Field Samples: Spiny Water Fleas, Lake Mendota, and Green Water

Field Samples is a weekly Q&A asking researchers what they’ve been up to and what they’ve learned. Today, CFL grad student, Jake Walsh, talks Lake Mendota and the invasive spiny water flea.

Who are you, where are you from, and how did you get to where you are now?

Jake Walsh taking a sediment core on Lake Gogebic on the Wisconsin/Michigan border. Photo: Jake Walsh
Jake Walsh taking a sediment core on Wisconsin’s Gile Flowage. Photo: Carol Warden 

I’m Jake Walsh, a PhD student with Jake Vander Zanden. I love watching the Minnesota Timberwolves play basketball (or what they’re passing for basketball now-a-days), playing tennis, long walks through my cruddy neighborhood with my wife and dog, and the occasional video game binge.
I’m from Hastings, MN (smaller town on the Mississippi south of St. Paul) and I got my BS in Biology at Hamline University in St. Paul. I got addicted to getting paid to go out boating while doing research with Dr. Leif Hembre at Hamline University. We were doing research on spiny water fleas’ effect on Daphnia’s stress response (elevated heart rate) and some genetics work on trying to track SWF’s movement across the Great Lakes Region.
This got me interested in
1) figuring out how I can get paid to enjoy lakes
2) how I make a career out of obsessing over zooplankton (I have since expanded my interests pretty substantially), and
3) how I can help provide insights into the problems posed by invasive species which naturally lead me to Jake Vander Zanden’s lab here at the CFL.
It wasn’t until I came and visited the CFL that I found out that SWF had invaded the lake in 2009. I swear that I had nothing to do with it.
Also, coming out of a small liberal arts school, I was (and still am) fairly certain that I wanted to help undergraduates enjoy the same research and learning experiences I did. Science is a lot of fun as is, and when you add fieldwork on a lake into the equation, you can see why I’d be passionate about getting others involved. I also have a cheesy reason for getting here: I believe that the earth was created for us to enjoy and take care of, so I’m honored to be a part of helping people enjoy it more through experiencing it, learning about it, and learning how to be better stewards of it.
Pretend we just boarded an elevator and you only have a one-minute ride to tell me about your work. (in this case, otolith related stuff). Can you capture it a few sentences?
The spiny water flea could be making Lake Mendota greener through eating algae-grazing Daphnia, compounding a problem that stems from manure and fertilizer run-off into the lake.   It’s really difficult to understand when and where the spiny water flea will be abundant and have negative effects on ecosystems.
One of the countless spiny water fleas Walsh counts under the microscope. Photo" Jake Walsh
One of the countless spiny water fleas Walsh counts under the microscope. Photo” Jake Walsh

I put together a population model that should help us figure out where spiny water flea might become abundant like it did in Mendota, where it went from undetectable to record densities in a single year.   There’s even evidence that the spiny water flea was here before 2009, just at low densities. We’re calling this low to high abundance transition a “sleeper cell” dynamic and we can use the model to predict when and where this might happen – which is useful since its almost impossible to detect spinies at low densities.
In your study, what question did you ask and answer or do you hope to answer? What other questions might your work lead scientists to ask?
If you love clear water, then these little Daphnia pulicaria are your best friend!  Unfortunately, they're also lunch for spiny water fleas.
If you love clear water, then these little Daphnia pulicaria are your best friend! Unfortunately, they’re also lunch for spiny water fleas.

Will the spiny water flea have cascading effects on water clarity in Madison’s lakes? Can we observe the “unobservable” early-stage population dynamics of the spiny water flea? Can we use our observations to predict where spiny water flea might be problematic in the future?
Not to sound harsh, but why should someone NOT in the field of freshwater sciences care about your work? What’s a bigger picture implication, in other words?
For Madisonians, the spiny water flea represents a threat to how we enjoy our lakes. More algae means more beach closures, stinkier shorelines, sick dogs, and greener water.
A mid-October algae bloom shows up on the Lake Mendota shoreline. Photo: Sam Oliver
A mid-October algae bloom shows up on the Lake Mendota shoreline. Photo: Sam Oliver

For people who enjoy other vulnerable lakes here in North America, this work could help keep spiny water flea, and its negative effects, out of their lake. The population model helps us be smarter about how we spend our money on spiny water flea. If we can figure out where spiny water flea is most likely to become abundant and have problems, we can be more efficient with where we allocate our money. Had we known what we do now, we could have spent more time and money keeping the spiny water flea in Lake Michigan or out of Lake Mendota.
What do you love about your work? What do you love, well, not-so-much?
I love being out in the field and I love sitting behind a computer screen digging through data and analyses (days fly by when I’m working on the lake or on a dataset). I also really enjoy that I’m put in a place to teach and mentor both in an academic setting and out in the “real-world”.
Sadly, I don’t love the repetitive microscope work in the lab. I love coming across species I haven’t seen before or really big individuals of a species (particularly looking for massive Daphnia), but working through samples with the same species composition until my eyes are fried just gets tedious. (This is why I hire so many undergrads to help out!)
Tell me about one funny, memorable, exciting or awesome moment from this project (either in the field or in the lab).
This isn’t just one time, but the spiny water flea tends to stay abundant in the lake through even the coldest months of the fall. So almost every year I have 2-3 sampling days that are sub-freezing temperatures, windy, choppy, and SUPER splashy and wet. I love these days, it makes me feel like I’m on The Deadliest Catch (just a tamer version of the show and I don’t really have the personality of a hard-
core fisherman). This time of year also means gorgeous mornings after the first snowfall before the lake has frozen. If the lake is calm and there’s snow all over the shoreline, I definitely linger a bit out on the lake.
Where do you hope to go from here?
I think there are some awesome things that I’ll be working on related to the spiny water fleas impact on our lakes’ food webs and with trying to scale my work up to all of North America to help improve our decision-making regarding spiny water flea.
It’d also be nice to find a job at some point, I’ll be wrapping up in December.
 

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