Coral Reef Ecosystems

Coral Reef Ecosystems
Is Earth’s climate and associated ecosystem about
to act erratically
Are humans to blame
What can we do

! --What is natural
! --What are natural variations and
what variations are controlled / caused by
human actions
! --What can we do to best serve
ourselves
! --Is the Earth ecosystem about
to die

The gross structure of climate change
and sea-level fluctuations - we know.

Climate changes. So what
Sea level fluctuates. So what

Can past fluctuations
of sea level help us
understand present
and future fluctuations
of sea level
What will happen
next

What are coral reefs
What is the concern
What is the evidence for concern
What can be done
What am I doing

WHAT IS A CORAL REEF

WHAT ARE WHAT CORALS IS CORAL

WHAT ARE CORALS
Animal
Mineral
Vegetable

Corals are animals
coral
polyp
jellyfish
sea anemone

Coral
Spawning

Corals are plants
Zooxanthellae: plant cells
within the coral tissue
Up to 50% of “coral” biomass
is plant material.

Corals are Minerals
Corals make skeletons of CaCO 3 (aragonite)

Global distribution of coral reefs

WHY DO CORALS DIE
DISEASE
OLD AGE
STRESS
! natural
! human-induced

STRESS
TEMPERATURE: ! too hot or too cold (climate)
SALINITY: !! too salty, too fresh! (climate)
TURBIDITY: ! algae (nutrients ocean circulation
! ! ! ! ! ! climate)
! ! ! sediment (land use, climate)
SEA LEVEL:!! too low, too high (climate)
WATER CHEMISTRY:! pH; CO 2 for skeletons (climate)
UV RADIATION:!
“POLLUTION”!
HUMAN CONTACTS
ozone!

Bleached coral could be environment warning
Monday, January 25, 1999
Scientists studying coral reefs in the
Florida Keys have found that 100-
year-old corals are suddenly
succumbing to diseases they were
previously able to resist. The
Cornell University researchers warn
this may be a sign of future
environmental stress on the planet.
http://www.enn.com

What is CORAL BLEACHING
Corals evolved in warmer environments than
today; so they should be able to survive. It may
be that if temperature change were slowly
increasing, corals could evolve, …
As water temperature “rapidly” rises above
normal (few degrees), corals are stressed and
their symbiotic zooxanthellae leave.
Temperature variability.

Mean Annual Temperature (1400 - present)

Mean Annual Temperature (1400 - present)
This is the concern.

El Niño
La Niña

Multivariate ENSO Index
Fluctuations: 3 to 7 years
The intensity of El Niño events is increasing.

Multivariate ENSO Index
Fluctuations: 3 to 7 years
The intensity of El Niño events is increasing.
(Really Perhaps this is part of a natural
variation in intensity.)

Aspergillosis (fungal)

Common plants and animals suffer from
diseases. Why not corals They do!
Black Band Disease (bacterial)

Black Band Disease

Unknown Disease

Coralline Lethal
Orange Disease
(CLOD)
Dark Spot
Disease

Red Band Disease
Rapid Wasting
Disease

HUMAN IMPACTS

HUMAN IMPACTS

ANCHOR DAMAGE

Miner’s
Canary

Surface temperatures have
warmed over the past century

WORLD
RESOURCES
INSTITUTE
The polar ice cap is melting

WORLD
RESOURCES
INSTITUTE
The polar ice cap is melting
How “natural” is this climate change

Humanity has grown in numbers over time
7,000
Millions of people
6,000
5,000
4,000
3,000
2,000
1,000
0
0 500 1000 1500 2000 2500
Year

Excess nutrients may spur algal blooms
Post 1972

For perhaps the first time in the history of our planet, a single
species may be close to exerting an effect that rivals the importance
of …. natural controls.
- Dennis Hubbard, coral scientist

Are global changes (in coral reefs) resulting from human
actions What is NATURAL

Earth’s Canary

How do Earth systems really work

Data
Fish Belt Transect Survey
2.5 m Colored Wire or Rod
100m Transect Line
Coral Reef

125,000 years old

coral rubble
in place corals

Catastrophic die-off of
corals YES.