Simulating Coral Reef Evolution

Coral reefs are one of nature's most beautiful and rich ecosystems, and rival
rainforests in biodiversity. This simulation shows the long-term evolution of a
coral reef, starting 21,000 years ago at the end of the last ice age.Coral
reefs are one of nature's most beautiful and rich ecosystems, and rival
rainforests in biodiversity. The January 1999 issue of National Geographic
featured "Coral Eden" on the cover and it was a lovely article. But it also had
a piece entitled "Coral in Peril". Coral reefs are very responsive to
pollution, overfishing, and - highly relevant to our research at NCAR -
changes in climate.

The work shown here is an embryonic effort aimed at modeling the long-term
evolution of a coral reef, starting 21,000 years ago which was at the end of
the last ice age. The fundamental goal is to develop a simulation capability
for the purpose of examining how changing conditions might affect the growth of
a reef. The parameterizations for this effort were developed based on transects
of the Great Barrier Reef.
This simulation begins 21,000 years ago, at the end of the last ice age. Over
time, the continental shelfs flooded, thus creating more habitat for coral
reefs, which flourished. The animation shows the temporal and coral-form
evolution of the reef over time. Corals play an important role in the carbon
cycle and there are quite a number of interesting ideas about possible roles
they may have played in the global climate. One hypothesis is that
shallow-water carbonate systems may have accounted for a big change of the CO2
seen in ice cores, corresponding to the period since the last ice age. There is
also the possibility of a positive feedback loop: sea-level rises providing
more habitat for coral reefs, the reefs flourish and produce more CO2, the
additional CO2 causes additional temperature increase and sea-levels rise even
more. It is an interesting point that coral reefs were once an important
source of CO2 released into the atmosphere, but now they account for only 1-2%
of human-generated CO2. In any event, one of the ideas central to this work is
that if we can successfully simulate how reefs grew since the last ice age, we
may be able to predict their evolution in the context of global change.

Global Earth System Models include vegetation models and, in the future, the
inclusion of a variety of ecosystem components will probably constitute a very
active and important area of research. A coral reef simulation such as the one
described here could be coupled with a global model to measure its response to
changing climate conditions, such as those produced by greenhouse-gas forcing.
Ultimately, such a simulation could both respond and provide feedback to the
overall system. About the Visualizations Data from the Kleypas Coral Reef
Simulation was processed to create a 3-dimensional dataset representing 210
timesteps of 100 years of topography, sea-level, and coral reef composition.

* Bathymettry: Shown in gray, this is the ocean floor upon which the coral
polyps build the "reef".
* Coral Forms: There are ten different "coral forms" managed by the
simulation. An individual coral form is a coral group that has been classified
by its basic form and response to various forcing functions. Each coral form
is represented by a different color.