(water bubbles)
- [Reporter] Some ocean scientists are raving about kelp.
- [Scott] There's a lot to like about kelp,
particularly in its ecosystems benefits.
- [Reporter] 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.
- [Reporter] 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.
- [Reporter] 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.
- [Reporter] 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.
- 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.
- [Reporter] In addition, it also is great
at capturing carbon at rates 50 times higher
than trees on land.
- 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.
- [Reporter] 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.
- 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.
- So I've marked the perimeter of the farm
with farm buoys.
You can see ones over there
- [Reporter] 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.
- That's some good looking kelp!
- [Reporter] 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.
- It's interesting that when we have
more complex food systems,
we don't value traditional foods.
- [Reporter] 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.
- Limu traditionally has been used in our practices
in the way we live, not just in our eating.
- [Reporter] And the prospect of large scale production
raises a red flag for some.
- 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?
- [Reporter] 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.
- 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.
(serene music)