ecosystems on the planet;

they are 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

the people who use the 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,

and 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 receded 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,

man groves,

and seagrass 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

that those smaller parks are connected,

because if they are not,

then they're probably not going to 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 just how much migration

is going on among the reserves within the system.

Now it is important to look at a variety of different species

because there is 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 are 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.