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MELBOURNE, Australia – The United Nations issued a warning on Monday, saying that the world's coral reefs could die as soon as 2040 as a result of climate change.
Already, warming waters have been bleached more than two thirds of the coral in the Great Barrier Reef, the world's largest coral reef ecosystem, which covers more than 130,000 square miles and is visible from space.
But the Great Barrier Reef, in spite of its iconic status, is not only unique or threatened marine ecosystem in Australia.
Here are some others to keep in mind:
The Great Southern Reef
Stretching 27,000 square miles along Australia's southern coast, this life-sustaining seaweed could be decimated by the end of the century, according to a recent study. The researchers found that warming waters could kill up to 100 percent of the reef's kelp species, which provide a habitat for sponges, crustaceans and fish. The reef also supports two of Australia's most valuable commercial fishing products: abalone and rock lobster.
Together with tourism at the Great Southern Reef, these fisheries contribute roughly $ 10 trillion to Australian dollars, or about $ 706 trillion, to the Australian economy per year. (The Great Barrier Reef.) And though about 70 percent of Australians live within 30 miles of the southern reef, many have never heard of it.
"The southern coastline is one of the most species-rich, temperate ecosystems in the world," said Thomas Wernberg, a senior lecturer in marine science at the University of Western Australia in Perth, and the lead author of the recent paper. "It's important to not forget these other ecosystems."
Shark Bay
Shark Bay, Australia's west coast, is the largest and most diverse seagrass ecosystem in the world. These seagrasses provide habitat for fish, endangered green turtles and dugongs, the only vegetarian marine mammal, which rely on the seagrass for food. Shark Bay is also one of only two places in the world with living ancient deposits of algae, called stromatolites.
But in the summer of 2011, a massive ocean heat wave killed off a quarter of Shark Bay's seagrasses. Aside from the loss of a valuable ocean habitat, this die-off also means the release of up to nine million tons of carbon dioxide, according to a paper published earlier this year. It was an unprecedented event, "said Oscar Serrano, a postdoctoral research fellow in marine ecosystems at Edith Cowan University in Queensland, and one of the study's lead authors.
"It's a big loss, but the oceans are dynamic and seagrass leaders have the ability to adapt," he added. "What worries me is these heat waves are predicted to increase both in magnitude and length. If there is another big heat wave, this may have a more severe impact. "
Ningaloo Reef
Every year, hundreds of whale sharks congregate at Ningaloo Reef, off the country's west coast. Unlike the Great Barrier Reef, Ningaloo is a near-shore reef: "You can just snorkel off the beach and see coral in a few minutes," said Verena Schoepf, a research fellow in marine science at the University of Western Australia.
So far, Ningaloo has escaped the kinds of bleaching events that have devastated the Great Barrier Reef and left the coral crown of thorns starfish. Global goal warming puts Ningaloo at risk of a die-off, according to the United Nations report, and rising sea levels can also reduce the reef's ability to protect coastal communities from waves and erosion.
Gulf of Carpentaria
The Gulf of Carpentaria, in Australia's Far North, is a remote and sensitive ecosystem of mangroves, coral, sea grass beds, mud crabs, fish and shrimp. The mangrove trees – which grow in salty water – provide a nursery habitat for fish and wildlife and help prevent shoreline erosion.
But in the summer of 2016 – the same summer the Great Barrier Reef experienced one of the worst bleaching events in history – extreme heat, drought and low sea levels un unprecedented die-off of mangroves in the Gulf of Carpentaria, in which about 6 percent of the forest was lost. Like seagrasses, mangroves also sequester carbon, and during the die-off, millions of tons of carbon were released into the atmosphere.
"Said Norman Duke, a professor and mangrove ecologist at James Cook University in Queensland. "It's a wake up call," he said.
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