This is first post in a series exploring a CFL project that hopes to shed new light on a familiar invasive species.
by Madelyn Anderson – “D” shaped shells, light and dark stripes, sticky byssal threads. These are all characteristics of zebra mussels, an invasive aquatic species. Only around an inch long, these little creatures can have big impacts. Wisconsin waters are proof. But how did they get here?
Once introduced, zebra mussels use byssal threads (protein packed ropes) to attach to hard surfaces. Logs, pipes, rocks, boats and more provide habitat for this species, which soon begins filtering water in search of food. Zebra mussels feast on plankton, which leaves less food floating in the water column for the rest of the food web. And they filter a lot of water – a single adult around 20 mm long can filter nearly 6 liters of water a day, which pulls nutrients down to the lake bottom where the Zebra mussels live and can clear the water of other organic matter that is important to the life of a lake. This filtering takes a toll, often resulting in a clear view to the bottom, or “benthic,” level of the lake.
Once introduced, zebra mussels use byssal threads (protein packed ropes) to attach to hard surfaces. Logs, pipes, rocks, boats and more provide habitat for this species, which soon begins filtering water in search of food. Zebra mussels feast on plankton, which leaves less food floating in the water column for the rest of the food web. And they filter a lot of water – a single adult around 20 mm long can filter nearly 6 liters of water a day, which pulls nutrients down to the lake bottom where the Zebra mussels live and can clear the water of other organic matter that is important to the life of a lake. This filtering takes a toll, often resulting in a clear view to the bottom, or “benthic,” level of the lake.
While improved water clarity may sound positive, this process (known as benthification) alters the typical flow of energy in a lake’s food web. With deeper light penetration and more nutrients down in lake sediments, benthic algae and aquatic animal communities shift.
According to postdoctoral researcher Tyler Butts, zebra mussels were first detected in Lake Mendota in 2015 and they reached peak densities in 2016, nearing 30,000 individuals per square meter. The discovery was made by students in an undergraduate limnology class here at the UW-Madison, and it spurred scientists at the CFL like Mike Spear and Jake Vander Zanden to take a closer look at how Lake Mendota would respond.
Almost a decade later, the species presence in Lake Mendota has declined dramatically, but there are still many questions. And, here at Hasler Lab, Butts is asking them.
“Through long-term data and small-scale experiments we are working to yield a deeper understanding of how invasive species affect nutrients, water quality, and the lower food web – including microbes,” said Butts.
While these topics have been researched, mainly in the Great Lakes, studies on the connections between zebra mussels and cyanobacteria blooms mostly occurred in oligotrophic (low nutrient) or mesotrophic (moderate nutrient) waters. Lake Mendota is classified as eutrophic due to its high nutrient and biological productivity levels, making this research unique. According to research technician, Joe Noeske, things can behave “shockingly different” in high nutrient systems.
This project, spearheaded by Jake Vander Zanden and Trina McMahon, will study these systems in multiple contexts.
“We’re exploring two Lake Mendota invasions, the spiny water flea in 2009 and the zebra mussel in 2015, to see how they operate in concert with other drivers of global change like climate change introducing higher temperatures and more precipitation in lakes,” Butts said.
The researchers aim to build a better understanding of ecosystem relationships and inform management as invasions become more common.
“Another novel piece of this research is that we’re tying in the microbial food web,” Butts said. “Thanks to Lake Mendota’s twenty-plus year record of microbial community dynamics shepherded by the McMahon Lab, which we’re expanding this summer with graduate student Jackie Lemaire”.
Through this three part blog series, we’ll take you along to unthread the mussel mystery in Madison’s waters. From sampling Mendota’s shores to getting face to face with mussels in the lab, it’s sure to be an adventure.
“If you want to beat your enemy you have to know them first,” said undergraduate technician Joey Munoz. “Realistically, zebra mussels are probably never going away. But we can learn how to cope with them, how to understand them.”