Dr Frances Orton

Project Title: Microplastic contamination of small water bodies and common toads (Bufo bufo) in agricultural and urban environments in Scotland

This research project aimed to quantify microplastic (MP) contamination of small inland water bodies and common toads (Bufo bufo) in agricultural and urban environments. The study had three aims: 1) To investigate MP abundance and characteristics (polymer type, shape, colour, size) in pond surface waters, sediments and tadpoles in reference, urban and agricultural ponds; 2) To analyse MP bioaccumulation in tadpole organs (guts, liver, brain); 3) To investigate potential impacts of MPs on tadpole morphology.

My findings so far suggest that reference, urban and agricultural ponds are highly polluted with microplastics, however, levels did not differ significantly between site type. Bioaccumulation of MPs was observed, and levels were concentrated in the gut, suggesting dietary uptake by tadpoles. A negative correlation between tadpole MP levels (items/g tissue-1) and morphology suggest that MPs are negatively impacting the health of wild tadpoles. These results provide important insights into the extent of microplastic pollution in small inland waterbodies, which currently do not form part of routine water quality monitoring, as well as potential links between microplastic ingestion and health-endpoints in amphibians. Data collected in this project will allow the design of environmentally relevant microplastic exposures to investigate the effects of microplastics on amphibian development, function, behaviour, and survival in a controlled laboratory setting in the future.

Covid-19 restrictions in 2020 meant that I could not continue travelling to field sites to collect samples. Since data collection needed to coincide with toad breeding, we had no choice but to delay the project until the following year. Fortunately, I was able to make use of the water and sediment samples that I collected in 2020 for method development purposes. Since some of my field sites were in remote locations, with agricultural sites occupying private land, it meant that I would be in contact with study assistants and landowners during fieldwork. It was important that I took extra precautions before and throughout fieldwork in 2021 to avoid exposing myself and others to COVID-19.