Science Interviews


Sun, 17th Oct 2010

Planet Earth - Plastics on the Beach

David Barnes, British Antarctic Survey

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Walk along any beach almost anywhere in the world and you'll find plastics washed up on the shore.  From plastic bags to lighters, bottle tops to flip-flops.  Plastics have even turned up on the coast of Antarctica!  But itís not only the visual effect of this human detritus thatís a problem.  Plastics actually carry pollutants and even life around the globe, sometimes having serious consequences.  Planet Earth podcast presenter Richard Hollingham joined David Barnes from the British Antarctic Survey on the Pebble Beach in the wind and rain sadly at Cley in North Norfolk...

Plastic BagsDavid -   So weíre going to walk along two strandlines.  One, the storm line where the last time there was a big storm thereís deposited lots of natural debris, but also man-made things, and along the strandline from the last big tide. And weíre going to walk along and look at some of the more persistent items of debris particularly plastic, and see what it tells us about the ocean, far away from these shores.

Richard -   So weíve got here a plastic bag and I think we can probably tell from the green lettering which supermarket that's from.  Itís torn and itís gone translucent, but itís still retained its essential plastic bagness.

David -   Yeah.  Plastic bags are made of very, very thin plastics, so they break down relatively easily with salt spray and UV light, as long as they stay in the top layer.  But even this couldíve travelled quite some distance and we can see that looking at it closely, you can see all sorts of things have started to get a grip on top of it, including foraminiferans.  So life has started to colonise this plastic bag.

Richard -   Thatís amazing.  You've also got down here Ė I think this is part of the heel of a shoe.

David -   What will happen with lots of these materials is when it starts to get broken up, the surface has got a very good texture for settlement because it slows down the water over it.  Its boundary effect will be slightly stronger than the smooth pebbles and other smooth things that are typically floating.  So life can get a grip and then it can be carried around.  But itís not just life.  These plastics will absorb all sorts of things such as toxic chemicals and transport those around as well.  And so, various groups over the UK and elsewhere have been studying what plastics can carry, how far they're carrying them, and what sort of effects they have.

FlotsamRichard -   And that for you is almost a bigger issue than that they're not aesthetically pleasing to see on a beach.  Here, weíve got a green bottle top, thereís a little bit of string here, the plastic bag, but itís the fact that not only these spread toxic chemicals in the environment.  They carry life around the environment.

David -   Yeah and we can see on this piece of plastic twine that weíve actually got two different species of hydroids, one on the base there and another one halfway up, and they're actually reproductively active.  They'll be releasing larvae, so this is not just transporting adults around.  These will be producing larvae that will settle wherever this goes.

Richard -   So these tiny little Ė almost twig-like projections on the side, they're alive and so, they kind of mingle in.  They almost become part of the twine there.

David -   Yeah and actually, Iíve found a 3rd species, so weíve got three species just on this insignificant little piece of twine.  These species are probably native to the UK, but thereíll be other species that come in that arenít and that's where the problem is.  It can make a big difference to local aquaculture and fisheries if some alien pest gets in, becomes established, and then really starts to outcompete or eat our native fauna.  But these pieces of plastic travelling for many years, perhaps decades, that that means we can get animals and algae, and other organisms from all over the world, landing on our shores.


Richard -   It doesnít, I suppose matter that thereís this twine with life clinging onto it here, but it might matter in other parts of the world.


David -   Itís still a problem here, but it is more a problem elsewhere.  We have to remember that looking along the strandline here, we can see lots of natural material.  We can see seaweeds and we can see bryozoans, and other animals especially crab shells that have floated here naturally and they've been doing this for a long period of time.  For hundreds of millions of years, life has been floating around this part of the world, but in the Polar regions where there arenít lots of things that float, there arenít shells that naturally float, there arenít seeds, and logs, and other material that we would naturally see on our strandline, then plastic there and other floating manmade debris has made a huge difference because itís created this new environment of things floating on the surface, transporting organisms that wasnít there before.


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