biogeochemical controls and feedbacks on the ocean primary production
DESCRIPTION
Biogeochemical Controls and Feedbacks on the Ocean Primary Production. Carbon Cycle. Marine Biota. Export Production. Export Production of Organic Carbon. Ocean Ecosystem Structure. Trophic levels and dynamics. Ocean Ecosystem Structure. Example of a more complex Food Web. - PowerPoint PPT PresentationTRANSCRIPT
Biogeochemical Controls and Feedbacks on the Ocean Primary Production
Carbon Cycle
Marine Biota
Export Production
Export Production of Organic Carbon
Trophic levels and dynamics
Ocean Ecosystem Structure
Example of a more complex Food Web
Ocean Ecosystem Structure
Energy Transfer between Trophic Levels is not efficient
Ocean Ecosystem Structure
Trophic levels and dynamics
Food Web
Energy
ENERGY
How about Mass Transfer?
How do we measure Biomass?
Alaska
200 km
Large scale Eddies
A useful way to keep track of biomass in the lower trophic levels is to follow the path of MACRONUTRIENTS
Carbon C Nitrogen N
Phosphorus P
Redfield Ratio
C : N : P106 : 16 : 1
Redfield A.C., On the proportions of organic derivations in seawater and their relation to the composition of plankton. In James Johnson Memorial Volume. (ed. R.J. Daniel). University Press of Liverpool, pp. 177-192.
source 1) atmosphere
source 1) not biological, not atmospheric2) fluvial
C : N : P
source 1) from N2 atmosphere gas2) ocean subsurface3) remineralization of dead organic matter4) biological (e.g. excretions)
Nitrogen appears to be the limiting factorin ocean productivity in todays oceans
A simplified diagram of an NPZD Ecosystem
Z
P
N
D
NO3
Chlorophyll
Largedetritus
Organic matter
N2 NH4 NO3
Water column
SedimentSediment
Phytoplankton
NH4
Mineralization
Uptake
Nitrification
Nitrification
Grazing
Mortality
Zooplankton
Susp.particles
Aerobic mineralizationAerobic mineralizationDenitrificationDenitrification
N2
Fixation
Mix Layer depth
Description of the oceanic ecosystem based on Nitrogen exchanges
A simplified diagram of an ecosystem
Carbon Cycle
Marine Biota
Export Production
Export Production of Organic Carbon
A simplified diagram of an ecosystem
Nutrient Sources for Primary Production
The fluxed of organic carbon must be sustained by an adeguate flux of macronutrients
If macronutrients are unavailable then the CO2 flux is reduced!
What are the controls on Export Production?
1) Ocean nutrient inventory
2) Utilization of nutrients in HNLC
3) Change Redfield Ratio
What are the controls on Export Production?
Surface CHL-A
1) Central Gyres 2) Upwelling Regions
Nitrogen appears to be the control duringmodern time.
(but was not always this way e.g. duringlat glacial maxima)
1) Ocean nutrient inventory
What are the controls on Export Production?
N* = N – 16 P (Gruber & Sarmiento 1997)N* = N – 16 P (Gruber & Sarmiento 1997)
N = 25790
NN22 fixation fixation
DenitrificationDenitrification
Modern TIME
2) Utilization of nutrients in HNLC
What are the controls on Export Production?
High Nutrient, Low (Medium) Chlorophyll Regions
Why aren’t the nutrients being completely utilized by phytoplankton?
Phosphorous Chlorophyll
Conkright et al., 1994
µm
SeaWiFs
3) Change Redfield Ratio
Do not know much about this!
What are the controls on Export Production?
END of Lecture
Southern Ocean HNLC
Biologically Mediated Exchange of CO2 Between the Ocean and Atmosphere
The fluxed of organic carbon must be sustained by an adeguate flux of macronutrients
Phytoplankton Blooms
Bands of the dionflagellate Lingulodinium polyedrum moving onshore over the troughs of a series of internal waves
Trophic levels and dynamics
Food Web
Energy
How about Cyanobacteria?
Hydrothermal vents and Chemosyntheticbacteria
