Why Are Nematodes Eating Plastic?

So far, we don't know. However, after finishing up with 51 out of the 90 total samples from this project, I am still shocked by the idea that these animals would even try to eat microplastics. For example, the picture from this week features a nematode with a microbead of ~5 micrometers in its gut. This individual's gut is approximately 15 micrometers wide, which means it has consumed a "food" item that is 1/3 of its size. While this may seem normal, consider that the smallest part of the human gut is around 2.5 cm, and though we take large bites of food, our digestive system breaks down that food starting with chewing in the mouth. Notably, there are other organisms that swallow large meals whole but they too have a laborious digestive process to make the food manageable.

Not much information is known, however, about why animals eat microplastics. There are three main hypotheses that offer suggestions: (1) the abundance of microplastics in the ocean means that organisms may encounter them more than food; (2) the small size of microplastics means that they are accidentally ingested during normal feeding activities; (3) organisms actively seek out the materials adhered to microplastics or that leach from microplastics. The project that I designed set out to test an aspect of the third hypothesis because many nematodes scrape or suck bacteria off of sediment particles.

As I said at the start of this week's blog, I just finished sample 51 of 90, which means I have about 2-3 more weeks before I will have a full data set on this project. However, because I still haven't resolved the fluorescence problem, I will need to spend some time testing out solutions, which means I will likely finish all this work by March (fingers crossed). I am very excited though, because based on some feedback I got when I presented the initial findings from this work, people are interested in hearing the final results and what the findings might mean for the future of microplastics and ecotoxicology research.

​Stay tuned!

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