Exploration of the impact of microplastics and co-pollutants on daphnia: comparison of lab strains and wild daphnids sensitivity to microplastics as a function of organism size and pre-exposure to a pollution gradient

Supian, Suffeiya (2022). Exploration of the impact of microplastics and co-pollutants on daphnia: comparison of lab strains and wild daphnids sensitivity to microplastics as a function of organism size and pre-exposure to a pollution gradient. University of Birmingham. Ph.D.

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Abstract

Plastic pollution has become a global issue as the impact of the small breakdown particles from plastic waste, and their interactions with wildlife in aquatic ecosystems, is of concern. Ingestion of plastic has been reported for a wide range of species, but little is known about the potential effects of such ingestion on individuals or populations. The aim of the thesis was to investigate the effects of exposure to MPs on Daphnia using a combination of laboratory and field approaches. Novel data for growth (eye-tail length, gut perimeter and body size length), as measures of effects from uptake of different microplastics sizes (i.e., 0.1 µm, 1.0 µm, and 10.0 µm), by two differently sized laboratory cultured Daphnia species (i.e., D. magna, D. pulex) are presented. The effect of pre-exposure to a pollution gradient (urban, suburban, rural) on the sensitivity of daphnids collected from the wild (including D. magna, D. pulex and D. obtusa) and subsequently cultured in the lab to a representative environmental pollutant, Sodium dodecyl sulphate (SDS), was explored. The EC50 values obtained are presented indicating that impacts from exposed parents are still evident 2 generations later, following culturing in clean water. Sensitivity of daphnids to SDS was further explored over 3 additional generations, by which time the EC50 values had converged, indicating that effects of the pollution gradient had been lost. Finally, the impact of adding microplastics on the SDS toxicity was explored, indicating that interaction between SDS and the microplastics increased the uptake and toxicity of SDS, indicated as reduced EC50 values and enhanced daphnid death compared to the SDS only exposure. The exception to this was with D. obtusa, where the small organism size may have resulted in avoidance of ingestion of the microplastics, resulting in lower apparent SDS toxicity, as a result of lower SDS bioavailability. The data presented in this thesis indicate that while microplastics alone are not very toxic, they can enhance the toxicity of co-pollutants, and that exposure of parents to pollutants can increase the sensitivity of offspring to subsequent pollutant challenges.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):