A QUANTITATIVE ANALYSIS OF MICROPLASTIC INGESTION IN NORTHERN NEW YORK BIVALVES

Plastics play a vital role in modern society, but their widespread use has led to the proliferation of microplastics in the environment. This study investigates the presence of microplastics in freshwater bivalves, specifically examining their ingestion and retention. Microplastics are commonly suspended in the water column, making filter-feeding organisms like freshwater clams susceptible to their intake. We hypothesize that freshwater clams ingest microplastics and expel larger particles through their digestive tract, while smaller particles are absorbed into their soft tissues.

Live freshwater clams were collected from lakes in northern New York and the Adirondack Park, and their fecal matter was analyzed. Samples were dissolved with FeSO₄ and 30% H₂O₂, and the remaining solution was stained with Nile Red to fluoresce plastics under blue light. Organic material was stained with Evans Blue for contrast. The solution was then filtered through 0.4-micrometer filter paper, which was examined under a Leica EZ4HD stereo microscope with a Nightsea fluorescence adapter. Using an in-house built automated microscope stage, images of the filter papers were captured, stitched together with Image Composite Editor, and fluorescent microplastics were quantified.

All samples contained microplastic contamination, categorized into three types: fibers, fragments (irregular particles >0.1 mm), and specks (rounded particles <0.1 mm). On average, 169 microplastics were detected per filter, comprising 128 specks, 36 fragments, and 6 fibers. When standardized for body weight, the counts averaged 35 specks, 11 fragments, and 2 fibers per filter. Comparisons between fecal matter and soft body tissues revealed an average of 24 specks and 10 fragments in fecal matter, versus 43 specks and 10.8 fragments in the soft tissues; fibers were recorded on average twice per filter.

These results suggest that smaller particles are more likely to accumulate in soft body tissues than in fecal matter. However, the interpretation is limited by the small sample size (30 counted filters) and ongoing data collection aims to enhance the statistical robustness of our results.