All language subtitles for Secrets of our Living Planet 4of4 Waterworlds 720p HDTV x264 AAC MVGroup org_Subtitles01.ENG

Ten million species

live on planet Earth.

Each one is remarkable.

But none can survive on its own.

All life depends upon connections.

Unexpected, invariably complex,

beautiful relationships between
millions of plants and animals.

In our waterworlds,

I want to show you why

this crab needs a tiger...
TIGER GROWLS

..why this giant otter
needs a snail...

..and why this shark needs a sponge.

Connections like these form
the planet's great ecosystems.

They're vital for all life.

I want to show you our world
as you've never seen it before.

This is the Gullfoss waterfall
in Iceland.

100 cubic metres of water
are falling here every second.

So this is just about as close
as I want to get,

because this is a dangerous
and volatile environment.

But for all of that danger,
these raging torrents contain

an ingredient
which is absolutely vital for life.

And the clue is in the name.

"Gullfoss" means "Golden Falls."

The colour is produced by millions
of tonnes of raging water,

relentlessly carving through
rock and soil.

And accumulating
that golden sediment.

And there's something else vital
being carried in this water...

oxygen.

Together, these are incredibly
potent ingredients.

At the moment,
all of this is just cargo,

being swept along by this
very fast-moving water.

But with ingredients like this,

if the environment changes,
then the potential for life is huge.

It doesn't matter where you are.

Most life on Earth
depends on the simple ingredients

that start upstream.

Places where, normally,

just a few specially-adapted
creatures can survive.

So, how do mere oxygen and sediment

ignite such a richness of life
downstream?

To find out,
I'm going to witness

one of the greatest explosions
of life on Earth.

Over millions of years,
waters from the Brazilian highlands

have flooded
into a vast lowland basin...

..the Pantanal.

Look at this!

These murky waters
are virtually boiling with fish.

I've never seen so much life
so densely packed into one place.

Every river and every tributary that
we've paddled up in the Pantanal...

CAIMANS SPLASH
..has been lined with these animals.

An estimate suggests there might be
as many as ten million caiman
living in the Pantanal.

That would make it the largest
concentration of land vertebrates
anywhere on Earth.

But the really staggering thing
about the animals in the Pantanal

is their sheer size.

Look at this wonderful bird.

It's called the jabiru stork.

The tallest flying bird
in South America.

This really is a land of the giants.

The world's largest snake,
the green anaconda,

which can grow to nine metres long.

Even the plants are monsters.

Look at this splendid spread
of giant water lilies.

Absolutely fabulous things.

A single plant produces
around 40 leaves

and each leaf can grow
to three metres wide.

BIRD CHEEPS

Even the rodents here
are the largest in the world.

These are capybara.

They're the dominant herbivore
in the Pantanal,

and they occur here in huge numbers.

And what does it take to catch
such an overgrown rat?

(Look at that! Look at that!)

We're about six metres from
a wild jaguar. It's unbelievable.

The jaguars in the Pantanal
are the biggest cats

anywhere in the Americas.

(Oh, my goodness!)

And then,
there's the apex predator -

the king of the river.

OTTER SQUEAKS
Giant otters.

Remarkable animals.

OTTERS SQUEAK

They're supremely adapted
for their aquatic lifestyle.

And given the size of these animals
and their abundance here,

this has to mean that this water
is literally full of fish.

It's like an Eden, it's just packed
- packed with life!

So, how did that cargo from those
barren mountain streams

help create this magical place?

Here's a jar of water.

I've just collected it
from the creek behind me.

And look, if I shake it, to mimic
the action of a waterfall,

swirling and frothing
in a violent eddy,

you can see that all
of the material here

is now held in suspension.

But what's so important
about that material?

What's so important
about that cargo?

Well, when water tumbles down
from the mountains,

through the fast-flowing streams,
along the giant rivers,

it's constantly grinding away
at the bedrock and the soil,

picking up material, so that when
it arrives here in the Pantanal,

it's filled full of silt,
sediment and detritus -

a heady cocktail
of inorganic and organic material.

And it's filled full of things
which are essential for life -

things like nitrogen and phosphorus.

And look - now the water in my jar
has begun to slow down,

the material in it
has started to settle out.

And this exactly replicates what
is happening here in the Pantanal.

In fact,
it's settled out right here,

and what I'm standing on
is a great plain of fertility.

BIRDS CHIRP

This land of giants
is exceptionally fertile

because that cocktail of nutrients
deposited by the rivers

has been trapped here.

Gradually,
they've built up, year-on-year,

over millions of years.

But this hugely productive process
has only been possible

thanks to the tireless work
of one species of animal.

It's so important
that even the giant otter

depends upon it
for its survival.

Now, you might expect my hero
of the Pantanal

to be one of the large creatures
that we've already seen,

but brace yourselves...
My hero...

is this, the apple snail.

And I can tell you that,
without this humble animal,

the Pantanal wouldn't - couldn't -
be such a rich environment.

But how on Earth
can a snail be so important?

The apple snail spends much
of its life on the river bed,

safe from most of its predators.

It has a fish-like gill that can
remove oxygen from the water,

so it can breathe
beneath the surface.

Here, there's plenty of food...

..because there's nothing that
an apple snail likes more to eat,

than dead and decaying vegetation.

Its teeth can saw through
the toughest plant fibres

and, unlike most animals,
it can digest cellulose.

But like all animals,
it needs to relieve itself

and that's when the magic happens.

It's miraculously recycled
all that dead material

back into accessible
nitrogen and phosphorous.

Five-star fertiliser
for the next generation of plants.

But that's not the only way
this species

recycles essential nutrients.

For hundreds of predators,
apple snails make a very tasty meal.

Young caimans
particularly enjoy them.

And each mouthful

helps spread the vital ingredients
of all life around the Pantanal.

It's thanks to all of this recycling
by the apple snail

that the Pantanal
is so full of so many giants.

But, in order to carry out
this pivotal role,

the snail has to overcome
one huge challenge -

one which puts the whole ecosystem
of the Pantanal on a knife edge.

THUNDERCLAP

April brings rains to the highlands
across central South America.

For months, the Pantanal
has been drying into a patchwork

of small pools and grass.

But now, the rivers swell.

They burst their banks
and drown the grassy plains.

This is the most dangerous time
for this ecosystem,

because the most important
ingredient for life is running out.

Clearly, there's no shortage
of sunshine here.

Nor is there any shortage
of nutrients.

No, what's in surprisingly short
supply in these waters, is oxygen.

As billions of tonnes of grass
is swamped, it begins to decay...

..stagnating the water
and robbing it of that oxygen.

The Pantanal is suffocating.

It will only survive
if that rotting grass

is rapidly recycled
into new forms of life.

The Pantanal now needs
the apple snail more than ever.

But without oxygen,
not even it can survive.

Thankfully, it has a secret weapon.

Uniquely amongst snails,

it possesses a beautifully-evolved,
telescopic appendage...

..a snorkel!

The snail pumps air straight into
a special lung.

And when it's breathed enough,
it returns to what it does best -

processing that rotting grass.

So whatever this place
throws at them,

billions of apple snails
keep munching away

and fertilising the Pantenal.

The aquatic ecosytem flourishes,

supporting enough fish to satisfy
the king of the river.

OTTERS SCREECH

The giant otter.

OTTERS SNORT AND SCREECH

SCREECHING CONTINUES

Just listen to that!

Their vocalisations are constant,
this family party,

constantly in touch
with one another.

These screeching calls
are territorial -

warning other animals that this
group owns this stretch of river,

and all of the fish in it.

Any rivals
are aggressively dealt with.

The whole family regularly patrols
a stretch of up to 20km.

And there's nothing
that frightens them -

not even caimans.

Now that they've got the river
to themselves,

it's down to the business
of catching fish.

And their appetites are insatiable.

Each animal needs to eat a tenth
of its bodyweight every day.

In the Pantanal,
there really is plenty for everyone,

and it's all thanks to a mollusc.

For me the most important species
in the Pantanal is the apple snail.

It's a true keystone species,

involved in everything
that's going on here.

It converts fish
and other matter into grass.

Grass and aquatic vegetation
into food.

It's even food itself,

and it can survive anything
that this place can throw at it.

It shapes and structures
the Pantanal.

Therefore, it's what we call
an ecosystem engineer.

Without it, all those millions
of caimans, the capybara,

the jaguar, and especially
the giant otter,

would struggle to live here.

And that's why the giant otter
needs the snail.

I like that.
I love the connectedness!

The tireless work of apple snails
over millions of years

has helped to create the Pantanal.

And all over the planet,
from the Florida Everglades,

to the Fens of East Anglia,

to the Nile, freshwater snails
and other wetland creatures

recycle material on an epic scale,

sustaining watery ecosystems,
and making them rich in life.

And thanks to these animals,
the impact of wetlands

on the planet is huge.

At one end of the wetland, the
raging water from mountain streams

is soaked up like a giant sponge.

At the other,
it's released in a steady flow.

In doing so, these wetlands ensure

that the rivers
and the animals downstream

get a reliable supply of water.

But as the river
makes its way to the sea,

life in the water faces
a much bigger challenge.

This is the end of the line
for the mighty Ganges.

It's the swamp of the Sundarbans,
on the coast of Bangladesh.

On the ground here, it feels
and smells like an alien world.

The whole place is pervaded
by the stench of rotten eggs,

generated by
sulphur-belching bacteria.

It's certainly a lot less inviting
than the Pantanal.

It's surprising that anything
survives here at all,

because life in this place

has to survive
some pretty tough challenges.

For a start, the silt.

You see,
when the water reaches the coast,

only the finest particles
are held in suspension

and when they drop out,
they form this...

..thick, gloopy mud. Whoa!

It's so thick,
that not even air can penetrate it,

so no oxygen can get into the soil.

And, as if that wasn't bad enough,
twice a day,

with the rise and fall of the tide,

this whole place floods.

Precious nutrients, in the form
of leaves, are flushed out to sea.

And, worst of all, everything
is drenched in bitter salty water,

which very few plants can tolerate.

But the Sundarbans is not the
hell on Earth that it might seem.

Look at this beauty!

A black-capped kingfisher.

A brahminy kite.

There are enough fish here
to support millions of people.

Macaque monkeys...

..chital deer, too.

And there's one creature
that is very special.

But it's extremely well hidden.

It's also a man-eater.

Tiger!

I can see the stripes on its back.

It's got its rump facing towards me,

its head's lying on the ground.

Wow!

It's about the worst ever view
of an animal that I've ever had,

and yet it's one of the best!

It's getting up.

Which way did it go?

After that tantalising
and remarkable view of an animal,

we've been able to follow a diary
of its movements, here in the mud.

And, if you look, you can see
that the tiger has come here.

Here's a pug mark, here's another,
here are three more.

But I think what's happened here

is that the tiger has come to this
point, it's changed its mind,

and it's turned around,
headed back this way.

There's another print there.

And it's gone off, into the forest.

And this is not a one-off.

Pictures from our camera traps
reveal,

that living in this salty,
drowned forest

is a large population
of Bengal tigers.

Surely one of nature's
most magnificent predators.

And despite the fact
that population estimates vary,

we think that a quarter

of the world's wild tiger population

might be living here
in the Sundarbans.

So, there has to be enough
food for them,

this has to be
a productive ecosystem.

But how can a muddy, salty,
sulphurous bog support so much life?

Well, the secret of the Sundarbans,
lies in beautiful

relationships that have evolved
between the most unlikely species -

including the tiger.

And it all starts with
a very peculiar plant...

..the mangrove - the only trees
that can survive in salty water.

They even expel some of that salt
through their leaves.

And as for the lack of oxygen
in the soil,

mangroves have a spectacular
solution -

not unlike that of the apple snail.

Now normally, plants access oxygen
through their roots

from tiny pockets of air
in the soil.

But in this sticky ooze,

these pockets
are virtually non-existent.

But then, the mangrove
is a pretty special plant.

All of these spikes sticking
out of the soil here are roots,

and they act a bit like snorkels,
sucking in oxygen out of the air

when the plant can't get it
out of this thick mud.

But then, the mangrove doesn't
just rely on its snorkels.

There's something else
going on here,

something you can only appreciate
at low tide.

Millions of crabs!

Leaf-eating crabs and fiddler crabs.

They're called fiddler crabs,

because they have this
vastly-enlarged front claw.

And when they're feeding, it looks
like they're playing the fiddle.

They also wave them
at any adversaries

in a relative show
of size and strength.

In fact, when they're fully grown,
that claw can represent 65%

of the crab's body weight -

quite an investment
for something to wave around

at your enemies.

These fiddlers are displaying
to defend their territories.

And their most valuable real estate
is underground.

This little fiddler is excavating
mud to create a burrow.

When he's finished,

it's going to be more
than half a metre deep.

His burrow gives him
somewhere to hide from predators,

like this stork.

And when the tide comes in,
from predatory fish.

These leaf-eaters
live in communal burrows,

and together, their tunnels
form an underground labyrinth.

All of these burrows
are vital for the mangrove.

At low tide, they channel
an air supply through the mud,

direct to the roots.

And it's not just oxygen.

The crabs even supply
the trees with food.

The first ingredient
is all those smelly bacteria.

Look really carefully,
and you can see this crab feeding.

It's picking up particles of soil
and passing them to its mandibles.

When it gets enough,
it forms them into a ball,

and it gradually removes
all of the organic material,

detritus and bacteria,

and then it discards the ball.

And you can see those that it's
processed lying on the surface here.

And if the crabs didn't do this,
this mud wouldn't be very nice -

a nasty, sulphurous ooze.

Racing against the tide,

this fiddler is taking bacteria-rich
mud back to his burrow.

Here, he'll recycle it
and release nutrients

for the roots of the mangrove.

Further up the beach,
this leaf-eater is also working hard

to gather his food
before the tide steals it.

These crabs collect
a staggering 80% of the leaves

that fall here in the Sunderbans

and store them at the bottom
of their burrows.

Where they, too, will essentially
fertilise the mangrove.

But best of all,

the burrows even help control
the saltiness of the swamp.

When the tide comes in,

toxic seawater
flows into the burrows

and mixes with fresh water.

And this allows the mangrove

to expend less of its energy
excreting salt,

and more on actually growing.

Without these burrows,

the Sundarbans
simply couldn't survive.

Together, the crabs
make a vast network -

a sort of Sundarbans tube system.

The scale of the tube system
is unbelievable.

Just one square metre
can have 300 tunnels.

Crabs are ecosystem engineers.

Without the many millions of them,

living in this mangrove,
the Sundarbans simply couldn't work.

That's why the tiger
needs the crab.

So the tiger needs the crab.
But it's more magical than that.

And there's an even more
unusual relationship...

..one that protects the Sundarbans
from a lethal threat.

Thanks to the crabs
gardening the mangroves,

the Sundarbans support
some large herbivores.

But too many eating too much
would soon damage the forest,

so it needs protection.

The monkeys have sounded a warning.

This family of chital deer
won't be staying much longer.

It's the very presence
of these terrifying predators

that protects the Sundarbans.

You see, in any ecosystem,

top predators exert
what we call "an ecology of fear".

And this influences the behaviour
and movement of their prey.

Here, that might be monkeys,
or deer, or humans.

In the Sundarbans,
the tigers keep

large numbers of people
out of the forest,

and they also keep
all the herbivores on the move,

so they don't damage the trees.

So, in a way, the tiger needs
the crab to help build this place,

but then the crab needs the tiger
to help protect it.

You've got to admit,
that's pretty neat.

And the result is this -

the largest mangrove forest
in the world!

This mangrove ecosystem is dependent
on a complex web of relationships

between species as diverse as crabs
and tigers to make it functional.

But surprisingly,
these connections don't end here,

because what happens on the coast,
where the river meets the sea,

actually has a profound effect
on what happens out there.

Across the planet, coastal
ecosystems, like the Sundarbans,

are essential for both
the land and the sea.

They act as barriers,
protecting the land from storms.

And they provide vital nurseries
for ocean-going fish.

But, more importantly, they trap
much of the silt and sediment,

so that clean water
flows out to sea.

And in the tropics,
this has a profound effect

on the world's richest
marine habitats...

..coral reefs.

And one of the finest on Earth
is here - the Maldives,

There's something
very odd about coral reefs.

Look at the water - it's clear.
It's absolutely crystal clear.

I can see
a vast and colourful coral city.

And across the world's oceans,

these are home to a quarter
of all marine species...

..from tiny clown fish...

..to the black-tipped reef shark.

This really is

the ocean equivalent
of a rainforest.

But it's also a puzzle.

The waters around this reef
aren't just low in sediment,

they're consequently
low in nutrients.

So, how on Earth
can they support so much life?

It was a puzzle that stumped
the world's most famous biologist,

Charles Darwin.

And thus it became known
as Darwin's Paradox.

And it took science more than
100 years to figure it out.

And guess what the key was?

Connections. Wonderful connections
between the species that live here.

Take the coral itself.

It's not made from one,

but from two organisms.

First, tiny creatures,
just a few millimetres in length,

called polyps.

Polyps spend their lives filtering

microscopic particles
in the clear waters.

But up to 90% of their food
comes from their coral partners.

Sheltering within the safety
of the polyps,

are colourful specks -

algae.

Like plants, these tiny algae
get most of their food

through photosynthesis, to make
sugars, powered by the sunlight.

So, whilst the polyps provide
the algae with protection,

in return, the algae
supply the polyps with food.

But this ecosystem
just doesn't add up.

As Darwin knew,
this fabulous diversity of life here

can't be sustained
by just sunlight alone.

It also needs vital nutrients,
things like nitrogen,

phosphorous and potassium.

And if it doesn't get
these from silt,

then where does it get them from?

Well, all of the animals

that live in these waters
excrete valuable nutrients.

But the constant tidal currents
quickly wash them away.

So, what the reef needs is something
that can hold on to those nutrients.

Well, there is such a thing,

and there's also
a very special creature

that's going to lead me
straight to it.

The hawksbill turtle.

They're strong swimmers,

but I need to keep up with it,
to see where it goes.

And I'm really hoping
that this one is hungry.

It's a rather odd-looking meal -
a sponge.

It's tough, but the sharp beak
of the hawksbill

can bite through its sinuous flesh.

What's clearly much harder

is actually keeping hold of it
in the swirling currents.

So turtles love to eat them,

but why does the reef
need the sponge?

Well, sponges are creatures that
live embedded amongst the coral.

And there are thousands of species.

They are amongst the most
bizarre animals on the planet.

They don't have eyes, a heart,
or a nervous system.

But the weirdest thing about
a sponge is the way that it feeds.

The sponge sucks the coloured water
out of this syringe.

The plunger
isn't even being touched.

As sponges siphon water
through their bodies,

they extract the nutrients.

Although those nutrients
are in tiny concentrations,

if the sponge pumps quickly,
it can get enough.

Their secret is the scale
with which they can do this.

A sponge like this one can pump
five times its own volume of water

through its feeding canal
in just one minute!

And a sponge, just 60cm in length,

can filter the equivalent
of an Olympic-sized swimming pool

in just five days!

So, as the animals on the reef
excrete nutrients,

it's the sponges that capture
and concentrate these viable food.

It's these nutrients
that help feed the reef,

benefiting everything
that lives here,

from the coral,
right up to the top predator.

This large-scale recycling
of nutrients

helps keep these nutrients
around the reef for longer,

delaying the inevitable
leaking away into the open ocean.

For that reason, it's the sponges
that are my coral reef heroes.

What I've learned here, is nothing
short of a revelation, really.

Everything is connected -
the fish, the turtles, the corals.

But it's not just these animals -
it's the sponges, too.

And further upstream,
the tiger and the snails.

And when all of these things
come together,

the connections
make this place work.

And it really does work,

because this is one of the richest
ecosystems on our planet.

Around the world, ecosystems
in shallow seas like these,

convert scarce nutrients
in the water,

to provide a haven
for a huge variety of sea life.

But the most miraculous place of all
is further out to sea...

..in the deep ocean.

And in this endless expanse,

it appears there's nothing
living here

and nothing to eat.

On the face of it,
it's devoid of life.

But, of course, it's not.

It's home to the world's
largest animals.

Thanks to connections that lead back
to those wetlands, upstream -

all the way back
to that apple snail.

All of the silt, the sediment,
and recycled organic material,

that's washed down from
the wetlands, the mangroves

and the coral reef,
where's it all gone?

Has it just washed out
into the open ocean,

to be lost for ever?

And if it has, what are the animals
that live here feeding upon?

Well, potentially, it could
have been a great waste of food,

if it weren't for the way
that the water moves.

All of those valuable nutrients

fall like marine snow
on the sea bed, far below.

But they're not lost for ever.

Deep sea currents
of unimaginable power,

stir up the oceans
on a global scale.

It may take centuries, but carried
by these upwelling currents,

many of those lost nutrients
eventually resurface.

A sudden bounty of all the
ingredients needed to sustain life.

And a feast for all the microscopic
algae - phytoplankton.

The plankton that live here
on the surface are dependent

on these upwellings of nutrients.

And when
they're able to combine them

with bright sunlight,
their population explodes.

These multiplying plankton
soon attract millions

of small crustaceans,
krill, larvae of all kinds

and many other creatures.

And together, they combine

to create the biggest
frenzy of life on our planet...

..a plankton bloom.

And plankton blooms attract
some awe-inspiring creatures.

Here, in the Indian Ocean,

I've come to witness
one of the most enchanting...

..the manta ray.

They fly through the water,

filtering and feeding
on the plankton.

They can eat 30 kg a day.

Astonishing! Astonishing!
Just so graceful!

And it's not just rays.

The plankton bloom has attracted
the world's largest fish.

This whale shark, may have swum
thousands of kilometres,

just to feast
on this plankton bloom.

And this great spectacle of life
is all thanks to connections

that stretch back,
right across our planet.

All of the debris of life on Earth
ultimately ends up here,

in the ocean.

And that's why
the marine environment

is so dependent
on healthy terrestrial ecosystems -

places like the Pantanal wetlands
and the mangroves in the Sunderbans.

That's why the ray needs the snail.

A giant fish needs
a moderately-sized mollusc,

thousands of miles away.

Unexpected, undeniably complex, but
a certainly beautiful connection.

But this
is really only the beginning.

Because the presence
of this plankton affects

not just life in the ocean,
but all life on Earth.

And that's because plankton blooms
are so dramatic

they can even affect the weather.

When the blooms reach their peak,
they alter the temperature

of the ocean's surface,

driving weather systems
across the whole planet -

systems that create rain.

So, here we are,
back at the beginning!

Some of the water
that's evaporated from the oceans,

is now pouring down
on these highlands,

and beginning its long journey
back to the sea.

It's remarkable to think
that this rain,

falling in this remote corner
of the North Atlantic,

is actually dependent
upon the activity

of microscopic plankton in the sea.

And that those plankton, in turn,
in order to flourish,

are dependent
upon the interconnectedness

of all of our waterways
and the life that lives in them.

And that is truly remarkable!

If you'd like to know more

about the fascinating
web of links between species,

the Open University
has produced some material

both to inform and inspire you.

For your free copy,

or to find out more about
Open University programmes,

phone...

or go to the website...

and then follow the links
to Open University.

Subtitles by Red Bee Media Ltd