Coral Reef Ecosystems
Our classical view of any ecosystem• Seen as systems which transform energy and process
organic matter
Primary producer
s
Primary consume
rs
Secondary
consumers
Detritus
Detritivores
• Seen as systems which transform energy and process organic matter
Primary producer
s
Primary consume
rs
Secondary
consumers
Detritus
Detritivores
= pathway for material (or carbon)
• Seen as systems which transform energy and process organic matter
Primary producer
s
Primary consume
rs
Secondary
consumers
Detritus
Detritivores
= pathway for material (or carbon)
= pathway for energy
HeatHeat
HeatHeat
HeatHeat
Heat
Heat
Organic veneer of a reef
Net water flow
C, N, P, O
C
N
P
O
CN
P
O
Lagrangian Control Volume
Measuring Ecosystem Dynamics
C
N
P
O
CN
P
O
Time 1
Time 2
Eularian control volume
Measuring Ecosystem Dynamics
Useful measures of ecosystem ‘metabolism’
Pg = gross primary productivity (gC/m2/day)
P/R = community respiration ratio
E = excess production (gC/m2/day)
Ocean Outer reef slope Forereef
Reef crest
Back reef Lagoo
n
Water columnPg .2-.8 ? 2-7 2-7 2.6-27 .01-2.9-12.9
E .01-.65 ? -1-5.1 .3-1.5-8.7-7.3 -1.3-1.4-.5-3.4
P/R .9-1.38 ? .5-5.5 1-4 .7-3.2 .1-1.4.7-1.4
Ocean Outer reef slope Forereef
Reef crest
Back reef Lagoo
n
Water columnPg .2-.8 ? 2-7 2-7 2.6-27 .01-2.9-12.9
E .01-.65 ? -1-5.1 .3-1.5-8.7-7.3 -1.3-1.4-.5-3.4
P/R .9-1.38 ? .5-5.5 1-4 .7-3.2 .1-1.4.7-1.4
CoralsMacroalgaeAlgal turfs
0 2 46 810
MicroalgaeMacroalgaeSeagrass
0 2 46 810
How do coral reefs differ from this model?
1. Fluxes– nutrient and otherwise
2. Scales
4. The “unknowns”
3. Fate of the carbon
Cycles – nutrient and otherwise
The level of any nutrient depends partly on the flux between pools
-depends on the type of reef
Barrier reef
Water movement
Level of recycling
Cycles – nutrient and otherwise
The level of any nutrient depends partly on the flux between pools
-depends on the type of reef
Barrier reef Fringing reef
Water movement
Level of recycling
Cycles – nutrient and otherwise
The level of any nutrient depends partly on the flux between pools
-depends on the type of reef
Barrier reef Fringing reef Atoll
Water movement
Level of recycling
Cycles – nutrient and otherwise
Barrier reef Fringing reef Atoll
Degree of system closure
+ (factors increasing)
- (factors decreasing)
Water residence time,Nutrient recycling,Internal fluxes,Infilling
Exports,External connectedness,Boundary fluxes,N limitation
Scales
-nutrient level-inputs from ocean-species composition-heterotroph/autotroph composition
Scales
-nutrient level-inputs from ocean-species composition-heterotroph/autotroph composition
Fate of the carbon
Primary producer
s
Primary consume
rs
Secondary
consumers
Detritus
Detritivores
CaCO3
The Unknowns
The Unknowns
Microbial community
DetritusDissolved organics
Water (& nutrient flux) within a reef
The Unknowns
Water (& nutrient flux) within a reef
The Unknowns
?