STARFISH NUMBERS INCREASE
The latest round of reef surveys monitoring starfish numbers in the
Cairns to Lizard Island area are leading scientists to believe another
major outbreak of crown-of-thorns starfish is imminent.
Starfish research committee (COTSREC) chairman Professor Graham Mitchell
said that crown-of-thorns densities have been observed 3 to 8 times higher
than normal in this area. These findings are a result of three coordinated
Reef-wide monitoring programs being carried out by GBRMPA, AIMS and Reef
users. Broad- and fine-scale monitoring of reefs north of Cairns have
been supplemented by reporting from tour operators through GBRMPA's COTWATCH
program.
Generally, the outbreaking populations are characterised by the presence
of both juvenile and adult starfish, with the potential for further increases
in numbers as they mature and reproduce.
Responding to the expected outbreaks, the Centre is funding additional
research and extension projects, including a new genetic study to identify
parental links within starfish populations. AIMS scientist, Dr John Benzie,
is investigating samples taken from initial brood stocks already collected
from the Lizard Island area and in storage at AIMS. A total of 1000 samples
will be collected from nine locations, including several reefs near Cairns
and Innisfail. Using DNA sampling techniques, he will determine if the
genetic composition of current outbreaks are the same as those from the
late 1980s, which may shed light on whether past and present cycles are
derived from the same source area. Dr Benzie will also compare the genetic
make up of starfish populations locally, and between the Reef's northern
and central regions.
Additional funding will also support further fine-scale field
surveys. This transect-based method has proved effective in detecting
small starfish in the early stages of a population increase. Udo Engelhardt
from GBRMPA will continue these surveys, which are already signalling
early warnings for likely starfish outbreaks next year. His research will
include a study into the effects of predation by large reef fish on small,
juvenile crown-of-thorns.
Finally, to keep the public and media informed about the predicted increase,
an updated information booklet will be produced about COTS monitoring,
local controls, basic biology, a discussion on possible causes and how
reefs recover from outbreaks.
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