Strangford Lough Waterworld

This ferry makes 23,000 crossings

between Strangford and Portaferry every year.

Hundreds of thousands of people make the trip across the narrows,

but none of the passengers gets to see what's down there, right under our noses.

This is Waterworld,

and this is Strangford Lough, the jewel in the crown of our coastline.

The scenery is beguiling, and for most of us,

the beauty of Strangford Lough is only skin deep.

But the Waterworld expedition will reveal the astonishing life

under this famous shore.

Joe Breen is a scientist with the Environment And Heritage Service.

He is leading our expedition in search of horse mussels,

also known by their scientific name, modiolas.

You've got to see mounds surrounded by mud,

and these mounds are actually mounds of horse mussels,

not very interesting in themselves, but the fact is they make

an artificial reef called a biogenic reef, and a hard substrate

onto which other animals can attach, and also come and live within.

So you're going to see the brittle stars, feather stars,

sea cucumbers, anemones.

We've located a site which is about 20 metres, and we're going to go to that.

Now, in this big vessel we're sitting in now,

we can't go anywhere near these beds,

because if we put an anchor down, we're going to do a lot of damage.

So, we're going into the smaller boat.

We'll go over, there'll be a light shot put down.

That boat won't anchor out of.

We'll just roll out over the side, down the shot, and do the dive.

And hopefully, we'll be on mussel bed.

Possibility we may not. That's the problem, you know.

Only 20 years ago, 15 years ago,

these mussel banks were all over the entire lough,

but unfortunately due to circumstances,

I don't know, there's 5% left, possibly.

-What happened to them, Joe?

-Unfortunately, trawling.

People just weren't aware. It's only now, with the advent of diving,

people can get down and see this damage.

Trawling has been stopped in the lough.

The important thing now is to make sure we protect what we have left.

What's the plan here? Who's going in first? Who's going in second?

-These two go in first.

-Yeah.

-Then the three of us will go in.

I'm ready for a challenging dive.

Strangford is a dark lough, and with such a limited amount of reef left,

it'll be tough to find the horse mussels.

More than 20 metres down, day fades to night,

and we discover a weird and wonderful world.

This is just such an amazing sight.

The bed of the sea is carpeted in brittle stars.

And in among all of them is this,

a fabulous creature called a sun star.

And it's eating its own kin. It's dining on brittle stars.

It's wonderful.

So many starfish, so few horse mussels, and so little time.

Unfortunately, we haven't found the horse mussel beds,

and I'm nearly out of air, so we've got to pop to the surface.

Surface to dive team, I understand that you are on your way up.

If possible, could you confirm this? Over.

The dive is almost finished, and suddenly, I'm in trouble.

My ears are hurting quite badly.

I couldn't relieve the pressure in my eardrums on the way up,

a rare and painful condition known as a reverse block.

My safety diver, Jim, was at my side the entire time,

but he couldn't help.

It's really shaken me.

Two up behind the out burner.

Ah!

That was horrific.

Oh!

-Did that hurt, Darryl?

-I was screaming on the way up.

-I got a...

-A reverse block?

A reverse block, that's never happened to me before.

The pressure as the water goes down, you clear,

like being on an aeroplane.

Swallow and relieve the pressure.

On the way back up, it, er, it started to kick in,

and I couldn't work out where I was in the water,

and the more I went up, the more the pressure built, and built, and built.

I was actually screaming, and I couldn't work out what to do.

And I know, I know what the manual says.

The manual says you stop, or descend, until it gets past, but I couldn't.

-I don't want to repeat that again in a hurry.

-Let's get you in, Darryl.

The drama over, we can look on the bright side.

But there are so many brittle stars down there,

I couldn't see the shells for the brittle stars over the top of them.

There were black ones, and the common ones,

and they were all writhing, arms up in the current, feeding.

Well, if you'd actually pushed them aside,

you'd have seen the modiolus just in there.

Nice site, but with the conditions, the current, the visibility,

a bit difficult.

We'll continue the search for horse mussels later.

But first, we're off to meet marine conservationist Kate Reeves,

who is convinced Strangford Lough must have more protection.

Strangford is really unique across Europe and probably the world

for the way that it's so special, with the way that the tide comes in.

Very different communities, as that tide goes all the way up the lough,

and different animals live in those different habitats.

What we need in Strangford is areas that are set aside,

where extractive human impacts cannot occur,

and things such as excessive fishing, unsustainable fishing,

and all the recreational activities that come in,

waterskiing, jet skiing, sailing.

It all has an impact on the birds, disturbs them, the seals,

and so we just want to make sure that it is all being done

appropriately within a very, very unique marine protected area.

All right, in you go, Kate.

We're making a very shallow dive, so my ears shouldn't be a problem.

We're on the lookout for charismatic crustaceans

with eyes like polished coals.

Their fellow mud dwellers are a bizarre bunch.

Down here, Neighbourhood Watch is always hungry...

..endlessly searching the current for food.

It's a case of eat or be eaten.

Kate and I don't have long to wait for a close encounter

of an unexpected kind, with a Dublin Bay prawn.

What about that, Kate? It's come out to see us.

It's fantastic, isn't it?

They're a beautiful colour, aren't they?

They are, bright orange,

I can't believe it.

Nobody would believe

that they could see something that colourful under our seas.

Look at those black eyes.

My goodness!

It's actually coming towards me right now.

He seems very aggressive.

Oh, no, he's coming for me!

He's coming for me!

I think he wants a fight.

He's heading for home.

They're not supposed to do that, you know.

They're supposed to be tucked up in their holes until night-time.

But that one is out for a stroll.

With trawling banned here, fishermen now trap prawns in pots.

But they're the most important commercial species

to trawlermen in the Irish Sea.

About eight million tons are landed here every year,

with a total export value of up to £70 million.

That's a lot of scampi.

Look how powdery that mud sediment is.

It's loaded with tiny creatures, crustaceans, worms, bacteria.

It's where all of the Dublin Bay prawns get their food from.

It's incredibly rich, and very, very, very full of life as well.

You wouldn't believe it, just looking at it, but it is.

On the move again, we spot the flimsy tentacles of a mud anemone.

These guys have a trick up their sleeve.

Their tentacles are waving very gracefully

in the tide that's running here.

I know, they are absolutely beautiful.

You wouldn't believe they were related to jellyfish, would you?

No. The rest of the body, I assume, is tucked away in the mud.

Anchored there.

It is. It's buried down there in the mud.

You wouldn't believe that creature could move as quickly as that.

I know, but if some predator is coming along to get you,

you'd have to get out of the way quickly.

We're on the move the next day to catch the tide

and, hopefully, sight of a horse mussel reef teeming with wildlife.

And our time on this dive is really quite limited

because that sweep of current is going to just flush us off it.

Comes in, floods in, and then it'll stop for about maybe half an hour,

an hour max, and then, whoosh, move you away.

We're in the right place and, happily, I'm feeling fine.

There are enormous starfish down here.

Yeah, unfortunately, these enormous starfish are chomping away on the mussels.

You get all the mussels stuck together, and find a clump.

The good thing is

starfish can actually get into those mussels' hearts.

I think we're looking for a few more than that.

Yeah.

This is quite an environment.

It's absolutely crawling with life.

Wonderful.

I love these.

Lightbulb sea squirts.

That's a blue velvet swimming crab. Very, very striking red eyes.

You can see him looking out.

The thing about these guys, they're vicious.

Most other crabs will shy away,

but this boy will go for you. He will chase you.

And even as a diver, he'll chase you up the line.

I don't want to get nipped.

And there they are, at last.

The gaping shells of horse mussels

are home to barnacles and a host of other animals.

I'm reassured, you know,

because I've been studying these mussel beds now for longer than

I can remember, and that site is in the middle of a trawl area.

And I'm happy to see that there are small clumps there now.

There wasn't many individuals, maybe seven or ten individuals.

In a proper clump, you'd have thousands.

Studies have shown this recently,

that the water moving from Strangford Lough,

it's not just bound up within the lough, it feeds the whole Irish Sea.

So if you could keep a good population of scallops and queenies here,

they'll be releasing millions and millions of young,

as little larvae, and they'll go out,

and then they'll go into the commercial beds.

If you destroy the nursery, you destroy the provider,

you can destroy everything.

So, it is very important. This area is a marine nature reserve,

it's a special area of conservation because it has these special habitats.

Among the mussels, a sea cucumber pulls food into its mouth.

Its related to starfish and uses its arms to trap plankton.

A juicy sea slug grazes peacefully on the reef.

And a sponge-encrusted spider crab seeks anonymity among feather stars.

It's magical.

This has been an absolute delight, to come down and see something

like this, which is just so rich,

but you don't get long down here.

I've got to go back up top. I'll see you later.

Subtitles by Red Bee Media Ltd

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