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Coral Reef Outplants: Sea Temperature an Often Overlooked but Vital Factor in Success, Scientists Find

Climate
Coral Reef Outplants: Sea Temperature an Often Overlooked but Vital Factor in Success, Scientists Find
Divers tend to coral outplants anchored to an underwater structure. NOAA

By Elizabeth Claire Alberts

Coral reefs are often called the "rainforests of the sea" because they harbor some of the highest levels of biodiversity of any ecosystem in the world. But as sea temperatures rise, coral reef systems are suffering mass bleaching events, leading to widespread mortality. One way to try and restore coral reef systems is coral reef gardening or "outplanting," a method of growing coral fragments in a nursery and transferring them to ailing reef systems. But like naturally grown coral, it's hard to keep outplants alive, especially with climate change steadily raising global sea temperatures.



A coral nursery loaded with detached corals in Hawai'i off the coast of O'ahu. NOAA Fisheries

A new study, published this month in Environmental Research Letters, shows that coral reef outplant survival dropped below 50% when temperatures rose above 30.5° Celsius (86.9° Fahrenheit).

"In normal coral reefs, an increase of one degree [Celsius, or 1.9°F] can cause bleaching and death," Shawna Foo, lead author and postdoctoral researcher at Arizona State University's Center for Global Discovery and Conservation Science (GDCS), told Mongabay. "But it was not actually known what temperatures were important for coral outplants to survive, maybe because they've been grown in different conditions, or maybe [it was thought that] they could be less resilient to temperature or more resilient to temperature."

Foo and her co-author, Greg Asner, director of GDCS, analyzed hundreds of coral outplanting projects that took place around the world between 1987 and 2018 to collect data on coral survival rates and outplant locations and dates. They also gathered data on global sea surface temperature, obtained from NOAA's Coral Reef Watch program. What they eventually found was that coral outplants reacted to temperature the same way as natural coral reefs.

A Staghorn coral nursery in Puerto Rico. NOAA

Growing coral is an extremely labor-intensive activity that can cost up to $400,000 per hectare. Sites for coral reef outplanting tend to be chosen based on water clarity, a suitable seafloor environment, and the presence of an existing coral reef. But temperature isn't always considered, Foo said. While many factors can lead to the demise of coral outplants, including algae outbreaks and unfavorable water chemistry, temperature plays a key role in outplant health and survival, according to the study.

Another key finding is that outplant survival increased at sites with more temperature variability, rather than at sites that remained at a constant temperature night and day.

"We find that corals that are in these more variable conditions actually have higher survival, and this is probably because exposure to variability is increasing the resilience to temperature change, and … being exposed to low temperatures means they actually have a little bit of reprieve as well," Foo said.

Scientists maintaining corals growing in a coral reef nursery. NOAA

Foo says she hopes this study will help coral outplant practitioners choose the best sites for coral gardens to boost survival. Temperature is becoming an increasingly important consideration, especially as ocean warming is expected to accelerate more than four-fold over the next 60 years.

"Although sobering for reef conservationists and managers, our findings provide a critical compass as to where reef restoration efforts can have their greatest impact in the future," Asner said in a statement. "Reef restoration is just now turning from a cottage industry to a global enterprise, and this needs to happen in concert with the changing global geography of ocean temperature."

Reposted with permission from Mongabay.

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By Elliot Douglas

In early October, Britain's Prince William teamed up with conservationist David Attenborough to launch the Earthshot Prize, a new award for environmentalist innovation. The Earthshot brands itself the "most prestigious global environment prize in history."

The world-famous wildlife broadcaster and his royal sidekick appear to have played an active role in the prize's inception, and media coverage has focused largely on them as the faces of the campaign.

But the pair are only the frontmen of a much larger movement which has been in development for several years. In addition to a panel of experts who will decide on the winners, the prize's formation took advice from the World Wildlife Fund, Greenpeace and the Jack Ma Foundation.

With more and more global attention on the climate crisis, celebrity endorsement of environmental causes has become more common. But why do environmental causes recruit famous faces for their campaigns? And what difference can it make?

'Count Me In'

"We need celebrities to reach those people who we cannot reach ourselves," says Sarah Marchildon from the United Nations Climate Change secretariat (UNFCCC) in Bonn, Germany.

Marchildon is a proponent of the use of celebrities to raise awareness of environmental causes. In addition to promoting a selection of climate ambassadors who represent the UN on sustainability issues, Marchildon's team has produced videos with well-known narrators from the entertainment world: among them, Morgan Freeman and Mark Ruffalo.

"We choose celebrities who have a lifestyle where they are already talking about these issues," Marchildon explains.

"Sometimes they reach out to us themselves, as David Attenborough did recently. And then they can promote the videos on their own social channels which reach more people than we do — for example, if they have 20 million followers and we have 750,000."

Environmental groups focused on their own domestic markets are also taking this approach. One Germany-based organization that uses celebrities in campaigns is the German Zero NGO. Set up in 2019, it advocates for a climate-neutral Germany by 2035.

German Zero produced a video in March 2020 introducing the campaign with "66 celebrities" that supported the campaign, among them Deutschland 83 actor Jonas Nay and former professional footballer Andre Schürrle. They solicit support as well as financial contributions from viewers.

"Count me in," they say, pointing toward the camera. "You too?"

"We are incredibly grateful for the VIPs in our videos," says German Zero spokeswoman Eva-Maria McCormack.

Assessing Success Is Complex

But quantifying the effectiveness of celebrity endorsement of campaigns is not a straightforward process.

"In order to measure effectiveness, first of all you need to define what is meant by success," says Alegria Olmedo, a researcher at the Zoology Department at the University of Oxford.

Olmedo is the author of a study looking at a range of campaigns concerning pangolin consumption, fronted by local and Western celebrities, in Vietnam and China. But she says her biggest stumbling block was knowing how to measure a campaign's success.

"You need a clear theory of change," explains Olmedo. "Have the celebrities actually helped in achieving the campaign's goals? And how do you quantify these goals? Maybe it is increased donations or higher engagement with a cause."

A popular campaign in China in recent years saw famous chefs Zhao Danian and Shu Yi pledge to abstain from cooking endangered wildlife. While the pledge achieved widespread recognition, both Olmedo and Marchildon say it's difficult to know whether it made any difference to people's actions.

"In life we see a thousand messages every day, and it is very hard to pinpoint whether one campaign has actually made a difference in people's behavior," she explains.

Awareness Is Not Enough

Many campaigns that feature celebrities focus on raising awareness rather than on concrete action — which, for researcher Olmedo, raises a further problem in identifying effectiveness.

"Reach should never be a success outcome," she says. "Many campaigns say they reached a certain number of people on social media. But there has been a lot of research that shows that simply giving people information does not mean they are actually going to remember it or act upon it."

But anecdotal evidence from campaigns may suggest reach can make an active difference.

"Our VIP video is by far the most watched on our social media channels," McCormack from German Zero says. "People respond to it very directly. A lot of volunteers of all ages heard about us through that video."

However, some marketing studies have shown that celebrity endorsement of a cause or product can distract from the issue itself, as people only remember the person, not the content of what they were saying.

Choosing the Right Celebrity

Celebrity choice is also very important. Campaigns that use famous faces are often aiming to appeal to members of the public who do not necessarily follow green issues.

For certain campaigns with clear target audiences, choosing a climate scientist or well-known environmentalist rather than a celebrity could be more appealing — Attenborough is a classic example. For others, images and videos involving cute animals may be more likely to get a message heard than attaching a famous face.

"We choose celebrities who have a lifestyle where they are already talking about these issues," says Marchildon from the UN. "You need figures with credibility."

McCormack cites the example of Katharine Hayhoe, an environmental scientist who is also an evangelical Christian. In the southern United States, Hayhoe has become a celebrity in her own right, appealing to an audience that might not normally be interested in the messages of climate scientists.

But as soon as you get a celebrity involved, campaigns also put themselves at risk of the whims of that celebrity. Prince William and younger members of the royal family have come under fire in recent years for alleged hypocrisy for their backing of environmental campaigns while simultaneously using private jets to fly around the world.

But Does It Really Work?

While environmental campaigns hope that endorsement from well-known figures can boost a campaign, there is little research to back this up.

"The biggest finding [from my study] was that we were unable to produce any evidence that shows that celebrity endorsement of environmental causes makes any difference," says Olmedo.

This will come as a blow to many campaigns that have invested time and effort into relationships with celebrity ambassadors. But for many, the personal message that many celebrities offer in videos like that produced by German Zero and campaigns like the Earthshot Prize are what counts.

The research may not prove this conclusively — but if the public believes a person they respect deeply personally cares about an important issue, they are perhaps more likely to care too.

"I personally believe in the power this can have," says Marchildon. "And if having a celebrity involved can get a single 16-year-old future leader thinking about environmentalist issues — that is enough."

Reposted with permission from DW.

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