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Warming and acidifying oceans are destroying the world's coral reefs and the diverse ecosystems they sustain. Reef habitats have already shrunk an estimated 30% to 50% since the 1980s, and experts say they could vanish almost completely in the next 20 years.
A recent study points to another threat to the survival of coral reefs: sudden drops in oxygen levels.
The study, published in Nature Communications, confirms the observations of scientists working to save coral ecosystems that are home to a large proportion of the world's marine life.
In September 2017, the study's lead author, coral reef ecologist Maggie Johnson, was preparing to free-dive in the Caribbean waters off the coast of Bocas del Toro in Panama for the Smithsonian Tropical Research Institute's long-term monitoring program of coastal ecosystems. While sitting on the anchored boat and putting on fins, Johnson saw calm, clear water. But after diving underneath the surface, she and a colleague noticed something very different.
First, they saw fish clumped together above a well-delineated line of murky water. Then, they spotted languishing creatures on the seafloor: urchins with drooping spines, deflated anemones that were lying flat, sea stars piled on top of each other trying to escape the murky water. After resurfacing, they detected a noxious, foul smell exuding from the water.
"This was unlike anything I'd ever experienced," Johnson, now a researcher at the Woods Hole Oceanographic Institute, recalled.
Consequences of ocean deoxygenation
Oxygen is an essential component for supporting life. When water temperatures rise, they hold less gas, which explains declining oxygen levels in warming oceans.
On the Panamanian coast, a sudden, localized drop in oxygen in the water had killed a large portion of the reef ecosystem, essentially by suffocating its inhabitants. According to the study, a mix of low wind activity may have caused low oxygenated water to stagnate while nutrient runoffs from agriculture and sewage may have promoted excess growth of algae that further depleted oxygen when they decomposed.
Some marine creatures, such as fish, were able to swim away. Most of them couldn't escape the dead zone, however. In just days, the sudden deoxygenation event had been catastrophic, according to Johnson.
"There were massive corals that were alive, that were really old. They've been there for potentially hundreds of years, and after the event, they were gone," she said.
Over the next six days of the deoxygenation event, the researchers monitored the reef and collected samples. They found that compared to before the event, the reef had lost half of its coral cover.
The study also reported that a year after the event, species of the community that included corals, sponges and algae didn't fully recover. The shallower reef, which seemed to fare better than the deeper reef — perhaps due to having more stress-tolerant coral species — showed slow signs of recovery.
"It's been years since the event, and the ecosystem — particularly down a little bit deeper — hasn't really recovered. It's not like this happened, everything died, and then it all came back. It doesn't come back," Johnson told VOA.
Microbes, they observed, did seem to regrow in a month after the event and demonstrated a speedier recovery.
Coral bleaching in reefs
Mass coral bleaching events, which can emerge over weeks or months, have been a huge concern for conservationists and ecologists as a leading cause of dying reefs. Warm water can drive coral to expel the colorful algae residing in their hard tissue, turning vibrant habitats a skeletal white.
Bleached coral can still recover, but if too much time passes without their algae residents to feed them nutrients, they'll starve and die. Or if events become too frequent, the coral will have no time to recover in between.
Stresses from deoxygenation events, as seen in Bocas del Toro's reef, can also cause coral bleaching. And while deoxygenation events may happen on a smaller scale than warming events, such as within a bay or a lagoon, the speed at which they occur can leave behind a devastated reef within days before response teams can even mobilize or detect them.
"When we think about hypoxic stress, coral reefs are not the first place I think of … but clearly, it happened there," said Francis Chan, a marine ecologist studying low oxygenation, or hypoxia, in the Pacific Ocean at Oregon State University. "It points a light to (asking) where else in the tropics is this a problem … and are we measuring low oxygen in the right places to see if we can catch these phenomena?"
Strategies for combating low oxygen stress in coral reefs include continuous monitoring, policy changes to address nutrient runoffs, and studying stress-tolerant corals.
"It's clearer and clearer, based on the science that we have today, that climate change is going to reduce the amount of oxygen that we have in a lot of marine ecosystems," added Chan. "Do we have climate-ready ecosystems? Do we have climate-ready research and a monitoring enterprise? That's where we have opportunities to do something."(VOA/HP)
The UN Environment Programme (UNEP) and The Ocean Agency, in collaboration with creativity partner Adobe, on Friday launched the Ocean League, a new campaign that showcases the power of creativity in driving positive change for ocean protection and climate action.
The ocean is facing a perfect storm of pollution, overfishing, and climate change, and these threats have pushed ecosystems such as coral reefs to the tipping point of collapse.
Coral reefs alone support 25 per cent of all ocean life and over half a billion people with food and income.
At this critical moment in time, the campaign invites individuals, leaders, organisations and brands to join the #OceanLeague and the Glowing Gone campaign, a global movement supporting greater ocean protection.
As a part of the collaboration, the Ocean League pledge for greater ocean protection is powered by Adobe Sign, making it easy to access and e-sign from any device.
Additionally, Adobe has created specially designed ocean-themed Adobe Photoshop Camera lenses, giving everyone the opportunity to immerse themselves in underwater worlds and share creative imagery to show their support.
“The crisis facing the ocean is one of the biggest environmental issues of our time. We need to be far more creative in our approach to create a groundswell of popular support and action for the ocean. This is why we are excited to have teamed up with Adobe on this campaign,”
said Leticia Carvalho, Head of Marine and Freshwater at UNEP.
On September 30, the UN Biodiversity Summit will take place, marking the start of a year packed with international conferences where conservation targets for the next decade will be determined — described as “the Super Year for the Ocean” by the UN Secretary-General’s Special Envoy for the Ocean, Peter Thomson.
UNEP, The Ocean Agency and Adobe will showcase this groundswell of support to policy-makers through visual displays at key events, with the specific goal of prioritizing coral reefs and oceans in the Post-2020 framework at the Conference of the Parties to the Convention on Biological Diversity in 2021 (CoP15).
“In this moment, the power of creativity and the ability for it to have a global impact has never been more relevant,” said Adobe Vice President Brand Marketing, John Travis.
“Adobe is committed to inspiring and enabling creativity for all, so that together we can create change. We are so proud to support UNEP and The Ocean Agency and empower the global community to take action towards ocean conservation.”
The campaign collaboration builds on the success of the #GlowingGone campaign, a partnership among UNEP, The Ocean Agency, Adobe and Pantone in 2019, which reached millions of people through creative challenges and sports events, such as the World Surf League.
The campaign brings attention to the ocean’s warning sign that is currently going unnoticed: corals glowing in fluorescent colours to protect themselves from rising ocean temperatures.
These fragile ecosystems are on the frontline of climate change and need the world’s attention.
“Ocean conservation is rarely prioritised as an issue, despite the fact that a healthy ocean is of fundamental importance to all life on earth. We know that a positive show of mass support, including global brands and celebrities, can inspire the policy and funding commitments we need from governments,a said Richard Vevers, CEO of The Ocean Agency. (IANS)
Sri Lanka’s state-owned Marine Environment Protection Authority on Wednesday warned that the country only had 10 per cent of live coral reefs in its oceans as 90 per cent had died due to pollution, illegal fishing methods and excessive climate change.
Dr Terney Pradeep Kumara, General Manager of the marine authority, told Xinhua news agency that urgent steps must be taken by the government to mark the remaining live coral reefs as “highly protected areas” and measures must be taken to move these live corals to deeper seas.
He said Sri Lanka, rich in coral reefs, had lost 90 per cent of its corals in recent years mainly due to illegal fishing methods such as bottom trawling and dynamite blasting, excessive climate change and high levels of pollution dumped into the seas.
“We urgently now need to save the remaining 10 per cent. At present, what we are observing is that the remaining 10 per cent is also facing a lot of difficulty due to high temperature levels.
“Therefore we expect all government agencies, private agencies and all the environmentalists to get together and help the government declare these reefs as highly protected areas and help transfer the living corals to deep areas to keep them alive,” he added.
Kumara said that by saving the remaining live corals, they would stay alive for decades which would help Sri Lanka attract more tourists which would strengthen the economy and the bio diversity of the country. (IANS)
- The communication patterns of a species of starfish that feeds on coral
- The crown-of-thorns starfish (Acanthaster planci) species is one of the few animals that can eat corals
- The presence of this species, referred to by the locals as onihitode or demon starfish in Japan
Tokyo, June 5, 2017: Japanese and Australian scientists have discovered the communication patterns of a species of starfish that feeds on coral.
This discovery, the scientists hope, will help in the preservation of the coral reefs as a single specimen of the crown-of-thorns starfish consumes up to 10 sq. metres of coral meat per year and is responsible for between 37 per cent to 99 per cent of the decrease in live coral cover, Efe news reported.
This crown-of-thorns starfish (Acanthaster planci) species is one of the few animals that can eat corals, Ken Baughman, one of the authors of the study by the Okinawa Institute of Science and Technology, said on Monday.
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The presence of this species, referred to by the locals as onihitode or demon starfish, in the waters off the coast of the Japanese village of Onna in the Okinawa island was first reported in 1957.
A native of the Indo-Pacific region, this species is experiencing a boom in population that has resulted in tens of thousands to millions of starfish in population densities of 150,000 per sq.km.
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Normally, reefs only have a few, says Baughman, adding But in recent decades the population outbreaks have tripled.
Baughman’s team and Australian researchers analysed the starfish’s genome, which for the first time has been completely sequenced.
It is kind of like an instruction manual for how to build a starfish. We can better understand crown-of-thorns starfish biology and consequently its behaviour, Baughman explained. (IANS)