August 2015 AIS Spotlight
Letter from the Director
As summer is heating up, so is the number of lakes infested with aquatic invasive species in Minnesota – especially, this year, with zebra mussels.
In July alone, zebra mussels were confirmed in six lakes – Clearwater, Ruth, Big Cormorant, Forest, Fish Trap, and Eunice – along with the Red River. Just last week, they were also confirmed in Lake Stella.
This development is distressing and top-of-mind for many MAISRC researchers, myself included. As more lakes become infested, the opportunity for infestations of additional lakes grows exponentially – sort of like blowing the seeds off a dandelion flower.
Many of these new infestations are undoubtedly human-caused and should serve as a reminder that it's as important as ever to be extremely diligent when recreating on our Minnesota waters. One aquatic invasive species violation is still too many – and is still enough to infest a new body of water.
Researchers at MAISRC are working across several fronts to address aquatic invasive species prevention and control, but research is just one piece of the puzzle. The human element will always be a crucial factor.
And just as these newly infested water bodies highlight what we are up against, what's happening in Lake Mille Lacs underscores why it matters. There are many factors at play in the case of Mille Lacs, including aquatic invasive species such as zebra mussels, spiny waterflea, and Eurasian watermilfoil. Lake Mille Lacs is one of the only lakes in the state where all three of these destructive species are present.
Although there is much yet to learn about the specific effects of these AIS, it's likely they have dramatically altered the base of the lake's food web – the foundation upon which walleye and other top predators depend. We know that the amount of "energy" now stored in zebra mussels and spiny waterfleas can't be ignored when trying to understand the ecology of Mille Lacs. Ultimately, one has to wonder about the cumulative effect of these invasions – especially when coupled with warming waters.
It's important now that we view the Mille Lacs experience as a reality check: an example of what is at stake for our natural resources and for our economy. Minnesota's lakes, rivers, and streams must be protected, and it's up to all of us to do our part.
Dr. Susan Galatowitsch
Director, Minnesota Aquatic Invasive Species Research Center
MAISRC graduate student thesis examines effect of herbicides on curlyleaf pondweed and native plants
A thriving native aquatic plant community made up of diverse and abundant plants is essential to maintaining a stable aquatic ecosystem. Native plants stabilize shorelines, reduce sediment resuspension, and balance the water chemistry by taking in phosphorus and releasing oxygen.
However, these delicate systems can be disrupted by the introduction of invasive aquatic plants such Eurasian watermilfoil and curlyleaf pondweed, both of which are becoming increasingly common in Minnesota lakes. (For reference, in 2004 Eurasian watermilfoil was found in 160 lakes in Minnesota; today, that number is over 300.) Curlyleaf pondweed presents issues in Minnesota lakes because it grows very dense stands that displace native species and produces hardy turions (a plant bud that allows the plant to survive in winter without setting seeds) for reproduction that are viable for two or more years.
How these aquatic invaders can be stopped without harming native plants became the focus of Dr. Ray Newman's advisee, John Jaka, who recently earned his master's degree and wrote his thesis on this issue. Jaka's research worked to address three specific objectives:
- The magnitude of the effect of herbicide treatments on curlyleaf pondweed;
- How native plants respond to curlyleaf pondweed herbicide treatments; and
- If reductions of curlyleaf pondweed abundance, biomass, and turion densities in the sediment will allow the native plant community to expand.
Jaka selected two lakes in the Twin Cities metro area – Lake Riley and Lake Susan – as well as one control – Mitchell Lake – on which to conduct his research. The lakes were treated with Endothall, an herbicide commonly used to control aquatic plants, for two consecutive years. Data were compared to several years' worth of pre-treatment data, including biomass (weight) and turion densities of both native and invasive species.
After observation and data analysis, Jaka found that low-dose, early-season endothall herbicide treatments successfully controlled curlyleaf pondweed within treatment years while having no measurable negative effects – judging by the frequency of plant occurrence, turion density, and overall biomass– on the native plant community. Curlyleaf pondweed frequency of occurrence, biomass, and turion production all declined by 90% or more in both treatment lakes. However, as in previous studies, native plants did not show big increases.
While this research did shine light on the effectiveness of this particular herbicide, what remains unknown is how to best enhance the response of native plants, particularly in lakes with poor water clarity.
Additional MAISRC research is working to address this through post-treatment monitoring and transplanting native plants to treated areas. The ultimate goal of this work is to reduce invasive aquatic vegetation and encourage a diverse aquatic plant community that provides forage and shelter for waterfowl, fish, invertebrates, and algae-consuming zooplankton; improves recreational opportunities for swimmers and boaters; and results in the most resilient overall system. Read the full paper here.
Thank you to the Riley Purgatory Bluff Creek Watershed District for their funding and support of this work.
Initial modeling shows promise for deterrence of Asian carp at lock and dams
When it comes to preventing the upstream movement of Asian carp in the Mississippi River, there's no single solution. There are, however, physical structures already constructed that may add one more piece to the puzzle – in fact, there are several of them. The Upper Mississippi River has a total of nine Locks and Dams below the one at Upper St. Anthony Falls, which was recently closed as part of the fight against these highly invasive fish. These systems already impede some movement of fish through the Mississippi River, leading MAISRC researchers to ask: how do we maximize the benefits of these existing systems to block Asian carp without impacting native fish?
Researchers Daniel Zielinski, Clark Dennis, and Peter Sorensen are developing a two-pronged system designed to do just that: deterring carps from moving through lock structures with acoustic deterrents; and altering gate operations to create water velocities that prevent carp from traveling through with minimal impact to native fish passage. To tackle the latter part of this project, researchers first have to better understand how water flows in and around lock and dam structures, as well as definitively learn how well Asian carp can swim.
When this work began in 2013, researchers were unsure about the swimming capabilities of Asian carp. Because of silver carps' impressive ability to jump out of the water, it was thought they were nearly as strong as salmon – the poster child for powerful swimming ability in North America – but this assumption had not been tested.
This summer, Sorensen traveled to the U.S. Army Corps of Engineers' (USACE) Research and Development Center in Vicksburg, Mississippi, to meet with Dr. Jan Hoover. Together, they used specialized equipment to study the endurance (how long fish can maintain a constant swim speed) of Asian carp at various speeds and determined that Asian carp are considerably weaker swimmers than salmon (watch a video of their mobile swim tunnel experiment here).
Then Zielinski, a civil engineer by training, used this information to create a fish passage computer model that predicts the swimming patterns of silver and bighead carp. He also gathered engineering drawings and bathymetry data (underwater depth measurements) provided by USACE for Lock and Dam #8 – the southernmost lock and dam structure in Minnesota, where USACE will consider initially implementing research findings. Lock and Dam #8 is also home to an experimental acoustic deterrent system which was installed by MAISRC researchers (and funded by the Environment and Natural Resources Trust Fund as well as with the support of private donations) in the lock chamber in 2014.
Partnering with the University of Minnesota Supercomputing Institute, Zielinski used this structural information to create a 3D computational fluid dynamics (CFD) model that includes over 10 million elements and provides velocity and turbulence characteristics for water flowing around and through the dam structure.
Ultimately, Zielinski is running the fish passage model through the CFD model to test a range of fish sizes, speeds, and routes, using the results to identify crucial locations where Asian carp may pass through the gates – and therefore where and when gate operational changes are needed.
This modelling work so far has confirmed that it is possible for water velocities around the lock and dam structures – in some cases created with as little as a 6-inch change in gate height – may exceed the swimming ability of Asian carp.
"By learning how fast and strong carp can swim, along with the velocity at which water is coming out of the dams, we can optimize gate function at the dam to prevent further movement of these fish," said Zielinski. "Plus, when we combine that with everything we're learning about the effectiveness of acoustic barriers in the lock, we have a control system that could be very species-specific and highly effective."
"This is a significant step forward and is certainly better than leaving the door wide open. As long as we can continue making incremental changes that have a positive impact on aquatic invasive species control and potentially the passage of native fish, we're moving in the right direction," Zielinski added.
This month, researchers are presenting their initial findings to the USACE, who will review and decide whether any of the recommendations may be implemented at Lock and Dam #8. Going forward with their research, Zielinski and Sorensen hope to more finely tune the models for Lock and Dam #8 and then begin adapting them for use at Lock and Dams #2-7. Stay tuned for further updates as this work progresses!
Register today for the AIS Research and Management Showcase!
Registration is now open for the 2015 Minnesota Aquatic Invasive Species Research and Management Showcase on Wednesday, September 16!
Join us on campus for a selection of talks about the latest MAISRC research on invasive carp, zebra mussels, invasive plants, and harmful fish diseases. Interact with faculty and researchers over lunch as they share the latest about their work. Then (new this year!), attend your choice of an afternoon field session to see demonstrations of methods used to advance the science of AIS detection and control and to gain insights for working on AIS issues in your community.
Please click here to see a listing of all on-campus talks and field sessions.
Space is limited and pre-registration is required, so sign up today. See you there!
MAISRC welcomes three new team members
Everyone at MAISRC is pleased to welcome three new students to our team: Melaney Dunne, Josh Poole, and Megan Tomamichel.
Melaney Dunne is a graduate student working with Dr. Ray Newman in the Riley Purgatory Bluff Creek Watershed District studying the native plant response to both carp removal and early season herbicide application on invasive aquatic plants, with the goal of finding effective management strategies. She is passionate about aquatic ecosystem conservation and management and seeks to explore various restoration methods on lakes and streams.
Josh Poole is a graduate student working with Dr. Przemek Bajer to study control of the Common Carp through the use of both biological control methods and piscicide. He is interested in aquatic ecosystem health and management and seeks to understand how invasive species can be sustainably managed.
Megan Tomamichel is a PhD student working with Dr. Paul Venturelli to develop a model to predict the spread and impact of the emerging Heterosporosis disease on the harvestable biomass of yellow perch (Perca flavescens). Her hobbies include fishing, cross country skiing, camping and taking care of her freshwater planted aquarium. Welcome, all!
MAISRC is a Watershed Hero, thanks to Minnehaha Creek Watershed District!
We are proud to announce that Minnehaha Creek Watershed District has named MAISRC a 2015 Watershed Hero! MAISRC, along with the Minnesota DNR, City of Shorewood, and the Christmas Lake Homeowners Association, is receiving the Outstanding Partner award, for our key roles in the response to the August 2014 discovery of zebra mussels in Christmas Lake. Read more about the Watershed Hero awards here. Thank you for this honor, and congratulations to fellow heroes!
MAISRC student Joey Lechelt wins AFS Award
This summer, MAISRC partnered with the Introduced Fish Section of the American Fisheries Society, to award funds of up to $500 to support student research on invasive fish, specifically developing strategies to advance understanding of the basic biology or ecology of invasive fish within the Upper Mississippi River Basin in order to more effectively control them.
It was announced this week that MAISRC graduate student Joey Lechelt was selected as the winner by a panel of external judges! Lechelt will travel to Portland, Oregon to present his findings on modeling evidence for physical removal as a viable option for invasive common carp at the American Fisheries Society annual meeting.
Support MAISRC with a gift today
Private donations make a real difference at MAISRC. The promising acoustic deterrent work described above was made possible through the support of private donations in 2014, and other work – such as studying food and sexual cues to aggregate carp - have been similarly funded. Help us do this critically important work with a gift today. Contributions to MAISRC provide us with much-needed flexibility to meet critical needs as they arise. The health of Minnesota's natural resources impacts everyone. Please consider a tax-deductible gift to MAISRC today: we're all in this together!