![Page 1: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/1.jpg)
Does Biological Community Structure Influence Biogeochemical Fluxes?
JGOFS Says Yes!
Anthony F. MichaelsAnthony F. MichaelsUniversity of Southern CaliforniaUniversity of Southern California
Wrigley Institute for Environmental StudiesWrigley Institute for Environmental Studies
![Page 2: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/2.jpg)
RoadmapRoadmap
• What do we mean by community structure?
• Selected survey of community impacts on global carbon cycle– HNLC– Particulate Inorganic Carbon– Nitrogen Fixation– Remineralization length-scales
![Page 3: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/3.jpg)
Tension and BalanceTension and Balance
• Biologist’s love of the details of life
• Biogeochemist’s need to simplify in order to model global dynamics
![Page 4: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/4.jpg)
What do we need to What do we need to get a food web?get a food web?
Phytoplankton
Zooplankton
NutrientsSinking
Particles
SinksStays Suspended
![Page 5: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/5.jpg)
What do we need to What do we need to get a food web?get a food web?
Phytoplankton
Zooplankton
NutrientsSinking
Particles
SinksStays Suspended
Bacteria
(Fasham et al., 1990)
![Page 6: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/6.jpg)
Time
Nitrate
Phyto
Zoop
P-Z-N Dynamics: Populations Change through TimeP-Z-N Dynamics: Populations Change through Time
![Page 7: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/7.jpg)
Nitrate
PhytoZoop
P-Z-N Dynamics: Populations Change through TimeP-Z-N Dynamics: Populations Change through Time
![Page 8: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/8.jpg)
Nitrate
Phyto
Zoop
P-Z-N Dynamics: Populations Change through TimeP-Z-N Dynamics: Populations Change through Time
![Page 9: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/9.jpg)
Nitrate
Phyto
Zoop
P-Z-N Dynamics: Populations Change through TimeP-Z-N Dynamics: Populations Change through Time
![Page 10: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/10.jpg)
Nitrate
Phyto
Zoop
P-Z-N Dynamics: Populations Change through TimeP-Z-N Dynamics: Populations Change through Time
![Page 11: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/11.jpg)
Nitrate
Phyto
Zoop
P-Z-N Dynamics: Populations Change through TimeP-Z-N Dynamics: Populations Change through Time
![Page 12: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/12.jpg)
So, what are we really asking?
Nitrate
Phyto
Zoop
P-Z-N Dynamics: Populations Change through TimeP-Z-N Dynamics: Populations Change through Time
![Page 13: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/13.jpg)
Phyto
Does it matter what biology is hidden within each box?Does it matter what biology is hidden within each box?
![Page 14: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/14.jpg)
Phyto
DiatomsPrasinophytesPrymnesiophytes
ProchlorococcusSynechococcus
Is this level of details necessary Is this level of details necessary to understand the carbon cycle?to understand the carbon cycle?
![Page 15: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/15.jpg)
Rephrase the QuestionRephrase the Question
Do we need more structure thanP-Z-N-B to capture the important
carbon dynamics for global scales?
(e.g., more phytoplankton, more zooplankton, viruses, marine snow, etc.)
![Page 16: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/16.jpg)
Pico-Phyto
Nano-Phyto
Micro-Phyto
Community Structure and Flux: Community Structure and Flux: Circa 1988Circa 1988
Start with big size range of plantsStart with big size range of plants
<2 µm 2-20 µm 20-200 µm
![Page 17: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/17.jpg)
Nutrients
Pico-Phyto
Nano-Phyto
Micro-Phyto
![Page 18: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/18.jpg)
Pico-Phyto
Nano-Phyto
Micro-Phyto
Nano-Nano-ZooZoo
Micro-Micro-ZooZoo
Meso-Meso-ZooZoo
Nutrients
![Page 19: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/19.jpg)
Pico-Phyto
Nano-Phyto
Micro-Phyto
Nano-Nano-ZooZoo
Micro-Micro-ZooZoo
Meso-Meso-ZooZoo
Nutrients
![Page 20: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/20.jpg)
Bacteria & Nutrients
Sinking Paricles
Stays Suspended
Pico-Phyto
Nano-Phyto
Micro-Phyto
Nano-Nano-ZooZoo
Micro-Micro-ZooZoo
Meso-Meso-ZooZoo
![Page 21: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/21.jpg)
Bacteria & Nutrients
Sinking Particle
s
Stays Suspended
Pico-Phyto
Nano-Phyto
Micro-Phyto
Nano-Nano-ZooZoo
Micro-Micro-ZooZoo
Meso-Meso-ZooZoo
![Page 22: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/22.jpg)
Foodwebs and Flux - 1988Foodwebs and Flux - 1988
• Focus on f-ratio and the amount of export from surface waters
• “Ryther-esque” outcome (# trophic steps, transfer efficiency)
• Imply that removal of carbon from surface is directly related to exchange with atmosphere
![Page 23: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/23.jpg)
Ocean biology maintains a vertical DIC gradient:Ocean biology maintains a vertical DIC gradient:Balance of biology and physicsBalance of biology and physics
Nitrate+Nitrite
Dissolved Inorganic Carbon
![Page 24: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/24.jpg)
What Processes Have Significant What Processes Have Significant Affects on Air-Sea Partitioning of Affects on Air-Sea Partitioning of
Carbon Dioxide?Carbon Dioxide?
1. Incomplete Nutrient Utilization (HNLC)
2. Particulate Inorganic Carbon:Organic Carbon Ratio
3. Changes in Nitrogen fixation:Denitrification balance (LNLC)
4. Changes in Remineralization Length-scales
Do food webs matter for any of these?
![Page 25: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/25.jpg)
1.1. Incomplete Nutrient Utilization in Incomplete Nutrient Utilization in the Surface Waters (HNLC)the Surface Waters (HNLC)
Century residence times
Decadal residence times
Millenial residence times Dissolved Inorganic Carbon
Nitrate+Nitrite
![Page 26: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/26.jpg)
Most of the ocean shows Most of the ocean shows near-complete nutrient utilizationnear-complete nutrient utilization
Surface Nitrate (µmoles/kg)
![Page 27: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/27.jpg)
Low Nutrient AreasLow Nutrient Areas
If nutrient levels stay near detection and if C:N:P stoichiometry is constant,
then P-Z-N might be enough for the global carbon models
– Those are some big “ifs”
– There is more of interest on this planet than just global carbon
![Page 28: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/28.jpg)
HNLC RegionsHNLC Regions
Changes in net utilization of surface nutrients Changes in net utilization of surface nutrients changes DIC gradient and air-sea partitioning changes DIC gradient and air-sea partitioning
(within limits)(within limits)
• High-nutrient, low chlorophyll areas (HNLC) in Southern Ocean, Equatorial Pacific, North Pacific and some coastal zones
• Trace nutrient limitation (Fe), Diatom blooms (Si)
• Reduce HNLC area - 15-100 ppm reduction in atm CO2
• Amenable to direct manipulation (political hot potato)
![Page 29: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/29.jpg)
Nutrient Cycling in the Modern Southern OceanNutrient Cycling in the Modern Southern Ocean
(Anderson et al., 2002)
![Page 30: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/30.jpg)
(Anderson et al., 2002)
Nutrient Cycling in the Glacial Southern OceanNutrient Cycling in the Glacial Southern Ocean
![Page 31: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/31.jpg)
Nutrient Cycling in the Glacial Southern OceanNutrient Cycling in the Glacial Southern Ocean
(Anderson et al., 2002)
![Page 32: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/32.jpg)
Nutrient Cycling in the Glacial Southern OceanNutrient Cycling in the Glacial Southern Ocean
(Anderson et al., 2002)
![Page 33: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/33.jpg)
1.1. Incomplete Nutrient Utilization in Incomplete Nutrient Utilization in the Surface Waters (HNLC)the Surface Waters (HNLC)
Influence of Community Structure?Influence of Community Structure?
• Taxa-specific responses to Fe• Si+N requirements in diatoms, N
requirements in other phytoplankton• Taxa-specific grazing responses• Ballasting issues
![Page 34: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/34.jpg)
2. Changes in2. Changes inParticulate Inorganic Carbon FluxParticulate Inorganic Carbon Flux
• Archer and Maier-Reimer, 1994
• Skeletons of coccolithophorids, foraminifera and pteropods
• Alkalinity change! Increase in PIC flux -> increase in pCO2
• Net effect on atmosphere depends on PIC:POC ratio
• Community structure effects analogous to remineralization length scale
![Page 35: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/35.jpg)
(Sarmiento et al., 2002)
![Page 36: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/36.jpg)
Carbonate Flux Linked toCarbonate Flux Linked to
Organic Carbon Flux via BallastingOrganic Carbon Flux via Ballasting (a la Armstrong et al, 2002)(a la Armstrong et al, 2002)
(Klaas and Archer, 2002)
![Page 37: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/37.jpg)
2.2. Changes inChanges inParticulate Inorganic Carbon FluxParticulate Inorganic Carbon Flux
Influence of Community Structure?Influence of Community Structure?
• Carbonate skeletons found in a subset of taxa: coccolithophorids, foraminifera and pteropods
• Ecosystem dynamics will determine relative contributions of these taxa
• Mix of autotrophs and heterotrophs - must be mix of top-down and bottom-up controls
• Some of these taxa susceptible to creating blooms
• Ballasting link to organic carbon fluxes, stronger for carbonate fluxes than opal (correlation - causation?)
![Page 38: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/38.jpg)
3. Changes in Nitrogen Fixation - Denitrification Balance
Century residence times
Decadal residence times
Millenial residence times
Lower DIC
Nitrate+Nitrite
Dissolved Inorganic Carbon
Higher DIC
Extra Nitrogen Fixation
![Page 39: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/39.jpg)
3. Changes in Nitrogen Fixation - Denitrification Balance
Century residence times
Decadal residence times
Millenial residence times
Lower DIC
Nitrate+Nitrite
Dissolved Inorganic Carbon
Higher DICExtraDenitrification
![Page 40: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/40.jpg)
Trichodesmium spp.Trichodesmium spp.Best Known Planktonic DiazotrophBest Known Planktonic Diazotroph
![Page 41: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/41.jpg)
Excess Nitrate (µmoles/kg)
Dep
th (
m)
1 Year
4 Years7 Years
7.5 Years
7.3 Years
9 Years
8 Years
11 Years
39 Years
29 Years
19 Years
15 Years
12 Years
0 4 50
200
400
600
800
1000
1200
Excess Nitrate = NO3 - 16*PO4
Data from BATS
![Page 42: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/42.jpg)
(Gruber and Sarmiento, 1997)
N* in the Atlantic Ocean
![Page 43: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/43.jpg)
(Deutsch et al., 2001)
N* in the Pacific Ocean
![Page 44: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/44.jpg)
(Husar et al., 1997)
![Page 45: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/45.jpg)
Key Assumptions and Dynamics:Key Assumptions and Dynamics:
• Iron from dust limits nitrogen fixation
• Reasonable flexibility in N:P ratios and nutrient controls on N-fixation
• Carbon Modeling
– NCAR Ocean GCM (Doney)
– Multi-compartment box model (Sigman)
– Add adequate N fixation for 1 Gt/y C fixation
– Restrict N fixation to 10-40° (N and S)
– C:N=6.6, Assume flexible N:P within N* range
– 100-300 year runs
![Page 46: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/46.jpg)
(Doney, Moore in prep)
![Page 47: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/47.jpg)
(Doney, Moore in prep)
![Page 48: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/48.jpg)
Nitrogen Fixation Feedback Cycle Hypothesis(as an example)
![Page 49: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/49.jpg)
Two Additional Biological Two Additional Biological Characteristics:Characteristics:
• Diazotrophs form large surface blooms
![Page 50: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/50.jpg)
![Page 51: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/51.jpg)
Two Additional Biological Two Additional Biological Characteristics:Characteristics:
• Diazotrophs form large surface blooms
• Nitrogen fixation dynamics seem to change on decadal time-scales (at least in the Pacific Ocean)
![Page 52: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/52.jpg)
Dave Karl and co-workers
![Page 53: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/53.jpg)
Dave Karl and co-workers
![Page 54: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/54.jpg)
3.Changes inNitrogen Fixation - Denitrification Balance
Influence of Community Structure?Influence of Community Structure?
• Diazotrophy found in a distinct subset of all prokaryotic taxa
• Chemical defenses against grazing in some• Some taxa symbiotic in eukaryotes (esp.
diatoms, creates silica requirement)• Denitrification - special environmental
conditions, specific prokaryotes
![Page 55: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/55.jpg)
4. Changes in remineralization length-4. Changes in remineralization length-scales and C-N-P stoichiometryscales and C-N-P stoichiometry
Century residence times
Decadal residence times
Millenial residence times Dissolved Inorganic Carbon
Nitrate+Nitrite
![Page 56: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/56.jpg)
Changes in remineralization length-scalesChanges in remineralization length-scales
• Depends on the depth horizon and ventilation time-scale:
– Annual: 10-20 Gt C/y – Multi-annual (>200 m): 5-10 Gt C/y– Multi-Decadal: 2-4 Gt C/y– > Centennial: ~1-2 Gt C/y
![Page 57: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/57.jpg)
![Page 58: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/58.jpg)
0
200
400
600
800
1000
1200
1400
0 2 4 6 8 10 12 14
b=1.5b=1b=0.7
De
pth
(m
)
POC Rain (mmolC/m2d)
1-3 GtC/yr
Export ~5-15 GtC/yr
Global PP~50 GtC/yr
Larger b value, more POC is recycled in upper oceanSmaller b value, more POC gets to deep ocean
Small b
Large b
Fz = F100 *(z/100)-b
![Page 59: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/59.jpg)
0.4
0.6
0.8
1
1.2
1.4
0 5 10 15 20 25
NABEEQPACASSO
Exp
on
ent,
b
POC Export at 100 m (mmolC m-2 d-1)
US-JGOFS Open-Ocean SitesUS-JGOFS Open-Ocean Sites
(Berelson, 2001)
(Martin et al., 1987)
![Page 60: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/60.jpg)
0.4
0.6
0.8
1
1.2
1.4
0 5 10 15 20 25
JGOFSMartin OceanMarginMartin Margin
Exp
onen
t, b
POC Export at 100 m (mmolC m-2 d-1)Berelson (in prep)
![Page 61: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/61.jpg)
Slope’s always positive---
best explanation-
Reactivity POC > Reactivity bSi
0
1000
2000
3000
4000
50000 0.5 1 1.5 2 2.5 3
Arabian SeaEqPac Central Cal.NABEUSJGOFS SO (NACC)Guinea BasinWalvis RidgeOS Papa
Wat
er D
epth
(m
)
bSi/Corg ratio (molar)Berelson (in prep)
![Page 62: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/62.jpg)
Can bSi content slow net particle settling rates?(Hypothesis: Yes)
Higher bSi Content
SteeperSlope
0
5
10
15
20
25
30
35
0 0.5 1 1.5 2 2.5
Sediment Trap Data
Slo
pe
(1/m
) x1
0^5
Si/Corg
at 3000 m
Berelson (in prep)
![Page 63: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/63.jpg)
0
50
100
150
200
Eq. (880-2284) Eq. (2284-3618)) 5°N (1191-2091)
El Nino Non-El Nino
Set
tlin
g V
eloc
ity
(m/d
ay)
Location (depth, m)
US-JGOFS EqPac—1992US-JGOFS EqPac—1992
Low Opal
Hi Opal
Berelson (2001)
![Page 64: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/64.jpg)
![Page 65: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/65.jpg)
1 mm
salp
euphausiid
copepod
Fecal Pellets
![Page 66: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/66.jpg)
Bacteria & Nutrients
Sinking Particle
s
Stays Suspended
Pico-Phyto
Nano-Phyto
Micro-Phyto
Nano-Nano-ZooZoo
Micro-Micro-ZooZoo
Meso-Meso-ZooZoo
![Page 67: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/67.jpg)
Bacteria & Nutrients
Pico-Phyto
Nano-Phyto
Micro-Phyto
Nano-Nano-ZooZoo
Micro-Micro-ZooZoo
Sinking Particles
SALPSSALPS
![Page 68: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/68.jpg)
Twice in a decade!Twice in a decade!
Enormous Blooms!
![Page 69: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/69.jpg)
Asexual reproduction by budding
![Page 70: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/70.jpg)
The Outer LimitsThe Outer Limits
~ 0.5 Gt C
~ 1 Gt C
![Page 71: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/71.jpg)
Ecosystems and Ecosystems and Plankton BloomsPlankton Blooms
• Ecosystems are complex-dynamical systems
• Bloom dynamics are poorly understood and hard to study
• Top-down vs bottom-up, a debate that is sorely lacking in ocean science
• Blooms created and controlled by internal dynamics of ecosystem, rarely bounded by external controls like nutrients
![Page 72: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/72.jpg)
4.4. Changes in remineralization length-Changes in remineralization length-scales and C-N-P stoichiometryscales and C-N-P stoichiometry
Influence of Community Structure?Influence of Community Structure?
• Mix of biological and physical sources to different types of sinking particles
• Ballasting signals (mechanisms?)
• Diatom blooms may have non-intuitive impact on remineralization length-scale
• Bloom forming organisms create unique time-space scale issues for remineralization and for science.
![Page 73: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/73.jpg)
ConclusionsConclusions
• Community structure matters for the partitioning of carbon between ocean and atmosphere.
• JGOFS has clarified some simple issues that now allow us to ask much more sophisticated questions.
• We still lack tools to study these processes on the time, space and taxonomic levels that are required.
• When community structure is important, the outcome is often emergent from internal dynamics.
![Page 74: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/74.jpg)
Future DirectionsFuture Directions
• Community structure where it matters (HNLC, nitrogen fixation, etc.)
• The “twilight zone” and below
• Bloom dynamics (when they occur and when they matter)
• Complex systems approaches
• Be ready for surprises (viruses, archea, who knows what else).
![Page 75: Does Biological Community Structure Influence Biogeochemical Fluxes? JGOFS Says Yes!](https://reader035.vdocuments.us/reader035/viewer/2022062314/5681456c550346895db23c1e/html5/thumbnails/75.jpg)
Thank you!Thank you!