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A sticky solution to microplastics?

 

Jellyfish offer a sticky solution to the problem of plastic pollution

Our oceans are full of microplastics and unnatural swarms of jellyfish. Could these beautiful animals possess a secret weapon to help clean up the environment?

The fried egg jellyfish ( Cotylorhiza tuberculata ) can have a bell that measures up to 60 cm in diameter. (Sarah Lawrynuik)

The fried egg jellyfish (Cotylorhiza tuberculata) can have a bell that measures up to 60 cm in diameter. (Sarah Lawrynuik)

Dec. 12, 2018, New Scientist

OUR hunt has got off to a slow start. When the sea is choppy, spotting our quarry is hard. But as the sun rises higher, our efforts are finally rewarded. Shielding her eyes against the light bouncing off the water, Tjaša Kogovšek points to a faint dark blob. Our boat moves closer, and she plunges her net in to scoop the creature into a white bucket. We have bagged our first trophy of the day.

I am in the Gulf of Trieste off the coast of Slovenia catching jellyfish with researchers from the country’s National Institute of Biology. Knowing their catch will ultimately die, Kogovšek has mixed feelings about the hunt. “At the beginning it was very difficult,” she says, “because their destiny is not nice after they are in my hands.” But she is also well aware that an explosion in jellyfish numbers in recent years is a serious problem, both for us and for the marine environment. And the international project Kogovšek is part of, called GoJelly, sees that as an opportunity. It believes it can tap these ethereal creatures to tackle another environmental scourge of our time: microplastic pollution. If successful, it will be a win-win.

A blooming problem

Jellyfish are among a select group of organisms that seem to thrive as humans trash Earth. Exactly why isn’t known, but one factor could be fewer competitors due to overfishing. Others may be the spread of jellyfish in ships’ ballast tanks, and the fact that jellies can live in oxygen-depleted, polluted waters. Whatever the causes, larger, more frequent jellyfish blooms – dense swarms of the creatures – are occurring in many parts of the world. That is bad news for tourism when they force beaches to shut. The blooms can play havoc with vital services, too, from power stations to water treatment plants, if they are sucked into water intakes. And they are also a problem for other marine life, and for fisheries, because jellyfish feed on fish larvae, so a rising population upsets the balance of already fragile ecosystems.

Extreme measures are being explored to reduce their numbers, such as acoustic shocks, electrocution and robot shredders. GoJelly’s approach seems tame in comparison. What truly sets it apart, however, is its aim to put excess jellyfish to good use. One of the creature’s key means of defence is the mucus it secretes. The dream is that this sticky substance can be used to filter microplastics out of water. It may sound fanciful, but GoJelly is in earnest. The project has been given €6 million by the European Union, and consists of 15 research teams in eight nations. This reflects the urgent need to reduce the increasing amount of tiny, non-biodegradable bits of plastic in the environment, in wildlife and even in the food we eat.

The day’s hunt over, back at the lab Kogovšek and her colleague Katja Klun measure each animal in the haul. There are dozens of native fried egg jellyfish (Cotylorhiza tuberculata), all around 30 centimetres in diameter, and some much smaller invaders from western Atlantic coastal waters called warty comb jellyfish (Mnemiopsis leidyi). Their ultimate destiny is to be chopped up and frozen, but first they are lightly stressed – prodded in their large white buckets – so that they secrete mucus. Then Klun extracts the transparent goo with a syringe, separating it from the seawater. It is an unusual job for a chemist. “I wasn’t used to working with slimy creatures,” she says. Nevertheless, her expertise is invaluable. She is analysing the chemical and physical properties of mucus from the jellyfish caught off Slovenia, and by GoJelly teams from Israel to Norway.

 
Stiky situation: a fried egg jellyfish will produce mucus when handled or gently prodded. (Sarah Lawrynuik)

Stiky situation: a fried egg jellyfish will produce mucus when handled or gently prodded. (Sarah Lawrynuik)

The roots of this surprising endeavour lie in the work of French scientists. In 2015, a team led by Philippe Barthelemy at the University of Bordeaux revealed that jellyfish mucus can filter gold nanoparticles from water. Like microplastics, they are tiny and do not react readily with other chemicals. The group found that the gloop from some jellyfish species made a better filter than that of others.

For now, Klun’s focus is on the stability of the gloop. It is rich in protein, glycoprotein, sugars and other substances, making it an ideal home for bacteria, which start to break down its constituent chemicals within hours, turning it from a viscous slime to a more watery substance. So Klun compares mucus from different species and individuals, and is experimenting with ways to keep the gelatinous structure intact. There is a way to go to show that this gloop can be used to filter microplastics – GoJelly only began in January 2018 – but Klun is optimistic. She holds up a test tube and swirls the contents. “You can already see just using your eyes that it is trapping plastics,” she says.

The next big challenge is to create a mucus-based filter that can be fitted to the outlets of commercial wastewater treatment plants. That task falls to Dror Angel at the University of Haifa, Israel, and his colleagues. “At the moment, we have no idea what this filter will look like,” he says. “We’re probably talking about something that has a large surface area, so that it has maximum contact with the particles in the water that it is treating.” It also needs to be inexpensive, and easily inserted into existing treatment facilities.

Cracking the mucus instability problem will be key for Angel’s team. “One of the things that we have found is that it isn’t that easy to work with,” he says. “So, will it have the same properties over a period of time? Or do we need to freeze it? Refrigerate it? There’s a whole big question of how to process the mucus initially to be able to use it.” It is early days, but his team hopes to have a prototype filter ready for testing at a local wastewater treatment plant sometime in 2019.

GoJelly’s ambitions don’t end there. The project is also exploring ways to make use of the leftover creatures. An Italian team wants to turn them into food, and is consulting partners in China where jellyfish have been a part of the diet for centuries. In Portugal, Norway and Germany, teams aim to turn them into feed for fish farms and fertilisers. GoJelly is even exploring the possibility of using jellyfish collagen in cosmetics.

All this makes Kogovšek feel better about the hunt. “I hope we can benefit from the jellyfish bloom and not just see them as pests,” she says. “They are very beautiful animals.”

This article was published by New Scientist online, as well as in the print edition issue 3208, published 15 December 2018.