Kelp Forests Generate $500 Billion per Year, Study Finds

Beneath Earth’s coastal waters lie vast forests of a nutritious and useful brown algae seaweed known as kelp. For thousands of years, kelp has sustained and been a part of the culture of people around the world.

A new study published in Nature Communications has found that the planet’s vast undersea kelp forests generate an average of approximately $500 billion per year, according to the journal Nature. The analysis looked at six types of seaweed and found that they were much more valuable than previously thought.

“Until now, most kelp-forest evaluations were regional,” said Cristina Piñeiro-Corbeira, a marine ecologist at the University of A Coruña in Spain who was not involved in the study, reported Nature. “This study is a step forward in understanding kelp forests and their importance for human well-being on a global scale.”

The study, “The value of ecosystem services in global marine kelp forests,” estimates that the services kelp forests provide — like acting as habitat for fish and other marine species caught for food and pulling nitrogen from seawater contaminated by sewage and fertilizer runoff — are worth from $465 to $562 billion per year globally. This means as much as $363,492 per acre is generated by each type of kelp forest per year — more than three times the amount earlier estimates suggested.

“Globally, kelp forests provide habitat for important fisheries of abalone, lobsters, reef fishes, and kelp itself. Additionally, through their high productivity, kelp forests draw carbon from the atmosphere, release oxygen, and help reduce marine nutrient pollution. Long before Charles Darwin wrote his essay on the Patagonian kelp forests, these habitats provided essential services for human society that continue to this day,” the study said.

Around 740 million people are thought to live within 31 miles of a kelp forest, which are common in polar and temperate climates.

“Archaeological excavations show how kelp forests facilitated southward travel for early peoples in the Americas some 20,000 years ago. During this migration, people relied on the food provided by kelp forests to survive,” the study authors wrote.

These large swaths of brown seaweed are home to more than a thousand species.

“Outside of the tropics, kelp forests are really the dominant [coastal] habitat,” said study co-author Aaron Eger, a marine scientist at the University of New South Wales in Sydney, Australia, as Nature reported. “These are the essential threads to marine ecosystems.”

The international research team considered the contributions of kelp forests to carbon dioxide removal, the cycling of nutrients and fisheries in evaluating their value. In order to do this, they gathered biodiversity survey data, estimates of kelp distribution and seafood prices from various parts of the globe.

Lobster and abalone made up more than 25 percent of the value of the fisheries value for kelp sites in many parts of the world. Among all the sites the researchers surveyed, giant seabass, lingcod, pollack and South American morwongs were the most valuable fish.

An average fisheries harvest from kelp forests is worth about $30,000 per year. Excess nitrogen removal by kelp forests is worth nearly $182,780 per acre per year. The world’s kelp forests are also remarkable carbon sinks.

Piñeiro-Corbeira said the value of kelp forests could be even higher, since the study looked at just three of the ecosystem services they provide. Other services of kelp forests include recreation and coastal protection, and Eger said taking these into consideration could increase their estimated value.

Piñeiro-Corbeira added that the study’s findings could encourage better conservation and management practices for kelp forests, and lead to them being considered more often in climate change policies.

“Anything we can do to address the climate issue is going to have a positive impact on the kelp forest,” Eger told AFP, as Phys.org reported.