Freshwater mussels are like the kidneys of the Great Lakes, filtering water from the basins in which they reside, according to biologist Daelyn Woolnough. And, adrift in these waterways are contaminants — from soap to pharmaceuticals.
Woolnough, a research assistant professor in Central Michigan University's biology department, is investigating how contaminants in the water and sediment impact the ecosystems and life cycles of freshwater mussels. She has partnered with Mandy Annis, a fish and wildlife biologist for the U.S. Fish and Wildlife Service, for this research, which is funded through a Great Lakes Restoration Initiative grant.
This groundbreaking research will help biologists draw a real-world, ecologically relevant understanding of how everyday contaminants impact the Great Lakes.
Your toothpaste could be hurting a species
"Freshwater mussels are the canary in the coal mine for our rivers," Woolnough said. "We're able to take their unique filtering capacity and test their tissues for these contaminants, which tells us about what's happening at the bottom of the rivers. They don't move around like fish do, therefore they tell us what's happening in that immediate location."
There are more than 40 species of freshwater mussels in the Great Lakes region and more than 70 percent of those species are endangered or threatened. And, because mussels can live upward of 75 years, a decline of a species concerns biologists like Woolnough. Freshwater mussels are partly in danger because of the zebra mussels that invaded the Great Lakes in the '80s. But, they also may be impacted by contaminants of emerging concern.
"Contaminants of emerging concern are in everything — shampoo, toothpaste, deodorant, lotions, pharmaceuticals and agricultural products," Annis said. "There's a diverse umbrella of chemicals that haven't been looked at in the environmental sense. We don't know what they do if they get into the water systems."
The contaminants and resulting impacts on wildlife and fish could affect ecosystems and watersheds across the Great Lakes, predominantly here in Michigan. A reduction in reproduction caused by contaminants — even as small as 10 percent — can be impactful, Annis said.
"Small, sublethal changes that reduce the ability to reproduce might be a game changer," Annis said. "After this research, we might be able to inform management decisions and conservation decisions, such as restocking animals."
Making mussels at CMU
This spring, Woolnough and Annis will return to the Maumee Basin to examine the effects of contaminants of emerging concern on mussels and fish. This predominantly agricultural area is where they began their research in 2016. With the help of CMU students, they will examine how contaminants in the water affect freshwater mussels — including their eggs, larval stages, sperm and growth. They'll later replicate the experiment in the Milwaukee River, a predominantly urban area.
In the summer, the research will continue with hundreds of largemouth bass housed in the vivarium in CMU's Biosciences Building. The fish are key to the freshwater mussels' life cycle.
"The native freshwater mussel has to release her larvae and it clamps on like a Pacman onto the gills of fish," Woolnough said. "It needs to stay on that fish for 20 to 40 days, depending on the fish species and then it drops off as a juvenile. That unique life cycle is what we are able to replicate here at CMU. We are the only people in the Great Lakes region who are doing it."
By making freshwater mussels on the fish in a laboratory controlled setting, Woolnough and her fellow researchers can apply doses of urban and agricultural contaminants to both the mussels and the fish throughout their life cycles. Most researchers often only examine the effect of a single contaminant in a short exposure, Annis said.
"The great thing about what CMU can bring to this is to do this life cycle experiment," Annis said. "You often see bits and pieces from what's really happening in the wild. By exposing these animals at the earliest stages, we are able to get that whole life cycle in the contaminant mix."
Woolnough said this collaboration is unique and will result in never-before-seen data.
"We are the leaders in the world of freshwater mussels here at Central," she said. "We will be the first people looking at these combinations."