Coral reefs are some of the most
spectacular ecosystems

on the planet.

They're also some of the most vulnerable.

But how can we protect the reefs

and the animals and plants
who rely on them?

And how can we make sure

our protected areas aren't hurting those
who use reefs to survive?

These are some of the big questions

facing marine conservation
biologists today.

Let's take Fiji, for example.

Fiji is series of islands
in the South Pacific Ocean.

To help balance the need
for conservation and making a living,

scientists had suggested
that instead of one big park

which provides a lot of coverage
for one reef system

while leaving the rest unprotected,

a better way is to create
a system of protected areas

nested together like pearls on a string.

This idea is called connectivity.

In this way, scientists can protect
lots of different habitats

while not excluding people
from their traditional fishing grounds.

Now, the only way this string-of-pearls
kind of reserve network is going to work

is if each park is connected
to other parks.

There are two main benefits to this.

First of all, insurance.

If something bad happens to one park,

say, an oil spill or coral bleaching,

then because that park
is part of a system,

it can be reseeded from other parks
that escaped the event.

The second benefit is representation.

By conserving many different areas,

scientists ensure that lots
of different habitats get protected.

This way, they can make sure
all the different marine habitats in Fiji,

such as coral reefs,
mangroves, and sea-grass beds,

are all represented.

This way, we don't unduly settle
any particular village or group of people

with the economic burden of having
their fishing grounds off-limits.

By sharing the cost
around the communities,

they can also share the benefits.

So if we agree
that rather than one big park,

we should have lots of parks

of different sizes
and covering different habitats,

then scientists need to make sure
those smaller parks are connected,

because if they're not,
they probably won't be self-sustaining.

But how do we know that?

That's where genetics and DNA come in.

By looking at how closely related

the fish in each one
of these small reserves in Fiji

are to each other,

scientists can figure out

how much migration is going on
among the reserves within the system.

Now it's important to look
at a variety of different species

because there's no guarantee
that what's going on with these guys

is what's going on with these guys.

But if we look closely
and at enough species,

we can see whether or not
the necklace is working.

What scientists have found
so far is that, in general,

there's a fair amount of connectivity
amongst the parks within Fiji.

But it's not just a big free-for-all;

rather, it seems that, for some species,

babies born in the far west
are having a hard time

making it to the islands in the far east.

To help deal with that,
conservation biologists are suggesting

that there be enough parks
in both the east and the west

to keep the populations healthy.

This isn't just in Fiji, either.

Lessons about reserve connectivity
can help across the world.

In places like Indonesia, Papua New Guinea

and the Bahamas,

scientists are using a variety
of tools to help understand

how individual parks
can function together,

so that their sum is greater
than their whole.

And this way, we can keep
the beautiful necklace

that is our coral reefs, intact.