Turning the plastic tide

by Janice Wormworth

Turning the plastic tide

Plastic — cheap, strong and durable — is a versatile material we’ve embraced for  70 years. Yet most of the plastic ever created is still with us today. And it’s choking life in our oceans, where the bulk of it ends up.

By 2025, the oceans could contain one tonne of plastic for every three tonnes of fish.

Oceans of plastic

All life on Earth is deeply linked to ocean ecosystems. They provide food, most of Earth’s oxygen, and much more besides. Vast and timeless, the oceans’ ability to absorb human pollution once seemed limitless.

No longer.

Today coastal countries send roughly eight million tonnes of plastic into oceans every year — five grocery bags for every 30 centimetres of coastline worldwide.  Every 11 years, global plastic production doubles.

Enlarge

A view of marine debris from below, as fish or sea turtles might see it. (Photo: U.S. National Oceanic and Atmospheric Administration)
A view of marine debris from below, as fish or sea turtles might see it.

Image: U.S. National Oceanic and Atmospheric Administration.

Out of sight, out of mind?

Scientists are trying to understand where it all goes. Some is swept into circular ocean currents, called subtropical gyres. They churn and collect plastic into five immense areas, including the Great Pacific Garbage Patch. Visitors say it’s like sailing through ‘plastic soup’.

In 2014, The 5 Gyres Institute published the first global estimate of marine plastics – 270,000 metric tons from 5.25 trillion particles. Video: Anna Cummings.

Though vast, the five ocean garbage patches are just the tip of the iceberg. Like smog particles through air, plastic spreads throughout our oceans. It’s been found in the remotest places — embedded in Arctic ice, in the deepest ocean trenches.

Deadly ghost nets lurk

Some of the biggest and most harmful pieces of plastic pollution are discarded fishing nets. Called ghost nets, they can be kilometres long. They entangle and trap marine creatures including turtles, whales and dugongs.

Enlarge

ghostnets
Location of ghostnets across northern Australia.

Image: Ghostnets Australia.

Microplastic: a big problem

At the other end of the size spectrum is harder-to-see microplastic pollution.  Half a centimetre or smaller, it forms as sun and waves break down bigger pieces. Scientists estimate up to 51 trillion particles of microplastic now pollute the ocean.

Microplastic includes microbeads, tiny plastic particles some health and beauty product makers add to things like toothpaste and face scrubs. One bottle of face scrub may contain 300,000 microbeads. They slip through filter systems and into the ocean, to become a major pollution problem.

Enlarge

Microplastic particles on a beach. Photo: courtesy of 5gyres.org
Microplastic particles on a beach.

Image: 5gyres.org.

No stomach for plastic

In 2016 researchers in Germany opened the bellies of sperm whales that died after becoming stranded. The plastic they found inside surprised them: a 13-metre fishing net, a car engine cover, and part of a bucket.

Whales are among the seven hundred different species of sea creatures eating plastic; seabirds and turtles eat very high levels.

Seabirds’ deadly plastic cargo

In 1960, plastic was found in less than five percent of seabirds’ stomachs, but by 2015 this share soared to 90 percent.  Albatrosses, petrels and shearwaters are especially likely to eat plastic.

Inside the stomach of a single seabird, scientists have found up to 200 pieces of plastic. Some birds carried plastic loads of eight percent of their body weight – like a 50-kilogram person carrying four kilograms of plastic in their gut.

shutterstock_419368657_small.jpg
Green Turtle entangled in a fishing net and strangled to death. Image: VisionDive / Shutterstock,com.

Turtles in trouble too

Though sea turtles can live 200 years, plastic cuts many lives short.  More than half the planet’s sea turtles have eaten plastic. When they do, downward facing spines in their throats prevent them from spitting it back up.  At special risk are Olive Ridley turtles (Lepidochelys olivacea). They dine on floating creatures of the open ocean including jellyfish — which look like plastic bags.

Plastic – it smells like dinner

Plastic, made from petroleum, could never be food. So why do seabirds and other marine creatures eat other plastic objects like bottle caps, plastic toys and cigarette lighters, that don’t look much like food?

Scientists believe the reason is smell.

When algae die and break down in the ocean, they release a sulphur-smelling chemical (dimethyl sulphide). Krill use this smell as cue to find their food: algae. Krill eaters, including seabirds, do the same, because it leads them to algae-eating krill.

Waste plastic in the ocean smells similar. Algae grow well on plastic, then decay, giving off the smell equivalent of a dinner bell. Since hungry marine animals link this odour to food, they are primed to eat the sulphury smelling plastic when they find it.

Cruel consequences of plastic meals

When seabirds and turtles eat plastic, it can block or pierce their intestines, killing them. Or they may starve to death, because their stomachs are too full of plastic to take on enough food. Plastic also poisons them by releasing its absorbed toxins.

Plastic pollution solutions

Plastic is a huge problem, but we can all help solve it. In Europe, when people used better ways to manage plastic, scientists found less plastic in seabirds within a few decades. We too can reduce the harm to sea creatures in a relatively short time.

shutterstock_190772084.jpg
You can help clean up our beaches and waterways. Image: Kochneva Tetyana / Shutterstock.com.

Cleaning up plastic already in the ‘tub’

Dutch inventor Boyan Slat is inspiring for young people who want to make a big dent in plastic pollution. In 2013, at age 17, Boyan started The Ocean Cleanup. Today this foundation has more than 50 staff who plan to use long floating barriers to remove half the plastic in the Great Pacific Garbage Patch in 10 years.

Enlarge

Fishing for plastic in the Great Pacific Garbage Patch
Fishing for plastic in the Great Pacific Garbage Patch.

Image: The Ocean Cleanup, via Instagram.

Not everyone can start a foundation like Boyan’s, but we can all help reduce plastic pollution on our coasts. Most, CSIRO found, was generated right here in Australia, deposited by people or swept to the coast by stormwater or wind.

This means that action here at home can solve the problem. So next time you visit the ocean, the Take 3 for the Sea campaign asks you to take 3 pieces of rubbish with you when you leave.

Or take part in Clean up Australia Day. On March 5, join hundreds of thousands of Australians as we clean up our local outdoor places. Register to join a site in your community or school, or start a site of your own. Want to do more? Clean Up Australia supports clean-ups any day of the year.

Enlarge

Reduce your use of plastic to prevent more ending up in our waterways.
Reduce your use of plastic to prevent more ending up in our waterways.

Image: Don Mammoser / Shutterstock.com.

Turning off the plastic ‘tap’

Even more important than cleaning up plastic pollution is making sure it never escapes in the first place. Recycling helps, but cutting the amount of plastic we produce and use is vital for a sustainable future.

Plastic bag bans

Plastic bags, often used for mere minutes, become litter forever. South Australia, Northern Territory, ACT and Tasmania have already banned single-use plastic bags.

If your state hasn’t banned them yet, ask your leaders to do their part to prevent 50 million of bags from littering our environment every year.

When you shop, take a cloth or other reusable bag with you, and say ‘No’ to these plastic bags. Why not take the Plastic Free July challenge, and extend your plastic-free choices to other months too!

Five more ways to go plastic-free:

More information:

References

  • Cover image: Plastic is a plague upon our oceans. Image: Mohamed Abdulraheem / Shutterstock.