Photosynthesis byproduct Photosynthesis end product [CH 2 O] Proton (& electron) donors Respiration end product Proton (& electron) acceptors Respiration byproduct H 2 O C [CH 2 O] HNO 3 HN HN HNO 3 HN N 2 or NH 3 NH 3 HN H 2 S H 2 S H 2 S H 2 S C CH 4 CH 4 C Also others Mn, U, Cr, Se, As, perchlorate Also others

2 Agouron_PW_lecture_4 2/1 B) FORMS OF RESPIRATION There are 6 or more oxygen consuming reactions, not all would be considered as forms of respiration. From Table 3.2, Raven & Beardall (in del Giorgio and Williams et al. 25) Oxygen consuming reactions Property Mehlerperoxidase reaction RUBISCO oxygenase Glycolate oxidase Chlororespiration Cytochrome oxidase Alternate oxidase V max (catalytic capacity at saturation) V max for gross evolution.15 of V max of RUBISCO carboxylase or gross evolution.8 of V max of gross evolution ~.1 of V max of gross ~.1 of V max of gross evolution (range.2-.3) As for cytochrome oxidase, but not additive with it. K ½(O2) mmol m ? In vivo effect of full non-cyclic chain Absolute requirement Absolute requirement Absolute requirement Inhibition Variable (inhibits or stimulates) Variable (inhibits or stimulates) In vivo coupling to C evolution No Via the pathways of glycolate metabolism Via the pathway of glyoxylate metabolism Via the pathways of supply of NAD(P)H Via the pathways that supply NAD(P)H Via the pathways that supply NAD(P)H Rate of 16 uptake relative to rate of 18 uptake ?

3 Agouron_PW_lecture_4 3/1 Two relevant forms in plankton rate measurements 1) Classical mitochondrial dehydrogenation 2) Mehler Reaction 1) Classical mitochondrial dehydrogenation Broad Outline ADP + P i ATP Substrate 2H + + 2e - Electron Transport System (ETS) H 2 O Overall Scheme of the Biochemistry of Respiration Proteins Carbohydrates Lipids -1ATP External Products & Reactants NH 3 Glycolysis +2ATP Reduced Pyridine Nucleotides NADH+H + C NADH+H + Acetyl-Co A +1GTP 2C TCA Cycle 3NADH+3H + FADH 2 3 6H 2 O Terminal Oxidation Sysyem +17ATP 5NADH+5H + FADH 2

4 Agouron_PW_lecture_4 4/1 Light 2) Mehler Reaction 2H 2 O H 2 O 2H + + 2e - Mehler reaction 2H + + 2e - NADP NADPH 2 C NADP [CH 2 O] The Mehler reaction is essentially a safety valve to release the congestion due to excess proton/electron production, it is not strictly a respiration reaction as it yields very little energy. Its biochemistry is complex: NADPH (d) NADP + GSSG 2 GSH AsA ( c) DHA (b) NADPH NADP + MDAR 2 MDA 2 AsA sapx H 2 O H 2 B 2 - SOD (a) PS II NADPH O O 2 2 NADP + - FD 2 SOD PS I 2 AsA H 2 tapx 2 MDA H 2 O A 2 H 2 O

5 Agouron_PW_lecture_4 5/1 PRODUCTION RESPIRATION ALGAL RESPIRATION (R A ) Light ADP + P i ATP 2H 2 O H 2 O Mehler reaction Substrate 2H + + 2e - 2H + + 2e - 2H + + 2e - NADP Electron Transport System (ETS) H 2 O NADPH 2 C NADP [CH 2 O] ADP + P i ATP Substrate 2H + + 2e - Electron Transport System (ETS) H 2 O OXYGEN PRODUCTION (GPP 2 ) MEHLER REACTION (R M ) ORGANIC CARBON PRODUCTION (GPP C ) HETEROTROPH RESPIRATION (R H )

6 Agouron_PW_lecture_4 6/1 C) ECOLOGICAL TERMINOLOGY AND PHYSIOLOGICAL EQUIVALENCES D) MEASUREMENT APPROACHES Gross Community Oxygen Production = GPP 2 Gross Community Organic Production (GPP C ) = GPP 2 R M Net Community Oxygen Production (NCP) = GPP 2 (R A + R H + R M ) = GPP C (R A + R H ) Net Primary (Algal) Oxygen Production (NPP) = GPP 2 (R H + R M ) = GPP C R H GPP C = R A + R H + NCP GPP 2 = R A + R H + R M + NCP 1) Light/Dark bottle 2) In situ diel curves 3) 18 GPP/ NCP 4) ETS 5) Post Light Incubation Dark 14 C loss 6) Derivations from Biomass 1) Light/Dark bottle 24 hr Light bottle = GPP O2 (R A + R H ) 24 hr Dark bottle = -(R A + R H ) Light-Dark bottle = GPP O2 (R A + R H ) + (R A + R H ) = GPP O2 = GPP C as R M = Assumes R A and R H are the same in the light as dark Including Mehler reaction 24 hr Light bottle = NCP = GPP O2 (R A + R H + R M ) 24 hr Dark bottle = -(R A + R H ) Light-Dark bottle = GPP O2 (R A + R H + R M ) + (R A + R H ) = GPP O2 - R M = GPP C Assumptions as above

7 Agouron_PW_lecture_4 7/1 2) In situ diel curves In situ O2 change Respiration rate 5 P-R 12hr 2.5 R 12hr GPP O2 = (-12hr) - (12-24hr) Resp O2 = R A +R H = 2* (12-24hr) NCP O2 = * (-24hr) Assumes R A and R H are the same. Experimental design at high latitudes, with extensive twilight or no real dark period is far from straightforward 3) 18 GPP/ NCP If it is assumed that 18 GPP is true gross O2 production i.e. GPP O2, then 18 GPP - NCP = GPP 2 (GPP 2 (R A + R H + R M )) = R A + R H + R M This gives a measure of all forms of oxygen consumption, including the Mehler reaction, in principle R A + R H can be measured from the dark bottle, so R M can be derived. What you do with it is not clear 4) Electron transport system measurement (ETS) 5) Post Light Incubation Dark 14 C loss

8 Agouron_PW_lecture_4 8/1 6) Derivations from Biomass Typically relies upon the use of allometric relationships (see Lecture 5, A) section 11) Resp = W*R *L B Where W is the biomass in the size group L L is its size characteristic (e.g. length or individual weight) R is a scaling factor B is the allometric coefficient (typically somewhere in the region of -.75) E) RESPIRATION OBSERVATIONS IN THE OCEANS 1) Who does it Percentage Contribution of Trophic Group Bacteria 4 Phytoplankton & Protozoa 2 8 Larval & Adult Zoopl. Unresolved Autotrophs Heterotrophs 3 Biomass Calc <1 Size fractionation <1 Biomass Models <1 Food web Models <1 Geometric mean <1 Biomass Calc 1<1 Size fractionation 1<1 Biomass Models 1<1 Food web Models 1<1 Geometric mean 1<1 Biomass Calc 1<1 Size fractionation 1<1 Biomass Models 1<1 Food web Models 1<1 Geometric mean 1<1 Biomass Calc 1<1 Size fractionation 1<1 Biomass Models 1<1 Food web Models 1<1 Geometric mean 1<1

9 Agouron_PW_lecture_4 9/1 2) What are the Rates Frequency (normalised to largest occurrence a) Frequency Distribution of Volumetric Rates 1 Photosynthesis Respiration to.1.1 to to to.1.1 to to to 1 1 to to to 1 1 to to 46 Rate (as mmol m -3 d -1 ) 46 to 1 Frequency (normalised to largest occurrence b) Frequency Distribution of Depth-integrated Rates Photosynthesis Respiration 1 to to to 1 1 to to to 1 1 to 215 Rate (as mmol m -2 d -1 ) 3) How does it vary with Time a) Time series of Respiration and Photosynthesis b) Phase Plot of Respiration and Photosynthesis 1 Metabolic rate (mmol m -3 d -1 ) Respiration (mmol m -3 d -1 ) 1 Heterotrophic Sector Autotrophic Sector Time (days) Photosynthesis (mmol m -3 d -1 ) c) Time development of P/R ratio d) Log-log Plots of Respiration versus Photosynthesis AUTOTROPHIC PHASE HETEROTROPHIC PHASE 2 P/R ratio Log (Respiration) as mmol m -3 d Time (days) Log (photosynthesis) as mmol m -3 d -1

10 Agouron_PW_lecture_4 1/1 4) How does it vary in Space 6 Number of Non-Atlantic Profiles Number of profiles 4 2 Number of Atlantic Profiles Area 7-8S 6-7S 5-6S 4-5S 3-4S 2-3S 1-2S -1S -1N 1-2N 2-3N 3-4N 4-5N 5-6N 6-7N 7-8N Latitude band Latitudinal Averages Latitudinal Totals 5 4 GP Latitudinal Average Resp Latitudinal Average NCP Latitudinal Average 5 4 GP Latitudinal Total Resp Latitudinal Total NCP Latitudinal Total Mean rate (as mmol O2 m -2 d -1 ) Total rate (as 1 15 mol a -1 ) S 6-7S 5-6S 4-5S 3-4S 2-3S 1-2S -1S -1N 1-2N 2-3N 3-4N 4-5N 5-6N 6-7N 7-8N 8-9N 7-8S 6-7S 5-6S 4-5S 3-4S 2-3S 1-2S -1S -1N 1-2N 2-3N 3-4N 4-5N 5-6N 6-7N 7-8N 8-9N 5) Will History Determine the Future God help us if it does! Gaarder and Gran's early work Riley & Steemann Nielsen's O2 studies Introduction of the 14 C technique Pommeroy & Johannes papers Starting up of the JGOFS programmes Steemann Nielsen's 14 C studies Koblenz-Mishke et al's 1968 paper Present number of 14 C observations:??1, to 25, Starting up of the JGOFS programmes 2, 4, 1,5 3, 1, O2 14C ETS 2, 5 1, 1/1/19 1/1/191 1/1/192 1/1/193 1/1/194 1/1/195 1/1/196 1/1/197 1/1/198 1/1/199 1/1/2 1/1/19 1/1/191 1/1/192 1/1/193 1/1/194 1/1/195 1/1/196 1/1/197 1/1/198 1/1/199 1/1/2 We ve been running a business with estimates of revenue but little knowledge of expenditure a sure route to bankruptcy!