Wild Asia: Kingdoms Of The Coast

Wild Asia

Asia's coasts are the frontier between two great rivals.

Land and sea constantly test each other's borders

along two hundred thousand kilometres of Asia's shoreline.

In the tropics, equatorial sun magnifies the power of earth and ocean

to nurture an extraordinary profusion of life.

There are sea creatures here

who cling to the coast throughout their lives -

others are ocean travellers who return to the coasts

only to breed and support their young.

Half the world away the seas of Asia's far north freeze

during long months of winter,

and lock their shores in brutal cold.

But when summer sun drives back the ice,

these bare coasts will thrive with life.

Land animals rely on the shoreline too.

Through countless generations they've survived on its rich seasons.

Asia's fertile coasts harvest the endless bargaining of land and sea,

and their own vital power reaches far inland and out into the ocean.

KlNGDOMS OF COAST

Monsoon clouds over the Indian mountain lands

are part of the great cycle of exchange between land and sea.

Heavy with moisture swept up from the ocean,

they burst - beginning a chain reaction which will reach the distant coast.

For the land animals it's a time of renewal.

Rich growth promises survivors of long dry months

that they'll see out a new season.

People have been starved of water too.

Usually the downpours a blessing and time for celebration.

Torrents of water laden with rich sediment

will prepare their land for crops.

But at sea level the water's blessing can turn into a curse.

When high rivers collide with high tides,

disastrous floods spill across vast areas of coastal plains.

Every drop of rain plunders the land.

But rivers that carry-off the spoils

must pass through forests spread like great nets along the coast -

waiting to steal the earth back again.

Mangrove forests turn raw sediment to energy -

and from India to Indonesia

they shield their soft and muddy coasts

against the forces of the ocean.

Plants and animals have been evolving

in these forests for 65 million years.

They still shelter and sustain a vast community of creatures.

Saltwater crocodiles are ancient users of the mangroves.

Long ago, these members of the crocodile family

adapted to hunt the fertile waters between land and sea.

High tide brings other predators from the ocean -

sea snakes hunting for gobi fish,

and stingrays which dredge the mud for crustaceans.

Mangroves are such a rich hunting ground

because they're a nursery for so many land and sea creatures.

This female's raising her young in these sheltered waters.

At nearly a month old,

they're confident enough to

venture freely amongst the mangrove roots.

They haven't eaten since hatching,

but when they're hungry

they'll hunt their first meal in the mangroves.

Their mother's lurking not far away,

discreetly checking-out intruders.

The pork pie crab's heavy armour would have done him little good

if he'd been just a bit slower, and she a bit closer.

But he gets the chance to sidle back to safety,

while she continues her patrol.

Tall mangroves are safe overnight roosts for Borneo's proboscis monkey.

In the mornings they're launching pads for sociable climbers.

Many other monkeys visit Asian mangroves,

but few depend on them as much as proboscis.

They house a powerful digestion inside their roomy stomachs,

so they can feed heavily on salty, tough mangrove leaves.

But as coastal forests have dwindled,

many groups now rely on remnant mangroves,

where even proboscis find the pickings lean.

The senior male on sentry duty is anxious -

careless visitors to the water's edge are moving into danger.

His alarm call alerts the troop.

A hidden crocodile's even more dangerous...

and the panic sends one monkey right into the jaws of danger.

But the croc's missed her opportunity.

The rest of the troop takes a more cautious route

back to the swamp forest.

Like the crocodile,

the trees have evolved to cope with this salty world.

The mud they grow on is rich, but it's starved of oxygen -

and the constant floods of sea water would poison most other plants.

What looks like drowned debris is the forest's answer to its problem.

These are the roots, and lungs, of living trees.

As soon as the tide falls they begin to harvest oxygen

through special breathing cells in their exposed roots.

And somehow tender young plants

are able to gain a foothold in this shifting, salty world.

Each mangrove species has a way of

giving its young a better chance of surviving.

Some get a head-start by beginning to

grow while still attached to their parent tree.

The long spears hanging down are immature mangroves,

which are only planted

when they're strong enough to survive the salty water.

A lucky fall can plant a new seedling.

But natural buoyancy and strong tides carry others far away -

perhaps to found a new forest.

The trees send more than their new-born to the ocean.

They use sunlight and air

to convert the nutrients of raw sediment into growth.

The forest's like an immense storage battery,

with every leaf an individual cell.

Each leaf that falls begins to release new energy to the water.

As the tide flows out of the mangrove

it carries-off a rich stew of rotting organic material.

Mangrove roots that

spike the foreshore trap debris from the ocean too.

As mangrove animals pick at this flotsam

they make their own contribution to the richness of the shoreline.

Monitor lizards make regular patrols,

searching for carrion delivered by the falling tide.

At low tide a huge community of creatures emerges

to feed on the mud.

Fiddler crabs pack the best part of their lives

into the time between the tides...

Females feed at frantic speed.

Hungry males are hampered by the super-claw

they use for defence and display.

The low, slack tide provides quiet water

and a gentle ramp for the young crocs to crawl ashore.

But they're still supervised by a watchful mother.

As they venture from the water,

the young crocs are feeling hunger for the first time -

and the mud is crawling with potential meals.

This female fiddler crab

could become an unwilling player in a young croc's graduation

from infant to hunter.

First the youngster stalks -

then, even out of the water, uses classic croc ambush technique.

Once in a good strike position, he freezes.

The head shake to tear the prey apart is all croc instinct -

one day he'll do it to pigs and monkeys.

But now he heads for shelter -

to avoid other foragers in the mangroves.

Troops of long tailed macaques know where in their territory

to find a meal and that low tide delivers good pickings.

They're such frequent foragers here

that they're also called crab-eating macaques.

It's said they use their tails to lure crabs from their burrows,

but they're more likely to dig vigorously to reach a meal,

which might be animal,

but could also be stranded nuts or fruits.

The sea's lowest ebb reveals the tidal zone,

neither earth nor ocean entirely rules these sandflats...

or the muddy world which christened the mudskipper.

Perhaps the fishes which first crawled out of the ancient seas

looked a bit like this.

They're creatures of two worlds -

fish which emerge from burrows to feed in the air.

They graze the film of algae that clings to the surface of the mud.

But these fish out of water have to breathe like fish.

So every few minutes they return to tide pools

to replenish their gill-pouches with new supplies of water.

His burrow is the centre of a male mudskipper's world.

This one could be mining a network of tunnels as much as 5 metres long.

The burrows of mudskippers and other tunnellers

play a vital part in taking air and water

down into the suffocating mud which has been dumped from the land.

As soon as the skippers emerge onto their muddy landscape

they stake their territory -

and they proclaim it by raising their flags.

A warning, gaping mouth may be enough to drive off an intruder.

If not, there's a full scale joust,

to the ancient rules of mouth-fighting.

Victory usually goes to the mudskipper energetic

enough to keep-up the ferocious display.

As the returning tide starts to shrink the landscape,

the skippers crowd onto the diminishing islands of mud.

They're running out of time to do all the things

that mudskippers have to do between the tides.

...Feed, maintain the burrow,

display and defend the territory, perhaps even find a mate.

Some are still trying frantically to complete their task list

as the tide closes over them.

Young seedlings have made good use of the low tide too,

to grow stronger and tighten their hold

on their slippery foundations.

As they mature, mangrove forests become great allies of the land,

colonising more and more of its muddy coasts

as it slowly pushes out its border with the sea.

The hard coasts of Indonesia are raised by a more dynamic force.

Towering volcanic islands

are stepping stones along a Pacific ring of fire,

marking the battleground between two great geological plates.

The land and the seabed are constantly twisted

and breached as the earth struggles against itself.

At any moment these beaded curtains of gas escaping

from the sea floor

could be torn apart by titanic volcanic forces.

Devastating eruptions on the surface leave their debris underwater.

Life must struggle out through suffocating blankets of volcanic sand.

The problem of surviving here often inspires bizarre solutions.

The feather mouth sea cucumber harvests sand

like an industrial mining machine,