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Living in shallow ocean waters off a third of the world’s coastlines are vibrant jungles of brown seaweed called kelp forests. These underwater canopies support a wealth of biodiversity and, according to new estimates, could be worth quite a bit themselves.

A new study led by UNSW Sydney suggests kelp forests are worth hundreds of billions to society through fisheries, nutrient cycling, and carbon removal. While the exact amount varied between regions and kelp type, the findings, published in , suggest they collectively provide an average of $US500 billion through ecosystem services – the benefits provided by ecosystems to humans – each year.

Dr Aaron Eger is the lead author of the study from UNSW Science. The marine ecologist is the founder and director of the – a research-driven not-for-profit dedicated to accelerating the protection and restoration of kelp forests worldwide.

“We have a deep cultural connection to this ecosystem. But our understanding of the economic value has been lagging behind other ecosystems competing for conservation funding,” Dr Eger says.

“Now, with this study, for the first time, we have the figures to demonstrate the considerable commercial value of our global kelp forests and the financial impetus for advancing kelp conservation and restoration efforts.”

Lead author of the study, Dr Aaron Eger. Photo: Danielle Holmes.

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Despite their commercial value, kelp forests are disappearing worldwide at an alarming rate from sea urchin overgrazing and climate change-related threats. In some places, such as Tasmania, up to 95 per cent of the canopy has already disappeared. Vital restoration projects and management strategies may go unfunded without work to understand the return on investment.

“Multiple drivers increasingly threaten kelp forests, so we must understand their economic contribution if we hope to accelerate efforts to save them and the more than 1800 species that rely on them,” Dr Eger says.

“These findings are also highly relevant as we have just launched the Kelp Forest Challenge, a global call to .

“By strengthening our understanding of their value, we can hopefully motivate governments, businesses, and society to reach these target values.”

Kelp forests support a wealth of biodiversity but are disappearing at an alarming rate. Photo: Unsplash.

The holistic value of kelp forests 

For the study, the researchers analysed the contribution of kelp forests to ecosystem services using fish and invertebrate surveys and measures of annual net primary production – or growth. This growth requires elements such as carbon, nitrogen, and phosphorus to be pulled out of the seawater, effectively cleaning the water and contributing to carbon sequestration – the storage of captured carbon in environmental reservoirs. 

They found the most significant economic value of kelp forests in fisheries production and uptake of nitrogen, contributing an average of $29,000 and $73,000 per hectare, respectively, annually. While the estimation for carbon sequestration was low ($163 per hectare annually) ecologically, it was comparable to seagrass meadows and terrestrial forests. Collectively, they could remove 4.91 megatons of carbon from the atmosphere per year – a number likely to increase further as more kelp forests are mapped.

“This is just a baseline study, so we expect the approximations will get more accurate as the field advances,” Dr Eger says. “There were also many other services we didn’t assess, including tourism, educational and learning experiences, and kelp as a source of food, so we anticipate the actual value of kelp forests in the world to be higher.”

Around 740 million people live within 50 km of a kelp forest. Photo: Ralph Pace.

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The findings could open new opportunities for marine management and conservation strategies, such as a credit system for offsetting emissions. Furthermore, Dr Eger says it can also encourage governments to develop new industries around restoring and managing kelp forests.

“Through the study, we found 740 million people live within 50 km of a kelp forest. So these systems have a significant role to play in supporting these people’s livelihoods and vice-versa,” Dr Eger says. “The more the public appreciates these high-value ecosystems living in their blue backyards, the easier it becomes for policymakers to support their protection.”

While the research is not intended to commodify kelp forests, Dr Eger says it ultimately helps draw attention to the need for more investment in kelp forest conservation.

“Putting the dollar value on these systems is an exercise to help us understand one measure of their immense value,” Dr Eger says. “It’s important to remember these forests also have an intrinsic, historical, cultural and social value in their own right.”

“Hopefully, it helps start more conversation about the role of these ecosystems in maintaining healthy oceans and ultimately healthy coastal communities and cultures.”