Microplastic pollution in aquatic environments may facilitate misfeeding by fish

Area of Science:

• Environmental Science
• Aquatic Ecology
• Toxicology

Background:

• Microplastic (MP) ingestion is widespread in aquatic animals, but the reasons for fish misfeeding are unclear.
• Biofilm formation on MPs in aquatic environments may influence their detectability by fish.

Purpose of the Study:

• To test the hypothesis that biofilm on microplastic surfaces facilitates misfeeding in fish.
• To investigate the relationship between biofilm development on microplastics and fish feeding behavior.

Main Methods:

• Spherical polystyrene (PS) microplastics were aged in freshwater for up to 22 weeks to allow biofilm growth.
• Absorbance measurements were used to quantify biofilm formation over time.
• Goldfish feeding experiments were conducted with aged MPs and food pellets to assess misfeeding and capture behavior.

Main Results:

• Biofilm formation on MPs increased exponentially within three weeks and plateaued around five weeks.
• Fish "capture" of MPs increased significantly with MP aging, although MPs were not swallowed.
• The duration of MP capture also increased significantly with MP aging.

Conclusions:

• Biofilm accumulation on microplastics alters their characteristics, potentially making them appear as prey to fish.
• The aging of microplastics and subsequent biofilm development may be a key factor driving misfeeding in fish.
• These findings suggest a mechanism for how microplastics are misidentified as food by aquatic organisms.