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

Norfolk Island has corals found nowhere else which could be rapidly lost ‘and we won’t get them back,’ Prof Bill Leggat says. Photograph: Tom Bridge View image in fullscreen Norfolk Island has corals found nowhere else which could be rapidly lost ‘and we won’t get them back,’ Prof Bill Leggat says. Photograph: Tom Bridge Norfolk Island’s unique corals under triple threat from disease, El Niño and now government-approved dredging Exclusive: Most of the island’s corals are likely to be species that have not been formally described by science, researcher says Get our breaking news email , free app or daily news podcast Scientists fear unique corals that fringe Australia’s remote Norfolk Island could disappear because of a triple threat of disease, El Niño and a federal government plan to dredge a neighbouring shipping channel. A failure to manage sediment and pollution washing into bays from cattle farming, cleared land along with wastewater has been blamed for widespread disease and outbreaks of algae over the corals. One expert said most of the island’s corals were likely to be species that have not been formally described by science, and would be unlikely to recover if lost. “We could rapidly lose the coral reefs and we won’t get them back,” said Prof Bill Leggat, a coral expert at the University of Newcastle who has been monitoring the island’s corals and the disease outbreak for five years. Sign up for the Breaking News Australia email Speaking from the island 1,600km north-east of Sydney, Leggat said since March there had been a three-fold increase in diseased corals during of one of the longest-running coral disease events recorded on Australian reefs. Water quality was a key problem, he said, where pollution and sediment would wash into the coral lagoons during heavy rain, promoting disease and algae. “The main issue is the nutrients that increase coral disease and then algal growth that puts more stress on the corals. It’s frustrating – we should be able to fix that,” he said. He said “white syndrome” disease on coral started with a white spot that gets larger and larger, killing the coral flesh and leaving the visible white skeleton behind. Norfolk Island, with a population of 2,200, has reefs running for about 2km around the three adjoining bays of Emily, Slaughter and Cemetery. The island attracts tens of thousands of tourists each year and was one of Australia’s earliest penal colonies before welcoming in 1856 the Pitcairn island descendants of mutineers of the famed HMS Bounty. View image in fullscreen According to researchers, runoff from Norfolk Island is damaging coral reefs. Photograph: Tony Miller/Alamy Prof Tracy Ainsworth from the University of New South Wales, a member of the team monitoring the island’s reefs, said between 30% and 50% of corals had shown symptoms of the disease over the past five years. Water monitoring carried out by CSIRO on the island has suggested pollution was likely to be coming from cattle manure, waste