Mermaid tears, or mermaid’s tears, are small pieces of plastic which float in the world’s oceans. These tiny chunks of plastic may not look like much when held in the palm of the hand, but when one considers the fact that they are widely distributed in the oceans, they can seem a bit more ominous. Mermaid tears are only one among many forms of plastic polluting the ocean, but some biologists fear that they may be especially insidious, because they are ideally sized for consumption by filter feeding animals.
There are two types of mermaid tears. The first is a unit of plastic known as a nurdle. Nurdles are very small pieces of plastic which are designed to be melted down and them molded or otherwise shaped to make plastic materials, and they are widely used throughout the plastic industry. The most common source for nurdles is industrial spills from trucks and container ships; because nurdles are so small, they are hard to contain, and they slip away from containers and into waterways or into the ocean directly.
The other form of mermaid tear is a small piece of plastic similar in size to a nurdle, caused by the wearing down of finished plastic items. For example, if a broken plastic cup ends up in the ocean, the parts will slowly break up even further, turning into small plastic mermaid tears. Studies on the plastic debris in the ocean seem to suggest that mermaid tears only break down up to a certain point, and after that, they will float in the ocean for thousands or perhaps millions of years, potentially causing serious problems. As they get smaller and smaller, mermaid tears are harmful to more and more organisms in the sea, as well.
Mermaid tears are a problem for a number of reasons. The first and most obvious is that they are ingested by marine animals, who cannot digest plastic. As a result, animals can sicken or die with large numbers of mermaid tears in their digestive tracts, and bigger organisms may consume mermaid tears when they eat smaller organisms. As a result, plastic becomes widely distributed in the marine food chain.
Perhaps more insidiously, mermaid tears can also contain chemical pollutants. In addition to the chemicals naturally present in plastic, these small plastic pellets can also pick up other chemicals and contaminants, ranging from toxins to endocrine disruptors, and any organism which ingests these chemicals will suffer as a result. Mermaid tears are essentially like tiny toxic sponges with a deadly payload, and in some cases the effects may not be noticed for several generations, but they can still be quite severe.
Cleaning up the huge accumulation of plastic in the ocean is basically impossible, although it is feasible to collect larger bits of plastic debris. Most biologists are focused on beach cleanup, and on the reduction of garbage which could end up in the ocean. Some fear that it may already be too late, thanks to the proliferation of mermaid tears which would continue to hurt marine organisms for thousands of years, even if we stopped all plastic production today.
Published May 22, 2008
Among clumps of seaweed or flotsam washed up on the shore it is common to find mermaids’ tears, small plastic pellets resembling fish eggs.
Some are the raw materials of the plastics industry spilled in transit from processing plants. Others are granules of domestic waste that have fragmented over the years.
Either way, mermaids’ tears remain everywhere and are almost impossible to clean up.
Dr Richard Thompson at the University of Plymouth is leading research into what happens when plastic breaks down in seawater and what effect it is having on the marine environment.
He and his team set out to out to find out how small these fragments can get. So far they’ve identified plastic particles of around 20 microns – thinner than the diameter of a human hair.
In 2004 their groundbreaking study reported finding particles on beaches around the UK. Historical records of samples taken by ships plying routes between Britain and Iceland confirmed that the incidence of the particles had been increasing over the years.
Now the team has extended its sampling elsewhere in Europe, and to the Americas, Australia, Africa and Antarctica.
They found plastic particles smaller than grains of sand. Dr Thompson’s findings estimate there are 300,000 items of plastic per sq km of sea surface, and 100,000 per sq km of seabed.
So plastic appears to be everywhere in our seas. The next task was to try and find out what kind of sea creatures might be consuming it and with what consequences.
Thompson and his team conducted experiments on three species of filter feeders in their laboratory. They looked at the barnacle, the lugworm and the common amphipod or sand-hopper, and found that all three readily ingested plastic as they fed along the seabed.
“These creatures are eaten by others along food chain,” Dr Thompson explained. “It seems an inevitable consequence that it will pass along the food chain. There is the possibility that chemicals could be transferred from plastics to marine organisms.”
There are two ways in which this might happen. Firstly, the Plymouth scientists want to establish whether there is the potential for chemicals to leach out of degraded plastic over a larger area after the plastic has been ground down.
The second aspect of this research is focusing on what happens when plastic absorbs other contaminants.
So-called hydrophobic chemicals such as PCBs and other polymer additives accumulate on the surface of the sea and latch on to plastic debris.
“They can become magnified in concentration,” said Richard Thompson, “and maybe in a different chemical environment, perhaps in the guts of organisms, those chemicals might be released.”
Whether plastics present a toxic challenge to marine life and subsequently to humans is one of the biggest challenges facing marine scientists today.
The plastics industry’s response is that much of the research is speculative at this stage, and that there is very little evidence that this transfer of chemicals is taking place in the wild.
It says it is doing its bit by replacing toxic materials used as stabilisers and flame retardants with less harmful substances.
Whatever the findings eventually show, there is little that can be done now to deal with the vast quantities of plastic already in our oceans. It will be there for decades to come.