Norfolk Island’s unique corals under triple threat from disease, El Niño and now government-approved dredging | Norfolk Island

Scientists fear unique corals on Australia’s remote Norfolk Island could be wiped out by the triple threat of disease, El Niño and the federal government’s plan to dredge a neighboring shipping channel.

Failure to manage the sediment and pollution coming into the bays due to cattle farming, cleared land and wastewater are seen as responsible for widespread diseases and algae outbreaks on corals.

One expert said most of the island’s corals were probably species not officially recognized by science and would be unlikely to recover if lost.

“We could lose coral reefs rapidly and not be able to get them back,” said Prof Bill Leggatt, a coral expert at Newcastle University who has been monitoring the island’s corals and the disease outbreak for five years.

Speaking from the island 1,600 kilometers northeast of Sydney, Leggatt said there had been a three-fold increase in diseased corals since March during one of the longest-running coral disease events recorded on Australian reefs.

He said water quality was a major issue, as pollution and sediment would wash into coral lagoons during heavy rain, causing disease and algae to form.

“The real problem is nutrients that increase coral disease and then algal growth, which puts more stress on the corals. It’s frustrating; we have to be able to fix that,” he said.

He said the “white syndrome” disease seen in corals begins with a white spot that gradually grows larger, killing the coral flesh and leaving behind the visible white skeleton.

Norfolk Island, with a population of 2,200, has reefs stretching for approximately 2 km around three adjacent bays: Emily, Slaughter and Cemetery.

The island attracts tens of thousands of tourists every year and was one of Australia’s oldest penal colonies before welcoming the Pitcairn island descendants of the mutineers of the famous HMS Bounty in 1856.

Prof Tracy Ainsworth from the University of New South Wales, a member of the team monitoring the island’s reefs, said between 30 per cent and 50 per cent of corals had shown signs of the disease in the past five years.

water monitoring carried out by CSIRO on the island He suggested that the pollution is likely to come from cattle manure, wastewater management, including septic tanks, and manure.

An El Niño developing in the tropical Pacific risks increasing water temperatures during the summer months, causing coral to bleach and potentially die, Ainsworth said.

The federal government’s infrastructure department won environmental approvals in April 2025 to dredge a channel to improve access to Kingston Pier, where many island supplies and tourists arrive. Work could start later this year.

Water quality issues, a plan to dredge near reefs and El Niño have created the perfect storm for corals, Ainsworth said.

“That’s the only thing you can do to kill the corals. There’s a lot of coral survival,” he said.

Neil Tavener, known locally as Snowy, is a 73-year-old lifelong island resident who floats on the coral most days. Before retiring, he worked in the island’s administration on water quality and public health issues.

“The lagoons and corals are the jewels in Norfolk Island’s crown; they are priceless,” he said.

“It took the white man maybe a few hundred years to fill it, but it’s happening little by little.”

Dr D., a coral taxonomist at the Queensland Museum and James Cook University. Tom Bridge surveys corals on Norfolk Island and Lord Howe Island, about 600 miles to the west.

About 40% of the corals in Norfolk and Lord Howe are probably found nowhere else, he said. They were isolated from other corals, meaning they had little chance of respawning due to the lack of neighboring reefs.

“The risk of extinction for these corals is really high, but it’s a silent extinction because they’re not even described.” [in the scientific literature]he said.

“The populations are quite small and isolated from each other. If you lose them, they won’t come back.”

A spokesman for the federal infrastructure department said the Kingston Pier project is a “critical upgrade” to deepen and widen the channel providing “access to all tidal ports” to accommodate “larger commercial, passenger and fishing vessels.”

The department was planning to award a contract for civil works in August, with rock wall repairs expected to take place in the coming months, followed by dredging work.

The statement said the project was approved under national environmental laws with strict conditions, including limiting dredging to 0.5 hectares, disposing of waste on land and real-time monitoring of water quality.

Independent experts will oversee monitoring “to protect the surrounding reefs and marine environment,” the statement said.

A spokesman for the Norfolk Island regional council said septic systems, wastewater, stormwater and other activities all needed “ongoing management to maintain water quality”.

The council said new strategies to manage waterways and cattle grazing are being developed and a working group with representatives from multiple government agencies has been formed to coordinate water quality management.