A new study has painted a "shocking" picture of the effects of plastic pollution on marine life.
The research, published on Tuesday, shows that 28 percent of fish in the Thames Estuary have ingested microplastics. In Scotland's Firth of Clyde Estuary, 39 percent of fish have been affected.
The study was carried out by scientists from the University of London's Royal Holloway, The Natural History Museum and the University of the West of Scotland.
It further found that, altogether, roughly one third of 876 fish and shrimp examined from both estuaries had ingested microplastics.
According to the National Oceanic and Atmospheric Administration (NOAA), microplastics are small pieces of plastic less than five millimeters long. They can, the NOAA states, "be harmful to our ocean and aquatic life."
The Marine Conservation Society has said that microplastics in the marine environment can carry toxins that could, potentially, be passed into animal tissue and then carried up the food chain to humans.
"People have started to really take note of the severity of plastic pollution and our research further demonstrates why this is such pressing issue," Alexandra McGoran, the PhD student who led the research, said in a statement.
"Both rivers are extremely diverse ecosystems, home to hundreds of different species," she added. "To see this large number of species that our plastic waste is putting in danger is actually rather shocking."
McGoran went on to state that the results of the study showed that more research into freshwater and estuarine ecosystems was needed "so we can better understand the effects microplastics are having on their inhabitants."
The research was published in the Marine Pollution Bulletin.