The full impact of coral bleaching across the Great Barrier Reef would become clearer this week as aerial surveys of hundreds of reefs are completed in the bottom two-thirds of the world’s biggest reef system.
An aerial survey carried out last week over almost 500 individual reefs between the Torres Strait and Cairns revealed some severe bleaching of corals closer to shore, but almost none on outer reefs.
From yesterday, the spotter plane headed south over reefs where satellite observations and temperature readings have shown corals are likely to have undergone higher levels of stress than those in the north.
Photo: Reuters
Scientists say that those corals could be found to have been badly bleached, as they are less used to higher temperatures and had escaped major impacts in 2016 and 2017.
Dave Wachenfeld, the chief scientist at the Great Barrier Reef Marine Park Authority, told reporters that whatever the survey concluded, the current bleaching should sound “a very loud alarm bell” on the plight of the reef under global heating.
Stress has been building across the length of the reef this summer with many anecdotal reports from tourism operators, tourists and recreational diver of severe bleaching.
Last month, average sea surface temperatures on the reef were 1.25°C above normal and the highest on record going back to 1900.
Corals bleach if the water temperature is too high for too long. Survival from bleaching depends on how high temperatures are and for how long. Some species of corals have higher tolerance than others.
Observations of conditions on the reef from satellites and in-water temperature loggers suggest central and southern parts have accumulated high levels of stress.
However, the authority said the full picture would only come clear once the aerial surveys were completed at the end of this week, and the data had been analyzed.
In 2016 and 2017, the world heritage reef experienced back to-back bleaching that was intense enough to kill almost half the reef’s corals over those two years.
Central and southern parts of the reef were not severely affected in those years, meaning they are not used to the stress and could be harder hit.
Terry Hughes, director of the Australian Research Council’s Centre of Excellence for Coral Reef Studies at James Cook University, spent 17 hours across four days in the air last week scoring bleaching on reefs with a staff member from the authority.
After completing the first four of nine days of aerial surveys, Hughes told reporters that most of the severe bleaching had been seen at coastal reefs.
On Friday, flying from Lockhart River to Cairns, Hughes said that corals at Princess Charlotte Bay at the bottom of the Cape York Peninsula had been severely bleached, but the impacts were much less on reefs further away from the coast.
Many of the outer reefs in the north — known as “ribbon reefs” because of their slim and snaking appearance from above — had escaped bleaching.
“A lot of the reefs we have been looking at were badly affected in 2016 and 2017,” Hughes said. “They don’t have a lot of corals on them and the corals that are there have managed to survive 2016 and 2017, and so they are tough.”
Hughes said it “remains to be seen what will happen in the south,” but there were more coral species in those areas — including staghorn and table acroporas — that would be more susceptible to bleaching.
Some of those central and southern reefs “have accumulated a lot of heat, particularly near the coast,” he said. “This is shaping up to be strongly coastal — 2016 and 2017 were cooler in the south and, this time around, it is not cool in the south.”
“Even if it turns out to be a relative moderate event compared to 16 and 17, it is still cumulative and because the footprints are different, the cumulative amounts of the reef that’s affected severely or moderately will go up,” he said.
William Skirving, of the US government’s Coral Reef Watch program at the National Oceanic and Atmospheric Administration, said the agency’s analysis showed how localized the stress had been.
However, whether that stress had translated to severe bleaching would be be answered by the aerial surveys, Skirving said.
“Let’s cross our fingers that the corals were not as susceptible as they were in the past,” he said.
A prominent Christian leader has allegedly been stabbed at the altar during a Mass yesterday in southwest Sydney. Bishop Mar Mari Emmanuel was saying Mass at Christ The Good Shepherd Church in Wakeley just after 7pm when a man approached him at the altar and allegedly stabbed toward his head multiple times. A live stream of the Mass shows the congregation swarm forward toward Emmanuel before it was cut off. The church leader gained prominence during the COVID-19 pandemic, amassing a large online following, Officers attached to Fairfield City police area command attended a location on Welcome Street, Wakeley following reports a number
‘GUARDIAN ANGEL’: The new security law would protect global investors’ rights, freedom, assets and investments in Hong Kong, a top Beijing official said Top Beijing officials in charge of Hong Kong affairs yesterday lashed out at critics of the territory’s new national security law, calling them “mantises and flies.” Hong Kong authorities last month enacted the territory’s second national security law, which expanded on legislation Beijing imposed four years ago to quell dissent after massive democracy protests in 2019 were quashed. The two laws together punish nine categories of broadly defined crimes — ranging from sedition and insurrection to foreign interference and theft of state secrets — with some carrying penalties of up to life imprisonment. The latest law raised concerns over further
SEEKING CHANGE: A hospital worker said she did not vote in previous elections, but ‘now I can see that maybe my vote can change the system and the country’ Voting closed yesterday across the Solomon Islands in the south Pacific nation’s first general election since the government switched diplomatic allegiance from Taiwan to Beijing and struck a secret security pact that has raised fears of the Chinese navy gaining a foothold in the region. The Solomon Islands’ closer relationship with China and a troubled domestic economy weighed on voters’ minds as they cast their ballots. As many as 420,000 registered voters had their say across 50 national seats. For the first time, the national vote also coincided with elections for eight of the 10 local governments. Esther Maeluma cast her vote in the
China’s growing hold over the Solomon Islands is “alarming,” a powerful opposition figurehead said yesterday, ahead of elections that could further entrench Beijing’s foothold in the region. “During these past five years, there have been so many things that China was involved in. It’s really alarming at the moment,” Daniel Suidani said in an exclusive interview. Suidani said he is troubled by what he believes is Beijing’s corrosive impact on democracy in the island nation. Solomon Islands has warmly embraced China under mercurial Prime Minister Manasseh Sogavare, with the two nations inking a murky security pact in 2022. A torrent of