Lobsters break down microplastics and release them back into the sea

Microplastics (MPs) have become abundant in the ocean, where they are easily ingested by marine organisms. In a new study published by the American Chemical Society, researchers have discovered that lobsters in the deep sea break down some of the microplastic material they ingest, releasing the secondary fragments back into the water.

Microplastic pollution eventually sinks to the bottom of the ocean, but just what happens to the contaminants in the deep sea is a mystery.

The Norway lobster, also known as langoustine, resides on the muddy seafloor. This makes the lobster an ideal subject for investigating microplastic contamination in the deep ocean. 

Based on the contents of their stomachs and digestive tracts, previous studies have indicated that lobsters can ingest plastics. In addition, another type of crustacean that lives in the water column is known to have the ability to break down plastic particles through digestion.

A team of experts led by marine ecologist Alessandro Cau set out to investigate whether this type of MP fragmentation happens in nature among species dwelling on the seafloor. The study was focused on lobsters collected near Sardinia in the Mediterranean Sea.

The researchers found that larger plastic particles became trapped in the stomach, while others passed into the gastric mill where food is broken down. Lobsters have small calcified plates that grind against each other, and much of the plastic particles were broken down and fragmented during this process. The smaller particles moved into the intestines, where they would have been released back into the sea.

“Our results show that the stomach can act as a size-bottleneck for ingested MPs, enhancing the retention of larger particles within the stomach and promoting fragmentation into smaller plastic debris, which is then released in the intestine,” wrote the researchers.

“Our results provide evidence that the langoustine is responsible for the fragmentation of MPs already accumulated in sediments through its scavenging activity and digestion. These findings highlight the existence of a new peculiar kind of ‘secondary’ MPs, introduced in the environment by biological activities, which could represent a significant pathway of plastic degradation in a secluded and stable environment such as the deep sea.”

The study is published in the journal Environmental Science & Technology.

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By Chrissy Sexton, Earth.com Staff Writer