Could we modify plankton to clean up the ocean?

07 February 2017

Question

Simon - Can plankton be genetically modified to consume and clean up the sea of tiny plastic particles in the ocean?

Answer

Chris Smith put Simon's idea to marine biologist Danielle Green...

Danielle - Well it’s a pleasure to hear such a beautiful accent. Zooplankton already do eat microplastics and they pretty much just pass straight through the body.

Chris - And by zooplankton you mean these are little microscopic animals?

Danielle - Little animals - copepods, amphipods, like little crustaceans, little crabs, and they already have been found loads of species to contain microplastics and in the lab they'll eat microplastics.

Chris - What is a microplastic?

Danielle - Technically the definition is it’s less than 5mm in diameter which isn’t actually the definition of microbe - they’re small pieces of plastic. They can either be purpose made - primary microplastics which are microbeads or exfoliants, things like that. They can also be secondary microplastics which are the breakdown of larger bits of plastic litter. Or, actually the most common source is synthetic clothing fibres.

Chris - Why are we worried about them if they’re just plastics bobbing around in the ocean? Why are they a worry?

Danielle - they’re the most abundant form of solid waste in the world at the moment and they’re increasing at a pretty quick rate. We’re not exactly sure how much they’re increasing. But they can go through the food web, and they’ve been found in laboratory conditions to cause harm to certain animals. So they can reduce reproductive rates and there’s a potential for huge knock on effects to the whole ecosystem as well. My own research has found that they can decrease the biomass of microalgae so this is the base of the food web. Because they’re in everything they can have an effect on everything potentially. We’re not exactly sure what they’re doing.

But in terms of the zooplankton and eating them, some other studies have found that they eat them and then poop them out and they become like an accumulation. They sink to the bottom of the sediment and then they become available for other organisms, so deposit eating worms (worms that eat the sediment) like lugworms. Then fish will eat the lugworm, so it’s another way of it becoming available to other organisms.

In terms of genetically modifying, as an Australian in particular, any sort of bio control terrifies me. We’ve had too many bad experiences. But there actually are people working on using bacteria to breakdown microplastics and plastic pollution in general. There was lots of work going on about this but I think it’s potentially dangerous given that a lot of things in the ocean that we use are made of plastic. You don’t want microbes spreading around willy nilly eating the bottom of your boat. You’ve got to be careful.

Chris - No sure. Sounds alarming. The worry, I presume, is that they’re going to be in the water for a really long time whatever the outcome, isn’t it?

Danielle - They’re increasing at a huge rate as well.

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