April 2015 Newsletter

Letter from the Director

Sue Dear Friends—

As you know, the faculty and researchers at the Minnesota Aquatic Invasive Species Research Center (MAISRC) are diligently focused on finding solutions to Minnesota’s most pressing AIS issues, from invasive carp to zebra mussels. However, conducting the research doesn’t always leave ample time to relay research findings and control options to the public. In order to help address this pressing need for communicating scientific information to the public while maintaining our focus on research, we are excited to announce that the Center has hired Danielle Quist as the new Aquatic Invasive Species Extension Educator with MAISRC!

Going forward, Danielle will play an integral role in the dissemination of science-based information about AIS research, biology, and control options—topics that are not systematically being addressed through other statewide programs. She will also be taking a lead on the development and training around the new AIS control database, which is being designed to generate valuable information from control efforts around the state.

This new position will help us leverage capacity throughout the state by working with existing University Extension personnel to expand programming and by coordinating closely with Sea Grant and the Minnesota DNR. Danielle will be closely connected to the Center and our current research projects, and will be well-equipped to speak to lake associations and other groups interested in learning about the status of AIS in Minnesota, current MAISRC research projects, and scientifically based control options for AIS.

Danielle earned her master’s degree in biology from the University of South Dakota, where she focused on large river ecosystem ecology, and her bachelor’s degree in environmental science from Winona State University. She has over six years of scientific research and monitoring experience, including sampling for aquatic invasive species in the Mississippi and Missouri River floodplains.

She also has over four years of teaching, interpreting, and outreach experience and has developed educational programs for a variety of audiences, most recently as a park ranger with the Mississippi National River and Recreation Area, where she educated the public about invasive species.

Currently, Danielle is gathering input from stakeholders and putting together a comprehensive program plan for her AIS work in Minnesota. With ice-out will come an increased need to connect with counties, lakeshore associations, and others who experience both the benefits of our resources and the impacts brought on by AIS.

Please join me in welcoming Danielle to the Center.

Dr. Susan Galatowitsch
Director, Minnesota Aquatic Invasive Species Research Center

MAISRC researcher leads a collaborative team to explain the enigma of common carp invasions

carp Common carp are one of the world’s most invasive fish and have long been a problematic presence in many Minnesota lakes. But the destructive fish – which search for food on the lake floor, disturbing sediment and uprooting vegetation – have never become abundant in some parts of the world, such as the Boundary Waters, while becoming superabundant in others.

This enigma inspired MAISRC researchers to study why carp become so invasive in some ecoregions but not in others, thereby helping to explain their invasion patterns in Minnesota and beyond. The results of the study, led by MAISRC researcher Dr. Przemek Bajer, were recently published in Diversity and Distributions, a leading journal of invasion biology.

Researchers studied over 550 lakes throughout different ecoregions in the Midwest, looking at factors such as lake clarity and productivity, different species of native predatory fish, and abundance of adult carp. Ultimately, researchers found that two simple ecological filters – lake productivity and abundance of bluegills – can explain the success of carp. Carp can become invasive only in regions with productive lakes that also have low abundance of bluegills, which eat carp eggs and larvae. In all other lakes, those that are clear and oligotrophic or which have high densities of bluegills, carp are not invasive because their eggs and larvae cannot survive the critical developmental period.

These ecological filters may help explain the different patterns of carp invasions among ecoregions – like the productive lakes of the Great Plains or Temperate Forest covering south-central Minnesota where carp are common, versus the oligotrophic Northern Forest of the Boundary Waters lakes, which are nearly void of carp.

By studying introduced species across different regions where they are or are not able to become invasive, researchers can better determine processes that facilitate invasions and also those that curb it.

“Before we can figure out how to control an invasive species like common carp, we need to understand what allows it to become so invasive in some regions and what’s holding them back elsewhere” said Dr. Bajer. “If we only look in areas where they are very successful, we may never find their weaknesses.”

Read the full paper, “Across-ecoregion analysis suggests a hierarchy of ecological filters that regulate recruitment of a globally invasive fish,” online here.

This collaborative work included other MAISRC researchers, the Minnesota DNR, and carp biologists from Iowa and Nebraska. Bajer’s research was funded by the Riley Purgatory Bluff Creek Watershed District and by Ramsey Washington Metro Watershed District; lake survey data and GIS resources were provided by Minnesota Department of Natural Resources, South Dakota Game, Fish and Parks, and Nebraska Game and Parks.

Completing population estimates to manage carp

On the heels of our recent announcement that common carp populations are under control in the Riley Chain of Lakes, MAISRC researchers continued their carp research and management efforts – this time in partnership with the Minnehaha Creek Watershed District on a 2.5-year project to study carp in the Six Mile Creek subwatershed. Researchers are taking the knowledge they gained from their work at Riley and applying it to a much larger and more complex watershed system.

carp The project, which is led by MAISRC research fellow Justine Koch and junior scientist Reid Swanson under the direction of Dr. Peter Sorensen, is a comprehensive assessment of common carp in the Six Mile Creek subwatershed. Their goal is to determine the distribution, abundance, movement patterns, and recruitment patterns of common carp throughout the area. This is the first step in an effort to understand how to sustainably manage common carp throughout the Six Mile Creek chain of lakes.

During the first full field season, electrofishing surveys revealed incredibly high estimates of common carp density and biomass. In an effort to validate these estimates, MAISRC partnered with commercial fisherman to recapture the carp that they had previously tagged in order to inform population data. Researchers had radio-tagged 30 carp in the Mud-Parley Lake system and tagged an additional 212 carp with small, plastic external tags called T-Bar tags.

When researchers set out to seine for the fish in mid-March, they were able to detect 15 of the radio-tagged carp. Despite a few snags throughout the day – like the net getting caught on underwater branches – fishermen were still able to enclose ten of the radio-tagged carp, and a grand total of a whopping 6,209 common carp (over a quarter of the total common carp population)! Several dozen gamefish were inadvertently captured as well, but were released back to the lake unharmed.

Of the carp that were captured, 54 had been previously tagged, which allowed researchers to estimate the total population size at roughly 23,000 carp in Parley and Mud Lakes combined. Developing a sustainable, long-term carp management plan is vital for controlling this highly invasive fish. Common carp are so invasive due to their high fecundity, low mortality rates, resilience, and ability to exploit productive and degraded waters for reproduction. By uprooting plants and releasing nutrients from sediments, carp degrade water quality and waterfowl habitat. Thanks to the Minnehaha Creek Watershed District for their support of this project! Stay tuned for more updates throughout the summer.

Monitoring and assessing risk for VHS in Minnesota waters

When you picture an aquatic invasive species, what comes to mind? Probably the small-but-problematic zebra mussel, a swath of Eurasian water milfoil, or perhaps the ubiquitous common carp. What may not come to mind, however, is a harmful fish pathogen called Viral Hemorrhagic Septicemia Virus (VHSV).

vhs Like other invasive species, it is non-native and was introduced to the area, it moves through different ecosystems with ease, and it has the potential to cause great ecological and economic harm. Unlike other invasive species, it’s a pathogen that has the ability to travel through water independent of its host and can therefore be very difficult to monitor.

VHSV can cause high mortality rates in both farmed and wild fish populations, making it of great concern to aquaculturists and recreationalists alike. As the name describes, visible symptoms often include hemorrhaging throughout the fish, which is not only unsightly, but can result in organ failure and eventual death. VHS was first found in the upper Midwest nearly ten years ago, and it has since been found in all five Great Lakes and inland lakes of Ohio, Michigan, New York, and Wisconsin – but not in inland waters in the state of Minnesota – and MAISRC researcher Dr. Nick Phelps would like to keep it that way.

Phelps, an Assistant Professor in the University of Minnesota’s College of Veterinary Medicine, has worked with the Minnesota Aquatic Invasive Species Research Center since its inception. One primary project has been to conduct surveillance and risk assessment projects to help further understand VHS’s effects on Minnesota.

Through surveillance work, Phelps and his team can establish where the virus can and can’t currently be found. Luckily, VHSV has not yet been found in inland waters of Minnesota. However, by conducting a risk assessment, they can identify places in Minnesota where the virus is most likely to appear, which can help prioritize management and control efforts. Risk is determined through a variety of factors, such as connectivity to infected waters, conducive water temperatures, linear distance to infected waters, and nearby boater movement. Learn more about Dr. Phelps’ research in this article, “Risk-Based Management of Viral Hemorrhagic Septicemia Virus in Minnesota.”

Figure: Map of the risk of VHSV introduction into Minnesota watersheds. Numbers within the watersheds identify the watersheds based on four-digit hydrologic unit codes. The darker the shading, the higher the risk of VHSV introduction.

Presently, 34 different species of fish can be infected by the Great Lakes strain of the virus. Humans and other animals are not known to be susceptible to the disease. However, researchers have discovered that while zebra mussels cannot be infected by the virus, they can carry it and act as a vector to infect other waters.

To help prevent the spread or introduction of VHS, follow basic aquatic invasive species rules: always clean your boat, dispose of your bait and bait water, and don’t move fish between water bodies. If you observe a fish kill or catch a fish you suspect may be diseased, please contact the DNR.

Exploring ways to sound to safely deter the advance of invasive carp

sturgeon When faced with the formidable goal of reducing the movement of invasive carp into and through Minnesota waters while also maintaining the ecological safety of native fishes, MAISRC researchers considered numerous options; everything from dams, to bubble curtains, lights, electricity, odor, and sound was discussed.

Although some of these options are used elsewhere, none was well-suited for Minnesota’s treasured lakes and rivers. Many options, such as closing locks and electrical barriers, halt the natural movement of all fish, both native and nonnative, and carry risks to the public. Here in Minnesota, researchers wanted to develop a new system that would preserve our native species and their ecosystems while also deterring the upstream movement of invasive carp, especially the silver or “jumping carp.”

With that goal in mind, MAISRC researchers developed a plan centered around certain qualities that make invasive carp unique: their super-sensitive hearing abilities as well as their apparent aversion to humans and their tendency to jump. Carp hear a wide range of frequencies, from approximately 100 to 3,000 hertz, while most native fishes – such as lake sturgeon and walleye – only hear sounds in the 100-6,000 hertz range, and then with much less sensitivity. (For reference, humans can hear from about 20 to 20,000 hertz.)

Armed with this information, along with the additional data that they are collecting on the swimming performance of carps (suggesting that carps often cannot pass through the gates in the locks and dams of the Mississippi River) MAISRC founder Peter Sorensen is now developing acoustical deterrents for use in locks. He and his team are employing an experimental approach to examine how certain sounds, perhaps when combined with other cues, can deter the movement of carps. Sufficient deterrence would mean that the critical number of adults needed to reproduce will not pass through, while native fish still do. This approach would not risk human safety or navigation through the locks.

This project kicked off in the winter of 2014. Now, it is currently focused on examining invasive carps (silver, bighead, and common carp) and lake sturgeon (pictured). Silver carp – the poster child for invasive carps – grow large and jump out of the water when disturbed by boaters. Lake sturgeon are of particular interest because they are threatened and migrate long distances to reach their spawning grounds.

Experiments presently focus on testing reactions to the sound of an outboard boat motor, chosen because of its complex and varied amplitudes and frequencies that fish seem to have a difficult time growing accustomed to. The sound is played into tanks, and researchers can observe the movement and behavior of the fish to determine their response.

The sound is turned on for two and a half minutes at a time, during which time researchers look for any change in fish distribution. “The carp exhibit an immediate response to this sound,” said MAISRC researcher Clark Dennis. “They seem agitated and clearly avoid the area near the sound source. On the other hand, the lake sturgeon didn’t seem to notice at all. The noise simply isn’t loud enough to them to inspire a behavior change.”

Following this success, researchers plan to test a large-scale acoustic deterrent in the auxiliary lock at Lock and Dam #1 in St. Paul this summer. They will use wild, acoustically tagged lake sturgeon and bigmouth buffalo to test their response to the sounds, which they will then compare to the behavior of common carp in the area.

“Ultimately, sound is a prevention tool with genuine potential – it can be targeted to carps, is safe and relatively inexpensive, and can be improved by combining it with other cues such as velocity at the gates.” Dennis added. “We also hope to combine its use with optimized eDNA detection. Overall, this is an extremely promising option that will have little impact on nontarget species.”

Dr. McCartney's zebra mussel lab gains new team members

Dr. Michael McCartney is at the epicenter of zebra mussel research in Minnesota, and now has new staff members on his team: postdoctoral researcher Dr. Sophie Mallez, laboratory assistant Sarah Peterson, and undergraduate student Michael Verhoeven.

Dr. Mallez’s research at MAISRC will focus on aspects of the population genetics and genomics of zebra mussels with the goal of understanding invasion sources and pathways of spread through Minnesota, the Upper Mississippi River, and the Great Lakes basin. Dr. Mallez is an expert in analysis of invasion genetic models, which she used in her doctoral research at the Sophia Agrobiotech Institute at the University of Nice, Sophia-Antipolis, France. She earned her master’s degree in Ecology, Biodiversity and Evolution from the Pierre and Marie Curie University in Paris. Her past research investigated the pathways of invasion of Europe by the pinewood nematode, an organism that causes pine wilt disease in Europe and Asia. We look forward to collaborating with her on zebra mussel invasion pathway research!

Sarah Peterson joined the McCartney lab in late 2014 and has continued her work on zebra mussel veliger larvae collected from Minnesota lakes and streams. She completed the analysis of samples from last summer’s studies on the Pelican and Gull Rivers, which allowed us to examine dispersal of veligers downstream in those rivers. Additionally, she completed work on Lake Winnibigoshish, where she found veligers to be present – but in very small numbers – in our summer 2014 plankton tows.

Michael Verhoeven, an undergraduate student, is also working on veliger larvae. He is using digital microscopic images to gather data on size-frequency distributions, with the goal to use these to estimate mortality of larvae in the plankton of a select group of Minnesota lakes.

We are delighted to welcome these new team members to the McCartney Lab!

Expanding research capacity for aquatic invasive plants

MAISRC is growing! We’re excited to welcome another new staff member to our team: postdoctoral researcher Dr. Adam Kautza. Adam will be working with Dr. Ray Newman on advancing Eurasian water milfoil control efforts, specifically on milfoil weevils and weevil-sunfish interactions.

Dr. Kautza has a diverse background in fisheries and wildlife, and most recently was teaching at the Ohio State University School of Environment and Natural Resources. He also earned his Ph.D. there, writing his dissertation on the consequences of landscape change on riverine food webs and aquatic-terrestrial linkages. He earned his master’s degree from the University of Idaho and his bachelor’s degree from the University of Wisconsin.

At MAISRC, he will focus on the indirect influences that sunfish may have on invasive Eurasian water milfoil. Sunfish have the potential to be a strong top-down control on milfoil largely via predation on native invertebrate herbivores such as milfoil weevils (and other aquatic insects). Identifying the unique effects of sunfish on milfoil herbivores can lead to important insights into methods for effectively managing fisheries in ways that promote effective and safe long-term biocontrol of Eurasian water milfoil.

Welcome, Adam!

MAISRC well-represented at American Fisheries Society meeting

Several MAISRC researchers presented their work at last month’s Minnesota Chapter of the American Fisheries Society annual meeting, which brought together fisheries professionals from throughout the state and featured presentations on everything from acoustic deterrence of carp to zebra mussel biomass. The Minnesota AFS meeting is a key opportunity for information exchange with Minnesota DNR fisheries personnel from around the state about the current research on invasives.

MAISRC researchers presented and discussed numerous research projects, and we are proud to announce that Peter Xiong, an undergraduate student with MAISRC, won the coveted "Best Poster" award! Peter presented, "Determining whether polyamines function as behavioral deterrents in a model filter-feeding invasive species, the bigheaded carp." Congratulations to Peter!

Thank you to the Pelican Lakes Association

The faculty, staff, and students at MAISRC would like to thank the Pelican Lakes Association for their generous gift of $10,000 to support the Center’s research on zebra mussels. We appreciate PLA’s recognition of the role research can play in helping to address the issues they confront.

“The Pelican Lakes in Crow Wing County are an environmentally wonderful area because of the pristine clear water, the many acres of undeveloped natural shoreline, and the heavily forested areas,” said Dr. Arthur Weaver, president of the Pelican Lakes Association Board of Directors. “The Association is devoted to protecting these irreplaceable natural assets for all to enjoy now and in the future. The major issues facing our lakes right now include the presence of zebra mussels and other aquatic invasive species. We are confident that the research that MAISRC is conducting in this regard is of critical importance and will provide solutions to these problems.” Thank you, Pelican Lakes Association!

Please consider a gift today – you help make our work possible. Your donations allow MAISRC to respond quickly and with flexibility to emerging AIS issues and needs.