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Coral reefs are some of the most[br]spectacular ecosystems

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on the planet.

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They're also some of the most vulnerable.

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But how can we protect the reefs

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and the animals and plants[br]who rely on them?

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And how can we make sure

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

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These are some of the big questions

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facing marine conservation[br]biologists today.

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Let's take Fiji, for example.

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Fiji is series of islands[br]in the South Pacific Ocean.

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

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scientists had suggested[br]that instead of one big park

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which provides a lot of coverage[br]for one reef system

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while leaving the rest unprotected,

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a better way is to create[br]a system of protected areas

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nested together like pearls on a string.

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This idea is called connectivity.

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In this way, scientists can protect[br]lots of different habitats

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while not excluding people[br]from their traditional fishing grounds.

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

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is if each park is connected[br]to other parks.

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There are two main benefits to this.

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First of all, insurance.

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If something bad happens to one park,

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say, an oil spill or coral bleaching,

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then because that park[br]is part of a system,

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

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The second benefit is representation.

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By conserving many different areas,

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scientists ensure that lots[br]of different habitats get protected.

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

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such as coral reefs,[br]mangroves, and sea-grass beds,

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are all represented.

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

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

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By sharing the cost[br]around the communities,

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they can also share the benefits.

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So if we agree[br]that rather than one big park,

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we should have lots of parks

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of different sizes[br]and covering different habitats,

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

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

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But how do we know that?

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That's where genetics and DNA come in.

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By looking at how closely related

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the fish in each one[br]of these small reserves in Fiji

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are to each other,

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scientists can figure out

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

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

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

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is what's going on with these guys.

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But if we look closely[br]and at enough species,

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we can see whether or not[br]the necklace is working.

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What scientists have found[br]so far is that, in general,

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

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

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rather, it seems that, for some species,

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babies born in the far west[br]are having a hard time

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making it to the islands in the far east.

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To help deal with that,[br]conservation biologists are suggesting

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that there be enough parks[br]in both the east and the west

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to keep the populations healthy.

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This isn't just in Fiji, either.

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Lessons about reserve connectivity[br]can help across the world.

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In places like Indonesia, Papua New Guinea

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and the Bahamas,

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scientists are using a variety[br]of tools to help understand

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how individual parks[br]can function together,

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so that their sum is greater[br]than their whole.

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And this way, we can keep[br]the beautiful necklace

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that is our coral reefs, intact.