Can microplastic pollution in freshwaters disrupt invertebrate mediated nutrient cycling?

We are seeking a highly motivated individual to carry out PhD research in the field of environmental pollution and toxicology, microplastics and freshwater ecology. This prestigious IAPETUS studentship, funded by the Natural Environment Research Council (NERC), will provide a platform to build an interdisciplinary research career in the field of integrated environmental and ecological sciences.

The successful candidate will be based at the University of Stirling, supervised by Dr Richard Quilliam and Dr Elma Lahive (at the Centre for Ecology and Hydrology), together with academic support from the Freshwater Science Research Group at Stirling (Dr Colin Bull, Prof Nigel Willby & Dr David Oliver) and the Emerging Contaminants research group at CEH.
Background

The most abundant form of litter in the environment is plastic. Microplastics (particle size < 5 mm) in particular, constitute a major threat to global aquatic ecosystems, although overwhelmingly, research has focused on marine rather than freshwater ecosystems. Microplastics from clothes, cosmetics and sanitary products are now common constituents of sewage systems and they frequently bypass the screening mechanisms designed to remove larger waste items from being discharged directly into rivers and exported to coastal waters. Recent research has focussed on the toxicity of microplastics to freshwater fish, with relatively little attention paid to the effects of microplastics on lower trophic levels. However, it is becoming increasingly clear that microplastics can be taken up by organisms at the bottom of food webs, with the potential for significant levels of bioaccumulation in higher trophic levels.

Freshwater invertebrates, e.g. insects, crustaceans and molluscs, play crucial roles in processes such as decomposition, the cycling of nutrients, and the translocation of organic materials. Freshwater benthic invertebrates are primarily involved in the successional degradation of organic matter, e.g. leaf litter, and thus have evolved a range of functional types, e.g. shredders, gatherers, grazers and filterers. However, despite their importance in nutrient cycling, our understanding of the effects of emerging pollutants, such as microplastics, on freshwater invertebrates is still limited. Recent research has suggested that at a broad scale, the ingestion of microplastics at environmentally relevant concentrations may not be immediately toxic to invertebrates in terms of fecundity and growth; although more sub-lethal and potentially long-term effects have been suggested. Yet, little is known about how microplastics in freshwater systems may impact the ecological functioning of macroinvertebrates or subsequent consequences for nutrient cycling.
Hence, the overarching aim of this studentship is to determine the effects of microplastic contaminants on, (1) specific functional types of freshwater invertebrates; and (2) the potential disruption of nutrient cycling (particularly carbon and nitrogen) in freshwater ecosystems.

Therefore, this studentship aims to deliver a step-change in our understanding of the multifaceted impacts of freshwater microplastic pollution
Key Research questions:
Specifically, the large gaps in our understanding of the indirect effects of microplastic contaminants in freshwater ecosystems will be directly addressed through this studentship by focusing on the following questions:

1. Does microplastic ingestion by different functional groups of freshwater invertebrates affect subsequent successional organic matter processing?
2. Is nutrient cycling in freshwater (e.g. carbon and nitrogen) reduced due to ingestion of microplastics by invertebrates?
3. What effect does microplastic ingestion have on feeding behaviours of freshwater invertebrates?
4. Does microplastic accumulation in the invertebrate gut alter the composition of faecal pellets?

More details at: http://www.iapetus.ac.uk/wp-content/uploads/2018/10/IAP2-18-71_Stirling_Quilliam.pdf