A mathematical-based modeling study concluded there are more microplastics in Lake Erie than previously thought.
Researchers at the Rochester Institute of Technology used a three-dimensional mass estimate to show where microplastics are accumulating on the bottom. The previous study was based on concentrations of microplastics taken from surface samples.
An estimated 381 metric tons
Juliette Daily, a mathematical modeling PhD student and study author, estimated the total of plastic in Erie at 381 metric tons. She looked at nine different types of polymers and found that three accumulated on the surface while the remaining six sank to bottom. The study also found the greatest accumulations was in the eastern end of Lake Erie.
“We specifically modeled microplastics, which our model showed tended to congregate near shore, specifically in the more eastern side of the lake because they can be pushed there by the current,” Daily said. “I can’t really say for certain what the fate of larger pieces is, but I would suspect that if it is made from a negatively buoyant polymer, it would sink pretty quickly.”
Other Great Lakes
Daily’s study dealt exclusively with Lake Erie, but she did say there have been high surface plastic concentrations in the other Great Lakes, and likely in the sediment.
Asked if the concentrations were great enough that there would be an impact on fish, Daily answered, “There has been plastic found in fish from the Great Lakes, so we know exposure is happening, but what that the effects of that exposure could be is difficult to say.”
Human health considerations
OFAH Fisheries Biologist Adam Weir added, “Research is ongoing and the ecological and human health implications with microplastics are not well understood at this point. That said, studies have shown that the effects can be variable amongst organisms, but prey foods that larger biota rely on, like zooplankton, are particularly susceptible to the impacts of microplastics including negative physical and/or toxicological effects.” He explained that could cause impacts through the food web.
OFAH has been advocating addressing the microplastic issue for many years. “The OFAH would like to see more research done on microplastics and freshwater ecosystems to improve the understanding of how the negative effects are potentially transported through the food web, impacts associated to valuable sport fish, and further investigations into fish consumption and human health considerations.