Red alert over coral bleaching in Great Barrier Reef

In response to the recent coral-reef survey findings, the Great Barrier Reef
Marine Park Authority (GBRMPA) has lifted its response to Level Three (meaning
severe regional bleaching), the highest level possible, in its coral bleaching
response plan.

In so doing, scientists have increased the status quo as reported in our story last week (March 16, 2016) about Several Coral Bleaching North of Cairns at Response Level 2.

"A level three response level means we’re stepping
up surveys in response to the coral mortality to help us better
understand the affects of various pressures on the Reef and help guide
management actions," GBRMPA Chairman Dr Russell Reichelt said.

"The health and future of the
Great Barrier Reef is a priority for us — bleaching reinforces the need
for us to continue working with our partners to improve the Reef’s
resilience to give it the best possible chance of dealing with climate
change impacts.

"This means reducing nutrient and sediment loads in
catchment run-off, continuing our program to control coral-eating crown
of thorns starfish and being part of a global compact to reduce overall
emissions," he said.

Minister for the Environment Greg Hunt has now announced greater financial support for further research on the coral bleaching outbreak on the GBR.

Bleaching most commonly occurs when warm ocean temperatures cause
thermal stress, leading corals to expel tiny algae, known as

Without the algae, the coral’s bright
white skeleton is revealed. Corals can recover from bleaching if heat
stress lessens and conditions return to normal.

While recent late monsoonal heavy rain and cloud cover in FNQ have brought relief to much of the Great Barrier Reef from the ongoing global coral bleaching event, recent underwater surveys have detected substantial levels of coral mortality in the remote far north on inshore Cape York reefs.

Diver teams have found the worst affected sites are near the tip of Cape York, with up to 50 per cent coral mortality because of prolonged higher than average sea surface temperatures.

However, Dr Reichelt said the extent and severity of bleaching varies greatly across the GBR and the late arrival of the wet season appears to have so far spared most sections of the 344,400 square kilometre Marine Park from coral die-off.

"Further wet weather has brought down ocean temperatures, providing reefs south of Cooktown with a much-needed reprieve," Dr Reichelt said.

"We now need to see if local weather conditions over the next few weeks are favourable enough to prevent further bleaching and to help these reefs recover from the minor to moderate bleaching that we’re continuing to see south of Cooktown.

"We still have many more reefs to survey to gauge the full impact of bleaching, however unfortunately, the further north we go from Cooktown, the more coral mortality we’re finding.

"The corals in the remote far north of the Reef experienced extremely hot and still conditions this summer, and were effectively bathed in warm water for months, creating heat stress that they could no longer cope with.

"The reefs that we’ve surveyed so far indicate the large low pressure system over the north last week simply arrived too late for some."

The Australian Government’s Reef 2050 management plan includes the culling of crown-of-thorns starfish and work to improve water quality through a reduction in land run-off.

Surveys show the crown-of-thorns control program is successfully protecting coral on targeted reefs. The average coral cover on these reefs is 34 per cent, and 75 per cent have more than 25 per cent average coral cover — well above the 10 per cent critical threshold for coral recovery, says the GBRMPA.

These gains have been made despite two severe tropical cyclones (Ita in 2014 and Nathan in 2015) which damaged several of the target reefs.

Visitors to the Great Barrier Reef are encouraged to support coral recovery by abiding by zoning rules which stipulate where and how certain activities can take place, reducing marine debris, and being careful not to anchor on coral.

Surveys into the extent and severity of the bleaching have been conducted by GBRMPA staff and Queensland Parks and Wildlife Service rangers, the Australian Institute of Marine Science and the Australian Research Council Centre of Excellence for Coral Reef Studies.

Despite what some pundits might think, coral bleaching caused by heat stress isn't something that can be fixed by throwing bucket loads of money at the problem. Global warming is a global problem.

Meantime, from our experience back in late-January out at Tydeman Reef, 100nm north of Lizard Island, with Nomad Sportfishing for the filming of the IFISH Apprentice, the GBR looked to our layman's eyes at least to be vibrant and teeming.

Hopefully, the end of El Nino finally brings cooling temperatures. You can read all about the
GBRMPA Coral Bleaching Response Plan here.