Succession in Microplastic

Plastic material is a ubiquitous component of nearly every ecological niche on the planet. Once broken down to pieces less than 5mm in diameter, these plastics are considered “microplastics”. Microplastics act as a substrate for bacterial and viral organisms which can lead to transmission of potentially dangerous pathogens. One organism that may negatively impact the health of animals is cyanobacteria through the production of cyanotoxins that can be harmful to many aquatic animals that might attempt to ingest microplastic. Research into the colonization and succession of cyanobacteria on microplastic has intensified over the years, with various strategies being employed to measure the volume of organic material found on microplastic. To investigate these succession dynamics in the Potomac River, three different types of plastic were sampled across 8 weeks. Samples were preserved for visualization with fluorescence microscopy, so that total cell counts and counts of cyanobacteria can be collected. While cell counts are still ongoing, a protocol was developed to visualize cyanobacteria. Each plastic piece was stained with DAPI and visualized using a light microscope, with two UV filters to capture various wavelengths. This research will be valuable in determining how cyanobacteria colonize different types of microplastics in a eutrophic aquatic environment.

Hello, my name is Victor Cregger. Today I will be going over my presentation on succession in microplastics, or simp for short, if you want to call it that. I want to thank everyone for joining me today, let’s not waste time and get right onto the presentation. I will be going over what microplastics are, the field work done, and the data extrapolated from that field work, and then future research and final remarks. On the left you’ll see I have cut up milk jugs and plastic bags, they were used during the experiment and will be covered in more detail shortly. First, what are microplastics? Microplastics are any plastic particulate less than 5mm in diameter. They are found in every corner of the world from the deepest part of the ocean to the most remote deserts on the planet. Microplastics are dangerous as they can act as a substrate for dangerous pathogens. Current research is being done to see if the pathogens can cross into the animal barrier and if we can contract diseases from that. Microplastics then serve as a potential health hazard. One phylum of bacteria that I am studying is cyanobacteria, because they produce cyanotoxin that is very dangerous to any organism that tries to ingest it. The goal of this experiment was to see if, when, and how these cyanobacteria populate microplastics over the course of 8 weeks. For the field work and data, I would like to first give thanks to Tom Hutchinson, as he provided much of the material used for the experiment as well as assisted in creating the experimental design. Without him this would have been very difficult so thank you Tom for the help. What we did is tie a rope to two anchored buoys and tied knots 2-3 feet apart from each other, the line itself was about 25 feet in length and this was taken right outside the Potomac science center dock. What I did was tie a mesh bag to each individual knot, each mesh bag contained different types of microplastic such as milk jugs, yogurt containers, and plastic bags. I had two sets of three different microplastic in case I ran out in one set, I would still have more material. Then I put the plastic into whirl Pak bags and placed them into 4% formalin tubes to be z fixed. This freezes cells in place so that I can look at the pieces under a microscope later on. Any sort of microplastic I had remaining was frozen in the -80 freezer for future study. Now that every sample is ready for microscopy, I can now conduct cell counts in the fall. I also collected water characteristics using a YSI and filter machine. The YSI tells me temperature, salinity, and just about every water characteristic that I need. This is to see if there is any correlation between cyano growth and the property of the water at that time. The filter again was to see what exactly was going on, so I have a pretty good snapshot of the river every Monday that I went to go sampling over 8 weeks. This is what I got from the YSI. The bottom table shows the water properties, there is a big difference in water property over the course of 8 weeks, and the top shows the identifier on what my plastic looks like. You’ll see I have polyethylene and polypropylene bags, and this again is to test to see if there is preferential treatment of cyano growth on plastic type. Unfortunately, I could not conduct cell counts at this time, the microscope I have does not have the filter I need to see cyanobacteria. They auto fluoresce at a specific wavelength, and I can not cover this wavelength with the filter I have. However, I do have a filtered microscope now that can hopefully see cyanobacteria, which will allow me to finish the experiment in the fall. This will help any future research, especially with the frozen material I have, this will allow us to see bacterial succession and other topics that may be picked up at a later date. Again, research into cyano growth in a eutrophic aquatic environment is always helpful. Thank you so much for watching my video.