Under the Sea

Millions of microscopic creatures, organisms and bacteria have been found living on tiny pieces of plastic pollution in the ocean.

Australians discard nearly 1.5 megatons of plastic each year, with only around one in five pieces recycled. And – as the old adage goes – everything eventually ends up in the ocean.

Julia Reisser, a PhD candidate from the University of Western Australia, has been studying oceans for years. She’s part of a team researching “garbage islands”, those places where ocean currents congregate to form island of millions of tonnes of microplastics.

Microplastics are plastic pieces less than 5mm large. They are formed when plastics we throw away – such as wrappers, cups, dental floss and fishing line – are broken down by sunlight and heat.

However, Ms Reisser’s interest isn’t in what microplastics are made of, or even where they come from. She studies the kinds of organisms that live on them.

“We were quite surprised to find a whole ecosystem living on the microplastics,” she says. “It’s a perfect environment for them.”

As plastic floats, the organisms have an underwater surface to live on that still gets sunlight.

“We find a very high diversity of organisms; [on] each piece you look at you find something different.”

“We’ve found 90 new organisms that weren’t known to be associated with plastics before. The vast majority are bacteria and microscopic plants such as diatoms, and also lots of tiny little creatures like invertebrates.”

 

In the food chain

Microorganisms can then be eaten by other organisms, or by tiny fish, and form the base of the food chain in their ecosystem. This would be great if it weren’t for the fact that plastic attracts considerable amounts of toxic material in the ocean.

“The plastic surface acts like a sponge to oily pollutants. The load of toxins on the plastic’s surface is thousands of times higher than in the surrounding water,” Ms Reisser says.

This means that the organisms absorb the pollutants, of which there are thousands in the ocean. Petroleum, insecticide, fertiliser and a myriad other toxic substances are all taken in by members of the microplastic community. These toxins are passed up the food chain, fish by fish.

This poses an even bigger problem when considering who’s at the top of the food chain. A recent study in Singapore showed that toxins commonly found on ocean plastics were showing up in fish markets. The effects of ingesting these chemicals in humans is still unknown – while we know we’re eating them, scientists don’t yet know what it’s doing to us.

 

In their ecosystems

Before humans started dumping large amounts of plastic in the ocean, they were clean, clear waters allowing the free passage of sunlight and animals. We’re slowly discovering that the popular saying touted by businesses “the solution to pollution is dilution” is not an effective fix.

“We have introduced a new type of habitat to certain areas,” Ms Reisser says.

“We have organisms that use these plastics like a boat … to travel around on the currents. Then you have the problems posed by invasive species.”

Enormous garbage islands are formed where ocean currents meet, creating whole new and unnatural habitats that are hazardous to the existing ecosystem.

“If you travelled to these areas, you’d see millions of pieces of floating garbage … and there’s organisms ingesting the plastics, there’s organisms getting entangled in them,” says Ms Reisser.

Declining populations of seals, sea turtles and birds are among the many deaths attributed to plastic in the ocean. There hasn’t been enough research on the subject to understand the long-term effects on many species, but many scientists believe that plastic debris will cause hundreds of extinctions before a solution is found.

 

In the future

But there might be a tiny piece of good news among the bad.  Recent research indicates that some of these organisms are biodegrading the plastics they live on.

“Among this plastic community are organisms that are breaking down the plastics. If we could harness these organisms, perhaps we could [also] use them on land to break them down,” says Ms Reisser.

This could be an effective solution for the 300 million tonnes of plastic that are produced every year internationally. On average, only 10 percent of plastic is recycled world wide, with the rest ending up in landfill and in the ocean.

Our “plastic footprint” is only becoming more important, and may become equally as central as the carbon footprint in 21^st century environmentalism.

Ms Reisser believes there’s even a possibility to turn plastic into other useful substances.

“Maybe we can use these bacteria for what we call bio-remediation. Maybe in the future we could have a compost system where you put your plastic waste in with these microorganisms, and they biodegrade your plastics or maybe transform it into a bio-diesel or bio-fuel.”

Currently there are studies investigating the creation of bio-fuel with organic waste such as dried cornhusks, but none with plastic waste.

Unfortunately, implementing strategies like these is years away. For now, we should be conserving the amount of plastic rubbish we produce.