Biogeochemical Controls and Feedbacks on the Ocean Primary
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
Ocean Ecosystem Structure Energy Transfer between Trophic Levels is not efficient
Trophic levels and dynamics Food Web Energy
ENERGY
How about Mass Transfer?
How do we measure Biomass?
Alaska
Large scale Eddies 200 km
A simplified diagram of an ecosystem
A useful way to keep track of biomass in the lower trophic levels is to follow the path of MACRONUTRIENTS Carbon C Phosphorus Nitrogen P N
Redfield Ratio C: N: P 106 : 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.
C: N: P source 1) atmosphere source 1) from N 2 atmosphere gas 2) ocean subsurface 3) remineralization of dead organic matter 4) biological (e. g. excretions) source 1) not biological, not atmospheric 2) fluvial Nitrogen appears to be the limiting factor in ocean productivity in todays oceans
Simple Nitrogen Model Phytoplankton Zooplankton Detritus Nutrients The arrows indicate fluxes between the pools of nitrogen
Description of the oceanic ecosystem based on Nitrogen exchanges N 2 Nitrification Mix Layer depth NH 4 NO 3 Uptake Phytoplankton Mineralization Grazing Chlorophyll Zooplankton Mortality Water column Fixation Susp. particles Large detritus Nitrification N 2 NH 4 Denitrification Sediment Organic matter NO 3 Aerobic mineralization
Carbon Cycle Marine Biota Export Production
Export Production of Organic Carbon
What are the controls on Export Production? 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 CO 2 flux is reduced!
What are the controls on Export Production? 1) Ocean nutrient inventory 2)2) Utilization of nutrients in HNLC 3)3) Change Redfield Ratio
Surface CHL-A 1) Central Gyres 2) Upwelling Regions
Detailed structure of the oceanic ecosystem
Phytoplankton Blooms and Physical Environement
Phytoplankton Blooms and Physical Environement Bands of the dionflagellate Lingulodinium polyedrum moving onshore over the troughs of a series of internal waves
Nonlinear Internal Waves and Phytoplankton Isopycnals
Why do we care about the Export Production?
What are the controls on Export Production? 1) Ocean nutrient inventory Nitrogen appears to be the control during modern time. (but was not always this way e. g. during lat glacial maxima)
Modern TIME N 2 fixation Denitrification N = 25790 N* = N – 16 P (Gruber & Sarmiento 1997)
What are the controls on Export Production? 1. 2) Utilization of nutrients in HNLC
Southern Ocean HNLC
Southern Ocean HNLC
What are the controls on Export Production? 1. 3) Change Redfield Ratio 2. Do not know much about this!
Southern Ocean HNLC
Biologically Mediated Exchange of CO 2 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 Chemosynthetic bacteria
- Slides: 54
