Scientists are calling for research into the impact of microplastics on baleen whales, basking sharks and manta rays amid fears they may be as harmful as larger pieces of plastic.

Marine megafauna feed by filtering thousands of cubic metres of seawater a day for plankton, meaning they are almost certainly also taking in the tiny particles of indigestible plastic, which appear to be prevalent throughout the world's oceans.

A study published in the journal Trends In Ecology And Evolution says little is known about the potential harm that is doing and is demanding further investigation.

Elitza Germanov, of Murdoch University in Australia, the lead researcher of the study, said: "We are still trying to understand the magnitude of the issue.

"It has become clear, though, that microplastic contamination has the potential to further reduce the population numbers of these species, many of which are long-lived and have few offspring throughout their lives."


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The study shows that, despite their huge size, at least some of these species are highly vulnerable to these tiny fragments - which typically comprise "microbeads" used in hundreds of different cosmetic products such as face washes and shower gels.

They find their way into the nearest river and on into the sea and it is estimated up to 51 trillion microbeads are currently in our oceans, while a single shower can flush away an estimated 100,000.

In a bid to reduce the amount of plastic in our oceans, a UK-wide ban on manufacturers making products containing microbeads came into force last month.

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Bottles and other larger plastic objects that break down into ever smaller pieces over hundreds of years are also playing a role.

Plastic-associated chemicals and pollutants can accumulate over decades and alter biological processes in the animals, leading to altered growth, development and reproduction, including reduced fertility.

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The study's co-author, Maria Cristina Fossi, said research on fin whales and whale sharks showed filter-feeding species were being exposed to toxic chemicals, perhaps through the breakdown of microplastics in their digestive systems.

“Exposure to these plastic-associated toxins pose a major threat to the health of these animals since it can alter the hormones,” she said.