Name: How Seaweed May Help Revive Our Oceans
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In some parts of the ocean, like in the Gulf of Mexico, there is so little oxygen in the water that marine life is actually suffocating. Could kelp help, or is it mostly hype?

Kelp’s ability to capture carbon from the ocean could help save marine ecosystems.

In some parts of the ocean, like in the Gulf of Mexico, there is so little oxygen in the water that marine life is actually suffocating. Could kelp help, or is it mostly hype?

How Seaweed May Help Revive Our Oceans

Kelp’s ability to capture carbon from the ocean could help save marine ecosystems.

Nature

Hope or Hype? How Seaweed May Help Revive Our OceansPublished August 1, 2022Narrator: Some ocean scientists are raving about kelp.Scott: There's a lot to like about kelp, particularly in its ecosystems benefits.Narrator: Because they think this seaweed can potentially help solve major problems in our oceans today, including dead zones, areas of the ocean where oxygen levels have dropped, killing off all kinds of sea life.Francis: Oxygen's just declining so low that fish, other invertebrates, they actually suffocate.Narrator: So, why is this happening? In many cases, it starts with nitrogen and phosphorus, often found in fertilizer, the stuff we use for agriculture, or even our lawns or gardens. Rainwater washes it into streams and rivers and it makes its way into the ocean.Francis: If there's too much nutrients that run down from watersheds into a bay, for example, it stimulates these phytoplankton blooms.Narrator: Phytoplankton are single-celled algae. And these blooms can grow out of control, sometimes even visible from space, choking off oxygen from the water and blocking sunlight to the plants below. Eventually the phytoplankton die and they sink.Francis: Even though they're really small, when they sink, they decompose, and in that decomposition process, bacteria will use up the oxygen that's near the sea floor.Narrator: In many cases, this process is what causes the loss of oxygen in the water. And that's what happened in the Gulf of Mexico. The Mississippi empties here, bringing high levels of nitrogen and phosphorus into the Gulf. This is where kelp comes in.Scott: So we started creating this little miniature farm here. One of the great attributes of of seaweeds is it's a potent way of absorbing all these luxurious nutrients that's far too much for the ocean to really fully absorb.Narrator: In addition, it also is great at capturing carbon at rates 50 times higher than trees on land.Scott: Carbon sequestration is one of the key goals for climate change that we need to address. So there's a lot of interest in growing seaweeds simply for sucking carbon and nitrogen out of the waters and putting them into a more stable form.Narrator: But to make an impact, you need a lot of kelp sucking up nutrients and it would take a decent amount of space in the ocean to grow it all.Scott: When you look at it on a map in congregate, it would be about as big as Iowa, but spread out all along the shoreline. And I'd say we're still at that level of trying to distinguish between what's real and what's possible.Scott: So I've marked the perimeter of the farm with farm buoys. You can see ones over there.Narrator: And then you need to harvest it to prevent it from dying and releasing all of the absorbed nitrogen and phosphorus back into the water.Scott: That's some good looking kelp!Narrator: And for farmers to want to grow this much kelp, they'd need a market to sell it, and the market for kelp in the US is still emerging.Scott: It's interesting that when we have more complex food systems, we don't value traditional foods.Narrator: Seaweed also has an important cultural significance. Some indigenous communities in the US have been harvesting it for centuries, like in Hawaii, where seaweed is known as limu.Scott: Limu traditionally has been used in our practices in the way we live, not just in our eating.Narrator: And the prospect of large scale production raises a red flag for some.Scott: There's concerns in the community about mass producing limu. We've had a lot of history where people have come in from outside of Hawaii and they've done these different types of activities but they're not really giving back to the communities here. That's one of the questions I always think, how is this helping my community?Narrator: And if we grew huge quantities of kelp for carbon capture, what would we do with it all? Some scientists are exploring the possibility of sinking kelp deep down into the ocean, several thousand feet below the surface, potentially sequestering the carbon for millions of years but there are still a lot of unknowns.Scott: What does happen to that carbon and the seaweed when it goes to 1,000 meters deep? It's not like it's a complete desert down there. There are still organisms growing. Is that a free lunch for somebody? Are we gonna have a great bloom of something else and some unintended consequences? We need to precede doing those grand ideas with experiments to see what the impact might be.

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How Seaweed May Help Revive Our Oceans

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Support Provided By

Explore More

Capturing Carbon: Where Do We Put It?

Three Solutions That Can Slow or Stop Climate Change

Oceans of Acid: How Fossil Fuels Could Destroy Marine Ecosystems