When you picture New York City, there are so many iconic things that come to mind.
But, before the yellow cabs and hot dog stands,
New York was known for something else:
Oysters.
From the 1600s through the 1800s, New York was booming with them.
And it was oysters, not hotdogs, sold streetside by the millions.
Oyster reefs covered over 220,000 acres along the coastline.
The reefs were so large that ships needed to navigate around them.
But, of course, this isn’t the case today.
Oysters were overharvested nearly out of existence,
and not just in New York.
Experts estimate we’ve lost 85% of the world’s oyster reefs in the last 200 years.
Today, we’re trying to put them back.
Because this animal that you often find on a dinner plate
might actually be an effective defense against the rising ocean.
We’re losing our coasts to climate change.
As oceans levels rise, the water erodes the shoreline.
This pushes the entire coast back,
encroaching on homes and destabilizing land.
So, enter the oyster.
This uncharismatic rock of an animal.
STEPHANIE WESTBY: Oh come on! You don't think they're charismatic?
KIM: I feel like… It’s not something I would call “cute.”
WESTBY: No, I can't argue with you there.
I've tried, but yeah, no, they're not.
Stephanie Westby has been helping to restore oyster reefs
in the US’s Chesapeake Bay for over 10 years.
WESTBY: Their charisma really lies in their functionality, rather than their form.
Oysters obviously don't move around.
And that’s exactly part of the appeal.
Oysters stick together. Literally.
Baby oysters called “spat” attach to older and even dead oysters
in order to grow.
WESTBY: And over generations, all of these oysters reproducing,
it builds up the oyster reef.
In some places, that sturdy reef can help defend the coast
by dampening the force of incoming waves.
WESTBY: If you have an oyster reef that's "intertidal" --
that sticks up at low tide --
then it can perform some of that wave energy protection function.
Oyster reefs can break up waves by catching the brunt of the force.
Part of the wave is deflected back to the ocean,
and the rest can more gently reach the shoreline,
which slows long-term erosion.
On its own, an oyster reef won’t *stop* a hurricane-level storm surge,
but it could definitely limit the damage.
And the larger they grow, the more protection they can offer:
As time goes on, sea levels will rise.
Unlike man-made breakwaters, that will need to be rebuilt over time,
oyster reefs just keep growing upward.
Various organizations around the world are working to restore oyster reefs.
But reef restoration isn’t as simple as just dumping oysters into a bay.
They need something to stick to in order to grow.
In New York, one organization puts recycled shells in cages
for oyster spat to grow on,
and groups in Bangladesh, and around the US,
have placed large concrete barriers offshore for oyster spat to grow on.
Now, on their own, concrete structures like this are actually effective breakwaters.
So... why add oysters?
To understand, it helps to look at a more familiar type of reef:
SEAN CORSON: Oyster reefs provide much the same function as coral reefs.
They provide the same kind of habitat.
They are the underpinning of the ecological systems where they exist,
just like coral reefs.
Oysters are filtration systems.
They eat by pulling in large quantities of water.
Algae, nitrogen, and other contaminants are eaten,
or harmlessly dumped to the bottom of the bay, and clean water is expelled.
A single oyster can filter up to 50 gallons of water every day.
As the water clarity improves, sea grasses start to grow, fish return,
and other sea creatures make the crevices in the reef their home.
CORSON: They are this aggregating, reef-building, hard structure.
And so, if you look at the way we try to deal with
reducing erosion right now, as a society,
for the most part, we put rocks, big pieces of concrete,
we set up, more or less, walls, to try to slow the rate of waves,
reduce the wind-driven erosion, that type of thing.
Oysters can serve in that capacity in many ways, but bring added advantages.
Places like New York City or even the Chesapeake Bay
are way too industrialized to bring back the reefs of the 1600s.
But that’s not really the point.
CORSON: I don't think we can put it back just the way it was.
I don't think that's necessarily a realistic goal.
But I think we've got a great opportunity when we start thinking about
multiple benefits, and the different kinds of needs of society,
whether it's to reduce wave impacts, or offset nutrient inputs,
or generally increasing the health and resilience of the bay.
Resiliency against the rising oceans isn't as simple
as undoing the mistakes we made in the past.
We don’t live the way we did 200 years ago, and the world looks very different.
But what we can learn from oysters, is that restoring one species from the past
can create a chain reaction to a more sustainable future.
CORSON: It feels hopeful.
And it feels like something that we can achieve.