Comparison of the polarization contrast of gelatinous zooplankton and a transparent single-use plastic bag—Implications for marine animals

Plastic pollution in the ocean is an increasingly detrimental issue for marine organisms. As a form of polarized light pollution, transparent plastic debris may be more visible and pose additional threats to organisms that can detect and interpret polarized light. Plastic can mimic the visual features of common marine prey items, such as transparent gelatinous zooplankton, which may lead to more significant plastic ingestion. We measured, in situ, the polarization and radiance contrast between a transparent plastic bag and gelatinous zooplankton with an underwater video polarimeter. The plastic bag had significantly higher polarization contrast than the gelatinous zooplankton, yet both shared similar radiance contrasts. This higher polarization contrast may contribute to the observed high ingestion rates of transparent plastic by marine organisms. Further study into the connection between polarization-sensitive organisms and plastic ingestion is recommended. •Transparent plastic is ingested in large quantities by marine organisms.•An underwater polarimeter measured in situ plastic and gelatinous zooplankton.•Transparent plastic had greater a polarization contrast than gelatinous zooplankton.•Polarization sensitivity may increase transparent plastic ingestion.