Half of the Planet’s Coral Reefs Have Been Lost Since 1950

China experiments on how to grow a coral reef

Global coral reefs have entered a distinctive human-dominated era, the Anthropocene, characterized by more frequent severe global coral bleaching events and regional-scale coral habitat degradation. The prime causes of this are increased ocean temperatures, increased light intensity and increased ocean acidity – all closely connected to climate change.

The most dramatic example of this is the severe coral bleaching of the Great Barrier Reef in waters northern Australia – the largest living structure on the planet – where up to 50% of the reef has been badly impacted

Coastal areas around the world are usually densely populated regions that are under increasing pressure from urbanization, intensifying land use, and industrial development. Compared with remote, pristine coral reefs, inshore reefs are at higher risk of degradation due to a combination of natural and direct human impacts.

A new study by a team of Canadian marine scientists on the Global Decline in Capacity of Coral Reefs to Provide Ecosystem Services has just been published in the scientific journal, One Earth. The paper says half of the world’s coral reefs have been lost since the 1950s. Along with overfishing and habitat destruction, the research pinpoints pollution and climate change as major causes.

The full scientific paper is available at the following link:

https://www.cell.com/one-earth/fulltext/S2590-3322(21)00474-7?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS2590332221004747%3Fshowall%3Dtrue

coral reef
The following extract explains.

It’s not just the size of coral reefs that have declined, however. It’s also their productivity, according to the study, which says biodiversity and fishing in coral reefs have both diminished since the 1950s. Biodiversity is down 63%, for example. Catches of reef-associated fish, meanwhile, peaked in 2002 and have been falling ever since despite increased fishing effort. The catch per unit effort—a common measurement of species abundance—is 60% lower today than it was in 1950.2

“It’s a call to action,” said the study’s lead author Tyler Eddy, who conducted the research while he was a research associate at the UBC Institute for the Oceans and Fisheries (IOF), and is now a research scientist at the Fisheries & Marine Institute at the Memorial University of Newfoundland. “We know coral reefs are biodiversity hotspots. And preserving biodiversity not only protects nature, but supports the humans that use these species for cultural, subsistence and livelihood means.”

The reason coral reefs are perishing so rapidly is that they’re ultra-sensitive to changes in water temperature and acidity, reports Smithsonian magazine daily correspondent Corryn Wetzel.

“[Coral] are animals with symbiotic partners,” explains Wetzel, who says coral polyps are highly dependent on zooxanthellae, colorful algae that live in coral tissue and produce food on which coral subsist. “When the polyps are stressed by changes in light, water temperature, or acidity, they break that symbiotic relationship and expel the algae in a process called bleaching. Corals have a short window to regain their symbiotic algae, but if corals are stressed for too long, their death is irreversible.”

The role of climate change in coral bleaching is well established. The International Union for Conservation of Nature (IUCN), for example, points out that greenhouse gas emissions from fossil fuel consumption have led to increased retention of heat in Earth’s atmosphere.3 In turn, that heat has caused the average global sea surface temperature to rise by approximately 0.13 degrees Celsius per decade every decade for the last century, according to the U.S. National Oceanic and Atmospheric Administration (NOAA).4

Soft Corals Coral Bleaching on the Great Barrier Reef

“The ocean absorbs most of the excess heat from greenhouse gas emissions, leading to rising ocean temperatures,” IUCN explains on its website. “Rising temperatures cause coral bleaching and the loss of breeding grounds for marine fishes and mammals.”

The impacts of climate change on coral reefs are especially devastating to indigenous communities on coasts, which typically consume large amounts of seafood—15 times more seafood than non-indigenous communities, in fact.

“It’s heart-wrenching for us to see photos and video of wildfires or floods, and that level of destruction is happening right now all over the world’s coral reefs and threatening people’s culture, their daily food, and their history,” says study co-author Andrés Cisneros-Montemayor, an IOF research associate at the time of the study, now an assistant professor at Simon Fraser University. “This isn’t just an environmental issue; it’s also about human rights.”

UBC Institute for the Oceans and Fisheries Infographic

Although there is a solution—curbing greenhouse gas emissions would halt the warming of the oceans and help preserve surviving coral reefs—the world is far from realizing it, according to IOF Director and Professor William Cheung, yet another co-author of the study.

“Finding targets for recovery and climate adaptation would require a global effort, while also addressing needs at a local level,” Cheung says. “Climate mitigation actions, such as those highlighted in the Paris Agreement, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, and the Intergovernmental Panel on Climate Change, all call for integrated action to address biodiversity, climate, and social challenges. We are not there yet.

Source: 2 Oct 2021, https://www.treehugger.com/coral-reef-climate-change-study-5204240#citation-4

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China experiments on how to grow a coral reef

For the past decade, Professor Wang Aimin and his team at Hainan University College of Ocean Sciences have quietly been growing a coral reef off Wuzhizhou island, not far from the city of Sanya.

Marine biologist Wang Aimin (Middle) ready to dive underwater near Wuzhizhou Island, Hainan Province, southern China.

The reef is established on a foundation of giant concrete frames, the coral quickly began to grow… and with the coral came the fish. The project has been so successful it’s now four times its original area of 1,000 mu (67 hectares). Since 2009, Wang has led a team in charge of developing “marine ranching” along Hainan’s coast. This is part of a wider national move to explore how artificial reefs might help restore marine environments and promote a sustainable “blue economy”. China is aiming to build a total of 178 marine ranches by 2025.

The first countries to establish marine ranches were Japan, South Korea and the United States. China initially adopted the practice as a way to restore its fishery resources. There’s an element of that on Wuzhizhou too. In addition to building artificial reefs to provide habitat for fish, since 2017 Wang’s team have been experimenting with shellfish seeding, which could help make their ranches more profitable and therefore likely to expand.

Wang hopes Wuzhizhou can become part of China’s efforts to develop “blue carbon sinks”. The coral and algae that grow on the reefs, and the shellfish the team hopes to seed there, are all forms of blue carbon the country is researching.

See CGTN article: https://news.cgtn.com/news/2021-02-07/Coral-farming-a-conservation-progam-with-lessons-to-teach-XGECo0sY6Y/index.html

Click link to see full China Dialogue article: https://chinadialogueocean.net/18896-how-to-grow-a-coral-reef-the-wuzhizhou-experiment/?fbclid=IwAR1N2d8Q3Yfna8lMKWXVIrin0HW6QDjkdqdTXIrwtVgulfXeV2sKCbVcjd0

Link to video: https://fb.watch/8pskN7FIEn/

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