Microplastics Make Marine Life More Vulnerable to Predators

New research shows that microplastics are making some marine animals less responsive, which leaves them vulnerable to predator animals.

Researchers publishing in the science journal “Biology Letters” say their investigation demonstrates how microplastics may be altering marine animal behavior in a way that could upset the balance of marine food webs.

The researchers, scientists from the French National Centre for Scientific Research, looked at the behavior of the common periwinkle, a species of small edible whelk or sea snail. Specifically, the scientists wanted to observe what happened when periwinkles who had been dining on microplastics in their environment encountered their natural predators, crabs. Would they react the same, or would their behaviors change? This question is one other research has touched on and has shown that animal behavior changes after ingesting microplastics over a prolonged period of time.

Unfortunately, the researchers found much the same here.

Using concentrations of microplastics at levels found on our beaches, which the periwinkles would ingest when they eat algae that has dined on plastics, the researchers dosed periwinkles in lab conditions. They then allowed predator crabs onto the scene. What the researchers observed was a marked lack of a chemical response from the periwinkles.

Normally, periwinkles would withdraw into their shells to hide or find a means of escape. When exposed to microplastics through water collected from beaches, the periwinkles did not appear to go through the same responses to an approaching threat, allowing the crabs to close in on their prey more easily and more successfully. Virgin plastics also had an impact, but not as much as those taken from the wider environment, suggesting this change in behavior is a result of the chemicals the plastics may be leaching after being in our oceans for a while.

“The whole set of behaviors are totally inhibited,” researcher Proffessor Laurent Seuront, of the National Centre for Scientific Research, told the Guardian. “It is worrying news. If the periwinkles are not able to sense and escape from the predator, they are more likely to disappear and then to disturb the whole food chain.”

So what is going on here?

Microplastics enter our environments through a number of ways and are virtually ubiquitous in our modern lifestyles. While we have taken some steps to reduce their use—for example by getting rid of microbeads in our cosmetics—you can still find microplastics in our cleaning products. They can even result from larger plastics breaking down over time during natural weathering.

When this happens, it is possible for tiny particles to then enter our environments.

Unfortunately, previous research has shown that microorganisms like algae and insect larvae are unable to distinguish between microplastics and their actual food and will gobble up the particles. When this happens, these organisms become repositories for the plastics. When larger animals eat them, in this case sea snails eating algae, the concentration of microplastics multiplies, and that has a compound effect.

The researchers theorize that microplastics are carrying heavy metals, whether in their own composition or by grabbing them out of the water. Heavy metals are known to change the hormone profiles of marine animals (and even humans) and could be interrupting the snails’ natural responses.

We might say, so what? These are sea snails after all, but there are a number of reasons why we should care.

Why Microplastics’ Impact on Sea Snails Matters

If this is happening to sea snails, it is almost certainly also happening in other species including the fish that humans eat. The researchers say it is highly likely that any animals that use chemical senses to observe the world around them could be affected by this microplastics problem, including the crabs that prey on periwinkles and fish.

If that’s the case, we need to think of microplastics not just as an environmental issue, which it most definitely is, but also as a potential health issue for humans.

Another reason to be concerned is that food webs, while resilient, can only stand sustained stress for so long. Periwinkle numbers going down may not be a pressing concern—there are a lot of sea snails, and some level of fluctuation can be tolerated. But, if this problem is impacting slightly larger animals, like the crabs, the food web’s integrity is quickly compromised. Crabs are are a key mid-range predator—from octopuses to sea birds—on whom many other species rely.

Collapse may not be imminent, but given the wider pressures facing our marine species, from noise pollution to global warming, this is yet another factor that could be contributing to the species loss we are seeing across the globe.

This is a first-of-its-kind study, and for that reason it is doubly valuable. While the researchers cannot directly prove that microplastics are the only culprit here, this is strong evidence of the impact microplastics are having on our wildlife. The researchers stress that reducing microplastics in our environment has to be a major focus of environmental work, while science has to work hard at understanding exactly what plastics are doing to our wildlife.

Microplastics may be tiny, but the issues they are causing for our environment and wildlife are truly massive and pervasive.

Photo credit: Getty Images.

39 comments

Chad Anderson
Chad A10 days ago

Thank you.

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Loredana V
Loredana V10 days ago

Those who survive are killed and eaten. Humans are a pest

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foteini c
foteini c10 days ago

thanks for sharing :(

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Barbara S
Barbara S11 days ago

thanks very much

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Anne Moran
Anne Moran11 days ago

Just stop making products that contain microbeads/microplastics.. - Grab a brain...

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Roxana S
Roxana S11 days ago

TYFS

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Glennis Whitney
Glennis W11 days ago

Thank you for caring and shring

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Glennis Whitney
Glennis W11 days ago

Sickening Thank you for caring and shring

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Glennis Whitney
Glennis W11 days ago

Deplorable Thank you for caring and shring

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Glennis Whitney
Glennis W11 days ago

Thank you for caring and shring

SEND