- New research suggests that kelp forests generate up to $562 billion each year by increasing fisheries productivity, removing harmful nutrients from seawater and sequestering carbon dioxide.
- The results suggest that kelp forests are about three times more valuable than previously thought, contributing the equivalent of Sweden’s total GDP to the global economy.
- However, experts say that kelp forests are generally overlooked and underestimated, and that many of these ecosystems are under threat around the world.
Forests of seaweed, a type of brown seaweed that grows in cooler waters, meander along the coast of South Australia. But many people don’t even know they exist, says Adriana Vergés.
“I live in Sydney — it’s Australia’s largest city — and it has absolutely beautiful kelp forests,” Vergés, a professor of marine ecology at the University of New South Wales (UNSW) in Sydney, told Mongabay. “But the people of Sydney know more about the Great Barrier Reef than their local kelp forests.”
Vergés says there’s also a lack of understanding of what kelp does and its value, although kelp forests play an important ecological role as they act as the “biological engine of temperate reefs.”
A new paper published in Nature Communications and co-authored by Vergés aims to fill some of these knowledge gaps by identifying the economic value of kelp forests. It suggests that kelp forests around the world provide three main ecosystem services worth billions of dollars annually: increasing fisheries production; the removal of excess nutrients such as nitrogen and phosphorus from the water; and the capture of carbon dioxide.
Forests of seaweed, a type of brown seaweed that grows in cooler waters, meander along the coast of South Australia. Image by Stefan Andrews / Ocean Image Bank.
Researchers studied six different kelp genera (Ecklonia, Laminaria, Lessonia, Macrocystis, Nereocystis, and Saccharina) and found that each of these forest types produces up to $147,100 per hectare ($59,500 per acre) per year worldwide, although the exact amount region and kelp type varied by forest. Collectively, the world’s kelp forests generate up to US$562 billion each year — about as much as Sweden’s entire GDP — making kelp forests about three times more valuable than previously thought, the study found.
Most of this economic value comes from the kelp forests’ contribution to fisheries production, as well as nitrogen uptake, which the study says generates values of $29,000 to $73,000 per hectare ($11,700 to $29,500 per acre) each year. As for carbon sequestration, the study suggests that kelp forests sequester about as much carbon as terrestrial forests or seagrass beds, but only contribute about $163 per hectare ($66 per acre) annually.
“The amount of carbon that kelp forests capture and store is very high and is similar to other very important habitats,” says Vergés. “But the value is low, and that’s only because the dollar value of carbon is low.”
Albert Pessarrodona, a marine ecologist at the University of Western Australia who wasn’t involved in the study, says it’s also difficult to accurately assess a kelp forest’s ability to sequester carbon because most of the carbon is trapped in the sediment – not in the seaweed itself.
“That means [it] Estimating exactly how much carbon can be sequestered (if any) is quite difficult as the carbon has to be traced from the kelp forests (the source) to the final sink,” Pessarrodona Mongabay says in an email. “Many scientists are currently working to establish the methods and sequestration potential of kelp forests.”
A slender Seadragon in the seaweed. The study suggests that kelp forests around the world provide three main ecosystem services worth billions of dollars annually. Image by John Turnbull via Flickr (CC BY-NC-SA 2.0).
Vergés says the study also failed to quantify other services, such as tourism and coastal protection, so the total value of about $500 billion a year is likely a “gross underestimate.”
The study’s lead author, Aaron Eger, a marine scientist at UNSW and founder and program director of the Kelp Forest Alliance, says the primary motivation in putting together this study was to communicate the value of kelp forests to try to achieve better stewardship and a to enable better protection of these ecosystems, many of which are under threat worldwide.
For example, it is estimated that 95% of the kelp forests around the Australian island nation of Tasmania have died due to climate change.
“Once you can communicate that value, people are more interested in a kelp forest,” Eger tells Mongabay. “And governments and governing bodies can work to better serve and manage these ecosystems if they know what’s there and how much it’s worth and how it’s factored into the decision-making process.”
The Kelp Forest Alliance, for which both Eger and Vergés serve on the board, recommends protecting 3 million hectares (7.4 million acres) and restoring 1 million hectares (2.5 million acres) of kelp forests by 2040 to support the biodiversity goals of the Kunming-Montreal Global Biodiversity Framework.
Pessarrodona commends the study for “demonstrating the immense value that kelp forest ecosystems have for coastal societies and economies.”
“This study is the first attempt to assess the economic value of three ecosystem services of kelp forests,” says Pessarrodona. “There [are] many other seaweed ecosystem services that have not been assessed, and many more nuances that need to be provided in the assessed services. This study opens the door for much more exciting research in the future.”
Elizabeth Claire Alberts is senior writer at Mongabay. Follow her on Twitter @ECAlberts.
Banner image: California sea lions swim in a vast seaweed forest. Image by Royal Botanic Garden Sydney via Flickr (CC BY-NC-ND 2.0).
Scientists strive to restore the world’s contested kelp forests
Citation:
Eger AM, Marzinelli EM, Beas-Luna R, Blain CO, Blamey LK, Byrnes JEK, … Vergés A (2023). The value of ecosystem services in global seaweed forests. Nature Communications, 14. doi:10.1038/s41467-023-37385-0
Biodiversity, Conservation, Economy, Ecosystems, Endangered, Environment, Environmental Economics, Fish, Fisheries, Forests, Marine, Marine Biodiversity, Marine Conservation, Marine Ecosystems, Oceans, Saltwater Fish Print
Comments are closed.