Potential pathways, trophic transfer and bioindicators of microplastics in freshwater systems

Abstract

Microplastic (MP) polymers, 0.1 µm - 5 mm in size, are ubiquitous within aquatic environments. Due to their small size there is a risk that they may infiltrate and transfer within aquatic food webs. Though a limited number of laboratory studies can facilitate our understanding of species susceptibility, the lack of field data from freshwater environments means that the spatiotemporal patterns governing MP exposure, as well as their associated dynamics within the freshwater environment are not well understood. There is a need therefore to assess MP exposure in Irish waters to gain an understanding of the current level of interaction between MPs and freshwater biota. Researchers at Galway-Mayo Institute of Technology, in collaboration with University College Dublin and Wageningen University, the Netherlands, have set out to address these knowledge gaps as part of a three-year EPA funded research project ‘Sources, pathways and environmental fate of freshwater microplastics’. Part of this research aims to 1) characterise and quantify polymer types present in an Irish freshwater system, and determine whether they vary longitudinally between habitats and regions; 2) identify the pathways of MP exposure through a comprehensive analysis of a freshwater food web; 3) evaluate the ecological implications of MP uptake under realistic exposure conditions (as far as possible), through laboratory trials and observation; and 4) explore the use of using bioindicator species, such as primary consumers and top level predators, for monitoring purposes, with a view to informing the EU Water Framework Directive (2000/60/EC) and Marine Strategy Framework Directive (2008/56/EC) on best practice guidelines for monitoring MPs in Irish waters.