Detection of ultrafine plastics ingested by seabirds using tissue digestion

Area of Science:

• Marine Biology
• Environmental Science
• Ecotoxicology

Background:

• Plastic debris poses a significant threat to marine ecosystems and wildlife.
• Existing methods for quantifying ingested plastic in seabirds often overlook ultrafine particles (1–1000 μm).
• This knowledge gap may lead to an underestimation of plastic pollution impacts on marine species.

Purpose of the Study:

• To develop and validate a standardized method for quantifying ingested ultrafine plastic particles in seabirds.
• To assess the prevalence of ultrafine plastic ingestion in Flesh-footed Shearwaters (Ardenna carneipes).
• To compare the efficacy of chemical (potassium hydroxide) and biological (corolase) digestion methods for plastic extraction.

Main Methods:

• Developed a digestion protocol using chemical and biological treatments to extract ultrafine plastics from seabird gizzards.
• Compared the cost-effectiveness and efficiency of potassium hydroxide versus corolase for plastic digestion.
• Quantified ultrafine plastic items in gizzards of Flesh-footed Shearwaters from Lord Howe Island, Australia.

Main Results:

• Potassium hydroxide demonstrated superior cost and efficiency compared to corolase for digesting gizzard contents.
• Ultrafine plastics were detected in 7.0% of analyzed Flesh-footed Shearwater gizzards.
• These particles constituted 3.6% of the total plastic items recovered, highlighting their underrepresentation in previous studies.

Conclusions:

• The developed method enables the first quantification of ultrafine plastic ingestion in seabirds.
• Current assessments of plastic loads and their impacts on seabirds are likely underestimated due to the exclusion of ultrafine particles.
• Standardized methods are crucial for accurately evaluating the ecological risks of microplastic and ultrafine plastic pollution.