Validation of a method to quantify microfibres present in aquatic surface microlayers

Abstract

Many of the methods for microplastics quantification in the environment are criticised creating problems with data validity. Quantification of microplastics in the surface microlayer of aquatic environments using glass plate dipping holds promise as a simple field method, but its efficiency has yet to be validated. We tested a standard glass plate dipping method to assess recovery of four common polymer microfibres and two common natural fibres, under three different salinities (freshwater, brackish water, saltwater). Overall recovery rates were low (26.8 ± 1.54%) but higher recoveries were observed under saltwater treatments (36.5 ± 3.01%) than brackish water (24.5 ± 1.92%) or freshwater (19.3 ± 1.92%). The fibre types showed different recovery rates, with acrylic yielding significantly higher recovery rates (37.0 ± 2.71%) than other fibres across treatments. No clear relationship between the density of the fibres and the recovery efficiency was seen. We suggest that, where this method is used for monitoring microplastics, the results will typically underestimate the total amount present, but that recovery is sufficiently consistent to allow comparison of differences between sampling locations. When comparing data across river-estuarine or similar transects salinity should be monitored to account for salinity-induced differences in sampling recovery.

Adopting a reductionist approach to advance acoustic deterrents in fish conservation

“…Globally, many populations of fish have suffered dramatic declines over recent decades [e.g., −36% in marine ecosystems between 1970 and 2012 (Reid et al, 2018) and −83% for fresh waters between 1970 and 2014 (Darwall et al, 2018)]. Potential explanations include climate change (Poff et al, 2012;Plagányi, 2019) and associated ocean acidification (Munday et al, 2014); overfishing (Le Pape et al, 2017); novel pollution such as microplastics (Birkenhead et al, 2020), noise (Currie et al, 2021), and artificial light at night (Vowles and Kemp, 2021); invasive species (Daniels and Kemp, 2022); and the cumulative effects of multiple stressors (Reid et al, 2018;Bayramoglu et al, 2019). Limiting the impacts of such factors in both the marine and freshwater environment forms a central tenet of a plethora of environmental legislation.…”