A new study from researchers at the Royal Melbourne Institute of Technology found that saving kelp forests is not only good for the oceans — it’s good for the economy as well.
In the study, which was published in Ecosystem Services, the team addressed the declining population of kelp forests, which are dense, biodiversity-boosting groupings of algae that grow in shallow coastlines around the world.
Although pollution and climate change have a hand in kelp forest destruction, lead author and RMIT senior lecturer Paul Carnell focused his attention on one kelp-munching culprit in particular: Sea urchins.
“Managing the bay’s sea urchin population is a practical step we can take to ensure the health of Port Phillip Bay, which is crucial to local ecosystems, tourism, and food security,” Carnell said in an interview with RMIT.
The research team gathered their data through exploratory dives in Port Phillip Bay, a horsehead-shaped body of water in southeastern Australia.
Their calculations were based on dive depth, travel time, local sea urchin density, and the potential nitrogen storage capacity of kelp.
In the economic impact report, Carnell and his colleagues estimated that a $50 million investment in targeted sea urchin culling and kelp restoration could lead to a cumulative return of $92 million.
“Now we have the figures to show this is also a smart economic investment,” Carnell said. “This approach can be targeted to specific areas of the bay, so we can get the greatest bang for our buck.”
Carnell said that the $50 million investment would create jobs in commercial diving sectors by paying crews to harvest sea urchins and cultivate emerging kelp forests.
The $92 million return-on-investment was attributed to boosts to recreational fishing in the region, as well as the economic benefits of planting carbon-storing kelp and removing nitrogen from the bay.
In the United States, marine biologists and researchers are also finding direct links between culling sea urchins and safeguarding kelp forests.
This April, researchers at Stanford University’s School of Humanities and Sciences published a study on the influence of predators in marine ecosystems. They found that fishing bans in protected areas could be the key to keeping kelp forests alive.
Joy Kumagai, a biology student who led the study, observed that spiny lobsters and California sheephead are tantamount to keeping sea urchins in check along the California coastline, a conservation effort which “indirectly promotes kelp growth.”
“In southern California, the two species that eat large adult urchins are fished,” Kumagai told Stanford.
Kumagai and her colleagues explained that prohibiting fishing from certain coastal areas can help kelp forests withstand extreme temperatures by preserving “trophic cascades,” or the indirect impacts of predators.
“This analysis provides robust evidence that protecting marine predators promotes the recovery of marine forests even in the face of prolonged marine heatwaves that have damaged ecosystems all along the California coast,” said co-senior author Fiorenza Micheli, the co-director of the Stanford Center for Ocean Solutions.
Similarly, a 2024 study published in PLOS Climate asserted that sea otters “can have an impact which cascades through the ecosystem” simply by snacking on sea urchins.
“Most notably, we found that kelp canopy declines along northern and southern mainland regions of [California] were offset by gains within the central coast, corresponding with the presence of sea otters,” observed lead researcher Kyle Van Houtan.
“Our results suggest that otters are critical to maintaining kelp forest health throughout their range, buffering long-term kelp loss where their population densities are highest in central California.”
This research was backed by an additional study, published in Nature in 2024, that found that otters slowed erosion of Central California’s creekbanks and marsh edges by 69%.
“It would cost tens of millions of dollars for humans to rebuild these creekbanks and restore these marshes,” co-author Brian Silliman, marine biologist at Duke University’s Nicholas School of the Environment, told the Center for Coastal Solutions.
“The sea otters are stabilizing them for free in exchange for an all-you-can-eat crab feast.”
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Header image via David Ciani (CC BY-NC-SA 3.0 US)
