Climate Change: Australian fish Starving, Great Barrier Reef Dying
Pastor Dale Morgan
*Climate Change: Australian fish Starving, Great Barrier Reef Dying*
AAP | Monday, 23 June 2008
Starving fish are killing sections of the Great Barrier Reef already
weakened by climate change, an Australian scientist says.
And some fish species also face extinction – with potentially serious
consequences for commercial fisheries.
Morgan Pratchett, of the James Cook University-based ARC Centre of
Excellence for Coral Reef Studies in Townsville, has spent the last two
months at Britain's University of Newcastle using chemical markers, such
as carbon 13, to study the feeding interaction between corals and fish.
The technology of using stable isotopes like carbon 13 has previously
been used to study the food chain in large marine food fisheries, but
never before to analyse fish behaviour and impacts on coral reefs.
"There's a whole suite of coral-feeding fish and during normal
conditions, they don't kill the reef," Dr Pratchett told AAP today.
"However, during periods of stress on the reef, they do contribute to
excess mortality among corals.
"The typical example is when you have coral bleaching and the coral is
already experiencing reduced energy reserves and then as the fish
continue to feed on them it imposes a further energetic cost."
Dr Pratchett said that butterfly fish, which are the main group of
coral-feeding fish, had all but disappeared from some sections of the
central Great Barrier Reef.
"We are already looking closely at one particular species, which is a
really specialised butterfly fish which could face a really high
extinction risk as a consequence of ongoing bleaching," Dr Pratchett said.
"It's already happened in some locations, that's for sure.
"Even in the central Great Barrier Reef during the bleaching that
happened in 2001 and 2002, this one species, which is the chevron
butterfly fish, disappeared entirely."
Their recovery had been so slow that only a few chevron butterfly fish
had been seen in the region in the last year, he said.
It was just another indication of the effects of global warming, he said.
"It's getting more and more serious and just another one of the stories
that show we need to respond to climate change.
"If this translates to other fish being affected, like commercially
important fish, then there's a significant economic cost associated with
it."
Dr Pratchett is in the first year of a five-year study which will
examine other species.
"One of the things I'm hoping to use the stable isotopes for is to study
the effect on coral trout and if they feed on butterfly fish, will they
be affected as well."
"Previously, studying what coral trout required catching the trout and
looking inside their guts, but the stable isotopes allow me just to take
samples of fish that have been caught for commercial purposes or
whatever and just analyse it that way."