You might see golden brown kelp washed up on shore in New England, or chopped up into soup at a Japanese restaurant. Assistant Professor of Biology Jarrett Byrnes sees kelp everywhere. According to estimates, kelp dominates one quarter of the world’s coastlines. And, as a new paper co-authored by Byrnes explains, it might be one of the last bastions of resistance to human impacts in the ocean – although this might be changing fast.
In the new paper, published in the Proceedings of the National Academy of Sciences (PNAS), Byrnes and his colleagues have examined data from around the globe, and found that one third of all kelp forests are in decline. But there is also good news. In some regions, kelp forests have remained stable, and in a few places, kelp populations are actually growing. This is all happening despite warming oceans, overfishing-enhanced urchin explosions, and increases in kelp harvesting.
While ecosystems like coral reefs and rainforests have received a lot of attention from scientists and conservationists, key information about kelp forests has remained a mystery.
“They’re not nearly as popular as coral reefs, even though they provide a huge amount of ecosystem services,” Byrnes said. Kelp provide habitat for commercially fished species like lobster, they buffer the coastline during storms, and kelp itself is used as food, fertilizer, and extracted for use in commercial products.
“Kelp are the rockstars of ocean resilience,” Byrnes said. “You can have a storm come through and rip out kelp and it will bounce back. Where they’re on the decline, you know something is wrong.”
This is the most comprehensive study to date of kelp forests around the world, and reveals that kelps are more resilient than expected. Despite an overall decline of kelp in many regions, the impact of humans has not been the same from region to region.
Byrnes says the key takeaway from his research is that local management can have big impacts on this important ocean habitat. In Tasmania, a “perfect storm” of warming seas, sea urchin invasion, and overfishing has led to kelp’s decline, to the point where giant kelp are actually considered endangered. However, Byrnes’ research shows that the type of decline that has happened in Tasmania isn’t inevitable everywhere.
“We can manage kelp forests to make them more resilient,” said Byrnes.