SIMON BOXALL: One of our big issues in the oceans today is plastic, and particularly what we call microbeads. Certainly we can see examples where wildlife gets plastic caught up in its gut, around its feet or its wings, and that’s bad news for the environment. As science has progressed over recent years, it’s becoming evident that these plastics not only break down mechanically to smaller and smaller particles, but those particles then get ingested by marine life. They’re like sponges. They absorb the pollutants of the oceans. And that means they get introduced to the marine food chain.
So what we need to do now is have a look at some of these products in a bit more detail, and how they can impact on our environment. So we’re now moving down to the laboratory on board Callista and looking at some of the things we find in our everyday lives that impact our environment. We’re used to seeing sort of plastic items like water bottles, food containers of various sorts, and of course, the dreaded plastic bag. And we’ve reduced, in some cases, the amount we use these things. Plastic bag use has reduced dramatically as countries around the world have introduced fees for the plastic bags. But also, if we are sensible, these things are recyclable. We’re short of plastics.
The plastic industry needs this stuff to be recycled, because it needs more plastic raw material. But when they break down, they break down to smaller and smaller particles. And these things can last in the environment for many hundreds of years. But the real danger comes through these things, microbeads. And microbeads are difficult because we can’t recycle them. We can’t catch them. They’re like sand. And once we’ve used them, we tend to wash them down the drain, whether they’re in cleaning products, cosmetics, whatever it happens to be. We’ve got no way of trapping them. And they’re too small to be caught in the sewage processing farms.
And so they end up, ultimately, in the oceans, and they work their way into the food chain in the marine environment. That’s not just causing toxicity in the food chain, but it’s also causing starvation, because if a zooplankton decides to eat one of these instead of a smaller zooplankton or a phytoplankton, it then gets stuck in its gut, and it means that zooplankton dies. There are trillions of these things on the planet today. There are trillions of zooplankton. And you could argue, surely we can afford to lose a few zooplankton. But we can’t. They are the base of the food chain, along with the phytoplankton.
And if we take out that base, it has a huge knock-on effect as you go up through the food chain– ultimately, culminating its knock-on effect on us, human beings. If you look at the scale of the ocean, we talk about there being millions of tonnes of plastics in the oceans. One of the big problems is you’ll find that whoever you speak to, you’ll get a different figure. We don’t know how much plastic we’ve put in the ocean so far. One of the problems is the ocean is vast. The ocean covers 73% of the planet. But it means that the number of particles per cubic metre of seawater isn’t as great as you think.
And it’s very difficult to try and measure these. One of the techniques we use is to use a plankton net, and we hope to then scoop up the particles and analyse them under the microscope. So here, we have a plankton net. A plankton net is used to filter through the water and to gather a sort of concentrated sample in what we call a cod end, this bottle here. So we drag this through the water. The water goes through the net, and that lets the water pass through, so we end up with literally cubic metres of water sitting in the bottle. But we then concentrate whatever’s in the water into our bottle.
And so we’re now going to deploy our plankton net over the side of the boat. We can either deploy this on station, vertically, or we can tow it behind the boat, if we want to get a much bigger sample.
So we’ve now lowered the net to about 10 metres. We’re now going to pull it up.
And as we do so, it’s literally filtering out around about five or six cubic metres of water filtered through that net.
And here, in the cod end, at the bottom, we’ve got the concentrate from that trawl. And if we look inside, we should see, wow, a lot of stuff from that very small amount of water. There’s phytoplankton there. There’s zooplankton in there. There’s some feathers. There’s also some plastic as well. So the question is, is the plastic in this bottle harmful? The research is still ongoing, and Southampton is very well placed for this sort of research.
We have a combination of physicists, chemists, marine biologists, and ecologists who are all looking at how plastic, a chemical constituent, impacts the oceans, how it gets into the food chain, how it affects the ecology of our oceans, and also how it gets distributed around the oceans. That’s where the physicist comes in. And we’re also ideally placed because we are an industrial city. We are a source, sadly, of some of these plastics that work their way into our environment. What we’re going to do now is look at these under the microscope, to see what’s in there. We’ll certainly see the zooplankton, the phytoplankton. Will we be able to see anything else?
So we’re now going to take our– well, we think between about three and five cubic metres of water that we filtered into this bottle, and we’re going to see what it looks like under the microscope. So we just prepared this. We can see here we have an amazing array of things. It’s full of phytoplankton, the small plants of the oceans, microscopic plants. It’s full of zooplankton. They’re swimming around. They’re very active at the moment. But also, there are lots of particles in here as well. As we go across, we can see here, look, very clearly, a fibre from us. That’s manmade. And also dotted around here, we can see these microbeads.
And it’s very difficult sometimes to distinguish them from the round phytoplankton and the microbeads themselves. And this is the problem the zooplankton have in trying to determine what’s plant and what’s plastic. If we go back to our original sample, can we see those microbeads? Well, actually, as it turns out, yes, we can. There’s a microbead there, right on the edge of our sample. You can see here you’ve got a small larval worm going around. Give you some idea of scale. There’s some phytoplankton. And there we can see one of these microbeads. These are quite big microbeads. Microbeads come in many shapes and sizes. But we are making differences.
If we do ban the microbeads, as is planned, if we are much more careful about recycling our plastics, we can make a difference. We can maintain this amazing diversity that we find in the ocean. But it is down to us, the people who are at the top of the food chain.