With kelp gaining recognition as “the ocean’s equivalent of trees,” decarbonizing oceans and providing critical habitat for aquatic species, scientists are racing to protect kelp forests from rising temperatures and disrupted ecosystems.
With human emissions of carbon dioxide driving up ocean acidity, kelp forests play a critical role in protecting many ocean species, the Washington Post reports. It provides physical habitat, while stabilizing ocean acidity through decarbonization. However, these benefits are disappearing, with kelp canopy cover decreasing globally by a third over the past decade, and in some areas by 95%.
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Beginning in 2013, a heat wave over a kelp forest along the California coast reduced the average canopy cover from two million to 60,000 square metres in just two years. Shortly thereafter, sea urchin populations exploded when a virus decimated their main predator, the sunflower sea star. Sea urchins, which play an important role in a healthy kelp ecosystem, will devour kelp if their population growth is not controlled by predation.
“It’s like this endless parking lot, stretching for miles in every direction, covered in purple urchins,” said Tom Dempsey, the Nature Conservancy’s California Oceans Program director, reports the Washington Post.
Scientists are strategizing ways to curtail the urchin boom. One approach is to create a commercial demand to harvest urchins, either to process their calcium carbonate-rich shells into fertilizer or for sale to restaurants. Unfortunately, “the type typically considered a cuisine are not the invasive purple variety that eat at the roots of kelp,” says the Washington Post.
Another approach is to increase starfish populations. An initial attempt to establish a starfish breeding colony failed, but developing knowledge of starfish ecology suggests promise for a second attempt. However, experts aren’t sure they can breed enough starfish to make even a small dent in the urchin population.
The Nature Conservancy is also working to supplement wild kelp populations with patches produced by an experimental kelp farm. The plan is to grow kelp in industrial tanks before transferring them into the Pacific to connect with wild patches through spore dispersal.
“There really is no single silver bullet option to solve this problem,” said Nature Conservancy marine biologist Frank Hurd. “We need to invest in comprehensive solutions to reestablish healthy, resilient ecosystems.”
Scientists hope their attempts will have an impact, but they say time and funding both limit their chances to conserve kelp in the global ocean ecosystem. And without kelp, says the Post, “entire ocean ecosystems would crumble.”
