A Canadian-led team of scientists has concluded that tropical coral reefs that feed millions around the world have lost about half their ability to support human communities since 1950.
© Provided by The Canadian Press
"I don't think any of us expected the declines to be as big as we found," said Tyler Eddy of Memorial University, lead author of the paper published Friday in the journal One Earth.
The paper is the first to tote up the cumulative effects of threats faced by tropical coral reefs from overfishing to pollution to climate change, the authors say.
"This is the first study that puts it all together," Eddy said.
It combines data from myriad sources.
Just the figures on reef extent drew on 14,705 surveys from 3,582 reefs in 87 countries. The conclusions on biodiversity were made from a database with more than a billion records on 100,000 species from plankton to mammals.
"We had to spend a lot of time standardizing the data," said co-author William Cheung of the University of British Columbia. "That was a big part of the analysis."
The findings are sobering.
Globally, reefs cover about half the sea floor they did in 1950. Catches of reef-associated fish peaked in 2002 at about 2.2 million tonnes and have declined about 10 per cent since then.
That's despite increased fishing efforts. The paper finds that what it calls "catch per unit effort" has declined about 60 per cent.
Imagine a fisherman with one hook casting it for an hour, Cheung said.
"Fifty years ago, they would have caught 10 fish. With 60 per cent decline, it means the fisherman would have caught five or fewer fish with the same amount of effort."
That's a powerful clue as to what's happening under the surface, said Eddy.
"That's an indication of how much fish is available to catch."
Finally, reefs around the world have lost almost two-thirds of their biodiversity. That not only affects the reefs but the other oceanic ecosystems they are connected to.
"It's an important part of the global system," Cheung said.
The study reports that coral reef fisheries are worth about $7.6 billion worldwide. It says about 6 million people — a high number of them Indigenous groups from small island states — depend on them.
But that's not the only cost.
Reefs protect shorelines from heavy storms by breaking and weakening waves produced by hurricanes, Eddy said. Destructive storms are expected to increase as the globe heats up.
Reefs also nurture tourism as well as the cultures of many coastal peoples.
"Our results highlight the sensitivity of coral reef ecosystems ... as well as the high dependence on them by human communities," the study concludes.
The threats include pollution from agricultural runoff, ocean acidification from greenhouse gases and damaging fishing practices such as trawling, as well as climate change.
Canada may not have any tropical coral reefs. But that doesn't mean the country isn't affected by their decline.
"Canadians are implicated in terms of our contribution to climate change," Eddy said. "This is really a global responsibility."
This report by The Canadian Press was first published Sept. 18, 2021.
— Follow Bob Weber on Twitter at @row1960
Bob Weber, The Canadian Press
"I don't think any of us expected the declines to be as big as we found," said Tyler Eddy of Memorial University, lead author of the paper published Friday in the journal One Earth.
The paper is the first to tote up the cumulative effects of threats faced by tropical coral reefs from overfishing to pollution to climate change, the authors say.
"This is the first study that puts it all together," Eddy said.
It combines data from myriad sources.
Just the figures on reef extent drew on 14,705 surveys from 3,582 reefs in 87 countries. The conclusions on biodiversity were made from a database with more than a billion records on 100,000 species from plankton to mammals.
"We had to spend a lot of time standardizing the data," said co-author William Cheung of the University of British Columbia. "That was a big part of the analysis."
The findings are sobering.
Globally, reefs cover about half the sea floor they did in 1950. Catches of reef-associated fish peaked in 2002 at about 2.2 million tonnes and have declined about 10 per cent since then.
That's despite increased fishing efforts. The paper finds that what it calls "catch per unit effort" has declined about 60 per cent.
Imagine a fisherman with one hook casting it for an hour, Cheung said.
"Fifty years ago, they would have caught 10 fish. With 60 per cent decline, it means the fisherman would have caught five or fewer fish with the same amount of effort."
That's a powerful clue as to what's happening under the surface, said Eddy.
"That's an indication of how much fish is available to catch."
Finally, reefs around the world have lost almost two-thirds of their biodiversity. That not only affects the reefs but the other oceanic ecosystems they are connected to.
"It's an important part of the global system," Cheung said.
The study reports that coral reef fisheries are worth about $7.6 billion worldwide. It says about 6 million people — a high number of them Indigenous groups from small island states — depend on them.
But that's not the only cost.
Reefs protect shorelines from heavy storms by breaking and weakening waves produced by hurricanes, Eddy said. Destructive storms are expected to increase as the globe heats up.
Reefs also nurture tourism as well as the cultures of many coastal peoples.
"Our results highlight the sensitivity of coral reef ecosystems ... as well as the high dependence on them by human communities," the study concludes.
The threats include pollution from agricultural runoff, ocean acidification from greenhouse gases and damaging fishing practices such as trawling, as well as climate change.
Canada may not have any tropical coral reefs. But that doesn't mean the country isn't affected by their decline.
"Canadians are implicated in terms of our contribution to climate change," Eddy said. "This is really a global responsibility."
This report by The Canadian Press was first published Sept. 18, 2021.
— Follow Bob Weber on Twitter at @row1960
Bob Weber, The Canadian Press
Damaged coral reefs cause decline in fisheries, risks for coastal communities
Fish catches along the world's coral reefs peaked nearly two decades ago
and have been diminishing since, according to a new study.
Fish catches along the world's coral reefs peaked nearly two decades ago
and have been diminishing since, according to a new study.
Photo by Tyler Eddy
Sept. 17 (UPI) -- The degradation of the world's coral reefs is causing a sharp decline in fisheries and putting coastal communities in peril, a new study has found.
Fish catches along the world's coral reefs peaked nearly two decades ago and have been diminishing since, according to a study published in the journal One Earth on Friday.
The catch per unit effort, a measurement of biomass, is 60% lower than in the 1950s, researchers found.
During that time frame, the global coverage of living corals and the biodiversity of species dependent on the underwater structure have declined by similar levels.
That meant a decrease in the capacity of coral reefs to provide food and livelihoods, sequester carbon and serve as a buffer against extreme climate events.
"The reduced capacity of coral reefs to provide ecosystem services undermines the well-being of millions of people with historical and continuing relationships with coral reef ecosystems," reads the study.
The future of human coastal communities that depend on coral reefs is in doubt, the study concluded. Indonesia, the Caribbean and the South Pacific are already seeing impacts to subsistence and commercial fisheries as well as tourism.
For the study, researchers conducted a global data analysis that covered coral reef trends and associated ecosystems that included living coral cover, biodiversity and changes in food webs, as well as fisheries and seafood consumption by indigenous peoples.
The study concluded that climate change, overfishing and pollution have put the world's coral reefs in jeopardy.
"Coral reefs are known to be important habitats for biodiversity and are particularly sensitive to climate change, as marine heat waves can cause bleaching events," Tyler Eddy, a research scientist at the Fisheries & Marine Institute at Memorial University of Newfoundland, said in a statemen
"Coral reefs provide important ecosystem services to humans, through fisheries, economic opportunities and protection from storms," said Eddy, who started the research when he was a postdoctoral fellow at the University of British Columbia's Institute for the Oceans & Fisheries.
Those impacts have come despite the marine-protection efforts, since they may lack enforcement and don't address the broader issue of climate change, the study said.
A study released last year similarly found that marine preserves have limited protective abilities when faced with rising global temperatures and coral bleaching.
Addressing the problem will require a globally coordinated effort in addition to local marine management, the new study found.
It also said that current efforts such as the Paris climate accords must additionally address direct causes of diminished coral reef capacity.
Sept. 17 (UPI) -- The degradation of the world's coral reefs is causing a sharp decline in fisheries and putting coastal communities in peril, a new study has found.
Fish catches along the world's coral reefs peaked nearly two decades ago and have been diminishing since, according to a study published in the journal One Earth on Friday.
The catch per unit effort, a measurement of biomass, is 60% lower than in the 1950s, researchers found.
During that time frame, the global coverage of living corals and the biodiversity of species dependent on the underwater structure have declined by similar levels.
That meant a decrease in the capacity of coral reefs to provide food and livelihoods, sequester carbon and serve as a buffer against extreme climate events.
"The reduced capacity of coral reefs to provide ecosystem services undermines the well-being of millions of people with historical and continuing relationships with coral reef ecosystems," reads the study.
The future of human coastal communities that depend on coral reefs is in doubt, the study concluded. Indonesia, the Caribbean and the South Pacific are already seeing impacts to subsistence and commercial fisheries as well as tourism.
For the study, researchers conducted a global data analysis that covered coral reef trends and associated ecosystems that included living coral cover, biodiversity and changes in food webs, as well as fisheries and seafood consumption by indigenous peoples.
The study concluded that climate change, overfishing and pollution have put the world's coral reefs in jeopardy.
"Coral reefs are known to be important habitats for biodiversity and are particularly sensitive to climate change, as marine heat waves can cause bleaching events," Tyler Eddy, a research scientist at the Fisheries & Marine Institute at Memorial University of Newfoundland, said in a statemen
"Coral reefs provide important ecosystem services to humans, through fisheries, economic opportunities and protection from storms," said Eddy, who started the research when he was a postdoctoral fellow at the University of British Columbia's Institute for the Oceans & Fisheries.
Those impacts have come despite the marine-protection efforts, since they may lack enforcement and don't address the broader issue of climate change, the study said.
A study released last year similarly found that marine preserves have limited protective abilities when faced with rising global temperatures and coral bleaching.
Addressing the problem will require a globally coordinated effort in addition to local marine management, the new study found.
It also said that current efforts such as the Paris climate accords must additionally address direct causes of diminished coral reef capacity.
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