Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Mud manifests history of clear water in murky Minnesota duck depot Lake Christina

Implications for ducks, fish, and landscape management

During peak migration days in the early 1900s, tens of thousands of canvasback ducks could be seen floating and diving on Minnesota's Lake Christina. Since midcentury, changes to the lake have diminished this grand, iconic spectacle.

Restoring it will require both top-down control of life in the lake, and bottom-up management of the surrounding landscape. So says a team of Minnesota scientists calling on extensive modern records and 200 years of history trapped in sediment, in a report released online last week in the journal Ecological Applications.

"Lake Christina is very important for the region culturally, and ecologically," said Will Hobbs, a scientist at the Science Museum of Minnesota and lead author of the report. "The lake is a significant stop-over for waterfowl migrating along the Mississippi Flyway, but it has been compromised since the 1950s."

Lake Christina has an unusually long history of management, offering a unique opportunity to study the effects of biological manipulations and management.

In the 1950s, the lake's clear water darkened to a green algal soup. By calibrating sediment cores to 25 years of modern records, the research team learned that Lake Christina had had clear waters for 100 years prior to European settlement in the late nineteenth century – the clear water was a stable state, and not an historical aberration. But now the lake is in a stable, murky state.
Managers have been struggling to regain clear waters in the lake for migrating waterfowl, particularly the big, rusty-headed canvasbacks. The ducks need a healthy meal of submerged aquatic plants to fuel their journey, but the dense algae blocks out so much sunlight that underwater plants like sago pondweed and wild celery can't grow.

A similar loss of submerged aquatic plants has developed at the canvasbacks' major historic wintering grounds on Chesapeake Bay.

"Life is not easy for a duck. You need those areas where you can stop and rest – large open expanses of shallow water with readily available food," said author Mark Hanson, a research scientist with the Minnesota Department of Natural Resources.

Two factors led to the clouding of the waters: an influx of nutrients from agriculture fed the algae, and a dam built in 1936 led to a fall in the population of tiny, algae-eating zooplankton. The dam doubled the depth of the lake, from two feet to four, allowing fish that eat zooplankton to survive the winter, and thrive.
To make the lake attractive for ducks, managers killed most of the fish in 1965, 1987, and 2003, each time achieving only temporary success. Within a decade, the fish recovered, and the algae followed.

Restoration of wetlands surrounding the lake has not, as yet, met hopes for lowered nutrient levels.

"It's very difficult to get the nutrients out of the lake," said author Kyle Zimmer, an associate professor at the University of St. Thomas who has studied the fish at Lake Christina for several years. "We know from the literature that these things can take time, and maybe top-down, active management allows that time, or at least simulates the outcome we want, even if a self-maintained stable state is not achieved."

Managers walk a fine line, balancing short and long term needs, and balancing the interests of ducks and duck hunters at Lake Christina with those of recreational anglers. This fall, top-down management will include a series of pumps and pipes installed to draw-down the water level, mimicking the natural winter fish kill.

"The study presents compelling evidence that, in the long run, managers need to focus on strategies that target landscapes, not just the food webs in the lakes themselves – bearing in mind that the short term is also important," said Hanson. "The people that live here today are very much in this culture of ducks and migratory water birds, and the incredible history around them. When we get all sectors working on lake ecology together, that's a very productive basis for the future."

"A 200-year perspective on alternative stable state theory and lake management from a biomanipulated shallow lake" was published online, ahead of print, on 19 March 2012. It is slated for the July edition of Ecological Applications. doi: 10.1890/11-1485.1. Click for abstract. To obtain a pdf, or associated images, contact Liza Lester.

Students at North Dakota State University, in collaboration with the Minnesota Department of Natural Resources, contributed significant contemporary data to this project from long term monitoring efforts at Lake Christina.

The Ecological Society of America is the world's largest community of professional ecologists and the trusted source of ecological knowledge. ESA is committed to advancing the understanding of life on Earth. The 10,000 member Society publishes five journals, convenes an annual scientific conference, and broadly shares ecological information through policy and media outreach and education initiatives. Visit the ESA website at or find experts in ecological science at

Liza Lester | EurekAlert!
Further information:

More articles from Ecology, The Environment and Conservation:

nachricht Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide

nachricht Malaysia's unique freshwater mussels in danger
27.09.2016 | The University of Nottingham Malaysia Campus

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Novel light sources made of 2D materials

Physicists from the University of Würzburg have designed a light source that emits photon pairs. Two-photon sources are particularly well suited for tap-proof data encryption. The experiment's key ingredients: a semiconductor crystal and some sticky tape.

So-called monolayers are at the heart of the research activities. These "super materials" (as the prestigious science magazine "Nature" puts it) have been...

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Prototype device for measuring graphene-based electromagnetic radiation created

28.10.2016 | Power and Electrical Engineering

Gamma ray camera offers new view on ultra-high energy electrons in plasma

28.10.2016 | Physics and Astronomy

When fat cells change their colour

28.10.2016 | Life Sciences

More VideoLinks >>>