Uptake of microplastics by the snakelocks anemone (Anemonia viridis) is commonplace across environmental conditions

Microplastics (<1 mm) are ubiquitous in our oceans and widely acknowledged as concerning contaminants due to the multi-faceted threats they exert on marine organisms and ecosystems. Anthozoans, including sea anemones and corals, are particularly at risk of microplastic uptake due to their proximity to the coastline, non-selective feeding mechanisms and sedentary nature. Here, the common snakelocks anemone (Anemonia viridis) was used to generate understanding of microplastic uptake in the relatively understudied Anthozoa class. A series of microplastic exposure and multistressor experiments were performed to examine particle shape and size selectivity, and to test for the influence of food availability and temperature on microplastic uptake. All A. viridis individuals were found to readily take up microplastics (mean 142.1 +/- 83.4 particles per gram of tissue) but exhibited limited preference between different particle shapes and sizes (n= 32). Closer examination identified that uptake involved both ingestion and external tissue adhesion, where microplastics were trapped in secreted mucus. Microplastic uptake in A. viridis was not influenced by the presence of food or elevated water temperature (n= 40). Furthermore, environmental sampling was performed to investigate microplastic uptake in A. viridis (n= 8) on the coast of southwest England, with a mean of 17.5 +/- 4.0 particles taken up per individual. Fibres represented the majority of particles (91%) followed by fragments (9%), with 87% either clear, blue or black in colour. FTIR analysis identified 70% of the particles as anthropogenic cellulosic or plastic polymers. Thus, this study provides evidence of microplastic uptake by A. viridis in both laboratory exposures experiments and in the marine environment. These findings support recent literature suggesting that external adhesion may be the primary mechanism in which anthozoans capture microplastics from the water column and highlights the potential role anemones can play as environmental microplastic bioindicators.

Automated summary

Microplastic uptake by the common snakelocks anemone (Anemonia viridis) was found to involve both ingestion and external tissue adhesion, with limited preference between different particle shapes and sizes. Environmental sampling also revealed that fibres were the predominant type of microplastic taken up by A. viridis in the marine environment.