April 2016 AIS Spotlight

Letter from the Director

sueDear friends -

With more than three dozen aquatic invasive species found in or threatening to invade Minnesota, it's challenging to set research priorities. The most effective and efficient statewide response to AIS is to have research-based solutions developed prior to the arrival of a species and to have solutions that address multiple species at the same time. Accomplishing both of these goals requires prioritizing research that may seem less urgent relative to specific species that are already spreading.

The Minnesota Aquatic Invasive Species Research Center attempts to balance these demands through its annual research needs assessment process. With input from the public, a technical team of university scientists and agency AIS specialists reviews the status and trends of AIS already in Minnesota as well AIS spreading elsewhere in North America that are likely to find suitable habitat in the state. This information is used by research needs assessment teams to identify critical uncertainties for all of the high priority species that, if answered, could lead to prevention or control.

With the critical gaps identified, we can then seek out researchers with the skills to solve the problems. We did this recently with a competitive request for proposals that was sent out nationwide. The projects that were selected, based on relevance to solving state problems as well as scientific merit, will be announced soon.

Also look for updates soon on our 2016 research needs assessment process, which will have more emphasis on natural and social systems, such as effective rapid response and understanding risk through economic impacts, as well as a focus on the search for controls for key species such as zebra mussels.

Until then, please enjoy reading updates on research efforts currently underway.

Sue Galatowitsch

Minnesota DNR funds Sorensen Lab $880,000 to advance carp deterrent research at Lock & Dams


The Sorensen Lab received a major boost from the Minnesota Department of Natural Resources in February when it received $880,000 to advance its research efforts to hold back Asian carp by utilizing the already-present Mississippi River locks and dams. 

The project seeks to answer two primary questions: whether ongoing lab and computer simulations are correctly predicting how to modify gate operations to stop Asian carp, and how well the underwater acoustic deterrent system installed in 2014 at Lock & Dam 8 is working . . . all while having minimal effects on native fishes.

“While our one-of-a-kind computer modeling is showing that small changes in gate operating procedures will hold back almost all Asian carp without affecting navigation, it will be very helpful to confirm these predictions and determine what improvements could be made,” said lead researcher Dr. Peter Sorensen.

This work will also provide new insight into native fish behavior in the Mississippi River. At Lock & Dam 2 near Hastings, the research team will track approximately 250 native fish (lake sturgeon, walleye, channel catfish, and bighead buffalo) as well as invasive common carp (as a surrogate to Asian carp) to monitor their behavior under varying velocity flows in the dam. The tendencies and abilities of fish to challenge and move through these fields have never been studied on a fine scale and will inform the velocity flow model.

Additionally, this project will examine how well the Asian carp acoustic deterrent system installed in 2014 at Lock and Dam 8 (near the Minnesota border with Iowa) is functioning. The underwater speaker system, designed and installed by MAISRC researchers with funding from private donors and the Environment and Natural Resources Trust Fund, was intended as an emergency experimental measure while other lock deterrent options were being evaluated.

For the first time, researchers will use a type of high-resolution imaging sonar to capture the location of all fish in the lock area when sound is both on and off, which will help us understand more about how their behavior is affected by sound. Previous MAISRC research has shown that carp are more sensitive to sound than many native fishes.

“Together, these systems offer a promising tool for keeping invasive carp back,” said Nick Frohnauer, invasive carp coordinator with the Minnesota DNR. “We are hopeful that this fish passage research will get us the information we need to make sound management and prevention decisions.”

“We are very excited to implement this work as soon as possible,” added Sorensen. The project is anticipated to take 18 months to complete. Watch our website for further developments.

MAISRC researchers examining effects of alum treatments on curly-leaf pondweed and native plants

clpMAISRC is kicking off research to evaluate the effects of alum treatments on native and invasive plants – particularly the problematic curly-leaf pondweed – in metro-area lakes this summer.

The application of alum (aluminum salts) can improve water quality by sequestering phosphorus in the lake sediment, which limits algae’s ability to grow. Whether or not this improved water clarity is enough to encourage the growth of native plants is yet to be determined.

Previous MAISRC research on invasive aquatic plants evaluated several management actions such as common carp removal and herbicide applications, and found that carp removal can enhance the population of both invasive and native aquatic plants, due to an increase in water quality and a reduction in sediment disturbance. However, since invasive aquatic plants were still outcompeting native plants, researchers are working now to determine how to best encourage native plants, particularly in lakes with poor water quality. This will be addressed in three ways:

1. Alum treatments
2. Post-treatment monitoring
3. Transplanting native plants to treated areas if need be

Transplanting native plants could also bolster the native plant community, if the plants did not germinate naturally as a result of the improved water clarity. Delicate aquatic plant communities can quickly be destabilized by invasive plants such as curly-leaf pondweed and Eurasian watermilfoil, which, thanks to their ability to grow abundantly in cool water with limited light, are eagerly taking hold in many Minnesota lakes.

The ultimate goal of this multi-year effort is to reduce invasive aquatic plants and support diverse native aquatic plant communities, which provide many important ecological functions. Learn more about curlyleaf pondweed research at MAISRC here. Funding for this project is provided by the Riley Purgatory Bluff Creek Watershed District.

New findings affirm risk of zebra mussel spread through downstream drift

zebra mussel

Recent findings from MAISRC’s Dr. Mike McCartney are shedding light on whether and how zebra mussels infest downstream lakes via natural waterway connections – a risk that we may overlook if we focus entirely on human-aided transport. Data is showing that while simply being connected to an infested lake does not guarantee infestation in a downstream lake, it significantly increases the likelihood.

Over the past two summers, McCartney and his team collected samples from lakes and streams throughout the state – all of which had a connected, infested lake upstream – and counted veligers within the waterbodies and at increasing distances downstream. They also installed cinder block samplers to count the zebra mussel juveniles that settled on the stream bottom. Their analysis showed that:

  • Zebra mussel veligers are traveling downstream– sometimes up to a billion per day –and especially in June. However, these numbers decline sharply with distance and can drop to zero prior to reaching downstream water body in some cases.
  • Most veligers are not settling on the stream bottom, but if they do, they do so only very close to the upstream lake (within a kilometer). The veligers that aren’t settling on the stream bottom may be delivered out of the stream into lakes or rivers where they might settle, mature, and eventually reproduce.

This new information reaffirms the Minnesota DNR’s policy of listing lakes downstream of known infested lakes as also infested, regardless of whether a live zebra mussel has been found. Essentially, the likelihood of a downstream lake becoming infested is high enough that it warrants the regulations that are enforced on confirmed infested lake.

“It’s not a given, but it’s better to be cautious,” said McCartney. “What is interesting here is how sharp the declines were, and where and in which months the veliger populations dropped to zero. Why does that happen and are there any clues here for prevention and control?” 

Going forward, more unknowns – such as the viability of veligers, the distances over which they are dropping off as they travel downstream, and the reasons why – are being and will be addressed. Ultimately, these data will be coupled with boater movement data to allow researchers to make more reliable predictions about the likelihood of future lake invasions, which can be used to better target prevention efforts.

These findings also reinforce the critical aspect of preventing spread whenever possible: once a lake is infested, it may infest many more.  Learn more about zebra mussel research and what you can do to prevent spread here.

Heterosporosis experiments begin in newly renovated MAISRC laboratory

heterosporisApproximately 800 yellow perch will soon call MAISRC’s recently renovated Lab and Holding Facility home. The perch are part of a research project to determine how much of a threat to Minnesota’s lakes and fish the disease Heterosporosis presents.

This research, which will study how long it takes a fish to become infected, what role temperature plays, and how it is spreading, will inform a disease ecology and population model for estimating the impact of Heterosporosis on Minnesota wild fish populations. The project will:

1. Study how many spores of Heterosporis sutherlandae it takes to infect a fish, and how long it takes to develop a clinical infection. Fish likely have some natural defense to protect against the parasite, but it is unknown how effective they are. To test this, researchers will expose the perch to different concentrations of the parasite in the lab and monitor them for symptoms.

2. Determine whether water temperate has an impact on the virus. Anecdotal evidence is showing that the virus appears more often in the winter, when fish immune systems are weakened. The optimal temperature for perch growth is 22° Celsius (72° F), but lake temperatures can range from 0 – 26° C (32° – 79° F). It’s possible that when fish are stressed by suboptimal temperatures or lack of energy stores, their ability to protect against the infection decreases.

3. Establish how the parasite is spreading. Currently, researchers know of two ways that an otherwise healthy fish can become infected: eating an infected fish, or coming into contact with spores shed through the waste of an infected fish. To study this further, researchers will infect perch and measure how many spores are released through waste, as well as expose healthy fish to infected fish and measure the rate of new infections.

“Coarse data on infection rates and impacts of the disease already exist, but much more refined data on fish behavior such as their ability to swim, whether they are eating more or less, and whether their  reproduction could be affected will greatly improve the model,” said Megan Tomamichel, a graduate student working on the project. “It’s important that we predict how the harvestable biomass of perch could be impacted by Heterosporosis because these fish are so important for recreation and aquaculture in Minnesota, as well as important prey for species like walleye.”

Heterosporosis is caused by the microsporidian parasite Heterosporis sutherlandae, and is currently found in 45 lakes in the Great Lakes region. The microscopic spores of the parasite live inside the muscle cells of the fist. As the parasite replicates, it ultimately ruptures the cell and liquefies the muscle tissue. It was first reported in Leech Lake in 1990 and is known to affect 15 species of freshwater fish, including walleye, rendering them inedible.

“We may learn that Heterosporosis is peaking in Minnesota, that it will likely continue spreading, or that it is simply a low-level endemic disease,” added Dr. Paul Venturelli. “Knowing this will inform what kinds of management responses are needed.” 


MAISRC welcomes three new team members!

The Minnesota Aquatic Invasive Species Research Center is pleased to welcome three new team members:


Megan Weber, MAISRC’s new Extension Educator, will play an integral role in the dissemination of science-based information about AIS research, biology, and control options. She will be developing the AIS Trackers program in close coordination with MAISRC researchers, University of Minnesota Extension, the Minnesota DNR, and other stakeholders. This work will complement the AIS Detectors program, currently being developed by Extension Educator Eleanor Burkett. 

Megan joins us from Marone Bio Innovations, Inc. – the manufacturer of Zequanox – where she worked on the control of invasive zebra and quagga mussels. She received her master’s degree in Environmental Studies from San Jose State University and her bachelor’s degree in Marine Biology from the University of California, Santa Cruz.


Alex Primus, a research associate who will be researching Viral Hemorrhagic Septicemia and Heterosporis. He has a strong interest in infectious disease, fish health, and the diversity of biological systems.


Maxwell Kleinhans, a junior laboratory technician contributing to the development of assays for detection of zebra mussel veligers in lakes and rivers. He is interested in research focused on understanding and conserving aquatic ecosystems.

Two new papers published by MAISRC researchers

MAISRC researchers Dr. Przemek Bajer and Joey Lechelt recently published a new paper explaining how modeling has shown that physical removal of carp might not work in lakes with few predators, highlighting the need for other control tactics. Read the full paper, Modeling the potential for managing invasive common carp in temperate lakes by targeting their winter aggregations, here.

Meanwhile, different research from MAISRC researchers Dr. Peter Sorensen and Dr. Daniel Zielinski is showing that bubble curtains could serve as a viable and inexpensive deterrent system for Asian carp, while having minimal impacts on other fish. Read the full paper, Bubble curtain deflection screen diverts the movement of both Asian and Common Carps, here.

Change of date for 2016 Minnesota Aquatic Invasive Species Research and Management Showcase

Please mark your calendars for Monday, September 12, to join us on campus for the 2016 AIS Research and Management Showcase! Note that this is a new date from what was initially announced, but everything else – location, time, and the opportunity to learn more about MAISRC's innovative research – remains unchanged. Keep your eye on our website for more details, including breakout session topics, in the coming months.

MAISRC researcher hosts disease modeling in aquatic ecosystems workshop

Last February, MAISRC researcher Dr. Luis Escobar hosted a workshop on disease modeling in aquatic ecosystems. The workshop provided state-of-the-art modeling tools to predict the spread of diseases, such as Viral Hemorrhagic Septicemia, in aquatic organisms. Attendees heard from various instructors on topics such as transmission models, social network analysis, and ecological niche modeling.

The attendees, a diverse group with representatives from the Minnesota DNR and the University of Minnesota as well as universities in Chile and Ecuador, described the workshop as thought-provoking and enriching, with one participant saying, “The workshop allowed me to fill knowledge gaps regarding the ecological niche modeling approach in disease biogeography. It also helped me to learn basic issues from other epidemiological areas, and was an enriching experience to me as a student to share and learn from U of M researchers.”

The workshop was conducted in collaboration with the Department of Veterinary Population Medicine and was funded through the Institute on the Environment’s MiniGrant program – thank you for your support!

New boat motor purchased in time for 2016 field season thanks to your support

Thank you to all the generous donors who supported MAISRC’s first-ever Crowdfunding campaign this winter! Through your support, we were able to purchase an important new backup motor for our boats that are in high demand from researchers throughout the summer field season.

You can donate online to support the Minnesota Aquatic Invasive Species Research Center anytime – private gifts truly make a difference and provide us with the flexibility to meet critical needs as they arise. Thank you!

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