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Biology and Management of Eurasian Watermilfoil

Biology and Management of Eurasian Watermilfoil






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    Biology and Management of Eurasian Watermilfoil Biology and Management of Eurasian Watermilfoil Presentation Transcript

    • Biology and Management of Eurasian Watermilfoil (Myriophyllum spicatum) 1 BUILDING STRONG®
    • Eurasian watermilfoil  Myriophyllum spicatum L.  Family Haloragaceae  Submersed plant forming surface mats, rooted to bottom, commonly grows in water from 0.3 to 5 m deep, occasionally deeper depending on water clarity  Native to Eurasia  Spread by boat trailers, human activity, wildlife BUILDING STRONG®
    • Eurasian milfoil (Invasive Exotic)- Rapid Canopy Formation – no native plants fill this niche- Evergreen (PHS under ice) - bolts rapidly in the spring- Bicarbonate use – efficient photosynthesis- Not preferred by grass carp- Spreads rapidly by fragments (boats, wildlife, harvesters)- Native weevil has some impact, but is not predictable- Where possible, drawdowns can be effective- Herbicides are the most widely used option in glacial lakes BUILDING STRONG®
    • Large Rootcrowns can Survive Overwinter Primed for rapid growth in early spring Dependence on recovery From vegetative tissue - can be a weak point in life cycle4 BUILDING STRONG®
    • Prolific Seed Production –Estimated – between 500,000to 1 M seed heads/acre - 12 to 24 seed heads per square footUp to 300 Million Seeds / AcreGood viabilitySeedlings – very fragileHybridity shows seeds areimportant5 BUILDING STRONG®
    • Several Species with Similar Morphology Coontail Eurasian Milfoil Variable Milfoil Limnophila CabombaParrotfeather Bladderwort BUILDING STRONG®
    • Advanced Identification Eurasian Hybrid NorthernTypically – Genetic analysis < 14 Leaflets4 Leaves per node14 Leaflets (6-16) per node 7 BUILDING STRONG®
    • Significant Milfoil and Hydrilla Presence 500Biomass (g DW m-2) Cold Water North Temperate Reservoirs vs 400 300 200 100 0 J F M A M J J A S O N D Lakes 500 Warm Water North TemperateBiomass (g DW m-2) 400 300 200 100 0 J F M A M J J A S O N D 450Biomass (g DW m-2) 400 350 300 250 200 150 Warm Water South Temperate 100 J F M A M J J A S O N D A Large Area of the Eastern US – High Energy Reservoirs / Turbid and high water level fluctuation BUILDING STRONG®
    • EWM History via Literature 1950’s – Invasive traits in the Chesapeake Bay ► Patten 1956 – Notes on the Biology of M. spicatum New Jersey Lake 1960’s - Large-scale control in Chesapaeke Bay and TVA with 2,4-D ► TVA = 1.1 Million lbs of 2,4-D acid – 1962-69 ► Large unexplained declines in Chesapeake(?) Effectiveness of drawdowns BUILDING STRONG®
    • EWM History 1970’s increased reports in inland lakes ► MI,WI, NY, NJ ► TVA and UW – several papers ► EWM in Canada Numerous publications on “Milfoil Biology” ► Grace and Wetzel 1978, Aiken 1979 Additional focus on 2,4-D use 10 BUILDING STRONG®
    • EWM History 1980’s ► Sediments/Water Quality – invasive growth ► More 2,4-D ► Further concern in Canada and Pacific NW 1990’s ► Movement into Minnesota ► Invasions and Declines ► Milfoil Weevils ► Herbicide selectivity – fluridone/triclopyr 11 BUILDING STRONG®
    • EWM Literature 2000’s ► Low rate fluridone – whole-lake mgmt. • MI, VT ► More research on Weevils ► Milfoil hybridity and implications for mgmt. ► More herbicide selectivity • Early timing with auxin mimics ► Abiotic factors that influence growth (China) ► Milfoil/Management/Fisheries 12 BUILDING STRONG®
    • Managing Plants vs. Expectations There is a general view that a “right way” exists to manage invasive aquatic plants ► The problem: • it is typically done in a state other than your own Why do management strategies vary so significantly? • State to State (rules/laws) • Region to Region (problem)  Lakes vs. Reservoirs 13 BUILDING STRONG®
    • To Manage or Not to Manage ? While an Invasive Exotic, Eurasian milfoil (EM) does not justify treating an entire aquatic system • Fisheries - EM provides beneficial habitat • Ecologists - chemical disturbance > biological  EM is “now a naturalized citizen” (damage already done) • EM is a symptom of the problem - nutrients Proper Management Reduces EM and negative impacts • As an invasive exotic, EM is the problem • Reduce EM and let native vegetation expand Manage to Remove EM & Native Plants will Recover • Restore the system by removing the exotic plant • Prevent spread to surrounding water bodies (Hydrilla – ME, WI) BUILDING STRONG®
    • Managing Eurasian watermilfoil Adirondack Park, NY (3000 water bodies) Back Bay ) " ► Hand-pulling via divers $385,000/year on Saranac ) " Square Bay Little Square Bay ) " ► Very limited use of herbicides Adirondack Park Bottle Bay ) " Fish Creek Bay ) " ) " ) " ) " Buck Island Saginaw Bay Pork Bay Eagle Island Maine DEP – Gilpin Bay ) " ¹ ) " ) " N. Gull Bay Dear Island ) " ) " S. Gull Bay Meters 0 500 1,000 2,000 3,000 4,000 ► No herbicides for milfoil control 4200 acres ► Hydrilla eradication w/herbicides for 6+ years Idaho Dept. of Ag. ► 2008 – $2M Eradication program initiated - Herbicides WA DOE ► Aggressive use of herbicides in select areas 15 BUILDING STRONG®
    • 3 Midwestern States – Different Approaches to EWM Control State Fluridone Liquid 15% State Fishery (whole-lake) 2,4-D Littoral Matching /APM Trmt . Rule Grants Friction MI Y N N N Y (6+6 ppb) DNREMN DNR N N Y Y Y (state (exceptions) grants)WI DNR N Y N Y YWhich is the “Right Way” ? 16 BUILDING STRONG®
    • Classical Biological ControlAlligatorweed and flea beetle Eurasian milfoil and weevil (Euhrychiopsis lecontei) -Most relevant question – will the organism provide “a timely & desired level of control” - Some organisms are very consistent - others are inconsistent BUILDING STRONG®
    • Mechanical Control - Little has changed in 30+ yrs - Increased Milfoil SpreadDrawdowns-Effective on many species (winter)-Effective for Milfoil control-Reservoirs vs. Lakes BUILDING STRONG®
    • At the end of the day, we treatwhere people live,work, & play ! 19 BUILDING STRONG®
    • Parrotfeather (Myriophyllum aquaticum)• Non-native aquatic plant from South America• Brought to U.S. in the late 1800’s likely as an ornamental plant• Has been, and continues to be, spread by the aquarium and water garden industries• Plant providers in San Francisco used to plant parrotfeather in the drainage canals behind their stores to have readily available plants BUILDING STRONG®
    • Parrotfeather is as far north as British Columbia, Canada BUILDING STRONG®
    • • Parrotfeather is heterophyllous• Plants can grow emergent leaves and/or submersed leaves• May have implications for selection of control techniques BUILDING STRONG®
    • Plant Description• Emergent leaves are greyish green, stiff and waxy, and occur in whorls around the stem• Submersed leaves are red to orange, in whorls larger than Eurasian watermilfoil• Dioecious species, however only pistillate plants are found outside of its native range• Staminate plants are rare even in native populations• Seed production is not known to occur• Reproduction is exclusively vegetative via fragmentation and stolons BUILDING STRONG®
    • Parrotfeather forms anextensive network ofadventitious roots BUILDING STRONG®
    • Parrotfeather Impacts• Parrotfeather can impede streams, ditches, and small water-bodies• Impeding of runoff results in flooding of adjacent lands• Increases flood duration and Waterfowl Pond in Alabama intensity• Provides a refuge from predation for mosquito larvae• Poses a threat to drinking water supplies in South Africa BUILDING STRONG Irrigation Canal in Idaho. Tom Woolf ®
    • Infestation near Lake, Mississippi ~ 0.20 acres (743 m2) January 2006 April 2006 Impedes access to livestock BUILDING STRONG®
    • Biology and Ecology• Parrotfeather will invade highly 10 y = 19.345 - 18.311x + 5.022x2 disturbed sites with high 8 r2 = 0.82 nutrient availability Mean Total Myriophyllum aquaticum Biomass (g DW pot-1) 6• Invasion will occur from 4 eutrophic>mesotrophic>oligo- 2 trophic waters 0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 Nitrogen 2.8 3.0 10• Parrotfeather can survive well y = 15.072 + 85.315x - 145.075x2 r2 = 0.78 8 on water column nutrients 6• Shallow habitats are more 4 susceptible to invasion than 2 deeper sites (10 ft) 0 Phosphorus 0.10 0.15 0.20 0.25 0.30 0.35 % Tissue Nutrients BUILDING STRONG®
    • Biology and Ecology Stolons - 40-95% total biomass 2006 2007 Emergent Shoot Starch (% DW) 8 Starch allocation is greatest 6 4 (16.3%) in stolons 2 0 Submersed Shoot Starch (% DW) 15 Roots stored less than 3.8% 10 starch 5 0 Starch (% DW) 20 Low points in both biomass and Stolon 15 10 starch allocation occurred from 5 0 October to March Starch (% DW) 8 6 Root 4 2 0 May May Nov Nov Oct Apr Oct Dec Jan Feb Apr Jun Aug Sep Jun Aug Mar Dec Jan Feb Sep Dec Jan Jul Mar Jul Time BUILDING STRONG®
    • Management Recommendations Management - exploit times of low energy reserves (fall and winter), or remove emergent shoots to gain access to the stolons and other submersed tissues. ► Herbicide applications are effective ► Water level manipulations are effective Management activities that target only the emergent shoots will not be effective at controlling this species Management - dictated by use patterns of the infested water body BUILDING STRONG®
    • 700 Peak Biomass 2006 600• Parrotfeather is 500 Target Management Target Management Mean Myriophyllum aquaticum 400 Total Biomass (g DW m-2) probably still in Missouri 300 200 100 0• Climate will support this 60 50 2007 species 40 30 20• Problematic infestations 10 0 will be limited to small 100 Peak Starch Content 2006 80 ponds and slow moving Mean Total Starch Content (g m-2) Target Management Target Management 60 streams where nutrients 40 20 are in abundance 0 2007 4 3 2 1 0 y y h il y ne ly t r er er er u ar ar rc Ap r Ma Ju Ju us be ob emb emb an ru Ma ug tem ct J eb A p O v c F Se No De Month BUILDING STRONG®