One of those scientists is University of Western Australia oceanographer Professor Carlos Duarte, who says the findings are not good news.
Presenter: Brian Abbott
Speaker: Professor Carlos Duarte, University of Western Australia Oceans Institute
DUARTE: Whereas we find only 1 percent of the amount of plastic that was estimated will actually be floating in the oceans, that could be seen as good news, but in fact, the disturbing reality is that we cannot account for where the 99 percent that is missing may be.
ABBOTT: What would cause plastic to just disappear, do they sink to the bottom, do they just yeah, where do the vanish to?
DUARTE: Well, there are about four possible processes that might remove this plastic. One of them is that the plastic follows up a process of continuous breaking down into smaller and smaller particles, so maybe some of the particles become too small for us to take them, because we're using nets to capture in these particles, and once they fall below point-two-millimetres and they will be outside our sampling. Another possibility is that microbes might be degrading these particles and there's some evidence for microbes being able to degrade plastic particles. The third possibility is that they might be colonised and overgrown by organisms that have shells like made of silicate or carbonate and they will be ballasted by these shells and then sink into the ocean. These shells may dissolve at about two-thousand-metres depth, but the particles may remain there. And our fourth possibility is that the plastic particles that are missing, might be ingested by fish. And that one possibilities unfortunately the most likely one, because plastic that is missing starts to (inaudible) at a range of about one to four millimetres in size, which is the feeding range of these fish. So the plastic might actually be coming into the topic food web of the ocean of which we humans are part.
ABBOTT: Can fish survive if they eat plastic, if fish are eating these micro-particles of plastic, surely it must be doing damage to their internal organs?
DUARTE: Yes the plastics themselves will have some mechanical damages and obstructions. The most important is that these plastics often have embedded chemicals that are toxic and even during their transit in the oceans, they're surfaces may absorb also pollutants from the ocean, so it's not just a mechanical affect of the particles themselves, but also the impact of the pollutants that these particles carry. And these microscopic fish are predated upon by tuna, by sword fish and also by squid all of which are in our dining plate.
But before we get too concerned about our dining plate being a source of plastics for us, we should first think that when we take our food from the supermarket, almost every piece of food is wrapped in plastic. So the least of our concerns in the plastics that may come to our dinner table, as ingested particles by fish and we should be doing something about the absurd amount of plastic that we consumed in our daily lives.
ABBOTT: So, you say there's a greater danger from the plastic that everything comes in from supermarkets?
DUARTE: Absolutely. We insist in wrapping up our food in plastic material, both when we purchase items from the supermarkets, but also even when we take our lunch to our office desk, we wrap it up in plastic, we put it in plastic containers and all of these plastics are sources of pollutants to humans and all of these plastics are sources of pollutants to humans, that's well demonstrated in the blood of each of us contain traces of these pollutants, so it means that we are exposed and I think we should first do something about the daily large amounts of plastics that we consume in our daily lives and that will also help in reducing the amount of plastic that reaches the ocean.
So there's already been some progress on these, because the recycling policies and awareness policies have reduced the per cent of the plastic that reaches the ocean. But because the global consumption of plastic has increased, even that per cent reaches the ocean may have declined, the total amount continues to increase and that is not a good trajectory for the oceans and is not a good trajectory for us humans who are using far too much plastic. We should be doing research in a materials that can replace the plastics, like polymers derived from plants, including seaweed, but we also should be more aware of the damage that plastic makes and then have choices in our daily lives that we reduce the amount the plastic we consume. And it is very possible to live happy lives without plastic around them.
ABBOTT: Has the introduction, particularly in Western countries I suppose of biodegradable plastic shopping bags in supermarkets made any dent in the amount of plastic that's getting into oceans?
DUARTE: Yes, it has, because without this introduction, the amount of plastic reaching to the oceans would have been greater, also policies that have a charge for the plastic bag puts in supermarkets have also make a different and policies to replace these plastic materials by polymers. For instance, there are plastics available in many supermarkets are produced from potato residues, that's also helping. So there's many steps that we have taken, but unfortunately, the total amount of plastic that we consume as a global population continues to increase.