From Heaven to Hell Atlantic: The Wildest Ocean on Earth

There's an ocean where giants gather to feast...

..where people battle the planet's roughest seas.

It stretches nearly 10,000 miles from Arctic to Antarctic.

From tropical shallows...

..to mysterious depths.

It's an ocean of extremes.

Engine room for storms 1,000 miles across.

It's also a sanctuary for the vulnerable.

People and animals brave this unpredictable ocean...

..risking it all for rich rewards.

This is the Atlantic - the wildest ocean on Earth.

The Caribbean, the Atlantic's sun-drenched paradise.

Its warm, shallow waters offer shelter and plenty of food.

The perfect place for this two-year-old Atlantic spotted dolphin to grow up.

The seas around him are bursting with life.

It's the richest corner of the Atlantic.

But paradise comes at a cost.

Over the next nine months, the sun's energy will push life here to its limits.

Caribbean heaven will soon turn to hell.

The sun is the tropical Atlantic's engine.

It heats the ocean and the coast of Africa

right across to the Caribbean, 3,000 miles away.

Here, there are huge expanses of crystal-clear sea.

There are coral reefs,

meadows of seagrass and mangrove forests.

There's a wider variety of marine life here than anywhere else in the Atlantic.

Living here can bring rich rewards.

Right now, it's February - the Caribbean's coolest month.

Even so, these shallows off the Bahamas are a balmy 23 degrees

and the water's full of sound.

CLICKING AND WHISTLING

The chatter of Atlantic spotted dolphins.

CLICKING AND WHISTLING

It's a safe refuge for them -

the deeper waters are patrolled by sharks.

Dolphins are highly social and play together and hunt together

in tight-knit groups, sometimes 50-strong.

These two mothers have teamed up

so their calves can play and learn from each other.

The calves are still suckling from their mums

and yet to fully develop their spots.

They've plenty of time to learn the ins and outs of dolphin social life.

They must learn a huge number of complex clicks and whistles.

CLICKING AND WHISTLING

Body language is important, too.

Play-biting helps build social bonds,

one of the first ways that young dolphins learn to interact.

Then there's fin-rubbing. Scientists compare it to a handshake or a hug.

It's all great fun but they're learning vital lessons.

From February on, the Caribbean gets a little warmer every day.

Good news for another marine mammal that simply can't survive without the heat.

A manatee.

Distant relative of the elephant, she's 3m long and weighs in at almost a tonne.

But despite her bulk, she has very little blubber to keep her warm.

She lives here because the water never drops below 20 degrees.

If it did, she'd die.

Lots of manatees overwinter in warm river estuaries.

Now, as sea temperatures rise, they spread along the Caribbean coast

in search of their favourite food - seagrass.

It covers huge areas of these shallows and the warmer and sunnier it gets, the faster it grows.

Over the coming months, she'll spend seven hours a day grazing these marine meadows.

It's manatee heaven - for now.

Change is on the way.

By April, the sun is just a little bit more intense.

A small change with big effects.

In the deep water beyond Belize's barrier reef,

the growing heat triggers a spectacular annual event.

Snappers.

They've gathered here in this one place for one hour for one reason.

Snappers are usually solitary and live over 20m beneath the surface.

Now the combination of rising temperature, day length,

and phase of the moon brings them together in shoals of 10,000 or more.

At dusk, the fish rise up towards the surface.

The females release their eggs, the males their sperm.

They're here to spawn.

They do it at dusk because the fading light makes life harder for predators.

But the snappers haven't gone entirely unnoticed.

A whale shark.

The length and weight of a double-decker bus.

But he's not after the snappers.

He hoovers up their eggs - tens of thousands in each mouthful.

Millions of eggs are lost but millions more survive.

The young will drift on the currents until they find a place of safety.

A mangrove forest.

Stretching all along the Caribbean coastline,

these forests hold a secret.

An extraordinary sanctuary, hidden beneath the surface.

The roots, draped with anemones, starfish and sponges, form a living barrier.

The bigger predators can't pass.

And make this a safe haven, not just for snappers,

but for the young of hundreds of species of fish.

It's an underwater wonderland.

These underwater forests are among the richest environments on Earth.

By providing sheltered nurseries,

they form a vital part of the web of life across the Caribbean.

Sustaining life in the shallows, the reefs, and the deep sea beyond.

But other forces affect life here.

And one of the most powerful has its origins 3,000 miles away in Africa.

The African sun makes the Sahara Desert one of the hottest places on Earth.

It's May and already the temperature is nearing 40 degrees.

The intense heat fuels powerful winds

which blow out from the desert and west into the Atlantic.

The trade winds.

They first hit land 400 miles off the African coast in the Cape Verde archipelago.

Desert islands, dominated by the wind.

The people here have an intimate relationship with both wind and sea.

They stitch their sails from old plastic sacks.

Head fisherman Xavier has an instinct for the wind.

It's all that stands between a successful trip and disaster.

The fishermen sail far out into the Atlantic.

Each trip can take a week or more.

The men are dependent on wind.

If it fails, they might not get home.

After a successful trip, the fishermen turn for home.

But the trade winds blow on, driving west across the ocean.

As they move, they pick up moisture from the sea below.

By May, the sun's heat evaporates billions of tonnes of water from the ocean surface every day.

Clouds build and the trade winds sweep them west.

When they finally reach the Caribbean,

they bring a vital resource to paradise.

Rain.

The rain washes mud from land to sea...

..and here, the mangrove roots slow the flow and the sediment settles.

The mud nourishes the mangroves and the roots act as a filter,

ensuring the waters of the Caribbean remain crystal clear.

It's June and the sun is at its height.

The clouds soon burn away.

Soon, the building heat will test many of the creatures that live here to their limits.

But for now, life is good.

Off the Bahamas, adolescent dolphins have formed a group.

They're getting their first spots, a sign of their new-found independence.

Now they've been weaned, they must hunt for themselves.

And for dolphins, hunting means teamwork.

The group have cornered an unlucky filefish.

But they don't plan to eat it.

The youngsters take turns to herd the fish, communicating in intense bursts.

More than just play,

the youngsters are learning to coordinate their movements and work as a unit.

Fortunately for the fish, they tire of their game.

The ability to work together will be crucial to their survival.

In mid-summer, the heat and light drives an explosion of plant life.

The seagrass is growing by three centimetres a day.

Good news for the manatee.

But there are also thick patches of algae growing on her back.

Conveniently, she's found a place nearby where she can get her back scrubbed.

Alongside the reef, young parrotfish have set up a cleaning station.

The fish get a meal and she gets cleaned.

Now, she can go back to the serious business of eating.

The tropical sunlight brings life to everything it touches.

In this coastal lagoon in the Bahamas, another animal can't get enough of it.

It may be moving slowly but this Cassiopeia jellyfish is in a hurry.

It's on its way to a sunbathing party.

Every day, hundreds of Cassiopeia cluster in the calmest, sunniest spots.

These are solar powered jellyfish.

There are algae that live just beneath their tentacles, which feed on the sun.

They photosynthesise and the nutrients they make are food for the Cassiopeia.

An arrangement that benefits both sides.

The jellyfish get free food, the algae get their own mobile greenhouses -

guaranteeing them a place in the sun.

These jellyfish rarely need to hunt.

With bright sunlight and algae on board, they thrive.

And when the sun sets, they will rest, ahead of another hard day's sunbathing.

As evening falls, the sun loses its power.

But at this time of the year, its influence persists far into the night.

After dark, the mangrove lagoons undergo a magical transformation.

Something that Clifford, a fisherman from Belize, plans to take advantage of.

All day long, an underwater life form here has been harvesting the sun's energy.

Now, that energy will be released.

As fish move through the water, they create a light show.

It's not the fish that are glowing - it's something much smaller.

Tiny single-celled creatures called dinoflagellates flourish in the rich warm waters of the mangrove lagoons.

And when they're disturbed, they glow.

Bioluminescence.

A shock to warn off predators.

They're charged up by sunlight, so the longer the days, the more intense the glow.

The bioluminescence is so powerful that Clifford can fish in the dark.

Further out to sea on the Caribbean's reefs,

there's another extraordinary night-time display -

a sign that the sun's power is now pushing the reef's ecosystem into overdrive.

It may not look like it, but this is a coral.

Scientists believe its glowing is an equivalent of sunscreen.

Corals have algae living in their cells.

As these photosynthesise, they produce food for the coral.

But too much ultraviolet light can damage them.

So the corals protect themselves.

A special protein absorbs the ultraviolet light,

and re-emits light of another colour.

By day, the sun is too bright for this to be visible.

But shining blue light on corals at night shows their fluorescent response.

It's a much-needed defence mechanism when there is no escape from the midsummer sun.

It's now August. Water temperatures have hit 29 degrees.

Many creatures seek refuge in the shade.

In Grand Cayman, millions of silversides gather in caves under the reef.

There's safety in numbers...

..but danger lurks here in the dark.

A monster the length of a man...

..with a ravenous appetite.

A tarpon.

He has explosive acceleration...

..hitting up to 40mph.

His cavernous jaws create a suction effect when he strikes.

He swallows his prey whole.

As more silversides enter the cave, more tarpon gather.

This seasonal feast is just too good to miss.

Heat is building in the water.

And temperatures are rising in the dolphin community, too.

DOLPHINS SQUEAK

This calf is trying to stay close to his mother.

She's in oestrus and has attracted the attention of an eager and persistent male.

Turning belly up and blowing bubbles signals his excitement...

..but she's not interested.

Avoiding a single male is relatively easy,

but groups working together are another matter entirely.

RAPID SQUEAKING AND CLICKING

Males from another group are on the hunt for a mate.

They're an established team, constantly communicating.

Their target is a lone female.

She tries to fend them off, but they are undeterred.

Pinning her to the seabed,

they use their echolocation to examine her

and see if she's ready to mate.

The noise alerts another group of males.

They also want access to the female.

And they're ready to fight for it.

COMMUNICATION INTENSIFIES

The groups bombard each other with a deafening barrage of sound.

The sounds normally used to stick together

now become an intimidating weapon.

Their head-to-head body postures and open mouths all signal aggression.

These encounters can escalate into violence,

but this time the intruders back off.

The calf watches and learns.

He's growing up in a dangerous world.

It's the end of August.

The sea is at its hottest.

On the reefs,

the rising heat is now putting life

under serious pressure.

Corals are very sensitive.

If summer water temperatures rise just one degree above average...

..it can have catastrophic effects.

The growing heat drives the corals to eject the symbiotic algae

that normally feed them.

Without their algae,

the corals lose their primary source of food

and in just a few days

they turn white.

If the temperatures stay too high for too long,

the corals will die...

..and the animals that rely on them

will lose their food and shelter.

The sun, once the engine of life...

..now threatens to destroy it.

The whole of the tropical Atlantic

now balances on a knife edge.

And 3,000 miles to the east,

a catastrophic event is building.

On Cape Verde off the coast of Africa...

..the hot winds from the Sahara are whipping the sea into a frenzy.

WAVES CRASH

The favourable conditions Xavier and his men rely upon are changing.

Water evaporating from the warm sea

generates turbulence and the Saharan winds.

These are dangerous conditions.

Xavier makes the decision to turn back.

He knows what's coming.

A tropical storm is brewing.

The fishermen have packed up their boats.

Storms blow over quickly here

because the trade winds blow them on across the Atlantic.

But as they travel,

some storms grow into monsters.

A chain reaction begins.

The hot waters and winds combine to drive a constant cycle of convection.

Warm air rises from the sea,

lifting moisture to create vast banks of cloud.

More air is sucked in below

and a vortex begins to form.

The storm roars across the ocean,

growing stronger with every mile.

When the winds reach 74mph,

this storm finally earns a new name.

A hurricane is born.

An unstoppable force of nature...

..with the Caribbean right in its path.

The countdown to destruction has begun.

Animals and corals,

already close to breaking point from the rising heat,

will soon face a violent and deadly assault.

The warm seas that nursed them through the first part of the year

now fuel the storm that threatens them.

Everything is about to change.

36 hours before impact,

the first signs of the coming hurricane appear.

WAVES THUNDER

Ocean swells roll across the once tranquil sea.

BELLS RING

An official hurricane warning is issued.

With 24 hours to go...

..winds hit 35mph.

The dolphins seek refuge in deeper water.

SQUEAKING AND CLICKING

Survival depends on sticking together.

This is when their ability to communicate will really count.

BINS CRASH

On land, those unable to evacuate

must batten down the hatches and wait.

12 hours before landfall,

huge walls of thunderstorms bring intense bands of rain.

GLASS SHATTERS

Winds now gust to over 70mph.

They batter the mangroves.

A rising surge of water driven on shore by the wind...

..engulfs the coastline.

The sea is an impenetrable murk.

At their peak, winds can hit 120mph.

The relentless power of the sun

has turned paradise into hell.

SILENCE

Hurricanes are one of the deadliest natural forces on the planet.

On land, they destroy property...

..but people can seek refuge.

Animals at sea have no protection at all.

Hurricanes can break up dolphin groups,

leaving stragglers lost and vulnerable.

Alone, a young calf is easy prey for sharks.

The mangrove forests bore the full brunt of the storm.

Their life-giving sediments are violently churned.

The turbid water appears lifeless.

MANATEE SNORTS

But the roots make the mangroves a safe haven.

Manatees head deep into the mangroves during hurricanes,

knowing they will find safety.

The trees act like a living crumple zone.

The roots dissipate the destructive energy better than any seawall.

They calm the waves and tame the surge.

The mangroves are the Caribbean's storm shelter.

The roots protect the precious fish nurseries

and in the aftermath,

they slow the moving water,

allowing sediments to settle and the waters to clear.

The mangroves don't just protect against hurricanes.

They can also benefit from them.

The storm surge disperses mangrove seedlings far and wide

and these will take root in clearings in the forest.

A sanctuary for the tropical Atlantic will continue to grow.

Out on the reef,

hurricanes take the energy out of the overloaded system.

Some corals are damaged,

but the torrential rain cools the waters.

The corals will take back their algae,

the reef will thrive again.

Off the Bahamas...

..hurricanes have been known to devastate dolphin groups.

The only way a stranded calf will survive...

..is to reunite with a group.

DOLPHINS SQUEAK

Nature has a way of bouncing back.

In groups that do lose calves,

scientists have found that females come back into oestrus

more quickly than usual.

The result is a baby-boom.

It's time for the group to reinforce all bonds.

CLICKING AND SQUEAKING

Life in the tropical Atlantic resumes where it left off.

For now, all is calm in paradise.

But soon the heat will build once again.

The sun creates opportunities for life,

yet it can also bring destruction.

All living things here must learn to survive both heaven and hell.

The vast opposing forces of this extraordinary ocean...

the Atlantic.

MUSIC: Mr Brown (Blend Mishkin Remix) by Dirty Dubsters featuring Bass Nacho

The warm sundrenched shallows of the Caribbean Sea

are teeming with life.

The Atlantic team spent more than 300 hours underwater,

all across the Caribbean

and met some very special animals.

From the tranquil lagoons of Belize...

..to the sandbanks of the Bahamas...

..and the spectacular caves of the Cayman Islands.

But to reveal some amazing new discoveries about corals,

the team had to turn to science

for a new way of looking at the world.

Scientists have recently discovered that some corals

appear to have a natural sunscreen.

And to reveal this in its full technicolor glory,

the team are to leave their usual habitat.

In Miami, the only US city actually built on a coral reef,

there's one place where corals are always in the spotlight.

Colin Foord is a marine biologist and cameraman

with a passion for corals.

Just the man to help producer Renee Godfrey

get the unique images of these amazing animals

that she's hoping for.

And in your photography and filmmaking of these corals,

-you're trying to take people, really, into a...

-Yeah...

-..a macro world.

-..into a macro universe.

Coral reefs are built by colonies of tiny animals.

Colin studies them with lenses that can magnify up to 200 times.

He rescues corals which are threatened by dredging

in Miami's waterways

-and relocates them to protected areas on the city's outskirts.

-TAPPING

Colin takes small samples of the city's corals

to study how well they cope with pollution and rising temperatures.

Some of his work involves a combination

of science and photography.

Corals are mysterious animals, they're mysterious creatures.

I see them as the most alien

and cosmic of the organisms on the planet

and I find that to be incredibly intriguing.

Colin uses blue light and zoom lenses with special filters

to reveal something that is barely visible to the naked eye

and impossible to film in daylight.

Now Renee is able to see exactly what she came looking for.

Under the blue light, the corals fluoresce.

Pigments in the coral absorb the ultraviolet component of the blue light

and re-emit it in different colours.

In the wild, it's thought this adaptation protects the coral

from the sun's damaging ultraviolet rays.

Oh!

-They really have opened up, haven't they?

-Hm.

The corals put out tiny tentacles to catch food from the water.

And with time-lapse photography,

the crew make the images even more revealing.

The coral is almost working on a different timescale than the human timescale.

Everything is much slower for a coral.

Working in a laboratory, we can film for a long period of time

and then speed up,

so you start to see the way that the coral...

You can see the mouth eating and moving.

You look at them and they don't look like they're very animate,

but once you stop and observe them,

you realise just how alive corals are.

They're just the most amazing colours.

It's really...

-Wow!

-Oh!

Renee has got the shots she came for,

revealing the coral's extraordinary adaptation for coping with the tropical sun.

But for Colin, filming these beautiful images

is part of a wider mission.

-You're showing corals in an incredibly artistic way.

-Yes.

On the one hand, we just want the corals to be able to present themselves.

Corals are these living art forms.

The natural beauty of these corals can sell themselves to the public.

As to, "Why should we care about the coral reefs?"

Perhaps you've never been able to get so close to a coral.

Well, look at these beautiful organisms.

Specialist photography is helping us to learn more and more

about these extraordinary life forms.

With passionate people like Colin on their side,

these cosmic corals of the Atlantic

may have a bright future.

There's no end to what his camera might reveal.