by AnnaKay Kruger
Michaela Kromrey clips herself into her bulky waders, fitting the straps over her shoulders and sealing herself into their protective rubber lining. We’ve dropped anchor near the shore of Jute Lake, and waves whip the side of the boat vigorously in the high wind. It’s a beautiful day, utterly devoid of cloud cover, but the wind is sharp and swift over the water, forcing us to don our sweatshirts and windbreakers to stave off the chill. Michaela and I, both UW-Madison undergraduates, wait in the boat while Ellen Albright, a student at Minnesota’s Macalester College, wades along the shoreline, dragging a tape-measure behind her.
Ellen paces out fifty meters and drops a small orange buoy into the water. Michaela explains that they’re looking for fallen logs, otherwise known as “coarse woody habitat”. Large logs with many branches are the ideal habitat for juvenile fish populations because they provide protection for fingerlings, or fish that are not yet fully developed but have fins and scales, and are capable of feeding themselves. (Editor’s note: CFL research underscored the importance of coarse woody habitat last year).
The prevalence of suitable habitat for fish populations in inland lakes is one of many variables being investigated in the Regional Lakes Survey out of Trout Lake Field Station. This ongoing study will happen every six years and primarily involves analyzing lake conditions for the purpose of mapping changes that occur over time.
According to Michaela, the best way to find logs is to “walk through the water until you trip over something.” Since I don’t have waders I do my best not to let the waves knock me out of the boat while Ellen and Michaela make their way through the shallows, armed with a clipboard and an ominous tool with adjustable jaws that Michaela refers to as a “pterodactyl”. Every so often they come upon a log and put the “pterodactyl” to work, using it to measure the log’s diameter and the number of branches jutting from it. Once they’ve catalogued every fallen log in the given fifty meters, they return to the boat and we make our way to the next site.
While Michaela steers us through the choppy waters, Ellen explains that one factor being considered in the frequency of shoreline “loggage” is human development. As people build cabins and docks along lakeshores, they can impact fish populations by disturbing or removing the fallen trees that provide habitat for developing fish. I consider my own cabin in Hayward, WI and recall one log in particular that has sat in the shallows near our dock for as long as I can remember – resembling an alligator with its eyes peeking above the water. I’d never bothered to consider that it might provide a place for fish to hatch and grow, protected from natural predators like the infamously sharp-toothed musky. I make an internal note to appreciate this log more when I next visit.
The data that Ellen and Michaela collect from Jute Lake, as well as from the twenty-seven other lakes that their team will be sampling throughout the summer, will indicate as to whether or not recent human development has had a significant impact on populations of freshwater fish.
After each fallen log has been measured and recorded, Michaela and Ellen spend the rest of the morning taking biological and chemical samples from the middle of the lake. They present me with a variety of tools and instruments that appear very complex, but don’t seem to give them any trouble as they filter chlorophyll from beneath the surface and collect zooplankton to examine back in the lab.
Ellen shows me a sample of zooplankton that she has caught using a large net shaped like an ice-cream cone called a “Wisconsin Net”. Attached to the bottom is a plastic canister full with tiny brown creatures resembling chia seeds. These, she tells me, are zooplankton, water-dwelling crustaceans that feed on phytoplankton and microscopic detritus near the surface. Populations of zooplankton are important because the tiny animals are a good measure of biodiversity and nutrient density in a lake.
At the other end of the boat, Michaela fills a graduated cylinder with water that she filters through a whirring pump. Every so often the flow of water stops and she attaches a new filter. Once the cylinder becomes full to a certain point, she dumps the filtered water back into the lake. “That’s the best part of the whole day,” she says, “dumping this bad boy out.” She lets me do the honors once or twice, demonstrating different throwing techniques.
This is the type of entertainment we provide ourselves while sampling, along with noisy choruses of “Bohemian Rhapsody” and “Uptown Funk”. Quality of song is of little consequence to us as we float idly in the middle of the empty lake, accompanied by nothing other than the whirs and beeps of machinery and the occasional call of a distant loon.
by AnnaKay Kruger