Wisconsin Lakes Convention Stevens Point, WI April 5, 2017

Transcription

1 Wisconsin Lakes Convention Stevens Point, WI April 5, 2017 Scott Provost, Michelle Nault, Ali Mikulyuk, Scott Van Egeren, Chelsey Blanke Wisconsin Department of Natural Resources

2 Aquatic macrophytes Key components of lake ecosystems Food for bugs, inverts, fish Biogeochemistry Refuge, habitat, food source Help maintain clear water with less algae 2

3 Different stakeholders, different goals Van Nes et al Peter Hedlund, Waterskiing CC BY NC SA 2.0 Jan Köhnlein, Northern Shovellers, CC BY NC SA 2.0

4 Goal of Aquatic Plant Management A balancing act: Satisfy stakeholder desires nuisance reduction, invasive species control Minimize ecological impacts

5 Some, but not all invaders have impacts 5 Vilà et al. 2011

6 Some, but not all invaders have impacts But control has a cost, too! 6 Vilà et al. 2011

7 USFWS, CC BY 2.0 Mark Goehle/USFWS, CC BY 2.0 K90, CC BY SA 3.0 Jax Strong, CC BY SA 2.0 7

8 Decisions must consider: > $2 million! TREATMENT vs. INVADER vs. NATIVES 8

9 Where is EWM? Eurasian watermilfoil (EWM) is a non-native submerged plant. Currently verified in ~650 inland lakes and flowages. Many lakes with public access still don t have EWM, especially in the north. Number of newly reported populations has possibly stabilized, but overall number of invaded lakes continues to rise.

10 Statewide Eurasian Watermilfoil Study What is the statewide distribution and abundance of EWM? n = 398 lakes

11 EWM vs Treatment vs Natives Evidence for treatment effects: Decreased native cover Altered community composition EWM vs TRT No evidence for EWM effects: No evidence for native cover effect Community effects similar to natives

12 Comparing all species Effects on average cover Effects on community composition

13 Hidden slide: In case of species specific questions

14 Takehomes Lakewide treatments produced effects on native macrophytes that were larger than EWM Ecological restoration vs. Nuisance relief Application to IPM Long term study much needed are impacts temporary? Are we exacerbating the problem, minimizing the problem or passing the buck?

15 Scale of Management How does the scale of management affect EWM efficacy and selectivity? Small-scale Herbicide or alternative management will be conducted at a scale which will not result in significant lakewide effects and effects are anticipated on a localized scale Large-scale Herbicide or alternative management will be conducted at a scale which will result in significant lakewide effects

16 2,4-D Concentration/Exposure Time 2.0 Small-Scale High dose Short exposure Green & Westerdahl, 1990 JAPM 28:27-32 ppmae Large-Scale Low dose Long exposure Recommended 2,4-D label rate: ppm (Hours) 1.0 ppm = 1.0 mg/l = 1000 ppb

17 Small-Scale Treatment Resources

18 2,4-D Concentration/Exposure Time High dose Short exposure 2.0 Green & Westerdahl, 1990 JAPM 28: ppm Small scale Treatments Recommended 2,4-D label rate: ppm (Hours) 1.0 ppm = 1.0 mg/l = 1000 ppb

19 24 2 ppm for good control (Green & Westerdahl, 1990)

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23 24 2 ppm for good control (Green & Westerdahl, 1990)

24 1 HAT % 50-75% 25-50% 10-25% 5-10%

25 2 HAT % 50-75% 25-50% 10-25% 5-10%

26 3 HAT % 50-75% 25-50% 10-25% 5-10%

27 5 HAT % 50-75% 25-50% 10-25% 5-10%

28 1 HAT % 50-75% 25-50% 10-25% 5-10%

29 2.5 HAT % 50-75% 25-50% 10-25% 5-10%

30 4 HAT % 50-75% 25-50% 10-25% 5-10%

31 6 HAT % 50-75% 25-50% 10-25% 5-10%

32 Preliminary Findings Actual CET in the field is more difficult to predict and maintain in smaller scale treatments Aquatic plant data is more difficult to collect and analyze in smaller scale treatments Rapid dissipation of herbicide occurs within 1-4 hours in many small-scale treatment sites No one size fits all solution - future research into other herbicides (diquat, combos) Future research into other IPM (hand-removal, DASH, etc.) for small-scale AIS control Future research into extending exposure time (i.e. barrier curtains)

33 Preliminary Recommendations Use the appropriate herbicide product for your expected exposure time. A short expected exposure time may require a fast-acting contact herbicide versus a systemic. Treat blocks (>5 acres) vs. amoeba shapes. Treat blocks when winds are <5 mph. Stronger winds increase dissipation rates and reduce contact time. Treat blocks on windward side of shorelines. Do not treat on leeward, protected shorelines. Treat early in the morning, or late in the evening when low winds may be sustained for a longer period of time.

34 Large-Scale Treatment Resources

35 2,4-D Concentration/Exposure Time 2.0 Green & Westerdahl, 1990 JAPM 28:27-32 ppmae Whole Lake Treatments Low dose Long exposure Recommended label rate: ppm (Hours) 1.0 ppm = 1.0 mg/l = 1000 ppb

36 Study Lakes 23 lakes Variety of lake types Range of sizes and depths Range of trophic status Treatments Large-scale liquid 2,4-D lakewide targets of ppb (epilimnetic) Application rates of ppb 8-100% of lake surface area treated Early season (spring) treatments Monitored from

37 2,4-D Degradation Majority of models highly significant (p <0.001) Mean [2,4-D] 1-14 DAT ranged from ppb 2,4-D half-lives ranged from 4-76 days Irrigation restriction (<100 ppb by 21 DAT) exceeded in more than half the treatments Analysis in progress to determine what variables affect degradation rates (lake type, trophic status, ph, etc.)

38 What variables affect herbicide degradation rates? Rate of herbicide degradation was generally observed to be slower in oligotrophic seepage lakes Clearer lakes (Secchi) exhibited slower 2,4-D breakdown versus more turbid lakes (p = 0.003, R 2 = 0.31). Seepage lakes exhibited significantly longer 2,4-D half-lives than drainage lakes (unpaired t-test, p = 0.005) Previous historical use of 2,4-D may also be an important variable to consider, as microbial communities which are responsible for the breakdown of 2,4-D may potentially shift over time with repeated use.

39 2,4-D Vertical Dissipation Mixed Lake Stratified Lake

40 Milfoil Control

41 Milfoil Control

42 Long-Term Milfoil Control

43 Statewide Watermilfoil Genetics Many misconceptions regarding hybrid watermilfoils (M. spicatum X sibiricum) Milfoil populations tested for hybridity through ITS genetic sequencing ~150 lakes in WI have HWM confirmed There is not one single hybrid watermilfoil, but it is rather a genetically diverse group that reflects recurrent hybridization Not all HWM appear to be tolerant to herbicides, but many show statistically significant differences in % control when compared to pure EWM

44 Alternative Large-Scale Treatments Explore use of other herbicides (i.e. fluridone, triclopyr) and combos (2,4-D/endothall) for large-scale treatments. These herbicides may be good alternatives for milfoil populations which have demonstrated lack of susceptibility to 2,4-D in the field and/or laboratory. As with all management, need to balance out efficacy for milfoil with selectivity towards natives. Low-dose Fluridone Low-dose Triclopyr Combinations (i.e. 2,4-D & Endothall)

45 Preliminary Findings Herbicide dissipation is rapid and large scale treatments can result in a whole-lake treatment if the scale of the treatment area is large compared to the overall lake epilimnetic volume Early spring, large scale 2,4-D treatments may result in longer persistence of herbicides than expected; may exceed 100 ppb (0.1 ppm) for >21 days EWM control looks promising, however damage to certain native species may occur and long-term effects on biotic and abiotic parameters is uncertain Hybrid watermilfoils need to be better documented and studied in both field and laboratory studies Herbicide monitoring is important, both to understand treatment efficacy, as well as ecological risks

46 Use what we learn Formal recognition will lead to practice Recognize science in APM SA Set policy through the process

47 Aquatic Plant Management Strategic Analysis Evaluation of pertinent information Historical aspects (<1940 present) Scientific information Socio-economic impacts Public participation Multiple opportunities Interviews Comment period (coming) NR [s. 1.11(2) (e) and (h)] More on Friday!

48 Aquatic Plant Management Strategic Analysis: We need your input Public participation, these are your lakes Future management decisions will be affected Think what you want the future to look like Public needs to believe in management

49 Change in management techniques Shift from native to AIS control Techniques that minimize damage to natives Matching products correctly Systemics in large treatments Contacts in spot treatments Long term integrated management strategies Proactive vs. reactive Prevention better than control

50 Evolving management with science Monitoring and evaluation Use standard techniques Focus on efficacy of target Work collaboratively agencies, academia, industry and citizens Share information

51 Years of work, where do we go? Is it time to implement what we know? What concerns do you have about the potential changes? Do you think AIS is the primary concern? Is navigation the primary concern, if so when? What is a fair balance between recreation and habitat? Or social and ecological concerns?