Never in Earth's history have the planet's oceans been in a sorrier state than they are today: polluted by raw sewage, industrial chemicals, and plastics; overfished at record levels; and suffering the effects of climate change such as coral bleaching and too-warm waters that affect the migration patterns and life cycles of marine species—and may even lead to more shark attacks. The oceans are an increasingly inhospitable environment for the thousands of types of fish that we humans like to eat, with our activities placing unprecedented strain on global fisheries.
Another major factor that's throwing underwater life into crisis is ocean acidification (OA), a phenomenon produced by carbon emissions that affects the food chain from the bottom up. As humans burn fossil fuels and mow down forests with abandon, the amount of carbon dioxide in the atmosphere skyrockets—and it has to go somewhere. It turns out that a significant portion of that CO2 is absorbed across the surface of the ocean, where it lowers the pH of the water and disrupts the ability of shellfish to form shells—and therefore survive. As little creatures like pteropods, a type of plankton, and oysters die off, the potential for a catastrophic ripple reaching the top of the food chain grows—which could ultimately mean no more tuna poke bowls, swordfish skewers, or whitefish salad-loaded bagels.
Since carbon emissions don't show any sign of slowing down, scientists around the world are working on stopgap solutions to help curb the amount of CO2 that the ocean has to take on. Recently, Washington State's Puget Sound Restoration Fund announced an intriguing plan to plant a kelp forest in one hectare of the Hood Canal, the westernmost portion of the Sound. One of the fastest-growing plants in the world, kelps are well-known for their abilities to suck up CO2 as they use it for photosynthesis. Scientists at the Restoration Fund, in partnership with Washington University's Washington Ocean Acidification Center (WOAC), hope that their mini kelp forest, which will be planted in December and harvested next summer, will help restore normal levels of pH in the Sound. If it does, kelp forests could potentially be planted underwater around the world in an effort to curb OA and encourage the normal growth of tasty shellfish.
We spoke with Terrie Klinger, WOAC's co-director, about the project.
MUNCHIES: Hi, Terrie. Can you tell me about OA's effects on the species we rely on for food? Terrie Klinger: OA decreases the amount of carbonate ions available to organisms, and that can influence their ability to form shells. Evidence so far indicates that at least some shellfish species are likely to be negatively affected. We've seen it here in Washington State and in Oregon; the Pacific oyster is vulnerable to changes in pH and CO2 concentrations. That suggests that in the future, it may become more difficult to commercially produce shellfish. And then broader effects on the seafood supply are expected—that's based on models and more indirect information, so we've yet to fully demonstrate the effects on food webs. But one could imagine that the seafood supply would be more broadly affected than simply cultivated shellfish.
Tell me about the kelp forest project. How might it help address OA? We've known for a very long time that sea vegetation—marsh plants, mangroves, seagrasses, and seaweeds—all consume CO2 during the normal process of photosynthesis. Some of these species grow really quickly, and have the capacity to assimilate substantial amounts of CO2 to fuel their growth. Kelps in particular grow very quickly, and they're native to Puget Sound, so it seemed like a really good idea to test the hypothesis that kelp might be able to remove meaningful amounts of CO2 from the surrounding seawater through the process of photosynthesis.
One reason that we're testing it here is because the Pacific Northwest shellfish industry is so interested in finding solutions that will allow them to keep growing shellfish. Shellfish cultivation is really important here in Puget Sound, and kelp are a native species here, so it seems like a good convergence. Also, the Sound's relatively calm waters make the project more tractable here than, let's say, on the outer coast. Farming kelp in a really wave-swept environment is nearly impossible.
Might the kelp provide any benefits besides helping to correct pH? Kelp are important species in near-shore habitats all along the West Coast. They provide important habitats for all sorts of organisms, including species that people like to eat, like different types of crabs.
What will be done with the kelp once it's harvested? Kelp behaves like an annual plant, and if you just leave it in the ocean, it will seasonally die back and the tissue will degrade, which means that the CO2 that's locked up in those tissues will just be re-released into the seawater. To effect change in seawater pH, you have to get the kelp out of the ocean. An interesting possible use for it is as biofuel.
Biofuel engineers are working on converting kelp or seaweed biomass to fuel analogous to the way that, say, corn biomass is converted to ethanol. Because of differences in plant chemistry between corn and kelp, there are differences in the process, but in the end you'd have something that could be used as a fuel or a fuel additive.
If the data shows some positive results, what might implications be for similar projects around the world? Kelp only grow in very specific places in the world; for instance, they're absent from the tropics. But they do grow along our coast and along similar coasts in Chile and in Europe, mostly in temperate waters. If there are positive results, I think that the first best outcome would be to renew incentives for protecting the natural stands of kelp that now exist, making sure that we keep what we have. And secondly, where it's feasible to restore kelp, where kelp might have been lost, that would be a good thing to do, and finally, in areas that are appropriate, to do advanced cultivation.
Sounds great. Do you have anything else to add? I think one thing I'd emphasize is that the most meaningful way to address OA is through regulation and reduction of carbon emissions. Looking toward the future—that is certainly the most important thing to do. In the meantime, we're trying to find remedies that help us buy some time, but they're certainly no substitute.
Thanks for speaking with us, Terrie.