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

?