Plastic ‘nurdles’ prevent sea urchins from developing properly, study finds | marine life

Sea urchins reared in heavily plastic-polluted seawater, including fragments collected from a Cornish surf beach, are dying of developmental abnormalities, Studies show.

Scientists placed fertilized sea urchin eggs in seawater with varying levels of plastic to compare the effects of newly made plastic pellets, or “noodles”, with the impacts of high levels of fragments found stranded on Watergate Bay in Cornwall.

They found that sea urchin larvae reared in water contaminated with pellets purchased from a plastic manufacturer developed significant abnormalities at the three concentrations tested (1, 5 and 10% plastic). Those raised in water contaminated with nurdles collected from the surf beach also died, but only at the highest concentration of 10%.

This suggests that newly made plastic, which still contains high levels of additives that leach into the water, is more harmful, the researchers say. Although the plastic concentrations tested in the study are rare in the ocean, they say, the lowest concentrations, around 1%, could occur during spills.

The research team – from the Anton Dohrn Zoological Station and the National Biodiversity Future Center in Italy, and the University of Exeter in the UK – previously found that plastic additives can harm sea urchin larvae and say the new study expands on that and reveals how the harm is caused.

“Larvae affected by plastic pollution showed developmental abnormalities, including skeletal, neural and immune cell malformations,” said Dr. Eva Jiménez-Gurifrom the Anton Dohrn Zoological Station and the University of Exeter.

“They also showed ‘radialization’ – meaning they had no proper symmetrical structure, and were rather formless and therefore unable to survive.

“In these larvae, the mitochondria (the ‘powerhouses’ of cells) were not functioning properly and they were showing signs of oxidative stress, which damages cells.”

“Even though plastic doesn’t kill animals through ingestion or entanglement, it can also kill animals through the chemicals in or on it,” Jimenez-Guri said.

“Our results indicate clear and specific detrimental effects of marine plastic pollution on the development of sea urchin larvae,” she said.

In the case of new PVC cores, the damage was caused by high concentrations of zinc which seeped into the water. Larvae exposed to 10% PVC pollution developed their gut outside their bodies, while 5% and 1% levels also resulted in fatal abnormalities.

Samples taken from the beach did not release high levels of zinc, as most of the additives they contained would have already been released into the sea.

However, from previous research, scientists have determined that these particles are known to collect a variety of persistent organic pollutants.

The article, published in the journal Science of the Total Environment, is titled: “Plastic leachate-induced toxicity during sea urchin embryonic development: insight into molecular pathways affected by PVC.”

The researchers, who identified the genes affected by the pollutants, are already investigating whether the nurdles could cause similar abnormalities in other species that respond on the same genes at key early stages of development.

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