All language subtitles for BBC.Secrets.of.our.Living.Planet.4of4.Waterworlds.XviD.AC3.MVGroup.org.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.

1n our waterworlds,
1 want to show you why this crab

needs a tiger-

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.

1 00 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.

1t 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, 1'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.

1've never seen so much life
so densely packed into one place-

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

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 4O leaves-

And each leaf can grow
to three metres wide-

Even the rodents here
are the largest in the world.

These are capybara.

They are the dominant herbivore
in the Pantanal

and they occur here in huge numbers.

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

(WHISPERS) 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-

0h, my goodness!

And then there's the apex predator,
the king of the river-

Giant otters.

Remarkable animals.

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's 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.

This land of the giants
is exceptionally fertile,

because that cocktail of nutrients
deposited by the rivers

has been trapped here-

Gradually, they have 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-

1t'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
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-

1t 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-

1ts 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-

1t has miraculously recycled
all that dead material

back into accessible nitrogen
and phosphorous-

Five-star fertilizer
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 to spread

the vital ingredients of all life
around the Pantanal-

1t's thanks to all 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)

(THUNDER RUMBLES)

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-

1t 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 fertilizing the Pantanal-

The aquatic ecosystem flourishes,

supporting enough fish
to satisfy the king of the river-

(SCREECHING AND SQUAWKING)

The giant otter-

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 2O kilometres-

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 body weight every day-

1n the Pantanal,
there really is plenty for everyone-

And it's all thanks to a mollusc-

For me, the most important species
here 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-

1n 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-

1t's the swamp of the Sunderbans,
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-

1t'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.

0oh!

Thick, gloopy mud.

0oh!

1t's so thick
that not even air can penetrate it-

So no oxygen can get into this 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 Sunderbans 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-

1t's also a man-eater-

(WHISPERS) Tiger!

I can see the stripes on its back.

It's got its rump facing towards me
and its head is facing...

His head's lying on the ground.

Wow!

It's about the worst 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.

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 Sunderbans.

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 Sunderbans
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.

You see, 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 up to 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 8O%
of the leaves

that fall here in the Sunderbans-

And they store them
at the bottom of their burrows,

where they too will essentially fertilize
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 Sunderbans simply couldn't survive.

Together, the crabs make a vast network -
a sort of Sunderbans tube system.

The scale of the tube system
is unbelievable-

Just one square metre
can have 3OO tunnels-

Crabs are ecosystem engineers.

Without the many millions of them
living in this mangrove,

the Sunderbans 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 is an even more
unusual relationship-

One that protects the Sunderbans
from a lethal threat-

Thanks to the crabs
gardening the mangroves,

the Sunderbans supports
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-

1t's the very presence
of these terrifying predators

that protects the Sunderbans-

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 Sunderbans, the tigers
keep large numbers of people

out of the forest, and they also keep
all of 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
upon 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 Sunderbans 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.

1 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 clownfish---

---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 1 00 years
to figure it out.

And guess what the key was.

Connections.

Wonderful connections
between the species that live here.

Take the coral itself- 1t'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 9O% 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 onto 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 1 need to keep up with it
to see where it goes-

And 1'm really hoping
that this one is hungry-

1t's a rather odd-looking meal -
a sponge-

1t'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-

And 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 60cm in length

can filter the equivalent
of an 0lympic-size swimming pool

in just five days!

So, as the animals on the reef
excrete nutrients,

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

1t'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.

And 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-

1n 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-

1t's home to the world's
largest animals---

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

and all the way back to that apple snail-

All of the silt, the sediment,
the recycled organic matter

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 do the animals
that live here feed 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-

1t may take centuries,
but carried by these upwelling currents,

many of these lost nutrients
eventually resurface-

A sudden bounty of all of 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 1ndian Ocean, 1've come
to witness one of the most enchanting-

The manta ray-

They fly through the water---

---filtering and feeding on the plankton-

And they can eat 3O kilograms 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 might 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 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.

And 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 0pen University has produced some
material both to inform and inspire you.

For your free copy, or to find out more
about 0pen University programmes,

ring...

0r go to the website...

and then follow the links
to 0pen University.