Soft corals and microplastics interaction: first evidence in the alcyonacean species Coelogorgia palmosa

Microplastics pollution differentially impacts coral reef systems, by threatening corals physically, through physiological distress and by increasing diseases. However, most of the studies to date have focused on scleractinian corals. The present work reports for the first time the patterns of microplastic ingestion and adhesion by the alcyonacean Coelogorgia palmosa. Feeding and adhesion tests were carried out with various concentrations of polyethylene microbeads. Results showed a wide range of surface adhesion, ranging from 3 to 1573 microbeads per coral fragment, suggesting that adhesion driven by mucus is the main mechanism of microplastic trapping. Polyethylene was ingested by 60% of coral fragments, and the average number of ingested microbeads was much lower compared to scleractinian corals. Considering the ecological importance of soft corals in coral reef ecosystems, specific attention regarding microplastic pollution effects on this taxon is recommended.