Science Interviews

Wetlands of London

We are talking about the science of wetlands in this episode of the Naked Scientists and February 2nd was World Wetland day.  So to find out more we decided to send our reporter Meera to the London wetlands centre which doesn't seem to be the idea location for wildlife.  That’s partly because it’s in the flight path of Heathrow airport but Meera wondered around the 43ha they’ve got there which is reed beds, lakes, lagoons and suchlike to find out not only about the species on show but how these ecosystems are protecting us humans as well as the wildlife that live there.

Meera - This week I’m at the London Wetlands Centre on the banks of the river Thames to find out just what goes on in these ecosystems.  Wetlands can be found all over the world as bogs, marshes, swamps and fens to name just a few.  They house a great diversity of wildlife that can’t be found anywhere else.  This is because of conditions specific to this ecosystem such as soil that is so waterlogged there’s very little room for oxygen.  Therefore, the plants you get in these particular wetlands are hydrophytes, meaning water loving, and they’ve adapted to survive with minimum oxygen.

That’s just one type of wetland condition and the numerous wetland variations are not only important to wildlife populations but to humans as well.  I’m here to find out why.

I’m out in the sheltered lagoon on this site with Martin Senior and Adam Salmon who both work for the wildfowl and wetlands trust.  Martin, what exactly is a wetland?

Martin - A wetland’s habitat where there’s water. There’s things like streams, ponds, rivers, canals, even your local duck pond. They’re all wetlands.

Meera - So Adam, why do you find the plants here and nowhere else?

Adam - They’re hugely diverse habitats, wetlands.  There’s absolutely thousands of species, even here, associated with them.  Take a few examples, things like snake’s head fritillary is very scarce here in England.  That will only do well in the right kind of soil with the right flooding regime.  They flourish here because the water levels are right.  The management is right: a bit of grazing, a bit of haymaking.  Then you’ve got reed beds that can’t be too deep, can’t be too shallow when they’re planted and when they’re pastured as well.

Meera - To get an idea of the types of species you can see in a wetland we’re off to the ponds onsite for a bit of dipping.  Another member of the team, Michelle Penelle, has joined us.  We’ve all got some nets and we’re fishing throughout the water to see what we can get.  What have we got in this tray so far, Michelle?

Michelle - Well, we have some beautiful caddisfly larvae.

Meera - You wouldn’t be able to tell anything was living in there really.  I would think it was random plants in the water.

Michelle - That’s the idea because they’re hiding from their predators.  They’ve built themselves homes and this species used bits of stick that they’ve cut off and stuck to their backs with sticky spit.  As they grow they add more and more sticks round the collar of their case until it’s about April or May.  They come to the surface, pupate and then hatch as caddisflies.  They wait ‘til that time because they feed on pollen from the plants and they need to wait until the flowers are out in the summer season. 

We also have some ramshorn snails but we’re starting to see things like newts coming out of hibernation.  The boys are out first and they’re covered in their spots and have crests along their back.  They come out to try and attract the females by doing lots of dancing and tail wagging.

Meera - What else could we see that we haven’t found to put in our trays today?  We’ve seen the newts and flies and the snails...

Michelle - We’ve got a few tiny water beetles.  There are more in the pond but because it’s very cold they’re in a sort of dormant state.  I’m surprised we still haven’t caught any freshwater shrimps because they’re very active this time of year and they’re all pairing up.  The male will actually hold onto a female shrimp and swim around with her in a pair for about a week.

Meera - Something else visitors can do in order to see more of the wildlife is to come into one of the hides.  What can we see here, Adam?

Adam - At the moment we’ve got some shoveler duck out there which are very much winter visitors.  At lot of these come from Eastern Europe and as far as Russia even.  This winter we’ve had upwards of three hundred birds.  We’ve also got wintering bittern here at the moment: vary rare species, very scarce in Britain, never mind Greater London.

Meera - What attracts them here then?

Adam - Well, the reed beds habitat specifically as they have to feed out of them.  They feel safe wintering in the reed beds at the moment.  We’ve also got widgeon grazing out on the marsh.

Meera - Which ones are the widgeon?

Adam - They’re the sort of male birds which have got the quite reddish heads with the yellow stripe over the top.  In flight they’ve got great big white wing bars: one of the more recognisable ducks.  At the moment you’ll see a lot of pairs of swans out there, mute swans.

Meera - Yeah, I can see those.

Adam - Usually there’s only one or two of those but this time of year they’re all getting their territories sorted out, pairing up.  There’s a lot of sparring going on so there’s a lot of excitement and fights going on all of the time in front of us.

Meera - Are they quite entertaining to see?

Adam - Yeah, yeah.  They’re quite popular really.  They do get very displaced and they’ll end up all over the reserve.

Meera - We’ve done a bit of pond dipping and we’ve been in the hide so we’re back at the sheltered lagoon. Martin, how many wetlands are being lost?

Martin - We know wetlands are disappearing faster than rainforests at the moment.  Many of the wetlands are in coastal areas so it’s easy when people are looking for extra land to build on.  Coastal areas are flat, they drain the marshes and they put huge settlements or often industry.  If you look around the British Isles there’s often a lot of industry close to the sea where there’s obviously ease of transport.  There’s a huge problem in that every time you lose the wetland you lose the wildlife that’s associated with it.  You can’t just build on wetland, you can’t drain wetlands.  They’re there for a purpose.

Meera - What exactly would the repercussions be if we were to just lose lots of them?

Martin - The repercussions both for this country and round the world are absolutely huge.  You’ve got the things like the loss of wildlife, the loss of biodiversity and with that it’ll affect the whole food chain.  Also, one of the major effects of losing wetlands is the protective role that they play.  Wetlands actually store water and slow it down.  When you have these almighty thunderstorms and see flooding this year a lot of the water that comes down I trapped in wetlands.  It filters slowly through and they act like a big sponge, slowly releasing it into the rivers and streams.  The issue, especially when you build on floodplains, is that all that water falls on tarmac and then straight into the drainage system which runs straight into the rivers.  You’re inundated with all this water that the system just can’t cope with.  As we lose more wetlands we lose that effect of controlling and slowing down and moderating what happens when we have heavy rainfall and storms.  We’ve seen how that’s affecting people already.  We’ve seen the increase in flooding and the poor people lose all their homes in this country.  Now imagine what that’s like in these very flat areas like Bangladesh and the impact that’s going to have with rising sea levels and loss of wetlands.

Meera - So, wetlands are important not only in maintaining unique species of wildlife but protecting human populations from natural disasters such as flooding.  So why not visit your local wetland centre and get just a glimpse of the diverse wildlife I’ve seen here today and also find out more about the ecosystem that protects us from being underwater.

February 2008