Interactions Between Plastic, Microbial Biofilms and Gammarus pulex: An Initial Investigation

Katey L Valentine,Alistair B A Boxall

doi:10.1007/s00128-021-03448-5

Katey L Valentine, Alistair B A Boxall

Open Access

https://doi.org/10.1007/s00128-021-03448-5

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Abstract

There is increasing evidence that microbial biofilms which form on the surface of marine plastics can increase plastics palatability, making it more attractive to organisms. The same information, however, does not exist for freshwater systems. This study observed the response of the freshwater amphipod Gammarus pulex when exposed to 3 cm-diameter discs of biofilm-covered plastic, both alone and when presented alongside its natural food. G. pulex did not fragment or consume the plastic materials, and the presence of colonised plastic in the immediate environment did not alter the amount of time organisms spent interacting with their natural food. This study provides baseline information for virgin and microbially colonised low-density polyethylene and polylactic acid film. Further studies, with other types of plastic possessing different physical properties and with different microbial biofilm compositions are now required to build further understanding of interactions between plastic, microbial biofilms, and freshwater shredding invertebrates.

Highlights

It is well-known that plastic pollution is ubiquitous throughout natural aquatic systems globally, and that a wide variety of organisms commonly interact with and ingest the plastic material they encounter in their environment (Davidson and Dudas 2016; Horton et al 2018)
A similar study was conducted by Hodgson et al (2018) who found that the common marine amphipod Orchestia gammarellus readily shredded three different types of 1 c m2 virgin and biofilm-colonised plastic film, with significantly more shredding seen in colonised plastic treatments
It was hypothesized that G. pulex will shred colonised Low-density polyethylene (LDPE) and poly lactic acid (PLA) films to feed on the attached microbial community and some shredding may be seen to a lesser extent on un-colonised virgin material

Summary

Introduction

It is well-known that plastic pollution is ubiquitous throughout natural aquatic systems globally, and that a wide variety of organisms commonly interact with and ingest the plastic material they encounter in their environment (Davidson and Dudas 2016; Horton et al 2018). Whilst one study found that the presence of a biofilm reduced the ingestion rate of microplastics by a species of hard coral (Allen et al 2017), many other studies have found that biofilms can increase attraction and palatability of plastic to marine organisms from many types of functional feeding groups (Savoca et al 2017; Vroom et al 2017; Hodgson et al 2018; Porter et al 2019; Pfaller et al 2020; Weideman et al 2020). It was hypothesized that the colonised plastic will be somewhat attractive to G. pulex, that they will show behavioural interest in it, and over time they will consume less of their natural food than when there is colonised plastic present

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