Fish Fry Day: Daphnia Update & Perch (H2O) Purifiers?

Lake Monona is crystal clear, while Mendota stays murky and, on Wednesday, we asked you to help us monitor Lake Mendota as we wait to see if the native zooplankton, daphnia pulicaria, can rally and clear up the situation after being decimated by a tiny invasive predator called the spiny water flea. Read that previous post here. And see coverage of the issue courtesy of NBC 15’s nightly news!


Lake Mendota, May 21st, from the Hasler Lab pier. Secchi depth .75 meters. Photo: Adam Hinterthuer

Yesterday, CFL graduate student, Jake Walsh sent in these updates on the current conditions on both Mendota and Monona, as well as his thoughts about how we might go about tackling the spiny water flea problem. Fortunately for us, it involves our very favorite fish fry species! 

Continue reading

Help Us Monitor Mendota: Is Clear-Water Phase a Memory?

 by Jake Walsh

Spiny water flea under the microscope. Photo: Jake Walsh

Spiny water flea under the microscope. Photo: Jake Walsh

We’ve written before about how an invasive zooplankton called Bythotrephes longimanus, or “the spiny water flea” (SWF) is eating our native algae-grazing friends, the tiny crustaceans called Daphnia.

This is important because, as phosphorus pollution leads to algae blooms and lower water quality, we are also losing the critters that keep that algae at bay and give us our annual spring “clear-water” phase. 

Since SWF was first detected by a group of UW-Madison undergrads in Lake Mendota in 2009, we’ve lost over 80% of our Daphnia pulicaria (the big Daphnia that eat a ton of algae) and over 2 feet of water clarity in Lake Mendota.

Image: Jake Walsh

Daphnia abundance and Secchi depth before and after spiny water flea detected in Lake Mendota. Image: Jake Walsh

However, 2014 may have been the worst yet. The intensity of SWF predation on Daphnia in the fall of 2014 was twice as high as any other year we’ve observed. It was so bad that, on September 2nd of 2014, the voracious spiny water flea caused the collapse of Lake Mendota’s Daphnia community and they still haven’t recovered as of today.  Where I used to pull in hundreds of thousands of Daphnia pulicaria in a single sample, I’m now often only finding a single tiny individual in my net.

If you love clear water, then these little Daphnia pulicaria are your best friend!  Are we losing them in Lake Mendota?

If you love clear water, then these little Daphnia pulicaria are your best friend! Are we losing them in Lake Mendota?

While we’ve seen “tough times” for Daphnia before, we’ve never witnessed anything like this in the four decades the Center for Limnology and Long-Term Ecological Research (LTER) scientists have monitored Lake Mendota.

As a result, water clarity in Lake Mendota has been downright dismal this year while Lake Monona, which doesn’t have a large SWF population, is looking nice and clear. In fact, last year’s average water clarity was BETTER in Monona than Mendota for the first time since we’ve been keeping records. Continue reading

Fish Fry Day Redux: Sneaking and Spawning

We’re swamped here at the CFL, so apologies for the slow posting. Today, though, we’ve dug up a classic post on one of the aquatic rites of spring – the crazy sex life of bluegill.

These guys can't wait for ice-off so they can start sneakin' Photo: Fargo-Moorhead Dive News

These guys can’t wait for ice-off so they can start sneakin’ Photo: Fargo-Moorhead Dive News

I know, I know, bluegill aren’t exactly a rare species. In fact, they’re often the first fish kids learn to catch and, as any avid fisherman can tell you, they sure are tasty! But did you know about their secretive (and sorta sordid) sex life?

Ted Bier gives tips for Fish IDs at CLA's "Yahara 101" event. Photo: A. Hinterthuer

Ted Bier gives tips for Fish IDs at CLA’s “Yahara 101″ event. Photo: A. Hinterthuer

A couple of summers ago, Ted Bier, a senior research scientist with the Long-Term Ecological Research program here at the CFL gave a talk at the Clean Lakes Alliance‘s monthly Madison-lake education series, “Yahara 101.” And that’s where I learned that, at any given time, there are THREE different kinds of male bluegill in our lakes.

And that all has to do with how they pass on their genes – or at least try to.

For a much more comprehensive read on this, may I suggest “The Secret Life of Bluegills,” by Dr. Dave Willis from South Dakota State University. But, here’s the lowdown –  Continue reading

Video: UW-Madison Undergrad Shares Fish Tales from Thailand

Vera Swanson is a UW-Madison undergraduate in the College of Agricultural and Life Sciences (CALS). She spent her spring semester in Thailand working with CFL grad student, Aaron Koning. Here’s her amazing video recap of life doing international fieldwork!

Vera’s Time in Thailand from Aaron Koning on Vimeo.

Elephants are just one of many considerations to keep in mind when working on Thai rivers. Photo: QSimple via Flickr

Elephants are just one of many considerations to keep in mind when working on Thai rivers. Photo: QSimple via Flickr

Fish Fry Day: Getting “Biggest Bang for Your Buck” in Conservation

by Kelly April Tyrrell

A few years ago, researchers at the University of Wisconsin-Madison Center for Limnology created the first map of all the road crossings and dams blocking the tributary rivers that feed the five Great Lakes. These tributaries serve as migratory highways, providing fish like walleye and lake sturgeon access to headwater breeding grounds.

Even the lowly road culvert, can have big impacts on fish passage. Photo: S. Januchowski-Hartley

Even the lowly road culvert, can have big impacts on fish passage. Photo: S. Januchowski-Hartley

“It painted a pretty horrifying picture of what it’s like to be a fish in the Great Lakes Basin,” says Peter McIntyre, an assistant professor in the center, who led that study. “Seven out of eight river miles are completely inaccessible to the fish.”

Photo: Tom Neeson

Tom Neeson

A new study from the same multidisciplinary team, published April 27 in the Proceedings of the National Academy of Sciences, describes a powerful new model to help decision makers maximize the cost-effectiveness of barrier removal projects that also restore migratory fish habitat. Recent years have seen growing efforts to chip away at the 7,000 dams and 230,000 road crossings that disrupt the basin’s 661 tributaries.

Notes Tom Neeson, a postdoctoral researcher at CFL and lead author of the study, “If you’re going to spend money on barrier removal projects, isn’t it critical to know which projects are going to give you the biggest bang for your buck?” Keep Reading –>

Water@UWMadison a Wisconsin Idea Symposium – May 11th

Water is a common theme in scholarship across the UW-Madison campus, where more than 100 faculty and staff are involved in water-related research. But what, exactly, everyone is up to and how might they inform one another’s work?

Madison from Lake Monona


At Water@UW-Madison – A Wisconsin Idea Symposium, we will try to gather this water-rich research into a common pool, where 50 UW-Madison faculty spanning biological, physical, social sciences, arts, and humanities will briefly highlight their scholarly work. . The event is free and open to the public.

Monday, May 11, 2015
8:15 a.m. to 12:45 p.m.
Gordon Commons, UW-Madison
770 W Dayton St, Madison, WI 53715

Talks will cover a remarkable diversity of topics – the global carbon cycle, agricultural runoff, groundwater protection, aquatic insects, water as a human right, and much, much more.  A detailed agenda for the symposium can be found here. Refreshments will be served. The symposium will close with a panel discussion.

A key goal of the symposium is to improve communication among water scholars from all corners of the UW-Madison campus, and to build stronger connections with non-governmental organizations, elected officials, agency staff, consultants, and concerned citizens.

We hope to see you there! To learn more, click here.



CFL’s Crowd-Sourced Secchi Slideshow: Happy Earth Day!

We asked, and you answered! It’s Earth Day and we’re continuing our shout out to the inventor of limnology’s most ubiquitous instrument. (Full captions to photos are posted below)

Click on images above for slideshow. Fuller captions describing images are provided below:


1 – Pietro Angelo Secchi, dropped the first disk off the side of the Papal Yacht in 1865. Image courtesy: University of Toronto

2 – 150 years later, a disk descends into Lake Mendota’s green, over-productive waters. Photo: Adam Hinterthuer, University of Wisconsin-Madison

3 – Secchi off a sailboat. Image: National Library of Australia

4 – Claude Reeves, Auburn University’s Area Extension Specialist demonstrates a Secchi at the Wiregrass Research and Extension Station in Southeast Alabama. Photo: Rusty Wright, Auburn University (CFL Phd, 1993).

5 – Secchi on a stick is recommended for pond management where a clarity target of 18-24 inches is ideal to achieve a good ratio of fish versus algae. Photo: Rusty Wright, Auburn University

6 – Kids help Trout Lake Station’s Noah Lottig read the winter Secchi depth on Trout Lake. Photo: Adam Hinterthuer

7 – Citizen scientist Tim Plude monitors the Secchi depth of Lake Tomahawk in Wisconsin’s Oneida County. Photo: Laura Herman, Wisconsin DNR

8 – Volunteers participating in the (NY) Citizens Statewide Lake Assessment Program will collect over 1000 Secchi readings this year. Photo: Nancy J. Mueller, Manager NYS Federation of Lake Associations, Inc.

9 – NYCSLA volunteers take Secchi depth readings in Java Lake in Western New York. Photo: Nancy J. Mueller.

10 – Unexpected “soupy” water awaited researchers this winter on Lake Monona. Photo: Ted Bier

11 – Stephen Eiser holds Secchi disks in both basins of Long Lake at the University of Notre Dame Environmental Research Center in Northern Michigan. An impermeable curtain prevents water flow between the basins. The East basin receives the majority of dissolved organic carbon load and has become darker in color the past two years. Photo: Jake Zwart

  1. – Measuring water clarity in Long Lake, Fond du Lac County. Photo: Eddie Heath, Onterra, LLC

13 – Large algae blooms are more common towards the end of the summer when water temperatures are warm. They’re also more prevalent in lakes with high inputs of nutrients from farm fertilizer and urban runoff. Photo: Eddie Heath, Onterra, LLC

14 – Off the coast of Belize, Carrie Cow Bay research station managers take Secchi readings near the Carribean coral reef. They’ve documented a decline in water clarity. Photo: Smithsonian National Museum of Natural History

15 – Kate Hamre, a graduate student in Cayelan Carey’s lab at Virginia Tech takes a sample at Falling Creek Reservoir (a GLEON site) in Virginia. Photo: Alex Gerling.

16 – On the shores of Lake Mendota, Center for Limnology post-doc, Hilary Dugan, holds a cookie made in honor of the Secchi disk’s 150th anniversary. Photo: Hilary Dugan

17 – On the slightly more frozen shores of Trout Lake, Center for Limnology post-doc, Jessica Corman, holds a similar cookie in tribute of the big day. Photo: Jessica Corman

  1. – A wolf holds a Secchi “disk,” in honor of the tool’s 150th birthday. Photo: Stephanie Schmidt, Alaska Department of Fish and Game.


16. Lake Mendota, Madison, WI. Photo: Hilary Dugan.

16. Lake Mendota, Madison, WI. Photo: Hilary Dugan.

The Secchi Disk Celebrates 150 Years of Clarity

Pietro Angelo Secchi

Pietro Angelo Secchi Image from: United States Navy

A time-honored instrument of limnology turns 150 today. The Secchi disk, the black and white plate at the bottom of many a limnologist’s rope, was invented by Pietro Angelo Secchi, an Italian Jesuit priest in 1865. In fact, the story goes, he first deployed the instrument into the waters of the Mediterranean, dropping the disk in over the side of the papal yacht. But, before Secchi made his indelible mark on our field of study, he made waves in another field.

Secchi was a prolific scientist, publishing more than 700 papers in his lifetime (1818-1878).  But the bulk of those papers were in his true discipline – astrophysics. Secchi is credited with developing the first spectral classification system for stars. He also discovered a comet (named after him), drew one of the earliest maps of Mars and served as a professor of astronomy and director of the observatory at the Roman College in the Vatican. Continue reading

Watch This! Madison East Student Documentary on the Yahara Lakes

It’s spring break in Madison and, while we’re not exactly out swimming or boating just yet, that doesn’t mean we can’t take a moment to love our lakes. Enjoy this video from Madison East High School students on what the lakes mean to our city and how folks (including CFL grad student, Sam Oliver) are working to better understand and protect them.

Lifeblood of Madison from Madison East High School on Vimeo.

I don’t know about you, but I’d say these students deserve a little time off for a job well done!

Researchers Get to the Bottom (& Beyond) of Lake Mendota Invasive Species

It looks like ice-off is only a couple days away on Madison’s lakes. Before we hit the completely open water season, though, here’s a look back at some semi-frozen fieldwork from early March. Graduate student, Jake Walsh, shares his experience coring Lake Mendota’s sediment layers…

by Jake Walsh

The past couple of Mondays I’ve been out coring Lake Mendota with Sam Muñoz (PhD student with Jack Williams in Geography – Sam is a paleoecologist) and Tom Shannon (undergraduate researcher in the Vander Zanden Lab).

Coring the sediment on Lake Mendota

Tom Shannon (left) and Sam Munoz, (right) prepare to take a lake sediment core sample. Photo: Jake Walsh

This was my first time leading any sort of winter sampling, so learning the ins and outs of driving the ATV, running the gas powered auger, and making sure the ice was safe (it was almost two feet last week and is still like a foot and a half this week but that doesn’t mean I’m not going to worry irrationally about ice conditions) was actually a really fun experience.

Driving through several inches of water and slush in 60 degree weather yesterday was a very strange, fun, and terrifying experience. The reason I was out in that slush was because I’m interested in looking at how long the spiny water flea (or, SWF, a tiny invasive zooplankton) has been in Lake Mendota. (This is an extension of the work from a previous blog post on sleeper cells).

We originally detected SWF in 2009 when it reached population densities higher than anything recorded anywhere else in the world, as far as I know. The water sample looked like SWF apple sauce to a class of limnology students out for a class lab with professor Jake Vander Zanden. However, my population model predicts that SWF could have been in the lake indefinitely, existing at low densities before some combination of temperature, water chemistry and other conditions allowed it to explode, “activating” this “sleeper cell” in 2009. So far, we’ve found a couple of SWF specimens in a sample from 2008 which corroborates the sleeper cell story, but this sediment coring will help us go back further. Continue reading

The Study, Science & Stories of Our Inland Waters