Dr Hugh
Sweatman, Senior Research Scientist at AIMS, has been involved in
monitoring the Great Barrier Reef for the last ten years.
"Cyclone Larry caused severe damage to some inshore reefs which
previously had high coral cover. The offshore reefs fared better
but one of the contributing factors of this was their low coral
cover caused by outbreaks of coral-eating crown-of-thorns starfish
six to eight years ago.
"When Larry arrived, most of the reef’s table and branching
corals were still quite small and low in profile, and therefore
not as susceptible to damage as larger colonies. Unfortunately,
the reefs that suffered the worst impact were the ones that had
the most to lose."
The AIMS team assessed the effects of the cyclone during a
research expedition to the inshore and offshore reefs between
Hinchinbrook and Cairns. The most commonly observed types of
impact on corals were breakage of fragile table and branching
colonies, and dislodgement of some small massive corals.
Expedition leader, Dr Katharina Fabricius said that while
Larry’s underwater impact on a few inshore reefs was severe, the
cyclone’s effect on offshore reefs was much less than she observed
after cyclone Ingrid which decimated reefs in the far north in
2005.
"Larry crossed over the continental shelf within five hours
which was too fast to generate extreme wave heights despite its
record wind speeds. This, in combination with the low coral
profile of the offshore reefs, may explain their lucky escape."
Dr Fabricius is concerned about the impacts climate change
could have on the frequency of intense cyclones and on the extent
of the damage they will cause to reefs in the future.
"Cyclones are normal events in the lives of coral reefs.
However, the intensity of cyclones is predicted to increase due to
global warming. It is imperative for us to understand how specific
characteristics of cyclones, such as wind speed wind direction,
wave height and duration of gale force winds, are related to reef
damage."
The AIMS Long-term Monitoring Team will continue to report on
the state and condition of these reefs as part of their ongoing
program to monitor the Great Barrier Reef.
