Original subtitles

SIAN PHILLIPS (VO): The Celtic Deep is part of the world's greatest living resource...

the ocean.

Producing two-thirds of the oxygen we breathe

absorbing half the carbon dioxide released from fossil fuels

regulating our weather.

This is a place that feeds us, gives us work...

and allows us to play.

It's also home to a vast array of wildlife

living beside us along some 2,700 kilometres of Welsh coastline.

Yet, the Celtic Deep is a fragile place.

For centuries, humans have taken its riches for granted

plundering its resources...

and now, as sea temperatures start to rise

climate change presents the planet's greatest ever threat.

But the tide is turning.

All around Wales, people are making a difference.

Animal experts, fishermen...

volunteers...

and campaigners...

ordinary people becoming extraordinary people.

Each protecting and preserving their piece of the Celtic Deep.

This is our ocean.

Our wildlife.

This is a story of heroes.

This is how most of us begin our lifelong love affair with the ocean.

As children...

on beaches like this glorious stretch of sand in Gower.

Humans love the sea.

We recognise this as a place of excitement and fun.

We don't always appreciate how much we need it

for solace and repair.

KWAME: Most surfers know that when you get in the ocean, you feel better.

Hasn't been an occasion where | haven't been able to clear my head

dive in the water, let the water wash over me

and kind of rinse your brain a little, so you feel refreshed

rejuvenated, and myself again.

SIAN (VO): Kwame Salam is a surf therapy coach based in Cardigan.

He knows from his own experience about the healing powers of the ocean.

KWAME: It's been my saviour for my own mental health, if you like.

Lost my father, my mother, my sister, all in a 12-year period.

So luckily for me, | had my own recovery tool.

SIAN (VO): Today, Kwame is on Poppit Sands

sharing his recovery tool with residents and staff

from the Clynfyw Care Home.

KWAME: Hello! Welcome to my office.

How are we all today? We good? Excellent!

We named our project “Tonic Surf Therapy".

“Tonnau" being a Welsh word meaning wave

and a "tonic" being something good for you.

We run single sessions and ten—week courses

for people on the mental health spectrum.

Groups of veterans with PTSD, substance misuse

and mixed disabilities.

So just being in this environment is enough for them.

It's not so much about the surfing, it's using the ocean

and the natural environment as arecovery tool.

SIAN (VO): There are lots of scientific studies

proving that what's called "Blue Space"

is hugely beneficial to our mental health and wellbeing.

You can call it a recovery tool or any scientific name you want.

But fundamentally, if you come to the beach, you feel better about yourself.

The natural environment is what is doing the work, really.

We're assisting the natural environment

but as their confidence grows, and as their wellbeing improves

they start to come out of themselves.

But seeing that benefit at the end is...

there's nothing better than that, really.

SIAN (VO): Kwame's "Tonic" has already helped hundreds of people

and he intends to expand the project across Wales.

KWAME: We're lucky in Wales to have this beautiful natural environment.

Other than the occasional weather issue, there isn't really any place better.

HE CHUCKLES

SIAN (VO): The mental health benefits of the sea are only now being understood.

But there's joy...

fun...

and excitement to be had

in a country surrounded on three sides

by 100,000 square kilometres of water.

And for generations, the Celtic Deep has also fed us

and given us our livelihoods.

In Tenby, there's always been a thriving fishing fleet

for centuries.

As our populations expanded

and massive towns and cities grew up

places like this couldn't meet the ever-increasing demand for fish.

Bigger and bigger catches had to be delivered

by now-industrialised fishing fleets from Wales and beyond

and over the last 120 years, this has decimated fish numbers.

MARK: I've lived in Dale all my life.

Couldn't think of anywhere else I'd want to be.

| first started fishing with my dad and my uncle.

When | was very young, we used to go down to the beach and catch some bass

with a rod on the surf beaches.

SIAN (VO): Mark Gainfort is one of the last fishermen

in the once-thriving fishing village of Dale in Pembrokeshire.

Back in the day then, there was plenty of mackerel.

You used to be able to catch six at a time

anywhere, really.

Used to be the good days, you know.

But things have changed over the years, now.

The mackerel have had a bit of a hammering, really, with the bigger factory boats.

SIAN (VO): To give the fish a chance to recover

Mark has adapted his fishing techniques

and now fishes sustainably

selling to the locals and tourists.

MARK: | used to do a lot of netting years ago.

| tend to line-—catch as much as | can now.

If you do catch the small ones on the rod, you can put them back.

SIAN (VO): If fish are landed before they're big enough to breed

the population quickly becomes unsustainable.

Pollock, probably not quite big enough for me to bring home

because by the time you've took a fillet off him

it's not going to be a huge amount.

So, we'll try and get a couple a bit bigger.

Off he goes.

People need to change their way

to eat a more sustainable fish

and at the minute, there does seem to be plenty of pollock

so, | mean, why can't people change from cod to pollock?

SIAN (VO): British consumers are starting to eat fresh sardines

a net-—caught fish.

Even jellyfish are nutritious, sustainable contenders for the fish and chip shop.

But until tastes change

Mark needs both his skills and patience.

| can go an eight, ten-—hour day and only get a few fish.

You could have an eight or ten-hour day and get no fish.

SIAN (VO): To help pay the bills, Mark has two other land-based jobs.

But he's not yet ready to give up the ocean.

MARK: If | Know I'm going fishing the next day

| can't sleep, you know, I'm excited about going out

cos it's just the place | love to be all the time.

| just can't wait to get up in the morning to go fishing.

No better place to be, you know.

SIAN (VO): Today, the biggest part of the Welsh seafood industry isn't fish.

It's the landing of crustaceans and molluscs.

Crabs...

shrimp...

scallops...

and the largest of them all, lobster.

This is Brett Gardner.

He's what's called a "potter"

fishing for lobster around the Llyn peninsular.

Brett's determined to preserve the future of Welsh fishing.

| came into this industry 30 years ago.

And, you know, | started with a 14-foot Mirror dinghy

and | was catching 17 lobsters a day just up this little run here

out of 23 pots.

And, you know, I'd die for that now.

SIAN (VO): As populations crashed

potters were forced to take smaller and smaller lobster

many before they'd produced any young.

It takes five years to reach maturity

and for around 50,000 eggs produced

only two will survive to adulthood.

The law now tries to enforce

that lobsters are only taken once they have bred for several seasons.

The rules on what we can keep, what we can't keep...

anything that is 90mm

is what you'd call a keeper

and it's about nine years, | would say, to get to 90mm.

SIAN (VO): Brett has joined a new Welsh initiative

so he doesn't waste time hauling up undersized lobster.

Bangor University did a project down South Wales

and they gave me the papers to read up on it.

SIAN (VO): They asked Brett to put an escape hole in his pots

allowing the smaller lobsters, under 90 millimetres, to escape.

And | thought, "I'll give it a try," so | put 25 of these gaps in

and | looked at 'em...

and | honestly expected

"This isn't gonna work."

But the following season, every pot has got ‘em in.

That's how effective it is.

SIAN (VO): Today, Brett has covered up the escape hole in one of his pots

to show the difference they make.

Everything here is undersized

and they just wouldn't be in the pot.

They'd be... it'd be an empty pot.

But obviously, this is there, and that stops them.

| mean, even this little chap hasn't got through it.

SIAN (VO): Putting these gaps in also saves potential stress

and injury to the small lobsters.

This stops fighting.

You know, it prevents them getting mutilated.

And the other thing that it most definitely does

it thins out ghost fishing as well.

SIAN (VO): Ghost fishing is a phrase used for animals

that get caught in fishing equipment lost at sea.

Lost pots trap lobster which then needlessly die.

So, if you lose a string, you know, the lobsters are able to get in and out.

SIAN (VO): While the gap reduces lobster deaths

Brett goes even further to protect the Welsh lobster population.

BRETT: This time of year, October.

Very difficult. Weather's hard.

Big percentage of the lobsters are carrying eggs

which | can take, but | don't.

So you're throwing more back than what you're actually keeping.

Y'know, she's a two-pound lobster, just full of eggs.

But all these are being landed at the moment, not by me.

SIAN (VO): In Wales, it's still legal to take egg-carrying females

known as "berried hens".

So, Brett puts a painless V notch in their tails.

With this notch, it's illegal to land the lobster

and it takes four years to grow out.

Lot of eggs under that one.

SIAN (VO): If left in the wild, lobsters can live longer than humans.

The females never stop producing young.

They also never stop growing.

And the bigger they get, the more eggs they can carry.

So, with large breeding females

Brett will often put conservation before profit.

She's 140mm, she is.

| would say she's as old as me.

She's probably worth about £40...

maybe £50.

That, to me, is a prime specimen of a lobster.

Plenty of room to keep eggs.

Who am | to take that out the water?

And because she's so big

I'm gonna make sure there's two in her.

So if you look after your own patch

technically, it should look after you.

And yes, you can argue

well, if you kept all the berried hens and kept all the big lobsters, yeah, you'd...

Yeah, but the thing is you've got to look after tomorrow as well as today.

We want a sustainable fishery

and the only way we're going to get it

is either by management

or by the consumer

to put the pressure on the fishermen to fish sustainably.

That's what we need.

SIAN (VO): When humans step in and give protection

a species can quickly start to recover.

Autumn on the Welsh coast.

The treacherous weather transforms much of it

into a wild, inhospitable place.

But in Pembrokeshire

this coastline also doubles as the perfect nursery...

for the local baby grey seals.

This pup is five days old.

The young seals feed up to six times a day

from their ever-—patient mums.

Just over 100 years ago

the grey seal population across the whole of the UK was only 500.

The seals were persecuted, taken mainly for their snowy-white pelts.

Now protected

Wales alone has a population of around 5,000 animals.

And there's a dedicated team of people who want to make sure

that seal numbers continue to grow.

TERRY: We've been dealing with seals now for some 30 years

and we can almost tell instantly

whether a seal needs our help.

SIAN (VO): Terry Leadbetter and John Beavis

are Pembrokeshire's seal rescue response team.

Between them, they rescue up to 70 seal pups a year.

Today, a member of the public has called about a seal pup alone on a beach.

TERRY: There's a lot of things to consider.

| mean, the first thing is whether the mother is in attendance

and then we look at the seal and look at its condition

if there's any injuries or whatever

and then we look at the weight of the seal, the size of it.

But we've been doing it so long now, we can almost do that instantly.

You can see on this one...

that tells us that that's about three weeks old.

Its mother's gone off and left it

and within a few days, all that white coat will moult off

and it's on its own.

And the reason for the red and blue is that we've seen it.

We know that it's OK, and if anybody else finds it

that saves us a 40-mile journey to come and check it again.

He'll make it off now. He'll go into the sea.

And he'll be OK.

SIAN (VO): Once in the sea, the pups grow quickly into adulthood.

Here, they spend much of their time hunting for fish and crustaceans.

INDISTINCT CHATTER - ANIMAL HOWLS

SIAN (VO): Meanwhile, back at Terry's house...

SEAL CRIES

...it's dinner time.

SEAL WAILS

SEAL GRUNTS - Alright, alright.

SIAN (VO): Even the smallest pups are abandoned by their mothers

and this is where Terry and his wife Anne have their work cut out.

When they're very young, | mean, they need liquidised food.

We can't replace the mother's milk.

So the next best thing for us

is to liquidise fish and feed them

through a tube into the stomach.

ANNE: There you go...

SEAL WAILS

There you go.

That was nice, wasn't it?

SIAN (VO): Seal pups are often abandoned due to human disturbance.

So Terry and Anne work flat out during the birthing season.

TERRY: Anne liquidises all the fish.

That's a lovely job, that, she loves doing that

and she prepares all the diets

and she'll go down and wash the seals.

And | just do the nice bits.

SIAN (VO): They also look after older seals with health issues.

SEAL RASPS

This one had a nasty abscess

but should soon return to the wild.

TERRY: There's just something about them

and the more you deal with them, the more you get to know them

and they've all got different...

different personalities.

How many people in this country have got the privilege

to be able to go and rescue these magnificent animals?

Because that's what they are.

| mean, they are so intelligent, you wouldn't believe

and, you know, to be able to do what we're doing is great

and | love it.

And I'll do it until | can't do it anymore.

SIAN (VO): While seals are a success story...

many other marine species need to be monitored and recorded.

The tides drive the rhythm of life around the Welsh coastline.

When the tide goes out

a whole marine treasure trove is revealed

if you Know where to look.

AARON: Today we're going to be doing a survey down on Dale beach.

Trying to basically find as many species

of as many different animal groups on the shoreline as possible.

SIAN (VO): Pembrokeshire is home to budding biologist

17-year-old Aaron Lock.

He leads a group of young marine bounty hunters

who record the wildlife wonders you can find at low tide.

AARON: This whole study that I'm doing

is actually going to influence the marine database

that is then used by marine biologists

to get recordings of species numbers across the coasts.

SIAN (VO): By regularly monitoring and counting animals and species

Aaron can get a picture of whether there's growth or decline in populations.

When it actually comes to the catching, we have two main things we like to do

which is sweep netting with a very large homemade net

and then boulder turning.

SIAN (VO): To count and log the various species

the team first have to catch

some very slippery characters.

Aaron's personal favourites are eels.

| think it's the biggest one yet. — MAN: Yeah.

Definitely the widest at least. Might not be the longest.

The worst thing about them is there's no direction they prefer to go in.

They will reverse, and they will go forward.

So you may think you've got their head

and then they'll just slip back out the other way.

SIAN (VO): Once in the bucket

the creatures are identified and logged by the team.

We've got a feather star, which is very pretty.

AARON: Scorpion fish's another thing

probably the most dangerous fish we actually got

because these guys do have a venomous thorn on the side.

Got a little clingfish. It's like a sucker fish.

This was the blenny we got very early on.

SIAN (VO): Today's survey counted an incredible

222 different species.

Not bad for a patch of Pembrokeshire mud.

AARON: | do believe that surveys like this are important.

If someone takes it upon themselves as a hobby to get a recording

of things they can find on one of their local beaches

that can easily go into the databases that can be used

very usefully by scientific teams

that want to understand a little bit more about our coastlines.

SIAN (VO): This group of young citizen scientists

are making a real difference.

Monitoring and recording wildlife off-shore isn't as easy.

Abersoch, on the Llyn Peninsular.

It's the height of summer.

But for most visitors

what lies beneath the surface is a mystery.

Often, a revelation.

From tiny bobtail squid

to sunken wrecks covered in corals and fish...

to over 40 species of shark.

The sea around Wales is home to a rich diversity of life.

Sharing these riches with everyone is essential for saving our oceans.

Out on his dad's boat, one local lad is determined to do just that.

Jake Davies is a young marine biologist

who's harnessing the power of video and the internet to reach out to the world.

So today, we're deploying some baited remote underwater video systems

also known as BRUVS.

So this is a simple design, it's an aluminium frame

with some weights attached to the bottom.

And then at the front, we've got a pole which holds the bait

which we use, often there's mackerel.

And then a GoPro sits here, which is pointing towards it.

SIAN (VO): Jake's BRUVS system lures in rarely-seen creatures

which he then uses for research

and also shares on social media.

JAKE: We leave it for about an hour

and you come back later and review the footage

and then you can see what different species have come.

SIAN (VO): People are particularly excited to see sharks.

JAKE: A lot of people don't really think we have sharks off the Welsh coast

and all of them are completely harmless species.

So last year, | put one up

which were two tope sharks swimming around.

It went almost global

because it was like, "This can't be the Welsh coast"

but it's like, it is.

And the response to the fact that they didn't think sharks were there

but now... now they do.

SIAN (VO): All filmed off the coast of Abersoch

Welsh marine life has gone large.

Jake estimates his footage has been seen globally

by tens of thousands of people.

JAKE: This gives us a bit more information and real-time footage

that's really good for scientific uses

but also the footage is really powerful when shared on social media.

People then get to see, themselves, what it's like down there.

It gives them that appreciation of what they have on their own doorstep.

SIAN (VO): With today's video footage captured

it's time to head back.

Once home, it will be logged and shared with the world.

While the coast of Wales is home to thousands of species of wildlife

some of our once-—common creatures have disappeared.

One of the most iconic and romantic

is the seahorse.

The last recorded sighting was in 2008.

But there's one woman who's made it her life's work

to bring this amazing creature back to Welsh waters.

Frankie Hobro is the owner and director of Anglesey Sea Zoo

a small aquarium with a remarkable breeding programme.

We are the only place that houses both species of British seahorse.

There's hippocampus hippocampus, which is the short—snouted seahorse

and there's hippocampus guttulatus, which is also Known as the "spiny seahorse"

which has these tencrils.

Not only do we house them, we breed them on a conservation breeding programme

with a view to re-releasing them back into the wild.

So, we homed some of the last wild-caught short-snouted seahorses

hippocampus hippocampus, here in 2008

and we started to try and breed them.

SIAN (VO): This was easier said than done.

Even keeping them in captivity is challenging

and no one had successfully bred both species

of the sensitive and fussy seahorse.

FRANKIE: The absolutely unique thing about it is the situation

it's where it is, right on the edge of the Menai Strait.

We can pump from the sea

to supply all the aquarium tanks.

So, we're able to see them exhibiting really comfortable behaviour

really natural behaviour

and that's when you get really happy animals

and that's how we can successfully breed and re-release animals as well.

The bloke has the babies, which is just, you know

it's so out there.

| mean, it's fantastic, really.

They can carry 400 of these tiny, tiny fries

so this poor male is really, really big by the time he gives birth.

SIAN (VO): Each year, only two fry per couple make it to adulthood.

It took Frankie nearly three years

before her captive pairs finally produced young.

FRANKIE: | think what | love about seahorses

is that everything about them is quirky.

So just the fact that they're really bad swimmers

and they kind of just like to sit around a lot

but when they feed, it's incredible.

So, the eyes are completely independent of each other.

And they spend several seconds focusing

and, when they focus, you can literally sometimes hear them click

as they snap the food up.

And they have to constantly feed

which is one of the reasons why, when you keep them in captivity

they need a lot of extra husbandry

a lot of particular foods, live food constantly.

And in the meantime, they're becoming more and more rare

everywhere in the UK.

SIAN (VO): So, the race is on

to return the seahorses successfully into the wild.

Frankie is getting closer

and when she does succeed

it will be a world-first for Wales.

FRANKIE: That would be a dream, if in sort of 20 years' time

we're looking at having seahorse populations re-established

and successful on their own

back in some of the coastal areas around Wales and other parts of the UK.

| mean, that would be absolutely fantastic

and, | mean, the fishermen, everybody, | think would love to see that.

SIAN (VO): For seahorses to be successfully released into the wild

there needs to be healthy and pollution-free habitats waiting for them.

Wales is a world leader in conservation.

This is Newgale, one of Wales' 40 Blue Flag beaches

the gold standard in clean-up conservation and excellent water quality.

But as much as 12 million tons of plastic alone

are dumped in the planet's oceans every year

and the threat that poses to animals and humans is utterly devastating.

One remarkable group of volunteers based in Pembrokeshire

is making a real difference.

DAVID: When | was younger, | got involved with, like, local beach clean-ups.

And as a scuba diver, then | became more aware of litter on the seabed.

SIAN (VO): David Kennard is the founder of Neptune's Army of Rubbish Cleaners

shortened to NARC.

NARC is a scuba diving group

who perform underwater litter picks.

| thought now's a good time to make a difference

and try and find other people who want to be part of that difference as well.

We've a very good volunteer base.

We've somewhere between mid—20s to 30 volunteers.

God, we've got all sorts. Well, for instance, I'm a plumber.

We've got people who are builders, we've got people who are doctors

nurses, taxi drivers.

It works on passion.

| mean, to dive in UK waters

they say if you can dive here, you can dive anywhere in the world.

You Know, sometimes for diving and visibility

with about a metre, metre and a half.

SIAN (VO): Over the years, David and the team

have come across some extraordinary finds.

DAVID: The rubbish that we would find on the seabed

can range from anything, you know, we had clotheslines

lawn mowers...

push bikes, skateboards...

loads of stuff.

A few years back, we found a car sat upright on the seabed.

SIAN (VO): The NARC team also works with local fishermen.

Today, they're retrieving lost lobster pots and fishing nets.

DAVID: Ghost fishing...

this involves lost commercial fishing equipment.

This, globally, makes up

for 640,000 tons of marine litter.

It's also lost equipment

with fish inside.

The fish will eat each other one by one

or will starve and so on.

And then the last one that would be in the pot

would then die of starvation

and then would act as new bait

in that pot, to attract more fish to go in.

SIAN (VO): The pots are returned to the surface

before they head to a sea angling site, often littered with fishing lines.

DAVID: The monofilament line is always the issue.

The biggest threat with that is that it takes so long to biodegrade.

You know, you're looking at 600 years.

It's also an issue for fish as well.

| mean, the lure is still there, it's still active.

You know, if it's shimmering in the sun

the fish sees it as prey and something to go for

so it goes for it.

Or the other thing that is just as bad as that

is, could be a crab or a lobster that has basically entwined itself

and wrapped itself continuously in the monofilament line.

So then we're spending a while then trying to cut off all the line

so as to not damage any of his limbs.

We go out and retrieve and rescue as much wildlife as we can.

SIAN (VO): By far the biggest threat to the ocean habitat is plastics.

More plastic is discarded into the ocean than any other type of litter.

If the scientists are right

by the time we get to 2048

they're predicting there'll be more plastics in the sea than fish.

| would love to think that NARC could be something positive

and that could postpone that or...

or make it that it's not the case.

It's great to be amongst a great...

great group of people who are equally as passionate

about protecting our seas and looking after our wildlife and so on.

So that's a great feeling.

That's a great feeling.

SIAN (VO): Plastics aren't just a threat to the marine environment.

They're also damaging human health

and play a major impact in the biggest threat facing mankind...

climate change.

Sian Sykes from Anglesey

is a stand-up paddleboarder

and campaigner against single-use plastics.

We're so fortunate to have such a beautiful coastline.

It's resilient.

The tide comes in twice a day, and it feels like a new beginning.

But we're taking advantage of it.

We're polluting it.

We're not being kind to it.

When | see plastic bottles floating on the ocean

it just breaks my heart that it's us humans

having an impact on this beautiful, beautiful environment.

SIAN (VO): To highlight the plastics issue

Sian undertook a record-breaking circumnavigation of Wales

on her paddleboard.

A 1,000-kilometre journey over 60 days.

Anglesey was awarded the UK's first "plastic free" status

thanks to her campaign

with a drop in single-use plastics.

The general public think plastics is litter

that somebody has just dropped litter in the street

but it's a lot more than that.

When the plastics end up in the ocean

they're breaking down into lots of microplastics

and that's getting into our food chain.

SIAN (VO): Sian uses her paddleboard to get to secluded coves

for clean-ups, spotting plastics both large and small.

It's estimated 51 trillion pieces of microplastics

are floating around.

A lot of fish are thinking it's food

and then we're eating the fish.

It's leading to us developing cancer

and | was heartbroken to find

that there's been studies showing

that microplastics have been now found in placenta.

SIAN (VO): But the actual manufacturing of plastics is an even bigger issue

that could impact on the whole planet.

They're using virgin plastics, which is using fossil fuel to create it.

And that, in turn, is having a massive impact on the environment

leading to climate change.

And for something that is used once

it is Causing a massive impact.

SIAN (VO): One village in North Wales

is set to become Britain's first climate change casualty.

Angela Thomas is clerk of Fairbourne Community Council.

She's lived here since 2013

in a house facing the seawall.

It's very easy to see why people are attracted to this place.

| mean, what could be more beautiful?

We have the Cardigan Bay behind us.

If you look further afield, you can see Cada Idris.

We have mountains, we have the estuary.

BIRD CRIES

SIAN (VO): Built on low level marshland in the 1800s

Fairbourne is now living on borrowed time.

The village of some 450 dwellings is set to be decommissioned.

The government plan to stop financing its coastal defences in 2054.

It is very hard to imagine

on a day like today

that the sea could rise so dramatically in years to come

that Fairbourne will have to be decommissioned.

It's beyond most people's thought patterns, to be honest.

But realistically, sometime in the future

we could possibly see the demise of Fairbourne

and many other communities on this North Wales coast

and the rest of the UK coast.

The climate has changed.

We can see it every day ourselves by different species turning up in the sea

the birds starting to want to build nests before time

spring flowers coming up before they should do.

SIAN (VO): Rising temperatures brings an increase in sea levels

and ferocious storms.

ANGELA: When we know that we've got a high tide coming

and that there's going to be a wind behind it

there's no doubting that we are worried.

We can lie in bed at night, and we can hear the "shhh"

of the sea on the shingle

and we think, "Hmm, wonder how high this tide is going to be?"

| don't think that most people go to bed at night, thinking

that they are in danger.

But it is in the back of your mind

and of course, as time goes on...

and if we continue to get these freak weather conditions

that is something that we will probably think about more and more.

SEABIRDS CRY

SIAN (VO): There are two main ways to slow down climate change.

One is reducing carbon omissions

the other is allowing the growth of habitats that capture the carbon.

Here, the ocean has its own version of a rainforest.

Seagrass beds are called “the lungs of the sea".

The only flowering marine plants

they absorb carbon dioxide and produce oxygen.

Home to thousands of species...

seagrass beds are one of the most important

yet threatened underwater habitats on Earth.

In the UK, increased human activity

has led to a 92% reduction in seagrass meadows.

RICHARD: | was starting off as an academic in a university

thinking I'm describing the death of seagrasses.

I'm describing why they're amazing

but why they're dying, and that's not actually changing anything.

SIAN (VO): Richard Unsworth is an "action academic"

leading Project Seagrass

a world-leading marine conservation charity

replanting seagrass meadows in Pembrokeshire.

As we stare a climate emergency in the face

and our whole climate system is breaking down

there's now a sort of increasing imperative

of humanity to protect and restore these systems

because they are fundamentally important to our coastal environment

and our terrestrial environment, you know.

If we want to fight climate change

we need to start restoring our oceans.

SIAN (VO): For the same area, a simple seagrass bed

absorbs and stores carbon 35 times faster than a tropical rainforest.

We've actually set up on a project

that's trying to collect over a million seagrass seeds

and plant them in a two-hectare area in Dale.

SIAN (VO): And that's what Richard and his team of volunteers are doing.

Step one, they collect seagrass from an established and healthy meadow.

It's a challenging thing to do.

We'd never collected a million seeds before.

We'd never done anything at this scale before.

I'm pretty lucky to have an incredible group of people around me

who support that work and enable it to happen, really, because it's...

collecting a million seeds is not some small operation

and it requires those many hands.

So once one of our volunteers has brought back a bag of seagrass seeds

we put it into an aquaria facility

with fresh seawater

and over a period of a month or two

what actually happens is that that whole shoot just rots away.

Eventually we're able to then separate all the seeds

and think about taking them to a site

for planting in the hessian bags.

SIAN (VO): It's a cold November day.

The hardy team of volunteers take the seed-filled bags

and drop them onto the ocean floor.

The bags stop the seeds

from being washed away by Dale's big tides.

Within six months, these seeds will have germinated

and the bags rotted away.

RICHARD: By planting seagrass in Dale

we're trying to inspire others to build on this mantel

and to learn to plant seagrasses

all around the UK.

SIAN (VO): And these seagrass meadows aren't just combating global warming.

They are vital to the success and return of many marine species.

If you're a juvenile animal

then it's an amazing place to hide.

So, it's this great kind of nursery environment for young fish

and if you're a slightly bigger animal

then it's a great place to hunt food.

And that means you just get this kind of congregation of life.

SIAN (VO): These underwater grasslands have 30 to 40 times more animals

than an area which is barren.

It feels incredibly good to be part of a positive project

that's trying to change the trajectory for our oceans

and what we're doing is only the start.

A very exciting moment, a very optimistic moment

to see that we are able to make these changes

and we can bring life back to our degraded seas.

SIAN (VO): The impact of climate change on the ocean is often hidden.

Small changes in sea temperatures can stop plankton from blooming

which in turn has an impact on the whole food chain

across the world's oceans.

DOLPHIN WHISTLES

The Celtic Deep is blessed by the presence of some of the world's most iconic animals.

Basking sharks, the second largest fish on Earth...

several species of dolphins

one of the world's most intelligent marine mammals...

DOLPHINS SQUEAK

...and finally, the spectacular fin whale

second only to the blue whale

as the largest animal ever to have graced the Earth.

On the Welsh-English border, one fin whale has been stranded.

Without help, it will die.

But there's a group of Welsh heroes who are straight on the scene.

Gem Simmons is a senior volunteer

from the charity British Divers Marine Life Rescue.

We don't think twice when we're called to a rescue, we're up and out.

We want to help that animal in any way that we can.

SIAN (VO): Gem is leading the rescue operation.

We hope to re-float and administer any first aid that the whale needs.

| think there's something very spiritual when you look in an animal's eye

and it's in distress, and it's having problems

and that's what keeps us going.

When initially called out

we assess the situation, we take a step back

and we look at things like breathing pattern

body condition, we note any injuries

and we take measurements.

SIAN (VO): It's often difficult to know why a whale becomes stranded.

We can rule out things like ship strikes or major trauma

because it has no obvious injuries.

SIAN (VO): However, new science suggests

that severe weather events caused by climate change

can cause a malfunction in echolocation.

So a whale could head to the shoreline thinking it's the deep ocean.

Until the tide returns, all Gem and the team can do

is make the ten-metre youngster as comfortable as possible.

Their skin is very delicate for a whale

so we want to keep them nice and moist.

So, we do that with wet towels and sheets.

We form, normally, a production line

where we'll pass buckets up and down the beach best that we can

to keep the animal nice and moist.

As the tide comes in, we want to get it upright

and then see if it's happy to swim off on its own.

SIAN (VO): Found throughout the world's oceans

the fin whale can grow up to 25 metres in length.

These giants come into the Celtic Deep to feed during the summer.

The sea has finally returned to the Dee estuary

and after a few hours, the whale is able to swim out.

| look at the team that turned up today

and | consider every single one of them heroes.

The RNLI, the coastguards

all of the local fishermen.

They are all heroes in their own way, cos they all want to help

and they all have animals’ best interests at heart

and it's so lovely to see

when you see some of the stuff that we do.

It's nice to know that there is good people and a good side

and potentially, a good outcome for our oceans.

SIAN (VO): Two days later, the young fin whale beached again.

This time, it couldn't be saved.

Gem and the team were there to the end.

Right now, our relationship with the ocean and the animals that live in it

is both precious and precarious.

So now is a time for heroes

for all of us to do what we can

however large...

or small...

to ensure that future generations will have this gift

so they too will know the wonders of the Celtic Deep.