A study, in the journal Trends in Ecology and Evolution, says the creatures may be swallowing hundreds of tiny bits of plastic a day.
Microplastic pollution has the potential to further reduce the population sizes of the large filter feeders, they say.
Yet, there is very little research being carried out into the risks.
Researchers from the US, Australia and Italy looked at data on threats to large filter feeders from microplastics. These small plastic pieces less than five millimetres long can be harmful to the ocean and aquatic life.
The Gulf of Mexico, the Mediterranean Sea, the Bay of Bengal and the Coral Triangle are priorities for monitoring, according to a review of studies.
“The full magnitude of risks of ingesting microplastics are yet to be fully investigated,” said Elitza Germanov of Murdoch University, Australia, and researcher at the US Marine Megafauna Foundation.
Possible risks include reduced nutritional uptake and damage to the digestive system when microplastics are ingested, she said.
Photo: Shiyam ElkCloner/Wikimedia Commons (CC BY-SA 3.0)