Plastic leachates increase feeding retention times in sea anemones

Plastic is accumulating in marine ecosystems, where it is consumed by marine animals. In the present study, we leached plastic pre-production pellets and plastic knives in high-performance liquid chromatography (HPLC) water for 24 hours. We offered sea anemones (Exaiptasia pallida) a glass fiber filter containing 7.5 μL of two types of plastic leachates, plastic pre-production pellet leachate or plastic knife leachate, and compared feeding behavior with control glass fiber filters (7.5 μl of HPLC-grade water only). We observed that anemones fed filters with plastic leachates had feeding retention times (the time from ingestion to egestion) 3.5 to over 4-fold longer than control anemones. Control anemones consumed filters for an average time of 16 minutes while treatment anemones consumed filters for an average time of up to 72 minutes for the high concentration tested of plastic pellet leachate. The rate at which filters were consumed or not did not differ between control and treatment anemones. Subsequent feeding of the egested filters to new anemones resulted in decreased feeding retention times. We characterized the polymer of the knives and pre-production pellets used in the leachate with Fourier transform infrared spectroscopy and determined that both were polystyrene. We used liquid chromatography-mass spectrometry to determine leachate chemistry, but the concentrations of chemical compounds fell below detection levels despite concentrating the leachate 25-fold. These results provide evidence that molecules leaching from polystyrene pre-production pellets and knives act as feeding stimulants for sea anemones.