Monitor Mendota: Water Clarity, Daphnia on the Rebound

Algal bloom. Photo: Eddie Heath.

Algal bloom. Photo: Eddie Heath.

Last week on this blog, we wondered if Lake Mendota’s clear water phase was a thing of the past. You see, last year, the algae-eating native zooplankton, daphnia pulicaria were so diminished by predation from the invasive spiny water flea, that their numbers couldn’t grow large enough to keep algae from clouding our waters. Combined with the phosphorus that runs off into our lakes and acts like algal fertilizer, well, you’ve got a recipe for a soupy mess. And this year wasn’t looking much better.

Imagine my surprise, then, when I stepped out onto the Hasler Lab pier this afternoon and saw this… Continue reading

All Aboard! 4th Annual Hasler Lab Open House

                    Join us FRIDAY, JUNE 12th for the                         Hasler Lab Open House!

Visitors board the Limnos for a "research cruise" on Lake Mendota.

Visitors board the Limnos for a “research cruise” on Lake Mendota.

If you’re in the Madison area, come on down for a “behind the scenes” event and spend a half hour or the whole afternoon exploring the science behind Wisconsin’s lakes, rivers and streams.

We’ll have hands-on science, FREE Babcock ice cream and a visit from the UW’s most iconic mammal, Bucky Badger.

Friday, June 12th, 2-6pm. And Hasler Lab (680 N. Park Street)

Visitors will:

  • Take a “research cruise” on Lake Mendota with CFL researchers
  • Meet the fish, plants and insects that call Madison lakes home
  • Try their hand at using various lake research tools
  • Catch plankton from our pier and ID them under our microscopes
  • Make aquatic-themed crafts at the Kids Crafts station
  • Talk with leading scientists about Wisconsin’s freshwater
  • Enjoy free Babcock Dairy Ice Cream
  • Meet Bucky Badger
  • And  more!

Here’s a slideshow of past open houses:

So bring the kids and come on out from 2-6pm on Friday, June 12th. We hope to see you here!

Parking available under Helen C. White library after 4pm and in the the Lake Street public parking ramp near the corner of Lake and State. 

*Note: Boat rides are first-come/first-served, ice cream is served until we run out, and Bucky Badger will be at the lab from 3-3:30pm. 

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

The Study, Science & Stories of Our Inland Waters