#34 - Quantifying microplastic pollution in marsh habitats

Abstract

Microplastics are classified as extremely small pieces of plastic in the environment resulting from the breakdown of plastic waste. They are approximately 5mm and usually hard to see with the naked eye. They can come in different shapes, sizes, color, and can be found everywhere, including marine habitats. Many organisms that encounter microplastics will consume them, which can cause biological defects. The purpose of this study was to quantify the microplastics within algal epiphytes and marsh sediment. Epiphytes from three sites were examined by collecting 2mm by 2mm samples from Spartina alterniflora stems; these were analyzed under a microscope to visually determine if microplastics were present. For sediment, we collected samples from two sites. These were examined using two different methods: 1) under a light microscope and 2) stained with Nile Red and then illuminated under a blue light and viewed with orange goggles, which caused the stained microplastics to fluoresce, making them easier to see. For the epiphyte samples, more plastics were found in the epiphytes than on bare stems, and the two larger species of algae (Ulva and Bostrychia) ensnared more pieces than the smaller cyanobacteria and green algal filaments. In the sediment, we saw that there was a drastic difference in the amount of microplastics visualized between stained and unstained samples. Large quantities of very small microplastics less that 1mm in length were apparent with the Nile Red stain but not observed in the unstained samples. These results add to our understanding of the patterns of plastic pollution between different types of epiphytes and between different sites. This could help us to assess marine animals’ exposure risk to microplastics. Future work will examine snails to determine the amount of microplastics in their guts.