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Tech & Science Coral bleaching a sign NT marine ecosystems threatened by rising temperatures, scientists say

01:30  14 march  2018
01:30  14 march  2018 Source:   abc.net.au

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Top End rangers filmed large patches of bleached coral from the air this year in the same area where they filmed healthy coral three years ago, and scientists are warning that more bleaching events are expected.

My Account Sign in Sign out Subscribe Subscribe. It’s also the longest bleaching event in recorded history, and scientists say it shows no evidence of ending any time soon. The fragile nature of coral reefs leaves them hypersensitive to climate change, but ecosystems above ground

Scientists are warning that entire ecosystems are dependent on keeping reefs healthy.© ABC News: Jane Bardon Scientists are warning that entire ecosystems are dependent on keeping reefs healthy. Coral bleaching in waters near the Cobourg Peninsula is ringing alarm bells that the Northern Territory's marine ecosystems are under threat from rising sea surface temperatures, scientists say.

Rangers at the Garig Gunak Barlu National Park on the remote peninsula, about 60km north-east of Darwin, filmed large patches of bleached coral from the air in January, in the same area where they filmed healthy coral in January three years ago.

Their finding followed a warning from the United States agency that monitors reef bleaching threats, the National Oceanic and Atmospheric Administration, that NT waters were on a red alert for water temperature rises of 4 degrees Celsius or more above average.

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As temperatures rise , mass coral bleaching events and infectious disease outbreaks are becoming more frequent. Climate change will affect coral reef ecosystems , through sea level rise , changes to the frequency and intensity of tropical storms, and altered ocean circulation patterns.

Coral makes up less than 1 percent of the underwater ecosystem yet helps to protect 25 percent of marine species, generates tourism revenue and boosts fishing, according to data from The Nature Conservatory. Many scientists say coral bleaching

"Cobourg is an extremely valuable marine park and we've seen some evidence coming out of there that they are suffering from coral bleaching," said Adele Pedder from the Australian Marine Conservation Society.

"There's evidence that we've recently had a sea surface temperature warming event that is like a heatwave underwater."

Ms Pedder said it would be tragic if some of the Territory's remote reefs died before many of them had been explored and studied.

"We know that climate change is having an impact, so we can expect more of these events, we can expect more coral bleaching happening in the NT," she said.

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Coral bleaching has affected virtually the entire Great Barrier Reef and many other coral reef systems globally, a result of the continuing rise in global temperatures and exacerbated by the summer's major El Niño "Mesophotic coral ecosystems are a seed bank for some organisms," said Professor Baker.

Study finds fragile marine ecosystems cannot grow fast enough to keep pace with sea levels. This article is over 1 month old. Australia’s Great Barrier Reef is already suffering coral ‘ bleaching ’ from rising temperatures .

Reefs in the NT's tropical waters were likely to be stressed by continuing sea surface temperature rises as global carbon emissions increase, said Selina Ward, a coral researcher from the University of Queensland's School of Biology.

Coral bleaching alerts were issued by a US agency for waters off the NT in January.© Supplied: NOAA Coral bleaching alerts were issued by a US agency for waters off the NT in January. "We keep having, or almost having, the warmest years on record, so at the moment that's the trajectory that we're on, that we're likely to get more and more bleaching events if we don't reduce our emissions quite drastically," she said.

Frequent bleaching events give the reefs less chance to recover, she said.

"If we have mortality, there's less time for new corals to come in and fill those spaces," Dr Ward said.

Dr Ward warned that entire ecosystems dependant on the reefs were threatened by coral mortality.

"Fish are dramatically affected by loss of coral, and as well as the fish, there are thousands of invertebrate species that live amongst the corals, so that's a problem," she said.

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Corals are the basis of diverse ecosystems , supporting a myriad of other creatures, and the researchers found the Bleaching is linked with global warming, as rising sea temperatures cause stressed corals to expel the “The Great Barrier Reef is certainly threatened by climate change, but

“This is a protected place and yet it’s not able to escape the temperature ,” said Angela Richards Dona of the Hawaii Institute of Marine Biology and a Cobb, who was not involved in the research, said it was “sobering to read about the level of bleaching at one of the crown jewels of coral ecosystems .

The Australian Marine Conservation Society is calling on the NT and Federal governments to improve coastal management to reduce other stresses on reefs.

Adele Pedder is calling on governments to reduce emissions and manage coastlines well.© ABC News: Jane Bardon Adele Pedder is calling on governments to reduce emissions and manage coastlines well. Ms Pedder said reefs not suffering from other pollution stresses were more able to recover from climate change-related bleaching.

"We know we need to keep our rivers clean, and flowing to the sea, we need to ensure that we don't roll out seabed mining in the NT," she said.

"And we need to implement protections like Indigenous Protected Areas, jointly managed national parks, and recreational fishing zones, so we can maintain our fishing lifestyle."

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