M.L. 2013 Minnesota Aquatic Invasive Species Research Center Subproject Abstract For the Period Ending June 30, 2019

SUBPROJECT TITLE: MAISRC Subproject 8: Risk assessment, control, and restoration research on aquatic invasive plant species SUBPROJECT MANAGER: Daniel Larkin AFFILIATION: University of Minnesota MAILING ADDRESS: 135 Skok Hall, 2003 Upper Buford Circle CITY/STATE/ZIP: St. Paul, MN 55108 PHONE: 612-625-6350 E-MAIL: [email protected] WEBSITE: http://larkinlab.cfans.umn.edu/ FUNDING SOURCE: Environment and Natural Resources Trust Fund (ENRTF) LEGAL CITATION: M.L. 2013, Chp. 52, Sec. 2, Subd. 06a

SUBPROJECT BUDGET AMOUNT: $822,000 AMOUNT SPENT: $820,251 AMOUNT REMAINING: $1,748

Sound bite of Subproject Outcomes and Results This project predicted invasion risk, assessed ecological impacts, evaluated control efficacy, and investigated factors limiting post-control recovery of native aquatic plants. This was applied to starry stonewort, Eurasian watermilfoil, and curlyleaf pondweed. This will refine approaches for invasion prevention, reduce populations of established AIS, and restore native species.

Overall Subproject Outcome and Results Aquatic invasive plants can lower native plant diversity, reduce habitat quality for fish and other animals, and interfere with recreation. To protect Minnesota’s water resources, steps need to be taken to prevent new invasions, control existing populations, and support recovery of native biodiversity. These efforts require sound, science-based guidance. To provide such support, we conducted research to predict invasion risk, assess ecological impacts, evaluate control efficacy, and investigate factors limiting post-control recovery of native aquatic plants. This work was applied to three target species at different stages of invasion: (1) Nitellopsis obtusa (starry stonewort), first found in Minnesota in 2015 and now known in 14 lakes; (2) Myriophyllum spicatum (Eurasian watermilfoil), found in 1987 and established in >300 lakes; and (3) Potamogeton crispus (curly-leaf pondweed), here for >100 years and in >750 lakes. For starry stonewort, we developed models to predict risk of further spread and prioritize search locations for statewide volunteer search efforts, experiments to determine how long starry stonewort remains can survive out of water (i.e., remain transportable by boaters), and field and lab-based control experiments to guide management. For Eurasian watermilfoil and curly-leaf pondweed, we investigated relationships with native plant biodiversity, finding that they displace native species, an effect compounded by lower water clarity, and contribute to “biotic homogenization”—loss of ecological distinctiveness. We are investigating how to better control these invasive species and foster recovery of native vegetation by synthesizing thousands of aquatic plant surveys and management records collected in Minnesota and by conducting in-lake removal and restoration experiments. This work will continue under a follow-up project (MAISRC Subproject 8.2: Impacts of invader removal on native vegetation recovery). Our findings help Minnesotans by highlighting practices needed to protect lake ecosystems and refining approaches for preventing invasions, reducing populations of established AIS, and restoring native species.

Subproject Results Use and Dissemination Information from this project has been disseminated through 10 peer-reviewed journal articles, 30 invited talks, 20 contributed presentations, 45 media stories, and resources published on the MAISRC website. Fully published articles (7 of the 10) are included as attachments. Project findings are being used to guide AIS spread prevention and management efforts involving the Minnesota Department of Natural Resources, lake associations, and other stakeholders. This project has also contributed significantly to MAISRC Subproject 10 (“Citizen Science and Professional Training Programs to Support AIS Response”).

- Page 2 of 2 - Environment and Natural Resources Trust Fund (ENRTF) M.L. 2013 Aquatic Invasive Species Research Center Sub-Project Work Plan Final Report

Date of Report: August 9, 2019 Final Report Date of Work Plan Approval: August 13, 2015 Sub-Project Phase 1 Completion Date: June 30, 2019 Project Completion Date: June 30, 2019

SUB-PROJECT TITLE: Aquatic Invasive Species Research Center Sub-Project 8: Risk assessment, control, and restoration research on aquatic invasive plant species

Sub-Project Manager: Daniel J. Larkin Organization: University of Minnesota – Minnesota Aquatic Invasive Species Research Center Mailing Address: 135E Skok Hall, 2003 Upper Buford Circle City/State/Zip Code: St. Paul, MN 55108 Telephone Number: (612) 625-6350 Email Address: [email protected] Web Address: http://larkinlab.cfans.umn.edu/

Location: Statewide

Total ENRTF Sub-Project Budget: ENRTF Sub-Project Appropriation: $ 822,000 Amount Spent: $ 820,251 Balance: $ 1,748

Legal Citation: M.L. 2013, Chp. 52, Sec. 2, Subd. 06a

Appropriation Language: $4,350,000 the first year and $4,350,000 the second year are from the trust fund to the Board of Regents of the University of Minnesota to develop and support an aquatic invasive species (AIS) research center at the University of Minnesota that will develop new techniques to control aquatic invasive species including Asian carp, zebra mussels, and plant species. This appropriation is available until June 30, 2019, by which time the project must be completed and final products delivered.

I. SUB-PROJECT TITLE: Implementing findings: An applied ecologist position and program

II. SUB-PROJECT STATEMENT: Aquatic invasive plants are a major threat to Minnesota’s lakes, rivers, and wetlands. AIS plants can grow densely and form surface mats, reducing space and light available to other plant species. This can lower native plant diversity, reduce habitat quality for fish and other animals, and change the way lakes function. Aggressive growth of AIS plants also interferes with boating, recreation, and other human uses. AIS plants can thus harm biodiversity, habitat quality, and human activity. Despite strong interest and investment in preventing new invasions, controlling existing infestations, and supporting the recovery of impacted waterbodies, there are still key gaps in scientific knowledge needed to support effective management. To help address these gaps, this subproject will involve applied research on four high-priority aquatic plant species that are invasive or potentially invasive in Minnesota lakes. These species are at different stages of invasion in Minnesota. Because of this, management priorities and associated research needs differ, from evaluating risk of future invasion and spread, to improving the toolkit available for control, to identifying strategies for aiding recovery of lakes affected by AIS: (1) Nitellopsis obtusa (starry stonewort) is a charophyte (green alga) that is a new invader in Minnesota, having been found in Lake Koronis (Stearns Co.) in summer 2015. Starry stonewort is native to Europe and Asia. It appears to be spreading rapidly in northern-tier lakes, after first being found in the St. Lawrence River in 1978. We will assess risk of further spread of starry stonewort in Minnesota based on climate and environmental factors and by testing how long starry stonewort can remain viable out of water—mimicking potential movement by boaters. We will also test methods for controlling starry stonewort, which has proven difficult and on which there has been almost no scientific research. For now, herbicides/algaecides are the most promising tool for controlling starry stonewort. To ensure that control efforts are as effective as possible while minimizing harm to native species, we will conduct laboratory experiments to test the efficacy and selectivity of different herbicides. This information is urgently needed during this window of opportunity to minimize impacts of starry stonewort to Minnesota lakes. (2) Myriophyllum spicatum (Eurasian watermilfoil) is native to Europe and Asia, was first found in Minnesota in 1987, and now occurs in 322 Minnesota lakes in 40 counties. (3) Potamogeton crispus (curly-leaf pondweed) is native to Europe, Asia, Africa, and Australia; has been in Minnesota since at least the early 1900s; and is now in 750 Minnesota lakes in 70 counties. Eurasian watermilfoil and curly-leaf pondweed have been a focus of management and research in Minnesota for decades. But there are still limits in our ability to effectively control these species and, following treatment, to support recovery of native plant species. We will analyze existing datasets, perform new field work, and develop a citizen-science monitoring program to improve understanding of factors that drive invasion of these species and influence the effectiveness of management efforts. Eurasian watermilfoil and curly-leaf pondweed are not new to Minnesota, but ≥ 94% of our lakes do not contain these species. Improved ability to manage these species and contain further impacts is needed. An undergraduate, graduate student, and postdoctoral researcher will be trained under this subproject. Findings will be disseminated through peer-reviewed publications, presentations, and outreach and extension programming for agency staff, lake service providers, lake associations, and other stakeholders.

III. SUB-PROJECT STATUS UPDATES:

Sub-Project Status as of May 5, 2016: Dr. Larkin’s full research proposal has been peer reviewed through the Center process, revisions were made, and its workplan and budget approved by MAISRC. Please see amendment request below to update the workplan accordingly. Additionally, an ecological niche model has been developed to determine the threat of starry stonewort spread in Minnesota. The model indicated that this species is persisting in novel habitats – meaning that it is occurring in areas here that are climatically distinct from its native range, and that conditions in portions of the upper Midwest and other regions in the U.S. are ideal for its growth and spread. Additionally, a

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convening in the next month of researchers and managers with starry stonewort experience is being led by Dr. Larkin to determine current research and management knowledge and gaps. There will be a public webinar hosted in conjunction with this meeting.

Amendment request as of May 5, 2016: Dr. Larkin’s full research proposal has been peer reviewed through the Center process, revisions were made, and its workplan and budget approved by MAISRC. We now seek an amendment to move $692,000 from the Budget Reserve of Subproject 8 and allocate it among 4 new activities as shown on the attached budget spreadsheet.

Section II Sub-project statement above has been revised and 4 new activity descriptions and their related outcomes have been added to section IV Subprojects and Outcomes, below.

Amendment Approved by LCCMR 5-11- 2016

Sub-Project Status as of January 31, 2017: This funding has enabled an active research program addressing applied issues in aquatic invasive plant management in Minnesota lakes. Research on starry stonewort has addressed spread risk using ecological niche modeling and ongoing work to predict vulnerability of individual Minnesota lakes to starry stonewort invasion based on environmental characteristics. Culturing of starry stonewort is being refined to enable laboratory experiments addressing starry stonewort climate and desiccation tolerance and chemical control. Field sampling and experimental germination of starry stonewort bulbils from areas treated with algaecides and/or mechanical harvesting revealed high capacity for reinvasion of treated areas. In-lake outcomes of starry stonewort management efforts are being monitored in collaboration with DNR and other external partners. Research on Eurasian watermilfoil and curly-leaf pondweed has shown that shallow lakes with higher native plant diversity are more vulnerable to invasion, and that these invasive plants are associated with rapid biotic homogenization of vegetation in these lakes (loss of plant community distinctiveness). We are compiling monitoring data from past treatments of Eurasian watermilfoil and curly-leaf pondweed in Minnesota lakes to investigate how management decisions and environmental conditions influence effectiveness of control and capacity for recovery of native plant communities. The curly-leaf pondweed component incorporates and builds upon previously ENRTF-funded work by Dr. Ray Newman (Subproject 9). Finally, our research is being integrated with joint MAISRC-Extension efforts to develop the Trackers citizen science program (Subproject 10). Research related to this project has been presented in peer-reviewed publications (one complete, two in revision, several in preparation), research and outreach talks (13 total, 12 invited), and media coverage (7 total, including print, television, and radio).

Amendment request as of January, 31, 2017: We request a budget amendment to reallocate resources from Activity 2 (hydrilla) to Activity 3 (starry stonewort). This change is motivated by our desire to avoid duplication of effort related to hydrilla research and the emergence of new opportunities to improve understanding of starry stonewort control effectiveness. We also request an amendment to redistribute funds within the Activity 3 budget for publication costs associated with making our starry stonewort ecological niche model available open access in a top-tier journal. Finally, we would like to add a new personnel line for a Research Fellow (no budget amendment required). These changes are further explained below:

• At the summer 2016 annual meeting of the Aquatic Plant Management Society, Dr. Larkin learned of a large, federally funded project addressing risk of hydrilla invasion in the Great Lakes region. The Great Lakes Hydrilla Risk Assessment is a $1.1 million project funded by the U.S. Army Corps of Engineers that funds research at three universities: Texas Tech University, University of Toledo, and North Carolina State University. After attending a series of talks about this effort, Dr. Larkin realized that the objectives he proposed to meet under activity 2 would be duplicative with this larger effort that is already underway.

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• Also during the last reporting period, there were seven new infestations of starry stonewort found in Minnesota. The DNR, lake associations, and other partners began rapid response efforts in several of these locations (in addition to control work already underway in Lake Koronis). This created an unanticipated opportunity to conduct research on in-lake outcomes of starry stonewort management efforts. Dr. Larkin and his team coordinated with the DNR and other partners and began collecting data from these treatments. This amendment will allow us to avoid duplication of effort in our research activities and enable new capacity to evaluate starry stonewort treatment outcomes in Minnesota. The net result will be moving the full budget for Activity 2 ($130,000) to Activity 3 accordingly: $128,421 to personnel, $3,139 to professional services and contracts, $4,460 to equipment/tools/supplies, and $1,750 to travel ($1,000 MN and $750 domestic). • We also request a budget amendment to Activity 3 to redistribute $1,495 from Supplies – lab & field to Services – office & general operating for costs of July 2016 publication of our starry stonewort ecological niche model in the open-access journal Scientific Reports. • We would like to add a line under Personnel for a Research Fellow position funded half-time on this grant for two years. This change does not require a budget amendment. We leveraged two additional sources of funding to enable this position: (1) Michael Verhoeven, a PhD student working on this project, received a competitive 1-year fellowship from the Conservation Sciences graduate program, which reduced costs associated with his position. (2) We received federal funding from the Army Corps of Engineers for research on hybrid milfoil invasion in northern-tier waterbodies. This funding provides the other half of the Research Fellow salary necessary to make this a full-time employment opportunity for two years.

Amendment Approved by LCCMR 2/6/2017

Sub-Project Status as of July 31, 2017: We have advanced progress of our research on several fronts. The completion dates for some outcomes have been amended and three small budget adjustments have been made. These updates are described below.

In the past 6 months, we have continued to address key applied questions in aquatic invasive plant biology and management in Minnesota lakes. Substantial progress has been made on addressing spread risk of starry stonewort using ecological niche modeling. This work has now advanced into lake-level risk prediction for individual Minnesota lakes based on water chemistry variables; findings from this work are being used to guide a statewide MAISRC/Extension citizen-science starry stonewort search effort (see Subproject 10 workplan update). Research on Eurasian watermilfoil and curly-leaf pondweed are elucidating the role of biotic interactions in risk of aquatic plant invasions and the outcomes of herbicide control efforts through compilation, synthesis, and analysis of large-scale datasets. Our work on Eurasian watermilfoil and curly-leaf pondweed includes cross-cutting collaborations with Drs. Ray Newman (Subproject 9) and Przemek Bajer (Subproject 4).

Michael Verhoeven, a graduate student conducting research under this project, was awarded a highly prestigious Graduate Research Fellowship from the National Science Foundation. Carli Wagner, an undergraduate conducting research on starry stonewort in Dr. Larkin’s lab, was awarded first place for her student poster presentation at the annual meeting of the Midwest Aquatic Plant Management Society. Rafael Contreras-Rangel is joining the project as a Master’s student advised by Dr. Larkin following positions with MnDNR and Conservation Corps Minnesota; Rafael was awarded a one-year fellowship by the University.

Research under this award has been presented in peer-reviewed publications (two complete, one in revision, three in review, and several in preparation), research and outreach talks (19 total, 16 invited), and media coverage (12 total, including print, television, and radio).

Anticipated outcome completion dates have been updated. For Activity 3, this includes a later start date for starry stonewort desiccation experiments and completing/analyzing experiments due to difficulties maintaining

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healthy laboratory cultures of starry stonewort—an understudied AIS for which little culturing information is available. For Activity 4, this includes a later date for initial Trackers sampling and quality control testing; this is due to previous delays in fully staffing Extension positions for the AIS Trackers program.

Three budget adjustments have been made. Costs for “Services – office & general operating” for Activities 3, 4, and 5 have been higher than anticipated (due to subscription software for underwater vegetation mapping), while costs for “Services – lab” have been lower than expected because of our purchase of a water quality sonde that performs several of the water chemistry tests we originally intended to submit for laboratory analysis. We have adjusted Activities 3, 4, and 5 to account for this, with the following amounts rebudgeted from “Services – lab” to “Services – office & general operating”: Activity 3 – $824, Activity 4 – $275, and Activity 5 – $275. Because this resulted in no change to the total professional/technical services and contracts category in each activity, no amendment request was required.

Amendment request as of July 31, 2017: We request approval to reallocate resources from Activity 3B to Activity 3D (no budget amendment required). In addition, we request budget amendments to reallocate resources within Travel. We also request approval to specify additional items to be covered under Supplies – Lab & Field. These changes are explained below:

• Under Activity 3B, we planned to test climate tolerance of starry stonewort under laboratory conditions to evaluate whether its spread in Minnesota might be limited by severe winters. We request to remove this from our planned activities for the following reasons: (1) At the time these experiments were proposed, there was only one known, relatively southerly location of starry stonewort in the state (Lake Koronis in Stearns/Meeker Counties), prompting the question of whether starry stonewort could establish farther north under harsher winter conditions. This is no longer the case; a majority of currently known infestations are in northern Minnesota (Cass, Upper Red, Winnibigoshish, Turtle, and Moose Lakes), including very large (>100 acre), well-established infestations (Winnibigoshish and Moose). There is no longer reason to believe that winter conditions are generally limiting within Minnesota. (2) Our experience maintaining cultures of starry stonewort in the lab over the past year indicates that it is difficult to maintain this species in a healthy state over the extended time periods required for adequate climate tolerance tests. And this experience has also shown us that laboratory algaecide trials, which are a high priority for management, will require more personnel time and materials than previously anticipated. Thus, we request to reallocate resources from Activity 3B to Activity 3D (control). This change does not require a budget amendment as resources allocated for climate tolerance tests would remain within Activity 3. • Costs for “Travel – Domestic” have been higher than anticipated, while costs for “Travel – MN” have been lower than expected. This is due to higher costs for attendance of national scientific meetings to share findings from our project and learn about the latest advances from other experts in the field. We have saved money on within-state travel by spending less on personal vehicle mileage and lodging than expected. We request budget amendments to Activities 4 and 5 to account for this, with the following amounts rebudgeted from “Travel – MN” to “Travel – Domestic”: Activity 4 – $750 and Activity 5 – $750. • As we have implemented our research, we have found that answering key questions will require SCUBA diving as part of our fieldwork, in addition to the boat-based work we have been performing. This is true for research addressing spread and control of starry stonewort (Activity 3), Eurasian watermilfoil (Activity 4), and curly-leaf pondweed (Activity 5). Thus we request that description of budget items for “Supplies – lab & field” has been modified to include SCUBA equipment, including wetsuits, regulators, and air for tanks. This does not require additional funds as we have had lower than anticipated costs for other laboratory and field supplies.

Amendment Approved: [08/03/2017]

Sub-Project Status as of January 31, 2018:

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Over the past six months, we have made substantial progress on our research addressing aquatic invasive plant biology and management in Minnesota lakes. We performed experiments testing desiccation tolerance of starry stonewort as part of our assessment of spread risk between lakes. We also established long-term, permanent monitoring locations on two infested lakes to evaluate rates of local spread of starry stonewort within lakes. We have continued to compile and analyze statewide aquatic plant survey data to understand the effects of herbicide treatments, environmental factors, and weather patterns on Eurasian watermilfoil and curly-leaf pondweed abundance and diversity of native plant communities. This work has informed and provided guidance for statewide AIS detection and decision-making through collaboration with Extension, lake associations, watershed districts, and MnDNR.

Since the last workplan update, we have disseminated our findings through (1) peer-reviewed publications (one paper has been accepted since the last update and two manuscripts are currently in revision and one is in review); six invited talks to agency staff, other researchers, and the public; two contributed talks at national scientific meetings; and 12 print, television, and radio stories.

Amendment request as of January 31, 2018: We request budget amendments to Activities 1, 3, 4, and 5 to balance higher than anticipated costs for Travel with lower than anticipated costs for Professional Services and Equipment/Tools/Supplies. Specifically:

For Activity 1 (change from $130,000 to $125,412, net: −$4,588): • Services – Lab would change from $300 to $0 due to lower than anticipated costs for this category. • Supplies – Office and Gen. Op. would change from $7,000 to $4,550 due to lower than anticipated costs for this category. • Supplies – Lab & Field would change from $4,600 to $2,762 due to lower than anticipated costs for this category.

For Activity 3 (change from $413,193 to $414,781, net: +$1,588): • Travel – MN would change from $3,633 to $5,221 due to higher than anticipated costs for this category. This is due to the size of the team needed for field work, the duration of fieldwork that our sampling requires, and the distance of starry stonewort lakes from St. Paul (2 to 4+ hour drives).

For Activity 4 (change from $139,403 to $140,903, net: +$1,500): • Travel – Domestic would change from $1,500 to $3,000 due to higher than anticipated costs for this category. This travel is necessary to present our findings at national scientific meetings, where we are able to interact with leading aquatic ecologists and invasive species researchers to familiarize them with our work and learn about the latest scientific advances in the field.

For Activity 5 (change from $139,403 to $140,903, net: +$1,500): • Travel – Domestic would change from $1,500 to $3,000 due to higher than anticipated costs for this category. This travel is necessary to present our findings at national scientific meetings, where we are able to interact with leading aquatic ecologists and invasive species researchers to familiarize them with our work and learn about the latest scientific advances in the field.

Amendment Approved: [02/16/2018]

Sub-Project Status as of July 31, 2018: We continued to publish manuscripts from our research on starry stonewort spread and management (Activity 3) and have initiated laboratory experiments to test effectiveness of different algaecides/herbicides and concentrations for products that are currently being used for starry stonewort treatments in Minnesota but have not been subject to rigorous evaluation through published, peer-reviewed experiments.

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We continue to acquire and synthesize monitoring data from statewide treatments for Eurasian watermilfoil (Activity 4) and curly-leaf pondweed (Activity 5). For both of these species, we have also initiated in-lake removal experiments to determine whether effective control of these AIS is sufficient to support recovery of native aquatic plant communities or whether additional management strategies (e.g., water quality improvement, native plant seed addition) are needed to restore native aquatic vegetation.

Over the last reporting period, we have communicated our findings through 3 peer-reviewed journal articles, 7 invited talks, 4 contributed presentations, and over 13 print, radio, and television stories.

Amendment request as of July 31, 2018: We request that description of budget items under “Supplies – lab & field” be modified to enable purchase of a watertight hybrid tablet for performing underwater light measurements in the field. Light availability is a major factor determining distribution and impacts of invasive aquatic plants. For our research on starry stonewort, Eurasian watermilfoil, and curly-leaf pondweed (Activities 3, 4, and 5), we have access to shared MAISRC instrumentation for measuring irradiation underwater (an Ocean Optics spectrometer). However, operation of the spectrometer requires connection to a device running a computer operating system (Windows, MacOS, or Linux) and we have no laptops suitable for on-water use. We request permission to purchase a Surface-style hybrid tablet with waterproof case and Windows operating system as a cost-effective means to increase our fieldwork capacity and efficiency. This request does not require any additional funds or rebudgeting.

Amendment Approved: [07/31/2018]

Sub-Project Status as of January 31, 2019: We continued to publish manuscripts from our research on starry stonewort spread (Activity 3) and are continuing to conduct laboratory experiments testing the effectiveness of different algaecides/herbicides being used for starry stonewort treatments that have not been subject to rigorous evaluation through published, peer- reviewed experiments.

We continue to acquire and synthesize monitoring data from statewide treatments for Eurasian watermilfoil (Activity 4) and curly-leaf pondweed (Activity 5). For both of these species, we have made substantial progress on in-lake removal experiments to determine the extent to which control of these AIS is sufficient to foster recovery of native aquatic plant communities or whether additional management interventions are needed to restore native vegetation.

Over the last reporting period, we have communicated our findings through 2 peer-reviewed journal articles, 6 presentations, and 8 media stories.

Amendment Request January 31, 2019: We also request budget amendments to Activities 3, 4, and 5 to offset greater than expected costs for in-state travel for fieldwork for Activities 4 and 5 with lower than expected costs for lab and field supplies for Activity 3. Specifically: Activity 3 – change from $414,781 to $413,925; Net: −$856 • Supplies – Lab & Field would change from $11,705 to $10,849 due to lower than anticipated costs for this category. Activity 4 – change from $140,903 to $141,403; Net: +$500 • Travel – MN would change from $1,883 to $2,383 due to higher than anticipated costs for this category. This is due to the amount of fieldwork required to sample and perform experiments related to Eurasian watermilfoil. Activity 5 – change from $140,903 to $141,259; Net: +$356

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• Travel – MN would change from $1,883 to $2,239 due to higher than anticipated costs for this category. This is due to the amount of fieldwork required to sample and perform experiments related to curly-leaf pondweed.

Amendments Approved: 03/18/2019

Amendment Request June 10, 2019: We request budget amendments to Activities 3, 4, and 5 to balance higher than expected costs for Activities 4 and 5 with lower than expected costs for Activity 3. Specifically: Activity 3 – decrease total Activity 3 budget from $413,925 to $411,374; Net: −$2,551 • Services – Office & Gen Op would change from $2,497 to $2,206 due to lower than anticipated costs for this category. • Repairs would change from $1,680 to $854 due to lower than anticipated costs for this category. • Auto Insurance would change from $2,880 to $2,142 due to lower than anticipated costs for this category. • Supplies – Lab and Field would change from $10,849 to $10,153 due to lower than anticipated costs for this category. Activity 4 – increase total Activity 4 budget from $141,403 to $142,543; Net: +$1,140 • Personnel would change from $128,421 to $130,671 due to higher than anticipated costs for this category, i.e., the labor-intensive nature of the fieldwork required to sample and perform experiments related to Eurasian watermilfoil. • Auto Insurance would change from $960 to $715 due to lower than anticipated costs for this category. • Supplies – Lab and Field would change from $4,400 to $3,735 due to lower than anticipated costs for this category. Activity 5 – increase total Activity 5 budget from $141,259 to $142,670; Net: +$1,411 • Personnel would change from $128,421 to $130,671 due to higher than anticipated costs for this category, i.e., the labor-intensive nature of the fieldwork required to sample and perform experiments related to curly-leaf pondweed. • Auto Insurance would change from $960 to $714 due to lower than anticipated costs for this category. • Supplies – Office & Gen Op would change from $60 to $132 due to higher than anticipated costs for this category. • Supplies – Lab and Field would change from $4,400 to $3,735 due to lower than anticipated costs for this category.

Amendment Approved by LCCMR: 07/02/2019

Overall Sub-Project Outcomes and Results: Aquatic invasive plants can lower native plant diversity, reduce habitat quality for fish and other animals, and interfere with recreation. To protect Minnesota’s water resources, steps need to be taken to prevent new invasions, control existing populations, and support recovery of native biodiversity. These efforts require sound, science-based guidance. To provide such support, we conducted research to predict invasion risk, assess ecological impacts, evaluate control efficacy, and investigate factors limiting post-control recovery of native aquatic plants. This work was applied to three target species at different stages of invasion: (1) Nitellopsis obtusa (starry stonewort), first found in Minnesota in 2015 and now known in 14 lakes; (2) Myriophyllum spicatum (Eurasian watermilfoil), found in 1987 and established in >300 lakes; and (3) Potamogeton crispus (curly-leaf pondweed), here for >100 years and in >750 lakes. For starry stonewort, we developed models to predict risk of further spread and prioritize search locations for statewide volunteer search efforts, experiments to determine how long starry stonewort remains can survive out of water (i.e., remain transportable by boaters), and field and lab-based control experiments to guide management. For Eurasian watermilfoil and

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curly-leaf pondweed, we investigated relationships with native plant biodiversity, finding that they displace native species, an effect compounded by lower water clarity, and contribute to “biotic homogenization”—loss of ecological distinctiveness. We are investigating how to better control these invasive species and foster recovery of native vegetation by synthesizing thousands of aquatic plant surveys and management records collected in Minnesota and by conducting in-lake removal and restoration experiments. This work will continue under a follow-on project (Subproject 8.2: Impacts of invader removal on native vegetation recovery). Our findings help Minnesotans by highlighting practices needed to protect lake ecosystems and refining approaches for preventing invasions, reducing populations of established AIS, and restoring native species.

IV. SUB-PROJECT ACTIVITIES AND OUTCOMES:

ACTIVITY 1: Aquatic Invasive Plant Project Development Description: Funding for this subproject has been leveraged to create a new tenure-track assistant professor and Extension specialist position (a 60% extension and 40% research appointment), which is filling not only a state, but a nationwide need in the area of invasive submersed macrophyte control and macrophyte ecology, restoration, and management.

Dr. Dan Larkin has been hired into this position and will start work August 31, 2015 to develop and lead subproject 8. Dr. Larkin will begin by meeting with resource managers, researchers, Extension staff, and other partners around the state to understand needs, identify research gaps, and formulate his research and Extension plans. His project development will also include travelling to evaluate potential field sites within the state and starting to assemble his laboratory and field capacity with purchase of key supplies and equipment.

Dr. Larkin’s plan will be submitted to MAISRC through the process described in the center’s MOU and will involve a pre-proposal presentation to seek input from MAISRC faculty and Extension staff followed by a full proposal submission to MAISRC. After receiving feedback through peer review of his proposal, Dr. Larkin will make any revisions necessary to his proposal and then develop an LCCMR workplan and budget. Once Dr. Larkin’s research proposal, workplan and budget have been approved by MAISRC, it will be amended to this workplan and budget and submitted to LCCMR for approval.

Summary Budget Information for Activity 1: ENRTF Budget: $125,412 Amount Spent: $125,412 Balance: $0 Activity Completion Date: Outcome Completion Date 1. Proposal submission to MAISRC for evaluation and peer review October 31, 2015 2. Revisions following peer review submitted to MAISRC February 15, 2016 3. Workplan submission to LCCMR March 15, 2016 4. Aquatic invasive plant project implementation April 15, 2016 5. Final subproject deliverable June 30, 2019

Activity Status as of May 3, 2016: Dr. Larkin’s full research proposal has been peer reviewed through the Center process, revisions were made, and its workplan and budget approved by MAISRC. An amendment is now being requested to add these activities to the workplan. Additionally, an ecological niche model has been developed to determine the threat of starry stonewort spread in Minnesota. The model indicated that this species is persisting in novel habitats – meaning that it is occurring in areas here that are climatically distinct from its native range, and that conditions in portions of the upper Midwest and other regions in the U.S. are ideal for its growth and spread. Additionally, a convening in the next month of researchers and managers with starry stonewort experience is being led by Dr. Larkin to determine current research and management knowledge and gaps. There will be a public webinar hosted in conjunction with this meeting. 9

Activity Status as of January 31, 2017: Proposal submission to MAISRC for evaluation and peer review, revisions following peer review submitted to MAISRC, and workplan submission to LCCMR are completed. Aquatic invasive plant project implementation is underway.

Activity Status as of July 31, 2017: Aquatic invasive plant project implementation is underway.

Activity Status as of January 31, 2018: Aquatic invasive plant project implementation is underway.

Activity Status as of July 31, 2018: Aquatic invasive plant project implementation is underway.

Activity Status as of January 31, 2019: Aquatic invasive plant project implementation is underway.

Final Report Summary: Aquatic invasive plant research was initiated under this activity, leading to funding approval for a peer-reviewed research program, establishment of a new research team at UMN, and successful implementation of all following activities.

ACTIVITY 3: Assessing risk of further starry stonewort spread in Minnesota lakes and evaluating control options

Description: Starry stonewort is a relatively new invader for North America and very new to Minnesota. Starry stonewort has an extensive native range in Europe and Asia, but is rare across most of that range—even classified as a priority conservation species in the United Kingdom and endangered in Japan. Despite its rarity as a native species, starry stonewort is expanding rapidly throughout the Great Lakes region. It is now widespread in Michigan’s Lower Peninsula, increasing in New York, and has recently been recorded for the first time in Indiana (2012), Wisconsin (2014), and Minnesota (2015). Unfortunately, there has been little applied research on starry stonewort, limiting our capacity to prevent and respond to new infestations. There have been only five peer-reviewed publications addressing starry stonewort as a non-native species in North America, and only one of those has been published since 1991. However, it is clear that starry stonewort can spread quickly within lakes and produce nuisance growth that interferes with recreation, it likely displaces native plants, and it may affect habitat quality for fish and other animals. When discovered in Lake Koronis, it already extended >250 acres. Starry stonewort is dioecious, and only males have been found in the U.S. to date, indicating that spread has been by movement of clonal (non-sexually reproductive) propagules—fragments and star-shaped reproductive structures called “bulbils.” In addition, occurrences have been concentrated near boat ramps and other high-use areas, implicating movement by boaters. There is great concern about starry stonewort, but little ecological knowledge to predict future spread and a limited toolkit available for its control.

A. Predicting risk of future starry stonewort spread in Minnesota

Ecological niche modeling for starry stonewort is underway. We used occurrence data from 8 countries, 19 climate variables, and remotely sensed environmental data to characterize the environmental niches occupied by starry stonewort in its native and invaded ranges. Initial findings indicate that starry stonewort has expanded into regions of the U.S. with climate conditions distinct from those found in its native range. Roughly one-third of Minnesota appears to constitute suitable habitat for starry stonewort, as do large portions of the Intermountain West, Great Plains, and Mid-Atlantic—areas with no known occurrences to date. 10

Next we will scale down risk assessment to individual lakes within Minnesota. We will use starry stonewort occurrence records from other states and associated environmental data (lake depth and size, water clarity, water chemistry, etc.) to characterize the types of lakes that constitute the best habitat for this species. We will then analyze environmental data for Minnesota lakes to identify those that most closely match these conditions. Information on human use and development will be incorporated to assess likelihood of introduction from source populations. This research will allow us to move from predicting starry stonewort invasiveness at a regional scale to predicting invasibility for individual lakes. Lakes identified as high risk will be recommended for targeted surveillance by the Detectors program, a MAISRC/ Extension program involving citizen scientists in AIS early detection efforts.

B. Intentionally Omitted

C. Laboratory experiments testing starry stonewort desiccation resistance

Spread of starry stonewort to new lakes appears to be through unintentional human movement, but how long it remains viable out of water is unknown. Healthy starry stonewort material (bulbils and shoots) will be subsampled from cultures, weighed, and randomly assigned to treatments. Large numbers will be used in each treatment (n ≈ 100) to account for potentially high variability. We will also evaluate different sized clumps of material, as larger clumps are likely to dry more slowly. Controls will be returned to water; desiccation treatments will be placed in environmental chambers for 24 hours, 2 days, or 5 days, mimicking time on land on a contaminated boat. Temperature, photoperiod, and humidity in chambers will be set to mimic summer conditions in Minnesota. If material rapidly dies or is still viable after 5 days, we will add shorter or longer time periods. At the end of each time period, treated and control materials will be reweighed and returned to water. Viability will be assessed by observing growth, inducing sprouting of bulbils, or using stains that bind to dead algal tissue. Material will then be dried and dry weight of control and desiccation treatments compared.

D. Laboratory experiments testing starry stonewort control options and non-target impacts to native plant species

We will use a two-phase approach to test herbicides for controlling starry stonewort. Small-scale, high- replication assays will be performed in environmental chambers using shoot segments and bulbils subject to different herbicides and concentrations. Herbicides with high effectiveness relative to controls will be included in more realistic tests using whole plants rooted in sediment. These tests will be performed in the MAISRC research facility, which has dedicated bench space for aquatic plant experiments. Chelated copper compounds are the main algaecides used for starry stonewort control; these are available in a variety of formulations, which can vary in efficacy. In addition, non-copper contact herbicides can also be used. We will test different copper formulations and the herbicides diquat and alkylamine endothall, both alone and in combination with copper. Control treatments will include low, medium, and high use rates per label recommendations to achieve different concentration/exposure times. Initial assays will be monitored at multiple time points for up to 14 days. Masses of bulbils and masses and lengths of shoots will be measured pre- and post-treatment and material will then be dried and weighed. Whole-plant tests will last ~28 d. Signs of injury will be visually monitored throughout the experiment. At the conclusion of experiments, above and belowground biomass will be harvested, dried, and weighed. For all tests, efficacy will be evaluated by analyzing measures of treated materials (length, mass, injury, etc.) relative to controls. Starry stonewort treatments need to not only be effective but also selective, so that harm to native species is minimized. Along with starry stonewort control tests, we will also expose native species to the same treatments. Copper compounds can be used for control of vascular plants as well as algae and are likely to have non-target effects on some native vascular plant species, as well as native charophytes, which are numerous in Minnesota. Species tested will include native charophytes closely related to starry stonewort and ecologically important vascular plants. Final selections will be based on availability of plant materials, what can be cultured in the MAISRC facility, and consultation with stakeholders and experts. Examples of candidate species include

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the charophytes Chara aspera (rough stonewort), Chara contraria (fetid stonewort), and Nitella flexilis (slender nitella) and the vascular plant species Elodea canadensis (Canadian waterweed), Vallisneria americana (water celery), Potamogeton illinoensis (Illinois pondweed), and Myriophyllum sibiricum (northern watermilfoil).

E. Field sampling to evaluate outcomes of starry stonewort control efforts in Minnesota lakes

Determining how to best control AIS requires a multi-faceted approach that integrates controlled experimental work with “real world” outcomes of actual in-lake management efforts. As of winter 2017, there are now 9 lakes in Minnesota known to have starry stonewort, and control efforts have begun in 7 of these lakes. This large increase in management activities since last spring offers new opportunities to conduct research on in-lake outcomes of starry stonewort treatments. Treatments to date include a mix of chemical and mechanical techniques. Chemical treatment has included copper-based algaecides and non-copper herbicides. Algaecide treatments have further included both liquid algaecides targeting aboveground plant biomass and use of granular algaecides intended to target starry stonewort bulbils to minimize reinvasion. Mechanical treatments have included use of mechanical harvesters, suction dredging, and diver-assisted suction harvesting. Furthermore, treatments have been applied as partial treatments of larger infestations to trial methods (e.g., in Lake Koronis) and as attempts to remove all starry stonewort from smaller infestations (e.g., in Lake Sylvia). These various efforts—which are largely operating by trial-and-error due to a lack of previous research that can guide management—present important opportunities to advance adaptive management of starry stonewort if sufficient, rigorous data are collected so that we can learn from them. We are working with the DNR, lake associations, and private-sector service providers to evaluate outcomes of these efforts. Where possible, we are sampling both before and after treatments and in both treated areas and untreated reference locations. We plan to conduct multi-year monitoring to evaluate longer- term trajectories of these efforts.

Summary Budget Information for Activity 3: ENRTF Budget: $411,374 Amount Spent: $411,374 Balance: $0 Activity Completion Date: Outcome Completion Date A1. Starry stonewort ecological niche modeling completed and paper published January 31, 2017 A2. Begin lake-level risk assessment for starry stonewort January 31, 2017 A3. Complete risk assessment and present results to MNDNR and other stakeholders July 31, 2018 C. Begin lab experiments testing starry stonewort desiccation resistance September 30, 2017 D. Begin laboratory experiments testing starry stonewort control options and non- January 31, 2017 target impacts to native plant species E. Begin field sampling to evaluate outcomes of starry stonewort control efforts in January 31, 2017 Minnesota lakes B–E. Complete experiments, analyze data, and present results to stakeholders June 30, 2019 A–E. Complete manuscripts and submit for peer review June 30, 2019

Activity Status as of January 31, 2017: Our ecological niche model for starry stonewort (in collaboration with Dr. Phelps’ MAISRC research group) was published in the journal Scientific Reports. We found that starry stonewort is occupying a climate niche in North America that differs from the climatic niche within which it occurs in its native range. This “niche shift” may partly explain its growing success in the U.S. as an invasive species—despite being a species that is threatened and even endangered in parts of its native range. Based on our estimation of its ecological niche, we predict that substantial areas of North America with no known starry stonewort occurrences (including portions of the Mid- 12

Atlantic, Great Plains, and Intermountain West) may be vulnerable to invasion should it be introduced into suitable waterbodies in those regions. A second paper addressing the potential effects of climate change on future starry stonewort distribution in Minnesota is currently in revision.

We have begun to perform lake-level prediction of starry stonewort invasion risk for Minnesota. Past research from elsewhere in starry stonewort’s native and invaded ranges provide data on water chemistry and other environmental variables associated with starry stonewort occurrence. We are integrating this information with statewide lake data from the MPCA to predict suitability of Minnesota lakes for starry stonewort. Preliminary results indicate that starry stonewort is more likely to invade lakes with higher pH and conductivity, predicting higher suitability in southern and central Minnesota lakes.

Laboratory work related to starry stonewort requires adequate plant material for use in experiments. We first collected starry stonewort from Lake Koronis in July 2016 and have been maintaining cultures in the MAISRC Containment Laboratory (MCL) since that time (Figure 1). The cultures have ebbed and flowed, with some plants dying while others have persisted. We have experimented with different tank sizes, growth substrates, nutrient additions, light intensities, and other factors to improve persistence. This refinement of culture conditions is ongoing. We have been able to keep plants alive and to grow new plants from bulbils; we hope to achieve increased vitality and biomass production.

We have also performed laboratory experiments to test outcomes of starry stonewort control efforts. It has become a common method to treat starry stonewort infestations first with liquid copper-based algaecides to reduce plant biomass and then follow up with granular algaecides intended to kill bulbils to prevent starry stonewort regrowth. We collected bulbils from areas of Lake Koronis that had been subjected to different management (algaecide only, algaecide + mechanical harvesting, untreated control) and have been tracking their germination in the lab. We are integrating these results with monitoring data collected by a third-party evaluator contracted by the Koronis Lake Association (KLA). Our preliminary findings indicate that treatments were effective in reducing starry stonewort biomass. However, bulbil production was high in treated areas, particularly in areas treated only with algaecide. Bulbil viability was uniformly high (approximately 65-75% of collected bulbils germinated over a two-month period) and was not impaired by algaecide treatment—including granular algaecide used specifically for bulbils. Thus, while treatments were effective in providing temporary reduction of nuisance growth, the potential for regeneration from bulbils appears to be high. This work is currently being prepared for submission to a peer-reviewed journal.

In summer-fall 2016, we sampled starry stonewort populations in 6 lakes, of which 5 were being treated. We also coordinated with MnDNR to share data and ensure good coverage from our collective monitoring efforts. We are also collaborating with biologists from the Wisconsin DNR, which has a similar number of infested lakes and where similar treatment efforts are underway. We have assembled metadata from both states documenting what treatments and monitoring have been applied where, so that we can synthesize outcomes to inform future management efforts.

The impacts of our starry stonewort research have been expanded through collaboration, outreach, and service to management agencies. We organized and led an international working group on starry stonewort. This meeting culminated in a webinar attended live by over 140 participants from Minnesota and other states and archived on the MAISRC website (http://www.maisrc.umn.edu/news/ssw-webinar). We will soon be submitting a review paper on ecology, invasion, and management of starry stonewort as a product of this effort. We also prepared and distributed a starry stonewort FAQs document and are developing a website to provide technical assistance to stakeholders impacted by starry stonewort. In addition, the working group led to a new research collaboration with Dr. Ken Karol (New York Botanical Garden) and a new extension collaboration with Paul Skawinski (University of Wisconsin-Extension). In addition, Dr. Larkin provides technical assistance on an ad-hoc basis to several lake associations and other stakeholders regarding starry stonewort invasion and management. He also serves on the DNR’s Starry Stonewort Guidance Group.

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Activity Status as of July 31, 2017:

In collaboration with Dr. Phelps’ MAISRC research group, a paper on potential future distribution of starry stonewort in Minnesota under different climate change scenarios was published in the journal PLoS ONE. Under present climate, the most climatically suitable areas for starry stonewort are predicted to be found in central and southeastern Minnesota. In the future, suitable areas for starry stonewort are predicted to shift in geographic range under some future climate models and to shrink under others.

We have developed lake-level risk maps based on water chemistry variables for starry stonewort invasion in Minnesota and Wisconsin (Figure 1). A manuscript based on this work is at an advanced stage of preparation and will be submitted shortly. Risk predictions are being used to guide prioritization of search locations for “Starry Trek,” a statewide citizen-science search effort to identify new starry stonewort infestations (See workplan update for Subproject 10—Aquatic Invasive Species Research Center Sub-Project 10: Citizen Science and Professional Training Programs to Support AIS Response).

We completed field and lab research investigating response of starry stonewort to mechanical and algaecide treatments performed in Lake Koronis in summer 2016. We found that mechanical harvesting and algaecides reduced starry stonewort biomass but did not impair viability of starry stonewort bulbils, indicating high potential for regeneration. This work has been developed into a manuscript to be submitted soon for peer review. An undergraduate researcher mentored by Dr. Larkin, Carli Wagner, was awarded first prize for student poster presentation at the Midwest Aquatic Plant Management Society Annual Meeting for her presentation of these findings.

Dr. Larkin has continued to lead an international working group on starry stonewort (the Nitellopsis working group) to synthesize the current state of knowledge and key research needs on the biology, ecology, invasion, and management of starry stonewort in the U.S. and internationally. The group has completed a review paper on starry stonewort, which has been submitted for publication and is currently in review.

We continue to refine methods for maintaining cultures of starry stonewort. In recent weeks, starry stonewort maintained in the lab since July 2016 has experienced dramatic declines. We will be collecting new plants and restarting cultures this summer to attempt to establish more robust material for laboratory experiments. Other ongoing research activities this summer include sampling of starry stonewort-invaded lakes, with a particular emphasis on Lake Koronis and Moose Lake because of their very extensive, well-established infestations, and experiments to evaluate desiccation tolerance.

Activity Status as of January 31, 2018:

The Nitellopsis Working Group’s review paper on biology, ecology, and management of starry stonewort has been accepted for publication in the journal Aquatic Botany pending minor revisions. Figure 1. Starry stonewort risk map based on lake-level water chemistry variables. Color scale indicates predicted low (blue) to high (red) risk based on an ecological niche model using a random forests algorithm. Black diamonds are known infestations. Muthukrishnan et al. (In prep). 14

The model developed to predict lake-level 1.0 starry stonewort invasion risk in Minnesota and Dry control 0.9 Wisconsin has been completed, submitted for * publication (currently in review), and 0.8 presented through several invited talks to * national, state agency, and public audiences. 0.7 This model was used to prioritize search locations for our successful Starry Trek event 0.6 (see Subproject 10 Workplan Update). The new 0.5 infestation that was discovered through Starry

Trek was identified as a high risk lake by our 0.4 model. lost mass of Proportion *

0.3 We submitted a manuscript on the effects of mechanical and algaecide treatments for starry 0.2 stonewort control in Lake Koronis. The manuscript received positive reviews and has 0.1 been revised and is currently awaiting the 0 editor’s decision. Results from this work were 0.25 hr 0.5 hr 1 hr 2 hr 4 hr 6 hr 12 hr 24 hr 48 hr 72 hr 120 hr D con presented at the annual Minnesota Aquatic Figure 2. Proportion of starry stonewort mass lost as a function of Invasive Species Research and Management desiccation time treatment for starry stonewort fragments (0.5 g). Points and error bars are means ± 1 SE. Points marked with an * indicate a Showcase in September 2017 and the significant difference between that treatment and the fully dried (positive) Clearwater River Watershed District AIS Forum control. At the 2-hr time point, fragments were completely dried. in January 2018.

We performed field and laboratory experiments to test the effects of desiccation on starry stonewort shoot and bulbil viability in order to evaluate risk of overland spread. For each experiment, we removed starry stonewort shoots and bulbils from water and exposed them to ambient drying for intervals ranging from 15 minutes to 5 days. We then rehydrated the material to simulate reintroduction to an aquatic environment. Shoot material was weighed before and after desiccation and following rehydration and weights of desiccated material from each drying interval was compared to weights for negative controls (wet material that was never dried) and positive controls (material that was completely desiccated in a drying oven) to determine how long starry stonewort can remain viable out of water. Bulbil viability was evaluated using a combination of a stain (tetrazolium) that indicates respiration and sprouting. We have analyzed these data and are in the process of preparing a manuscript for peer review. Results indicate that starry stonewort fragments (0.5 g) were no longer viable after 2 hours of drying (Figure 2), small clumps (5 g) were no longer viable after 24 hours of drying, and large clumps (45 g) were no longer viable after 72 hours of drying. Bulbils were no longer viable after 4 hours of drying. These results will inform efforts to understand and prevent starry stonewort spread via overland transport by boaters.

We continued starry stonewort sampling efforts on Lake Koronis and Moose Lake and set up long-term monitoring stations in both lakes to determine local (within-lake) rates of spread of starry stonewort. To do this, we placed underwater transects across gradients of starry stonewort invasion – from highly invaded areas to areas that are currently uninvaded. We sampled starry stonewort and the associated plant community using a combination of diving to assess underwater quadrats and biomass sampling from a boat. This effort will allow us to assess rate of spread of starry stonewort and begin to assess impacts on lake plant communities.

We have successfully reestablished starry stonewort cultures in the lab using a combination of fresh shoot material and bulbils from Lake Koronis. The health of our cultures has improved through increased filtration to remove nuisance filamentous algae and increases in CO2 concentrations. We will use material from these

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cultures for experiments to test algaecides for starry stonewort control, an activity that will form the basis for Master’s research by a new graduate student, Rafael Contreras-Rangel, who started in August 2017.

Activity Status as of July 31, 2018: The Nitellopsis Working Group’s review paper on biology, ecology, and management of starry stonewort has been published in Aquatic Botany (https://www.sciencedirect.com/science/article/pii/S0304377017303820), where it is currently listed as one of the most downloaded articles of the last 90 days.

Our manuscript in collaboration with the Koronis Lake Association and Blue Water Science on outcomes of starry stonewort control efforts in Lake Koronis was published in Lake and Reservoir Management (https://www.tandfonline.com/doi/abs/10.1080/10402381.2018.1442893). The paper received national coverage through the Associated Press (www.apnews.com/b11f6db81d1f4ae39e02b36c4e89d67c/Research-on- fighting-starry-stonewort-yields-limited-success).

Our paper on starry stonewort invasion risk based on lake water chemistry has been revised and resubmitted and is pending acceptance.

We presented results of our starry stonewort desiccation tolerance experiments (research to assess risk of overland spread of starry stonewort by boaters) through several invited talks and have prepared a manuscript on these results that is close to being ready for submission.

We have begun the pilot phase of our laboratory algaecide trials for starry stonewort control. We are currently testing starry stonewort responses to different concentrations of a copper algaecide to standardize protocols for quantifying plant injury/mortality through visual observations, biomass measures, and chlorophyll spectrofluorometry. We are able to consistently produce healthy plants by sprouting bulbils and after finalizing protocols will be able to transition into full implementation of laboratory trials.

Activity Status as of January 31, 2019: Our paper on starry stonewort invasion risk based on lake water chemistry was published in Aquatic Botany (https://www.sciencedirect.com/science/article/pii/S0304377018300081?via%3Dihub).

This invasion risk prediction was again used to prioritize search locations for our second annual Starry Trek event (see Subproject 10 Workplan Update), which again yielded a new starry stonewort detection. In this case, the first population to be identified in Hubbard County.

A paper on starry stonewort spread risk based on boater movement, in collaboration with Dr. Phelps’ research group, was published in Journal of Oceanology and Limnology (https://link.springer.com/article/10.1007%2Fs 00343-019-7208-z).

Our paper on desiccation tolerance of starry stonewort (to assess risk of overland transport by boaters) is at an advanced stage of preparation and will be submitted to Journal of Aquatic Plant Management.

We continue to work on laboratory algaecide trials for starry stonewort control. Unfortunately, the graduate student performing this research has taken a medical leave of absence, which has delayed our progress on this outcome. We still expect to complete the planned trials on efficacy of algaecides for starry stonewort control, but we will not be able to complete the further step of testing non-target impacts of algaecides on native species (see amendment requested above). Funds for that portion of Activity 3 will be retained within the algaecide trials work. Non-target impacts of algaecide on non-target plants are an important question and will potentially be addressed in future research on starry stonewort control.

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Final Report Summary: Our paper on desiccation tolerance of starry stonewort as an indicator of overland spread risk has been accepted for publication in the Journal of Aquatic Plant Management.

We completed laboratory algaecide trials for starry stonewort control. These trials consisted of two separate fully controlled and replicated experiments assessing effects of algaecides on starry stonewort bulbils and starry stonewort stems. For each experiment, we evaluated six different algaecides (CaptainXTR, Komeen, Nautique, CutrineUltra, CutrinePlus, and AlgimycinPWF) at five different concentrations (0.125, 0.25, 0.5, 0.75, and 1.0 ppm), i.e., spanning a range of products and achieved concentrations representative of in-lake starry stonewort control efforts. For the bulbil experiment, we evaluated bulbils both underneath and on top of sediment to simulate realistic within-lake conditions. We placed bulbils in jars with water and sediment, treated jars with each algaecide at each concentration, and then observed jars for sprouting for 10 weeks. Our results indicate that the algaecides we examined had little effect on bulbil sprouting compared to controls regardless of algaecide or concentration (Figure 3), but that sprouting was much higher when bulbils were underneath the sediment. These results correspond with field observations of bulbil resistance to algaecides. For the stem experiment, we allowed bulbils to sprout and grow for six weeks before treating. We assessed the effects of algaecide treatment at 1, 7, 14, and 21 days following application by examining stem condition (e.g., stem height and color) and harvesting the stems at day 14 and 21 to measure wet and dry biomass. As expected, higher algaecide concentrations caused greater deterioration of stem condition, regardless of the type of algaecide used. At higher concentrations, all algaecides performed similarly. The results from these trials will inform starry stonewort treatment efforts and inform realistic expectations for treatment outcomes.

Figure 3. Percent of bulbils spouted in the algaecide trails for bulbils placed underneath the sediment. Data from all concentrations are combined for each algaecide.

Overall under this activity, we used climate-based models to assess risk of further starry stonewort spread in the state, water-chemistry based models to predict lake-level risk and prioritize search locations for statewide volunteer search efforts, experiments to determine how long starry stonewort remains viable out of water, and field and lab-based control experiments to develop guidance for management.

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ACTIVITY 4: Eurasian watermilfoil management: Factors influencing invasion, treatment effectiveness, and post-treatment recovery of native vegetation Description: Eurasian watermilfoil is native to Europe and Asia and was first found in Minnesota in 1987 in Lake Minnetonka. Management efforts in the years since have employed mechanical harvesting, biocontrol, and herbicides. Research and monitoring have shown that eradication is rarely possible, but that infestations can be strategically managed to minimize negative impacts while avoiding unintended damage to native vegetation, which can be harmed by overly aggressive management. There is large variability among lakes in the extent to which Eurasian watermilfoil reaches nuisance growth levels. There is also high variation in the outcomes of treatment efforts. In some cases, management can greatly reduce Eurasian watermilfoil abundance and facilitate recovery of native plants. In other cases, control has been minimally effective or native plants have not recovered. This is an area with high potential for coordinated research-management partnerships to improve management effectiveness. We will address this area of need by synthesizing and analyzing existing monitoring datasets, performing new field work, and developing new capacity in the state for citizen scientists to contribute to monitoring treatment outcomes.

A. Factors influencing spread and nuisance growth of Eurasian watermilfoil

It has been estimated that as many as 4,700 more Minnesota lakes could become invaded by Eurasian watermilfoil. So while this species is not new to the state, it will continue to invade new lakes, posing challenges for affected property owners and lake users. We will use the approaches described above for hydrilla and starry stonewort to assess invasion risk for individual lakes in Minnesota that have not yet been invaded by Eurasian watermilfoil. There is much more information available about Eurasian watermilfoil invading Minnesota lakes than there is for the potential and new invaders, hydrilla and starry stonewort. Thus we can delve deeper with this species, investigating factors that influence outcomes of invasion, specifically, the extent to which it aggressively spreads within a lake, reaching nuisance levels vs. remaining a relatively minor, less harmful component of lake vegetation. We will synthesize existing monitoring data from MNDNR, watershed districts, and other partners to identify factors that influence invasion outcomes. Surrounding land use, lake characteristics, and water and sediment properties are likely factors affecting invasion extent and we will test these as potential predictors. In addition, invading species’ success is shaped by their interactions with organisms already found in a habitat. It has been shown in a variety of systems that, where native plants are more abundant and diverse, there can be “biotic resistance” to invasive plants, so that while new species may invade, they are less likely to become dominant. We will test whether there is evidence of this phenomenon in Minnesota lakes using large-scale, long-term lake monitoring datasets from MNDNR. Because “nature abhors a vacuum,” it may be that one way we can help prevent nuisance growth of Eurasian watermilfoil and other invasive plants is through management that supports diverse communities of native aquatic plants.

B. Identifying best practices for controlling Eurasian watermilfoil and supporting post-treatment recovery of native plant species

Ongoing management of Eurasian watermilfoil and other invasive plants represents a largely untapped opportunity for “learning while doing” about treatment efficacy. Control efforts are numerous; each treatment is a potential replicate in a large-scale experiment—if necessary information about management actions, environmental conditions under which treatments are applied, and key ecological responses can be captured and analyzed. We will pursue this through a coordinated program of synthesizing existing monitoring data, performing new field research, and developing capacity for citizen scientists to contribute to monitoring outcomes of AIS management efforts. With other MAISRC researchers and an Extension Educator, we will develop a program called “Trackers” to train volunteers to monitor AIS abundance changes over time and in response to management, initially focusing on Eurasian watermilfoil (with parallel development of zebra mussel monitoring). Sampling will include pre/post monitoring and untreated control and reference sites to differentiate management effects from background variability. Along with species sampling, Trackers will record environmental data, such as water and 18

Secchi depths, and management information. Participants will enter results into a centralized database hosted and managed by the University of Minnesota. We will perform follow-up sampling at subsets of Trackers sites for quality assurance of citizen science data and methods will be revised if issues are identified. In addition, many past treatments have been monitored under lake vegetation management plans, but this information has rarely been synthesized. We will work with MNDNR and watershed districts to compile this information. By capturing data from ongoing management, we will increase capacity for collective learning about treatment efficacy, identifying how methods (e.g., mechanical harvesting, use of different herbicides), covariates (e.g., water quality, time of year), and their interactions influence outcomes of control efforts. Reducing aquatic invasive plants is one important objective, supporting recovery of native vegetation another. Effective management requires a balanced approach, so that AIS control does not come at the expense of damage to non-target native plants. We will synthesize existing monitoring data, partner with agency staff and lake sampling professionals, and perform field work to track native plant species’ responses to AIS management. One challenge of this effort is the inherent difficulty of sampling plants that are underwater, which can lead to a phenomenon called “imperfect detection”—failure to identify species that are in fact present. In addition, feasible, reliable estimations of abundance are a persistent challenge in aquatic vegetation. We will address these sampling issues by comparing different methods, critically evaluating the information gained along a continuum of sampling effort: from the most thorough but most technical and time-intensive (diving) to the most commonly used approach (point-intercept rake sampling from a boat) to the types of methods that could be feasibly employed by Trackers. This will allow us to refine our sampling protocols.

Summary Budget Information for Activity 4: ENRTF Budget: $142,543 Amount Spent: $141,727 Balance: $816 Activity Completion Date: Outcome Completion Date A1. Compile existing datasets for investigating spread and nuisance growth of July 31, 2017 Eurasian watermilfoil A2. Analyze data to identify key factors influencing spread and nuisance growth of January 31, 2018 Eurasian watermilfoil B1. Begin development of Trackers program July 31, 2016 B2. Begin fieldwork for refinement of sampling methods and data collection July 31, 2016 B3. Begin Trackers sampling and quality control testing July 31, 2018 B4. Analyze data collected by Trackers and synthesizes outcomes of Eurasian January 31, 2019 watermilfoil control efforts A–B. Complete fieldwork and data analysis and present results to stakeholders January 31, 2019 A–B. Complete manuscripts and submit for peer review June 30, 2019

Activity Status as of January 31, 2017: We have been pursuing three main avenues to evaluate the factors driving Eurasian watermilfoil invasion and the efficacy of different management strategies: • We are analyzing large (1,102 lakes), multi-year datasets (2002-2014) in collaboration with the DNR to evaluate how Eurasian watermilfoil invasion is influenced by environmental factors and biotic interactions with native plant communities. Our preliminary findings indicate that lakes with the highest native plant diversity are most at risk of Eurasian watermilfoil invasion—because the factors that support high native diversity make these lakes hospitable for Eurasian watermilfoil as well. This effect outweighs biotic resistance that can be imparted by high native diversity at finer spatial scales (plots within lakes). We also find evidence that Eurasian watermilfoil is driving “biotic homogenization” of lakes—causing lakes to become less distinct in their plant species composition over time. A phenomenon that is concerning from a biodiversity conservation perspective and that is occurring 19

rapidly in these systems (in <15 years vs. published findings from terrestrial Midwestern habitats where homogenization has occurred over ~50-year time scales). • We are compiling monitoring data from past Eurasian watermilfoil management to evaluate how environmental factors and differences in treatments influenced efficacy of management in terms of both Eurasian watermilfoil suppression (subsequent frequency of occurrence and abundance) and recovery of native plant communities (diversity, abundance, and composition). • We are developing the AIS Trackers citizen science program to provide new capacity in Minnesota for evaluating outcomes of Eurasian watermilfoil management efforts. Progress related to that program is reported in the workplan update for Subproject 10—Aquatic Invasive Species Research Center Sub- Project 10: Citizen Science and Professional Training Programs to Support AIS Response.

Activity Status as of July 31, 2017: Our analysis of how invasion by Eurasian watermilfoil, curly-leaf pondweed and other non-native aquatic plant species is influenced by environmental factors and biotic interactions with native plant communities has been submitted for publication and is currently in review. In this research, which was performed in collaboration with MnDNR, we found that invasive plants win in their interactions with native plants: there was evidence of competitive exclusion of native species by invasive species but not evidence that diverse native communities can slow invasion through biotic resistance. This is compounded by the fact that lakes with the most diverse native vegetation were also the most invaded, posing a threat to conservation of native plant diversity (Figure 3).

In a collaborative, cross-cutting analysis with Dr. Bajer’s common carp research program (Subproject 4), we have found that common carp invasion not only drives net loss of aquatic vegetation (as has previously been demonstrated by Dr. Bajer) but also causes significant shifts in plant community composition. There are both “losers” and “winners” of common carp invasion. Winners—species that were more likely to be found as common carp abundance increased—included 80% of the invasive aquatic plant species present in our dataset (Eurasian watermilfoil, curly-leaf pondweed, purple loosestrife, and narrowleaf cattail). Losers—significant declines with common carp invasion—included key native species, notably close native relatives of the invasive winners; species that have threatened/endangered status in other Midwestern states, such as water marigold and flatleaf bladderwort; and wild rice, Minnesota’ state grain and a sacred plant to Tribal communities. The net effect of common carp is not only loss of diversity but also shifts to lower-quality plant communities increasingly dominated by invasive species. This pattern is consistent with “invasional meltdown” in Minnesota lakes, i.e., invasive fish are promoting secondary invasions by non- native plants. Our work demonstrates the importance of co-managing different AIS rather than targeting individual species in isolation.

Activity Status as of January 31, 2018: Our manuscript describing the influence of environmental factors and biotic interactions on invasion by Eurasian watermilfoil, curly-leaf pondweed, and other non-native aquatic plant species in Minnesota shallow lakes has been accepted for publication in the Journal of Ecology.

Continuing with his Master’s research, Mike Verhoeven has now compiled data from over 500 aquatic plant surveys. These data were collected from 60 lakes and cover 10 years of plant management by 11 different organizations. We have reached out to additional sources of data through emails, phone calls, and presentations at events such as the Minnesota Aquatic Invasive Species Figure 3. Minnesota shallow lakes with higher native plant Research and Management Showcase. To date, 61 species richness were invaded by more non-native plant managing organizations and consultants have been species. Muthukrishnan et al. (In press). 20

identified as having suitable data, of which 35 have agreed to contribute data, and 16 have already shared their data. We expect this to yield approximately 1500 surveys from 200 lakes. As data come in, they are standardized to ensure that any newly added data will successfully merge with previously compiled data. We will be analyzing these data to evaluate how herbicide treatments, weather, and environmental factors affect Eurasian watermilfoil abundance and the diversity of native plant communities. After a temporary embargo while we submit our initial manuscripts, these data will be made publicly available in a searchable, online database hosted by the University of Minnesota’s Digital Repository (“DRUM”). All data contributors have been made aware of this planned publication of the data. This activity dovetails with our AIS Trackers program (Subproject 10), as data collected through both subprojects will populate a common database analyzable by us and future researchers to advance adaptive management of curly-leaf pondweed.

Activity Status as of July 31, 2018: Our paper on how environmental factors and native plant diversity influenced invasion by Eurasian watermilfoil and other non-native aquatic plant species in Minnesota shallow lakes has been published in the Journal of Ecology (https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1365-2745.12963) and was covered by state (e.g., www.mprnews.org/story/2018/03/14/study-plant-diversity-doesnt-protect-lakes-from-invaders-u- of-m) and national media (e.g., www.usnews.com/news/best-states/minnesota/articles/2018-03-18/study- plant-diversity-doesnt-protect-from-aquatic-invaders).

We continue to acquire and synthesize monitoring data from statewide efforts to manage Eurasian watermilfoil.

In-lake Eurasian watermilfoil removal experiments—paralleling those begun earlier for curly-leaf pondweed— began in July 2018. See Activity 5 for details.

Activity Status as of January 31, 2019: Our paper on the influence of Eurasian watermilfoil, curly-leaf pondweed, and other invasive macrophytes on biotic homogenization of Minnesota shallow lakes is at an advanced stage of preparation and will be submitted for publication shortly.

We continue to acquire and synthesize monitoring data from statewide efforts to manage Eurasian watermilfoil and curly-leaf pondweed. We have developed a pipeline for collating aquatic plant monitoring data, and have so far produced a dataset comprising over 100,000 individual sampling points from across 50 lakes.

We have continued to implement our in-lake experiments investigating limits on restoration of native macrophytes in areas dominated by Eurasian watermilfoil and curly-leaf pondweed. In summer 2018, we established 76 of our 128 experimental sites for this activity in Metro-area lakes.

Final Report Summary: Our work to synthesize monitoring data from across the state has resulted in the creation of what is, to our knowledge, the most comprehensive aquatic plant database for the state of Minnesota. We continue to work to assemble data, and have recently surpassed 3,000 surveys of aquatic plant communities. We are using these compiled data to evaluate management effectiveness for Eurasian watermilfoil control and native plant responses to invasive plants and control efforts. These data are also being used to evaluate influence of Eurasian watermilfoil invasion under a newly funded MAISRC Subproject 29 (“Will property values cool as AIS heat up?” P.I. Hansen)

Establishment, manipulation, and data collection have continued on in-lake experiments. To date, we have established 88 of 128 experimental sites for this activity. During the 2019 field season, we have also evaluated plant communities in experimental plots (Eurasian watermilfoil removal treatments) using sonar to assess vertical habitat structure and light spectrometry to assess changes to resource availability. These additional

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measurements will refine our understanding of plant community changes with invasion and the extent to which invasive plant control can foster native plant recovery.

ACTIVITY 5: Curly-leaf pondweed management: Factors influencing invasion, treatment effectiveness, and post-treatment recovery of native vegetation Description: Curly-leaf pondweed is native to Europe, Asia, Africa, and Australia and has been in Minnesota since at least the early 1900s. Curly-leaf pondweed is one of the first aquatic plants to come up in spring and can achieve dense growth that displaces native plant species. After forming nuisance mats, it dies back in mid- summer, and dead plants can accumulate on shorelines. One of curly-leaf pondweed’s ecological advantages is that it can reproduce vegetatively through production of turions, hundreds of which can come from each plant. Turions remain dormant in the sediment through the summer and germinate in the fall. Germination rates can be as high as 80%, and turions can remain viable in the sediment for two or more years. Like Eurasian watermilfoil, curly-leaf pondweed has been a persistent challenge for aquatic plant management, and the same challenges—explaining variability in invasion extent, refining control practices, and supporting post-treatment recovery of native vegetation—apply to curly-leaf as well. Work under this activity will parallel the research described above for Eurasian watermilfoil.

A. Factors influencing spread and nuisance growth of curly-leaf pondweed

While curly-leaf pondweed is not new to the state, it will continue to invade new lakes, posing challenges for affected property owners and lake users. We will use the approaches described above for hydrilla and starry stonewort to assess invasion risk for individual lakes in Minnesota that have not yet been invaded by curly-leaf pondweed. There is much more information available about curly-leaf pondweed invading Minnesota lakes than there is for the potential and new invaders, hydrilla and starry stonewort. Thus we can delve deeper with this species, investigating factors that influence outcomes of invasion, specifically, the extent to which it aggressively spreads within a lake, reaching nuisance levels vs. remaining a relatively minor, less harmful component of lake vegetation. We will synthesize existing monitoring data from MNDNR, watershed districts, and other partners to identify factors that influence invasion outcomes. Surrounding land use, lake characteristics, and water and sediment properties are likely factors affecting invasion extent and we will test these as potential predictors. In addition, invading species’ success is shaped by their interactions with organisms already found in a habitat. It has been shown in a variety of systems that, where native plants are more abundant and diverse, there can be “biotic resistance” to invasive plants, so that while new species may invade, they are less likely to become dominant. We will test whether there is evidence of this phenomenon in Minnesota lakes using large-scale, long-term lake monitoring datasets from MNDNR. Because “nature abhors a vacuum,” it may be that one way we can help prevent nuisance growth of curly-leaf pondweed and other invasive plants is through management that supports diverse communities of native aquatic plants.

B. Identifying best practices for controlling curly-leaf pondweed and supporting post-treatment recovery of native plant species

Ongoing management of curly-leaf pondweed and other invasive plants represents a largely untapped opportunity for “learning while doing” about treatment efficacy. Control efforts are numerous; each treatment is a potential replicate in a large-scale experiment—if necessary information about management actions, environmental conditions under which treatments are applied, and key ecological responses can be captured and analyzed. We will pursue this through a coordinated program of synthesizing existing monitoring data, performing new field research, and developing capacity for citizen scientists to contribute to monitoring outcomes of AIS management efforts. With other MAISRC researchers and an Extension Educator, we will develop a program called “Trackers” to train volunteers to monitor AIS abundance changes over time and in response to management. Sampling will include pre/post monitoring and untreated control and reference sites to differentiate management effects 22

from background variability. Along with species sampling, Trackers will record environmental data, such as water and Secchi depths, and management information. Participants will enter results into a centralized database hosted and managed by the University of Minnesota. We will perform follow-up sampling at subsets of Trackers sites for quality assurance of citizen science data and methods will be revised if issues are identified. In addition, many past treatments have been monitored under lake vegetation management plans, but this information has rarely been synthesized. We will work with MNDNR and watershed districts to compile this information. By capturing data from ongoing management, we will increase capacity for collective learning about treatment efficacy, identifying how methods (e.g., mechanical harvesting, use of different herbicides), covariates (e.g., water quality, time of year), and their interactions influence outcomes of control efforts. Reducing aquatic invasive plants is one important objective, supporting recovery of native vegetation another. Effective management requires a balanced approach, so that AIS control does not come at the expense of damage to non-target native plants. We will synthesize existing monitoring data, partner with agency staff and lake sampling professionals, and perform field work to track native plant species’ responses to AIS management. One challenge of this effort is the inherent difficulty of sampling plants that are underwater, which can lead to a phenomenon called “imperfect detection”—failure to identify species that are in fact present. In addition, feasible, reliable estimations of abundance are a persistent challenge in aquatic vegetation. We will address these sampling issues by comparing different methods, critically evaluating the information gained along a continuum of sampling effort: from the most thorough but most technical and time-intensive (diving) to the most commonly used approach (point-intercept rake sampling from a boat) to the types of methods that could be feasibly employed by Trackers. This will allow us to refine our sampling protocols.

Summary Budget Information for Activity 5: ENRTF Budget: $142,670 Amount Spent: $141,738 Balance: $933 Activity Completion Date: Outcome Completion Date A1. Compile existing datasets for investigating spread and nuisance growth of curly- July 31, 2017 leaf pondweed A2. Analyze data to identify key factors influencing spread and nuisance growth of January 31, 2018 curly-leaf pondweed B. Analyze data collected by Trackers and synthesize outcomes of curly-leaf January 31, 2019 pondweed control efforts A–B. Complete fieldwork and data analysis and present results to stakeholders January 31, 2019 A–B. Complete manuscripts and submit for peer review June 30, 2019

Activity Status as of January 31, 2017: We have been pursuing three main avenues to evaluate the factors driving curly-leaf pondweed invasion and the efficacy of different management strategies: • We are analyzing large (1,102 lakes), multi-year datasets (2002-2014) in collaboration with the DNR to evaluate how curly-leaf pondweed invasion is influenced by environmental factors and biotic interactions with native plant communities. Our preliminary findings indicate that lakes with the highest native plant diversity are most at risk of curly-leaf pondweed invasion—because the factors that support high native diversity make these lakes hospitable for curly-leaf pondweed as well. This effect outweighs biotic resistance that can be imparted by high native diversity at finer spatial scales (plots within lakes). We also find evidence that curly-leaf pondweed is driving “biotic homogenization” of lakes—causing lakes to become less distinct in their plant species composition over time. A phenomenon that is concerning from a biodiversity conservation perspective and that is occurring rapidly in these systems (in <15 years vs. published findings from terrestrial Midwestern habitats where homogenization has occurred over ~50-year time scales).

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• We are compiling monitoring data from past curly-leaf pondweed management (which incorporates and builds upon data collected by Ray Newman as part of Subproject 9) to evaluate how environmental factors and differences in treatments influenced efficacy of management in terms of both curly-leaf pondweed suppression (subsequent frequency of occurrence and abundance) and recovery of native plant communities (diversity, abundance, and composition). • We are developing the AIS Trackers citizen science program to provide new capacity in Minnesota for evaluating outcomes of curly-leaf pondweed management efforts. Progress related to that program is reported in the workplan update for Subproject 10—Aquatic Invasive Species Research Center Sub- Project 10: Citizen Science and Professional Training Programs to Support AIS Response.

Activity Status as of July 31, 2017: The research and analysis discussed above under Activity 4 also included evaluation of invasion by curly-leaf pondweed, the target species of Activity 5. This activity status update, therefore, includes elements of what is reported above.

Our analysis of how invasion by curly-leaf pondweed, Eurasian watermilfoil, and other non-native aquatic plant species is influenced by environmental factors and biotic interactions with native plant communities has been submitted for publication and is currently in review. In this research, which was performed in collaboration with MnDNR, we found that invasive plants win in their interactions with native plants: there was evidence of competitive exclusion of native species by invasive species but not evidence that diverse native communities can slow invasion through biotic resistance. This is compounded by the fact that lakes with the most diverse native vegetation were also the most invaded, posing a threat to conservation of native plant diversity (Figure 2).

In a collaborative, cross-cutting analysis with Dr. Bajer’s common carp research program (Subproject 4), we have found that common carp invasion not only drives net loss of aquatic vegetation (as has previously been demonstrated by Dr. Bajer) but also causes significant shifts in plant community composition. There are both “losers” and “winners” of common carp invasion. Winners—species that were more likely to be found as common carp abundance increased—included 80% of the invasive aquatic plant species present in our dataset (curly-leaf pondweed, Eurasian watermilfoil, purple loosestrife, and narrowleaf cattail). Losers—significant declines with common carp invasion—included key native species, notably close native relatives of the invasive winners; species that have threatened/endangered status in other Midwestern states, such as water marigold and flatleaf bladderwort; and wild rice, Minnesota’ state grain and a sacred plant to Tribal communities. The net effect of common carp is not only loss of diversity but also shifts to lower-quality plant communities increasingly dominated by invasive species. This pattern is consistent with “invasional meltdown” in Minnesota lakes, i.e., invasive fish are promoting secondary invasions by non-native plants. Our work demonstrates the importance of co-managing different AIS rather than targeting individual species in isolation.

As part of his Master’s research, Verhoeven is compiling and analyzing plant data collected by entities across the state to determine how herbicide treatments interact with weather patterns to control curly-leaf pondweed (incorporating and building upon data collected by Ray Newman as part of Subproject 5). We are also examining the effects of these treatments on native plants, which could either benefit due to release from competition by curly-leaf pondweed or be harmed by non-target impacts of herbicides. Widely adopted common methods for plant surveys have allowed us to draw together a set of 65 lakes covering 15 years of plant management. These surveys comprise the work of MnDNR, watershed districts, University staff, and consultants, who have to date contributed over 400 surveys to our lab. Using the data-compiling methods developed on the curly-leaf pondweed dataset, we have begun the process of expanding these analyses to include management of Eurasian watermilfoil. We have also spread our net farther and wider in search of data, and have confirmation that over 20 organizations will be contributing data to the second stage of this research.

Activity Status as of January 31, 2018:

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The research and analysis discussed above under Activity 4 also included evaluation of invasion by curly-leaf pondweed, the target species of Activity 5. This activity status update, therefore, includes elements of what is reported above.

Our manuscript describing the influence of environmental factors and biotic interactions on invasion by curly- leaf pondweed, Eurasian watermilfoil, and other non-native aquatic plant species in Minnesota shallow lakes has been accepted for publication in the Journal of Ecology.

Continuing with his Master’s research, Mike Verhoeven has now compiled data from over 500 aquatic plant surveys. These data were collected from 60 lakes and

cover 10 years of plant management by 11 different organizations; we are analyzing these initial data in collaboration with Ray Newman (Subproject 5). We have reached out to additional sources of data through emails, phone calls, and presentations at events such as the Minnesota Aquatic Invasive Species Research and Management Showcase. To date, 61 managing organizations and consultants have been identified as having suitable data, of which 35 have agreed to occurrence of Frequency contribute data, and 16 have already shared their data. We expect this to yield approximately 1500 surveys from 200 lakes. As data come in, they are standardized to ensure that any newly added data will successfully merge with previously compiled data. We will be analyzing these data to evaluate how herbicide Figure 4. Frequency of curly-leaf pondweed occurrence as a function of snow cover in Minnesota lakes. treatments, weather, and environmental factors affect curly-leaf pondweed abundance and the diversity of native plant communities. After a temporary embargo while we submit our initial manuscripts, these data will be made publicly available in a searchable, online database hosted by the University of Minnesota’s Digital Repository (“DRUM”). All data contributors have been made aware of this planned publication of the data. This activity dovetails with our AIS Trackers program (Subproject 10), as data collected through both subprojects will populate a common database analyzable by us and future researchers to advance adaptive management of curly-leaf pondweed.

We have begun analyzing these data to evaluate how herbicide treatments, weather, and environmental factors affect both curly-leaf pondweed abundance and the diversity of native plant communities. Our preliminary analyses indicate that herbicide treatments appear to be effective for reducing curly-leaf pondweed abundance and greater winter snow cover is associated with reduced curly-leaf pondweed frequency of occurrence (Figure 4). This indicates that curly-leaf pondweed treatments are effective at reducing frequency within a lake, and that years with higher winter snowfall will likely result in less spring curly-leaf pondweed growth. We are currently preparing a manuscript on these findings for submission to a peer-reviewed journal.

Activity Status as of July 31, 2018: Our paper on how environmental factors and native plant diversity influenced invasion by curly-leaf pondweed and other non-native aquatic plant species in Minnesota shallow lakes has been published in the Journal of Ecology (https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1365-2745.12963) and was covered by state (e.g., www.mprnews.org/story/2018/03/14/study-plant-diversity-doesnt-protect-lakes-from-invaders-u- of-m) and national media (e.g., www.usnews.com/news/best-states/minnesota/articles/2018-03-18/study- plant-diversity-doesnt-protect-from-aquatic-invaders).

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We continue to acquire and synthesize monitoring data from statewide efforts to manage curly-leaf pondweed.

To understand when and where invasive species removals are a useful means of restoring submerged aquatic plant communities, we have begun experiments focused on restoring macrophyte communities dominated by curly-leaf pondweed and Eurasian watermilfoil in Metro-area lakes. We are measuring native plant community responses to two factors: invader removal (to determine if aquatic invasive plants are suppressing native diversity and their removal alone is sufficient to spur native vegetation recovery) and seed addition (to determine whether native plant community recovery is limited by seed availability/dispersal). These experiments will inform efforts to restore native aquatic plant communities where they have been replaced by invasive species. We are also testing invader removal and seed addition across a range of water clarity conditions, to further determine the extent to which water clarity (i.e., light availability for photosynthesis) constrains restoration potential. Finally, by performing these experiments on two different invasive species that differ in seasonal growth patterns, we are testing how invader phenology affects competition with native species, i.e., does an invader that grows early in the season before native vegetation (curly-leaf pondweed) have less of a negative impact on native species than an invader with more phenological overlap (Eurasian watermilfoil). This has important implications for understanding how invaders’ traits influence their ecological impacts and potential for effective management. As of mid- July, we had established 64 experimental plots (5m × 5m each), with 32 of these having had curly-leaf pondweed manually removed by divers (mean biomass removed: 1.2 kg wet weight per m2) and 32 as non-removal control plots. Crews are currently establishing an equivalent set of plots for Eurasian watermilfoil and measuring native plant community diversity and composition in each of the 128 plots. These plots will be maintained and measured annually until 2021, providing detailed, experimental understanding of how invader removal influences native vegetation recovery.

Activity Status as of January 31, 2019: Our paper on the influence of curly-leaf pondweed, Eurasian watermilfoil, and other invasive macrophytes on biotic homogenization of Minnesota shallow lakes is at an advanced stage of preparation and will be submitted for publication shortly.

We continue to acquire and synthesize monitoring data from statewide efforts to manage curly-leaf pondweed and Eurasian watermilfoil. We have developed a pipeline for collating aquatic plant monitoring data, and have so far produced a dataset comprising over 100,000 individual sampling points from across 50 lakes.

We have continued to implement our in-lake experiments investigating limits on restoration of native macrophytes in areas dominated by curly-leaf pondweed and Eurasian watermilfoil. In summer 2018, we established 76 of our 128 experimental sites for this activity in Metro-area lakes.

Final Report Summary: We are currently revising a peer-reviewed paper on the influence of environmental factors and herbicide management on populations of curlyleaf pondweed in Minnesota.

Our work to synthesize monitoring data from across the state has resulted in the creation of what is, to our knowledge, the most comprehensive aquatic plant database for the state of Minnesota. We continue to work to assemble data, and have recently surpassed 3,000 surveys of aquatic plant communities. We are using these compiled data to evaluate management effectiveness for curlyleaf pondweed control and native plant responses to invasive plants and control efforts.

Establishment, manipulation, and data collection have continued on in-lake experiments. To date, we have established 64 experimental sites for this activity. During the 2019 field season, we have also evaluated plant communities in experimental plots (curlyleaf pondweed removal treatments) using sonar to assess vertical habitat structure and light spectrometry to assess changes to resource availability. These additional

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measurements will refine our understanding of plant community changes with invasion and the extent to which invasive plant control can foster native plant recovery.

V. DISSEMINATION:

Description: We will publish multiple peer-reviewed papers and present findings at state, regional, and national scientific meetings addressing aquatic ecology, invasive species management, and other relevant topics. Extension programming will be developed to translate scientific findings to professional audiences, e.g., agency staff and lake service providers. Presentations will also be made to the public through the annual MAISRC showcase and other forums, such as the State of Water Conference. Outreach materials will be developed and posted to the MAISRC website.

Status as of January 31, 2017: Dissemination of project findings was performed through:

Publications: Escobar, L. E., H. Qiao, N. B. D. Phelps, C. K. Wagner, and D. J. Larkin. 2016. Realized niche shift associated with the Eurasian charophyte Nitellopsis obtusa becoming invasive in North America. Scientific Reports 6:29037. DOI: 10.1038/srep29037. One manuscript is currently in revision and three are in review

Invited talks • Upper Midwest Invasive Species Conference. La Crosse, WI, 19 October 2016. • Aquatic Invaders Summit. St. Cloud, MN, 06 October 2016. • AIS Research and Management Showcase. St. Paul, MN, 12 September 2016. • Aquatic Plant Management Society Annual Meeting. Grand Rapids, MI, 18 July 2016. • State of Waters Conference. Alexandria, MN, 15 April 2016. • Minnesota Native Plant Society Symposium. Minneapolis, MN, 02 April 2016. • Legislative-Citizen Commission on Minnesota Resources. St. Paul, MN, 15 November 2016. • U.S. Fish and Wildlife Service. Bloomington, MN, 08 September 2016. • MAISRC Center Advisory Board. St. Paul, MN, 01 September 2016. • Fisheries & Aquatic Biology Seminar, University of Minnesota. St. Paul, MN, 02 April 2016. • Conservation Sciences Brownbag Seminar, University of Minnesota. St. Paul, MN, 22 March 2016. • Rice Creek Watershed District. Blaine, MN, 02 February 2016.

Contributed talks • Aquatic Plant Management Society Annual Meeting. Grand Rapids, MI, 18 July 2016.

Media coverage • News segment about starry stonewort research. KSTP ABC 5 (Minneapolis/St. Paul). Nov 14, 2016. • Radio interview about aquatic invasive plant management. WOJB 88.9, Woodland Community Public Radio (Reserve, WI). Oct 26, 2016. • Starry Trek: An unknown species showed up where none had been before, and researchers sprang into action. CFANS Solutions Magazine. Fall 2016. • More questions than answers for starry stonewort in Minnesota. Associated Press. July 12, 2016. URL: http://tomcherveny.areavoices.com/2016/07/12/more-questions-than-answers-for-starry-stonewort-in- minnesota/

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• Boost the fight against Minnesota’s newest aquatic invader. Star Tribune Editorial. April 13, 2016. URL: http://www.startribune.com/boster-the-fight-against-minnesota-s-newest-aquatic-invader/375622961/ • Minnesota does battle with first starry stonewort infestation. Associated Press. April 11, 2016. URL: http://www.twincities.com/2016/04/11/minnesota-starry-stonewort/ • Lake Koronis projects augment starry stonewort research. St. Cloud Times. April 10, 2016. URL: http://www.sctimes.com/story/sports/outdoors/2016/04/10/attacking-aquatic-invasives-lake-koronis- pilot-projects-augment-starry-stonewort-research-inspections/82604972/

Status as of July 31, 2017: Dissemination of project findings was performed through:

Publications Romero-Alvarez, D., L. E. Escobar, S. Varela, D. J. Larkin, and N. B. D. Phelps. 2017. Forecasting distributions of an aquatic invasive species (Nitellopsis obtusa) under future climate scenarios. PLoS ONE 12(7): e0180930. One manuscript is currently in revision and three are in review

Invited talks Larkin, D. J., M. Beck, and P. Bajer. 2017. Invasional meltdown in Minnesota lakes? Common carp promote invasive aquatic plants. MnDNR Fisheries Research Meeting. St. Paul, MN, 27 June 2017. Muthukrishnan, R. 2017. Prediction of starry stonewort invasion risk in Minnesota based on lake level habitat suitability. Invited speaker Shingle Creek and West Mississippi Water Management Commissions meeting. Brooklyn Park, MN. Muthukrishnan, R., and D. J. Larkin. 2017. Prediction of starry stonewort invasion risk in Minnesota based on lake level habitat suitability. Invited speaker and panelist for starry stonewort special session. Midwest Aquatic Plant Management Society Annual Meeting. Milwaukee, WI, 28 February 2017. Larkin, D. J. 2017. Starry stonewort: What is it, what do we know, what are we researching? MnDNR Roundtable. Bloomington, 6 January 2017.

Contributed talks Wagner, C., W. G. Glisson, and D. J. Larkin. 2017. Starry stonewort (Nitellopsis obtusa) remains viable following herbicide treatments in a Minnesota lake. Midwest Aquatic Plant Management Society Annual Meeting. Milwaukee, WI, 28 February 2017. First place in student poster contest

Media coverage • Taking on starry stonewort's opening act. Duluth News Tribune. June 17, 2017. URL: http://www.duluthnewstribune.com/news/outdoors/4284191-taking-starry-stoneworts-opening-act • Minnesota boaters urged to fend off new invasive plant. WCCO TV CBS Minnesota. May 11, 2017. URL: http://minnesota.cbslocal.com/video/3665213-minnesota-boaters-urged-to-fend-off-new-invasive- plant/ • Lake Koronis is test lab in fight against invasive species. MPR News. April 20, 2017. URL: http://www.mprnews.org/story/2017/04/20/as-starry-stonewort-spreads-lake-koronis-is-test-lab-in-fight • Invasive aquatic weed, starry stonewort, creeps across US. Associated Press. February 4, 2017. URL: https://www.washingtonpost.com/national/invasive-aquatic-weed-starry-stonewort-creeps-across- us/2017/02/04/e77a16a2-eafd-11e6-903d-9b11ed7d8d2a_story.html • News segment about starry stonewort research. KSTP ABC 5 (Minneapolis/St. Paul). Nov 14, 2016.

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Status as of January 31, 2018: Publications Muthukrishnan, R., N. Hansel-Welch, and D. J. Larkin. In press. Environmental filtering and competitive exclusion drive biodiversity-invasibility relationships in shallow lake plant communities. Journal of Ecology. Two manuscripts are currently in revision and one is in review

Invited talks Larkin, D. J. 2017. Research on spread risk and management of aquatic invasive plants. Fisheries Division Aquatic Plant Management Program Annual Meeting, Minnesota Department of Natural Resources. Alexandria, MN, 17 Oct 2017. Verhoeven, M. 2017. Environmental drivers of curlyleaf pondweed invasion. Fisheries Division Aquatic Plant Management Program Annual Meeting, Minnesota Department of Natural Resources. Alexandria, MN, 17 Oct 2017. Larkin, D. J., and R. Muthukrishnan. 2017. Using water chemistry to predict lake-level starry stonewort invasion risk in Minnesota and Wisconsin. An Action Plan for Starry Stonewort: Aligning Research and Management Priorities. Oconomowoc, WI, 7 September 2017. Larkin, D. J., and R. Muthukrishnan. 2017. Aquatic plant invasions: ions and drivers and carp (oh my) AIS Research and Management Showcase. University of Minnesota. St. Paul, MN, 13 September 2017. Verhoeven, M., and W. Glisson. 2017. Something old, something new: Curly-leaf pondweed and starry stonewort management. AIS Research and Management Showcase, University of Minnesota. St. Paul, MN, 13 September 2017. Larkin, D. J., and R. Muthukrishnan. 2017. Habitat suitability for starry stonewort in Minnesota. Aquatic Invasive Species Risk Management Workshop, University of Minnesota. St. Paul, MN, 22 August 2017.

Contributed talks Muthukrishnan, R., and D. J. Larkin. 2017. Oral presentation. Untangling multiple drivers of biodiversity- invasibility relationships in Minnesota shallow lake communities. Annual Meeting of the Ecological Society of America. Portland, OR, 9 August 2017. Larkin, D. J., M. Beck, and P. Bajer. 2017. Oral presentation. Invasional meltdown in northern lakes: Common carp invasion favors non-native plant species. Annual Meeting of the Ecological Society of America. Portland, OR, 7 August 2017.

Media coverage • Inside a St. Paul lab's battle against aquatic invaders. MPR News. September 22, 2017. URL: https://www.mprnews.org/story/2017/09/22/minnesota-aquatic-invasive-species-research-center- showcase • Lake Osakis searched for starry stonewort. Osakis Review. August 30, 2017. URL: http://www.theosakisreview.com/news/4320090-lake-osakis-searched-starry-stonewort • Statewide search finds new infestation of starry stonewort. Bemidji Pioneer. August 24, 2017. URL: http://www.bemidjipioneer.com/sports/outdoors/4317279-outdoors-notebook-statewide-search-finds- new-infestation-starry-stonewort • Catch me if you can: Divers hope to clear Grand Lake of starry stonewort before it spreads. St. Cloud Times. August 23, 2017. URL: http://www.sctimes.com/story/news/local/rocori/2017/08/23/catch-me-if- you-can-divers-hope-clear-grand-lake-starry-stonewort-before-spreads/590435001/ • Starry stonewort found in third Stearns County lake. Star Tribune. August 15, 2017. URL: http://www.startribune.com/starry-stonewort-found-in-third-stearns-county-lake/440594543/

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• Invasive weed starry stonewort reaches 1 more Minnesota lake. Pioneer Press. August 15, 2017. URL: http://www.twincities.com/2017/08/15/invasive-weed-starry-stonewort-reaches-1-more-minnesota- lake/ • ‘Lake killer’ starry stonewort found in Grand Lake. St. Cloud Times. August 15, 2017. URL: http://www.sctimes.com/story/news/local/rocori/2017/08/15/grand-lake-starry-stonewort/568056001/ • Starry stonewort confirmed on 1 new Minnesota lake. Fox 9 KMSP-TV. August 15, 2017. URL: http://www.fox9.com/news/273962641-story • Volunteers scour Minnesota lakes for newest invasive: starry stonewort. Star Tribune. August 8, 2017. URL: http://www.startribune.com/volunteers-scour-minnesota-lakes-for-newest-invasive-starry- stonewort/439107723/ • Starry Trek 2017: Volunteers needed for citizen science event. Winona Post. July 24, 2017. URL: http://www.winonapost.com/News/ArticleID/55321/Starry-Trek-2017-Volunteers-needed-for-citizen- science-event • Starry Trek comes to Beltrami County: Volunteers needed for Aug. 5 event to help search for starry stonewort. Bemidji Pioneer. July 17, 2017. URL: http://www.bemidjipioneer.com/outdoors/environment/ 4298842-starry-trek-comes-beltrami-county-volunteers-needed-aug-5-event-help • Starry Trek 2017. Sun Focus. July 16, 2017. URL: http://focus.mnsun.com/2017/07/16/starry-trek-2017/

Status as of July 31, 2018: Publications Larkin, D. J., A. K. Monfils, A. Boissezon, R. S. Sleith, P. M. Skawinski, C. H. Welling, B. Cahill, and K. G. Karol. 2018. Biology, ecology, and management of starry stonewort (Nitellopsis obtusa; Characeae): A Red-listed Eurasian green alga invasive in North America. Aquatic Botany. DOI: 10.1016/j.aquabot.2018.04.003 Glisson, W. J., C. K. Wagner, S. R. McComas, K. Farnum, M. R. Verhoeven, R. Muthukrishnan, and D. J. Larkin. 2018. Response of the invasive alga starry stonewort (Nitellopsis obtusa) to control efforts in a Minnesota Lake. Lake and Reservoir Management DOI: 10.1080/10402381.2018.1442893 Muthukrishnan, R., N. Hansel-Welch, and D. J. Larkin. 2018. Environmental filtering and competitive exclusion drive biodiversity-invasibility relationships in shallow lake plant communities. Journal of Ecology DOI: 10.1111/1365-2745.12963. Two manuscripts are currently in revision

Invited Talks Muthukrishnan, R. and D.J. Larkin. 2018. Spread risks, impacts and management of starry stonewort. Pelican Bay Watershed District Conference. Detroit Lakes, MN. Muthukrishnan, R. 2018. Life in a changing world: Understanding community resilience and vulnerability to anthropogenic stresses. University of South Dakota. Department of Biology. Muthukrishnan, R. 2018. Life in a changing world: Understanding aquatic community resilience and vulnerability to anthropogenic stresses. University of Nebraska, Omaha. Department of Biology. Verhoeven, M. 2018. EWM & Hybrid milfoil: what you should know! Milfoil Morning: Milfoil Management Workshop, St. Croix River Association. Lindstrom, MN. 11 April 2018. Larkin, D. J. 2018. Starry stonewort: Impacts, management strategies, and next steps. Aquatic Invaders Summit III. Spring Lake Park, MN, 28 February 2018. Muthukrishnan, R. and N. Phelps 2018. Will AIS get to your lake and will they survive? Targeting resources where the risk is greatest. Aquatic Invaders Summit III. Spring Lake Park, MN, 28 February 2018.

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Glisson, W., and M. Verhoeven. 2018. Something old, something new: Curly-leaf pondweed and starry stonewort management. Clearwater River Watershed District Aquatic Invaders Forum. South Haven, MN, 13 January 2018.

Contributed Presentations Larkin, D. J. 2018. Oral presentation. Starry Trek. State of Water Conference. Breezy Point, MN, 12-14 April 2018. Verhoeven, M. 2018. Oral presentation. Killing invaders to boost native species: Or are we? Natural Resources Association of Graduate Students Annual Symposium, University of Minnesota. St. Paul, MN. 25 May 2018. Verhoeven, M. 2018. Poster presentation. Winter, water and herbicide: A retrospective analysis of factors driving curlyleaf pondweed dynamics in sixty Minnesota lakes. Research Spotlight Fundraiser, Conservation Sciences, University of Minnesota. St. Paul, MN, 25 April 2018. Verhoeven, M. 2018. Poster presentation. Winter, water and herbicide: A retrospective analysis of factors driving curlyleaf pondweed dynamics in sixty Minnesota lakes. Aquatic Invaders Summit, Minnesota Lakes and Rivers Advocates. Minneapolis, MN, 28 February 2018.

Media coverage • There is hope: MAISRC met last week in continued effort to fight invasive species, Detroit Lakes online, 6/16/2018, www.dl-online.com/news/4461438-there-hope-maisrc-met-last-week-continued-effort- fight-invasive-species • Area residents hear U of M approach in fight against AIS, Perham Focus, 6/14/2018, www.perhamfocus. com/news/science-and-nature/4459812-area-residents-hear-u-m-approach-fight-against-ais • AIS Research Center to host showcase, Fergus Falls Journal, 6/4/2018, www.fergusfallsjournal.com/ 2018/06/ais-research-center-to-host-showcase/ • Workshop Focuses on Aquatic Invasive Species, Fox21, 6/2/2018, www.fox21online.com/2018/06/02/ workshop-focuses-on-aquatic-invasive-species/ • AIS symposium set for June 8 in Detroit Lakes, Park Rapids Enterprise, 6/2/2018, www.parkrapids enterprise.com/news/4454487-ais-symposium-set-june-8-detroit-lakes • Another invasive algae is established in Pennsylvania waters , AP (several outlets), 5/18/2018, www.post-gazette.com/sports/outdoors/2018/05/18/Invasive-algae-impacts-Pennsylvania-fishing-Lake- Erie-aquatic-weeds-Lake-Arthur-environmental-impact-starry-stonewort/stories/201805180088 • Minnesota Bound feature, Minnesota Bound, 5/13/2018, www.youtube.com/watch?v=T3E6NQ- 1Vd4&feature=youtu.be • Minnesota Aquatic Invasive Species Research Center, Open Rivers, 5/3/2018, editions.lib.umn.edu/ openrivers/article/maisrc/ • Milfoil Morning Stillwater Gazette, 3/31/2018, www.hometownsource.com/stillwater_gazette/milfoil- morning/article_0ed918be-339c-11e8-89df-7383be450623.html • ‘U’ Experiment On Invasive Weed Yields Limited Success, AP (several outlets), 3/26/2018, www. apnews.com/b11f6db81d1f4ae39e02b36c4e89d67c/Research-on-fighting-starry-stonewort-yields- limited-success • Study: Plant Diversity Doesn’t Protect From Aquatic Invaders, AP (several outlets), 3/19/2018, www. usnews.com/news/best-states/minnesota/articles/2018-03-18/study-plant-diversity-doesnt-protect- from-aquatic-invaders • Can’t foil that milfoil, MinnPost, 3/15/2018, www.minnpost.com/glean/2018/03/emmer-sponsors- farmer-mental-health-bill • U of M study: Plant diversity doesn't protect lakes from invaders , Minnesota Public Radio, 3/14/2018, www.mprnews.org/story/2018/03/14/study-plant-diversity-doesnt-protect-lakes-from-invaders-u-of-m

Status as of January 31, 2019: Publications

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Muthukrishnan, R., R. S Sleith, K. G. Karol, and D. J. Larkin. 2018. Prediction of starry stonewort (Nitellopsis obtusa) invasion risk in upper Midwest lakes using ecological niche models. Aquatic Botany 151:43–50. Escobar, L. E., D. Romero-Alvarez, D. J. Larkin, and N. B. D. Phelps. 2018. Network analysis to inform invasive species spread among lakes. Journal of Oceanology and Limnology DOI: https://doi.org/10.1007/s00343- 019-7208-z. One manuscript is currently in revision.

Contributed Presentations Verhoeven, M. R., D. J. Larkin, and R. M. Newman. 2018. Oral presentation. Constraints on curlyleaf: an evaluation curlyleaf pondweed biology and management through analysis of monitoring data from across organizations. International Symposium of the North American Lake Management Society. Cincinnati, OH, 1 November 2018. Larkin, D. J., R. Muthukrishnan, W. Glisson, C. Wagner, and R. Contreras-Rangel*. 2018. Oral presentation. Predicting and responding to starry stonewort invasion in Minnesota lakes. North American Invasive Species Management Association & Upper Midwest Invasive Species Joint Conference. Rochester, MN, 17 October 2018. Verhoeven, M. R., D. J. Larkin, and R. M. Newman. 2018. Oral presentation. Constraining curly-leaf: effects of repeated herbicidal control and environmental conditions on curly-leaf pondweed. North American Invasive Species Management Association & Upper Midwest Invasive Species Joint Conference. Rochester, MN, 17 October 2018. Larkin, D. J., and W. Glisson. 2018. New findings on new invaders: The latest on starry stonewort spread and hybrid watermilfoil behavior. AIS Research and Management Showcase, University of Minnesota. St. Paul, MN, 12 September 2018. Verhoeven, M. R., D. J. Larkin, and R. M. Newman. 2018. Oral presentation. Constraining curly-leaf: effects of repeated herbicidal control and environmental conditions on curly-leaf pondweed. Aquatic Plant Management Society Annual Meeting. Buffalo, NY, 17 July 2018. Wagner, C. K., W. Glisson, M. Verhoeven, R. Contreras-Rangel, R. Muthukrishnan, and D. J. Larkin. Oral presentation. Desiccation tolerance of the invasive alga starry stonewort (Nitellopsis obtusa) in Minnesota lakes. Aquatic Plant Management Society Annual Meeting. Buffalo, NY, 17 July 2018.

Media coverage • Our Lake, Our Legacy: protecting Minnesota’s life at the lake. UMN Driven to Discover campaign. https://twin-cities.umn.edu/news-events/our-lakes-our-legacy-protecting-minnesotas-life-lake • Why a Minnesota lake has become a giant, living laboratory. KSTP (and ~6 other sources). September 30, 2018. https://kstp.com/news/lake-koronis-giant-living-laboratory-starry-stonewort-invasive- species/5080264/?cat=1 • Area volunteers help in search for invasive species. ABC Newspapers. September 15, 2018. https://www.hometownsource.com/abc_newspapers/free/area-volunteers-help-in-search-for-invasive- species/article_074cf0b6-b871-11e8-aa7d-8708351a3a41.html • Volunteers discover starry stonewort infestation. Fergus Falls Journal. September 9, 2018. https://www.fergusfallsjournal.com/2018/09/volunteers-discover-starry-stonewort-infestation/ • New invasive algae infestation found by volunteers in statewide search. Faribault Daily News. August 11, 2018. http://www.southernminn.com/faribault_daily_news/community/article_bbd819c8-aa83-54b6- b18f-899f227fbd02.html • Invasive starry stonewort found in first Hubbard County lake. MPR News. August 31, 2018. https://www.mprnews.org/story/2018/08/31/invasive-starry-stonewort-found-in-first-hubbard-county- lake

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• As lake invaders dig in, Minnesota worries what comes next. MPR News. August 29, 2018. https://www.mprnews.org/story/2018/08/29/minnesota-lake-koronis-invaders-what-comes-next • COLA COLUMN: Focus your eyes on invasive Starry Stonewort. Park Rapids Enterprise. August 25, 2018. http://www.parkrapidsenterprise.com/sports/outdoors/4490546-cola-column-focus-your-eyes- invasive-starry-stonewort

Final Report Summary: New dissemination since January 2019 workplan update:

Publications Muthukrishnan, R., and D. J. Larkin. In review. Invasive species and biotic homogenization in Minnesota aquatic plant communities. Global Ecology and Biogeography. Verhoeven, M. R., D. J. Larkin, and R. M. Newman. In revision. Constraining invader dominance: Effects of repeated herbicidal management and environmental factors on curlyleaf pondweed dynamics in 50 Minnesota lakes. Freshwater Biology. Glisson W. J., M. R. Verhoeven, C. K. Wagner, R. Muthukrishnan, R. Contreras-Rangel, and D. J. Larkin. In press. Desiccation tolerance of the invasive alga starry stonewort (Nitellopsis obtusa) as an indicator of overland spread risk. Journal of Aquatic Plant Management.

Invited Talks Larkin, D. J. 2019. The thin line between native and invasive in watermilfoil and other macrophytes: challenges for invasive species detection, outreach, and management. Annual Meeting of the Society of Wetland Scientists. Baltimore, MD, 30 May 2019.

Media coverage • Searching for starry stonewort: County continues to monitor invasive algae found in five lakes. Bemidji Pioneer. June 23, 2019. URL: https://www.bemidjipioneer.com/sports/outdoors/4629235-searching-starry- stonewort-county-continues-monitor-invasive-algae-found • In one Minnesota lake, researchers remove invasive 'lake killer' by hand. MPR News. May 19, 2019. URL: https://www.mprnews.org/story/2019/05/19/minnesota-lake-researchers-remove-invasive-starry- stonewort • Grand Lake residents fight back against starry stonewort. WJON. May 10, 2019. URL: https://wjon.com/grand-lake-residents-fight-back-against-starry-stonewart/ • Invasive species in area lake contained for now. KNSI Radio. May 6, 2019. URL: http://knsiradio. com/news/local-news/invasive-species-area-lake-contained-now • WAPOA to host roundtable on aquatic invasive species. Brainerd Dispatch. April 20, 2019. URL: https://www.brainerddispatch.com/news/4601387-wapoa-host-roundtable-aquatic-invasive-species • Protecting our outdoor heritage: preventing the spread of aquatic invasive species. Grand Rapids Herald Review. March 23, 2019. URL: https://www.grandrapidsmn.com/opinion/letters_to_editor/protecting-our- outdoor-heritage-preventing-the-spread-of-aquatic-invasive/article_c190718e-4cdf-11e9-a0e6- bf0032f7a9b6.html

Overall project summary:

Publications: 10 Escobar, L. E., H. Qiao, N. B. D. Phelps, C. K. Wagner, and D. J. Larkin. 2016. Realized niche shift associated with the Eurasian charophyte Nitellopsis obtusa becoming invasive in North America. Scientific Reports 6:29037. DOI: 10.1038/srep29037.

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Romero-Alvarez, D., L. E. Escobar, S. Varela, D. J. Larkin, and N. B. D. Phelps. 2017. Forecasting distributions of an aquatic invasive species (Nitellopsis obtusa) under future climate scenarios. PLoS ONE 12(7): e0180930. Larkin, D. J., A. K. Monfils, A. Boissezon, R. S. Sleith, P. M. Skawinski, C. H. Welling, B. Cahill, and K. G. Karol. 2018. Biology, ecology, and management of starry stonewort (Nitellopsis obtusa; Characeae): A Red-listed Eurasian green alga invasive in North America. Aquatic Botany 148:15–24. Glisson, W. J., C. K. Wagner, S. R. McComas, K. Farnum, M. R. Verhoeven, R. Muthukrishnan, and D. J. Larkin. 2018. Response of the invasive alga starry stonewort (Nitellopsis obtusa) to control efforts in a Minnesota Lake. Lake and Reservoir Management 34:283–295. Muthukrishnan, R., N. Hansel-Welch, and D. J. Larkin. 2018. Environmental filtering and competitive exclusion drive biodiversity-invasibility relationships in shallow lake plant communities. Journal of Ecology 106:2058–2070. Muthukrishnan, R., R. S Sleith, K. G. Karol, and D. J. Larkin. 2018. Prediction of starry stonewort (Nitellopsis obtusa) invasion risk in upper Midwest lakes using ecological niche models. Aquatic Botany 151:43–50. Escobar, L. E., D. Romero-Alvarez, D. J. Larkin, and N. B. D. Phelps. 2018. Network analysis to inform invasive species spread among lakes. Journal of Oceanology and Limnology 37:1037–1041. Glisson W. J., M. R. Verhoeven, C. K. Wagner, R. Muthukrishnan, R. Contreras-Rangel, and D. J. Larkin. In press. Desiccation tolerance of the invasive alga starry stonewort (Nitellopsis obtusa) as an indicator of overland spread risk. Journal of Aquatic Plant Management. Verhoeven, M. R., D. J. Larkin, and R. M. Newman. In revision. Constraining invader dominance: Effects of repeated herbicidal management and environmental factors on curlyleaf pondweed dynamics in 50 Minnesota lakes. Freshwater Biology. Muthukrishnan, R., and D. J. Larkin. In review. Invasive species and biotic homogenization in Minnesota aquatic plant communities. Global Ecology and Biogeography.

Invited Talks: 30

Contributed Presentations: 20

Stories in Print, Broadcast, and Digital Media: 45

Web resources:

Table 1. Web pages for aquatic plant management research and outreach supported under this subaward (sites established Feb. 2016–Aug. 2017, views through Jun. 2019, *indicates page retired following website reorganization).

Unique Total Topic URL views views Aquatic invasive plants AIS in Minnesota: plants* — 1,644 2,143 Larkin team page www.maisrc.umn.edu/team-larkin 1,179 1,491 Risk assessment, control, and restoration www.maisrc.umn.edu/node/1231 401 508 research on aquatic invasive plant species

Starry stonewort Starry stonewort* — 3,734 4,501

About starry stonewort www.maisrc.umn.edu/about-starrystonewort 854 965

Starry stonewort research at MAISRC www.maisrc.umn.edu/starrystonewort- 384 518 research

Starry stonewort webinar recording www.maisrc.umn.edu/news/ssw-webinar2 246 308

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Unique Total Topic URL views views Meta-analysis of treatment outcomes to www.maisrc.umn.edu/starry-analysis 170 175 advance starry stonewort management in Minnesota Characterizing starry stonewort phenology, www.maisrc.umn.edu/ssw-phenology 146 164 growth conditions, and impacts to guide management Eurasian watermilfoil Eurasian watermilfoil* — 2,342 2,901

Eurasian watermilfoil research at MAISRC www.maisrc.umn.edu/eurasianwatermilfoil- 226 351 research

About Eurasian watermilfoil www.maisrc.umn.edu/about- 296 337 eurasianwatermilfoil Ecology and biology of invasive hybrid www.maisrc.umn.edu/hybrid-watermilfoil 171 196 watermilfoil in northern tier waterbodies Totals 11,793 14,558

VI. SUB-PROJECT BUDGET SUMMARY:

*This section represents an overview of the preliminary budget at the start of the project. It will be reconciled with actual expenditures at the time of the final report. See the Sub-Project Budget document for an up-to-date project budget, including any changes resulting from amendments.

A. ENRTF Budget Overview: Budget Category $ Amount Explanation Personnel: $761,604 Larkin- Assistant Professor/ Extension Specialist, Research Fellow, Postdoctoral Fellow, Graduate Students, Undergraduate Research Assistants/Field Technicians Professional/Technical Services and $13,358 Services - office & gen oper., Services - lab & Contracts field, Repairs – lab & field, vehicle insurance Equipment/Tools/Supplies: $25,223 Supplies - office & gen oper., Supplies- lab & field Travel: $20,066 Travel – MN, Travel – Domestic TOTAL ENRTF BUDGET: $820,251

Explanation of Use of Classified Staff: N/A

Explanation of Capital Expenditures Greater Than $5,000: N/A

Number of Full-time Equivalents (FTE) Directly Funded with this ENRTF Appropriation: Assistant Professor = 3 FTE Graduate Research Assistants = 1.25 FTE Postdoctoral Fellow = 2 FTE Research Fellow = 1.2 FTE Undergraduate Research Assistants = 2.25 FTE

Number of Full-time Equivalents (FTE) Estimated to Be Funded through Contracts with this ENRTF Appropriation: 0

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B. Other Funds: $ Amount $ Amount Source of Funds Proposed Spent Use of Other Funds Non-state U of M, Dept. of FWCB $50,000 $43,225 U of M funds for capital expenditures ($45,000 for truck, boat, and trailer) and computing resources (lab computers and printer) State $ $ TOTAL OTHER FUNDS: $50,000 $43,225

VII. SUB-PROJECT STRATEGY: A. Sub-Project Partners: Ranjan Muthukrishnan, Ph.D., Postdoctoral Associate; Michael Verhoeven, Graduate Research Assistant; and Carli Wagner, undergraduate researcher will be key members of the subproject team. Dr. Larkin has an appointment with U of M Extension and an Extension Educator (Megan Weber) will be involved in development of the Trackers program. The citizen scientists participating in Trackers will be key contributors. This subproject has been shaped by extensive discussions with MNDNR staff. Watershed districts and lake service professionals will also be important partners in this effort. Results will be communicated to policymakers, lake associations, and the public through publications, presentations, and outreach. B. Sub-Project Impact and Long-term Strategy: This project will begin a new focused effort to create biologically and economically sound solutions to prevent and control key aquatic invasive plant species affecting Minnesota waters. It will also disseminate scientific information that assists the MN DNR, watershed districts, lake associations, and citizen groups around the state with control strategies so that we are increasing the state’s capacity to respond to AIS and contributing to an ultimate change in condition (management or elimination of AIS). C. Spending History: Funding Source M.L. 2008 M.L. 2009 M.L. 2010 M.L. 2011 M.L. 2013 or or or or or FY09 FY10 FY11 FY12-13 FY14

VIII. ACQUISITION/RESTORATION LIST: N/A

IX. VISUAL ELEMENT or MAP(S): N/A

X. ACQUISITION/RESTORATION REQUIREMENTS WORKSHEET: N/A

XI. RESEARCH PROPOSAL: N/A

XII. REPORTING REQUIREMENTS: Periodic work plan status update reports will be submitted no later than January 31, and July 31. A final report and associated products will be submitted within two months of the anticipated sub-project completion of June 30, 2019

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Environment and Natural Resources Trust Fund M.L. 2013 Sub-Project Budget of M.L. 2013-06a: Aquatic Invasive Species Research Center

Project Title: Aquatic Invasive Species Research Center Sub-Project #8: Risk assessment, control, and restoration research on aquatic invasive plant species Legal Citation: M.L. 2013, Chp. 52, Sec. 2, Subd. 06a Project Manager: Dan Larkin Organization: University of Minnesota – Minnesota Aquatic Invasive Species Research Center Sub-Project Budget: $822,000 Sub-Project Phase 1 Length and Completion Date: 4 Years, June 30, 2019. Project Length and Completion Date: 6 Years, June 30, 2019 Date of Report: August 9, 2019 Activity 1: Program development Activity 3: Assessing risk of further starry Activity 4: Eurasian watermilfoil management: Activity 5: Curly-leaf pondweed management: stonewort spread in Minnesota lakes and Factors influencing invasion, treatment Factors influencing invasion, treatment ENVIRONMENT AND NATURAL RESOURCES TRUST FUND evaluating control options effectiveness, and post-treatment recovery of effectiveness, and post-treatment recovery of BUDGET native vegetation native vegetation BUDGET ITEM TOTAL Activity 1 Activity 3 Activity 4 Activity 5 REVISED TOTAL TOTAL Activity 1 Budget Amount Spent Balance Activity 3 Budget Amount Spent Balance Activity 4 Budget Amount Spent Balance Activity 5 Budget Amount Spent Balance BUDGET SPENT BALANCE Personnel (Wages and Benefits) - Total $115,000 $115,000 $0 $385,262 $385,262 $0 $130,671 $130,671 $0 $130,671 $130,671 $0 $761,604 $761,604 $0 Larkin- Assistant Professor/ Extension Specialist: $512,000 including salary and benefits (66.2% Salary, 33.8% benefits) 9 months (2016,2017,2018); 7 weeks summer salary (2016, 2017); 6 weeks summer salary (2018), FTE Glisson - Research Fellow: $54,817 including salary and benefits ; (74.8% salary, 25.2% benefits), 2 years, 0.5 FTE Post Doctoral Fellow: $111,537 including salary and benefits (81.7% salary, 18.3% benefits), 2 years, 1.0 FTE Graduate Student: $119,586 including salary and benefits (82% tuition + benefits) summer 2016- spring 2019, 0.5 FTE Undergraduate Student: $10,120 ($11/hr, 100% salary, 0% benefits), spring 2016 - spring 2019, 0.11 FTE Professional/Technical Services and Contracts - Total $100 $100 $0 $9,058 $9,058 $0 $2,894 $2,101 $793 $2,893 $2,099 $795 $14,946 $13,358 $1,587 Services - office & general operating (printing, mailing, publication costs, $100 $100 $0 $2,206 $2,206 $0 $334 $333 $1 $335 $333 $2 $2,975 $2,972 $3 etc.) Services - lab (genetic and chemical analyses) $0 $0 $0 $3,856 $3,856 $0 $1,285 $493 $792 $1,285 $492 $793 $6,426 $4,841 $1,585 Repairs - lab & field (lab instruments, vehicle, and boat) $0 $0 $0 $854 $854 $0 $560 $560 $0 $560 $560 $0 $1,974 $1,974 $0 Auto insurance for field vehicle $0 $0 $0 $2,142 $2,142 $0 $715 $715 $0 $714 $714 $0 $3,571 $3,571 $0 Equipment/Tools/Supplies - Total $7,312 $7,312 $0 $10,333 $10,333 $0 $3,795 $3,795 $0 $3,867 $3,783 $84 $25,307 $25,223 $84 Supplies- office & general operating (software, paper, folders, computer $4,550 $4,550 $0 $180 $180 $0 $60 $60 $0 $132 $94 $38 $4,922 $4,884 $38 notebooks, etc.) Supplies - lab & field (miscellaneous laboratory supplies, tanks, reagents, $2,762 $2,762 $0 $10,153 $10,153 $0 $3,735 $3,735 $0 $3,735 $3,689 $46 $20,385 $20,339 $46 and consumables; gas for boats, sampling supplies; equipment for SCUBA sampling, including wetsuits, masks, BCDs, regulators, a safety dive computer, dive weights, air for tanks, and related accessories; hybrid tablet for underwater light measurements) Travel - Total $3,000 $3,000 $0 $6,721 $6,721 $0 $5,183 $5,160 $23 $5,239 $5,185 $54 $20,143 $20,066 $77 Travel - MN (gas for truck, personal vehicle mileage, food, and lodging for $2,500 $2,500 $0 $5,221 $5,221 $0 $2,183 $2,183 $0 $2,239 $2,185 $54 $12,143 $12,090 $53 fieldwork, meetings, and conferences) Travel - Domestic (airfare, food, and lodging for conferences; travel to meet $500 $500 $0 $1,500 $1,500 $0 $3,000 $2,977 $23 $3,000 $3,000 $0 $8,000 $7,977 $23 with partners in the region ) COLUMN TOTAL $125,412 $125,412 $0 $411,374 $411,374 $0 $142,543 $141,727 $816 $142,670 $141,738 $933 $822,000 $820,251 $1,748