Jamie Walker The Australian 21 Jun 14;
CYCLONES have emerged as the biggest wrecker of the Great Barrier Reef, surpassing the voracious crown-of-thorns starfish as a destroyer of corals.
Seven severe cyclones in nine years — two of them rated maximum-strength category five — have caused unprecedented damage to the reef, intensifying concern that the blows are coming too fast for it to withstand.
Nearly half of all coral lost in the past three decades is attributed to cyclone damage, according to management agency the Great Barrier Reef Marine Park Authority. But hope for the World Heritage-listed marine wonder can be found in a distant quarter: Scott Reef in the steamy Timor Sea.
The isolated outcrop came back from the dead after being devastated by another scourge of the Great Barrier Reef, coral bleaching, in the scorching summer of 1998.
A vast expanse of the reef was also hit by one of the worst bleaching episodes on record.
When Australian Institute of Marine Science researcher James Gilmour reached Scott Reef, 300km northwest of Broome, it was a “wasteland’’ of dead and crumbling coral, coated in algae. A few hardy specimens survived at the bottom of the lagoon. “Our initial thought was that it would take several decades to recover ... I certainly wasn’t confident that I was going to see it come back to what it was in my lifetime,’’ says Perth-based Dr Gilmour, 41.
Little happened for five years. But then the reef exploded into life, regenerating from corals that had survived the mass bleaching.
By 2004, soft new growth was crowding out the pink algae. Today, the reef is alive with stunning staghorn, elkhorn and table corals, set against schools of brightly coloured tropical fish.
“The lesson we have learned from Scott Reef is that, if the water quality is very good, reefs are very resilient,’’ Dr Gilmour told The Weekend Australian.
He believes that the news has implications for the Great Barrier Reef as its management is reviewed by UNESCO and at a Senate inquiry.
UNESCO’s World Heritage Committee backed away this week from a threat to list the reef as “in danger’’, allowing Australia another year to address concerns about port development in the marine park area.
Institute research director Jamie Oliver said the work on Scott Reef had benchmarked the regenerative capacity of corals.
But the Great Barrier Reef Marine Park Authority’s ecosystem, conservation and resilience director, David Wachenfeld, questioned whether compromised reefs would get time to recover as the frequency of severe weather and other attacks increased.
“What are the chances that a reef is going to get away for a decade with no bleaching event, no heatwave, no cyclone, no flood, no crown-of-thorns outbreak?
“These days, the chances of that are pretty low … the gaps between severe impacts to the reef are getting smaller and smaller,’’ Dr Wachenfeld said.
The mass bleaching episode in 1998 was followed by another big die-off of coral on the Great Barrier Reef in 2002, as heatwave conditions associated with an El Nino weather system took hold along Australia’s eastern seaboard and interior.
Bleaching happens when sea surface temperatures exceed the summer average by more than 1C for several weeks running, overwhelming the heat tolerance of corals. Concern is mounting that an El Nino will form this year.
A submission compiled by veteran reef scientist Ove Hoegh-Guldberg to the ongoing Senate committee inquiry into the management of the reef asserts that bleaching will result in the “loss of close to 100 per cent of corals” on the Great Barrier Reef by mid-century.
Professor Hoegh-Guldberg, director of Queensland University’s Global Change Institute, said from Washington that Australia should join the effort to develop fourth-generation nuclear power technology to mitigate climate change and its impact on the reef.
