Are we underestimating microplastic abundance in the marine environment? A comparison of microplastic capture with nets of different mesh-size

Penelope K. Lindeque*, Matthew Cole, Rachel L. Coppock, Ceri N. Lewis, Rachael Z. Miller, Andrew J.R. Watts, Alice Wilson-McNeal, Stephanie L. Wright, Tamara S. Galloway

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

319 Citations (Scopus)

Abstract

Microplastic debris is ubiquitous and yet sampling, classifying and enumerating this prolific pollutant in marine waters has proven challenging. Typically, waterborne microplastic sampling is undertaken using nets with a 333 μm mesh, which cannot account for smaller debris. In this study, we provide an estimate of the extent to which microplastic concentrations are underestimated with traditional sampling. Our efforts focus on coastal waters, where microplastics are predicted to have the greatest influence on marine life, on both sides of the North Atlantic Ocean. Microplastic debris was collected via surface trawls using 100, 333 and 500 μm nets. Our findings show that sampling using nets with a 100 μm mesh resulted in the collection of 2.5-fold and 10-fold greater microplastic concentrations compared with using 333 and 500 μm meshes respectively (P < 0.01). Based on the relationship between microplastic concentrations identified and extrapolation of our data using a power law, we estimate that microplastic concentrations could exceed 3700 microplastics m−3 if a net with a 1 μm mesh size is used. We further identified that use of finer nets resulted in the collection of significantly thinner and shorter microplastic fibres (P < 0.05). These results elucidate that estimates of marine microplastic concentrations could currently be underestimated.

Original languageEnglish
Article number114721
JournalEnvironmental Pollution
Volume265
DOIs
Publication statusPublished - Oct 2020

Keywords

  • Microplastics
  • Net
  • Ocean
  • Plastic
  • Pollution
  • Sampling

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