Understanding Eurasian Watermilfoil

Transcription

1 Understanding Eurasian Watermilfoil John D. Madsen Geosystems Research Institute Mississippi State University Cultus & Nicola Lakes Water Quality & Eurasian Watermilfoil Workshop, Fraser Basin Council, Abbottsford, BC, Canada February 15, 2013

2 Eurasian watermilfoil Overview Taxonomy and description Distribution Habitat Ecological range Problems Propagation and spread Growth and phenology

3 Benefits of Aquatic Plants Stabilize lakes sediments, reducing resuspension Increase sedimentation, reducing turbidity Provide habitat for insects, forage fish, fish spawning and YOY fish Provide food for waterfowl, other animals

4 Invasive vs. Native Community Invasive Myriophyllum spicatum Native Potamogeton sp. Mixed stand

5 Eurasian watermilfoil Myriophyllum spicatum L. Aquatic family Haloragaceae Forms dense nuisance surface canopy Herbaceous evergreen perennial Spreads by root crown / runner and autofragment Nonnative from Europe and Asia

6 Eurasian watermilfoil Problems Nuisance growth interfering with recreation Human use impacts Ecosystem impacts

7 Human Use Impacts of Commercial Navigation Hydropower Flood Control Eurasian watermilfoil Spread of insectborne diseases Recreational impairment Property value Human health

8 Ecological Effects of Eurasian watermilfoil Degradation of water quality Reduction in species diversity Suppresses native plant species Potential impacts on endangered species Alters animal communities

9 Fall River, CA Hennepin Lake, IL Pend Oreille River, WA Mobile Bay, AL

10 Lake Minnetonka, MN Lake Hortonia, VT Waneta Lake, NY Houghton Lake, MI Remetrix, Inc.

11 Taxonomy Wholly-aquatic family Haloragaceae Two genera Myriophyllum and Proserpinaca Fourteen Myriophyllum species in the US, twelve are native Four native species are shown for western North America Two invasive species Myriophyllum spicatum in Vermont

12 Taxonomy of Myriophyllum Despite fifty years of work on Eurasian watermilfoil in North America, there are persistent concerns and confusion, even among professionals, on how to tell Eurasian watermilfoil from native watermilfoil species (particularly northern watermilfoil). Recent genetic evidence of hybridization further exacerbates the confusion

13 Myriophyllum species in the US Scientific Name Common Name Native or Nonnative Myriophyllum alterniflorum DC Alternate flower watermifloil Native Myriophyllum aquaticum (Vell.) Verdc. Parrotfeather Nonnative Myriophyllum farwellii Morong Farwell s watermilfoil Native Myriophyllum heterophyllum Michx. Variableleaf watermilfoil Native* Myriophyllum hippuroides Nutt. ex Western watermilfoil Native Torr. & A. Gray Myriophyllum humile (Raf.) Morong Low watermilfoil Native Myriophyllum laxum Shuttlw. ex Loose watermilfoil Native Chapm. Myriophyllum pinnatum (Walter) Cutleaf watermilfoil Native Britton, Sterns & Poggenb. Myriophyllum quitense Kunth. Andean watermilfoil Native Myriophyllum sibiricum Komarov Northern watermilfoil Native Myriophyllum spicatum L. Eurasian watermilfoil Nonnative Myriophyllum tenellum Bigelow Slender watermilfoil Native Myriophyllum ussuriense (Regel) Russian watermilfoil Native Maxim. Myriophyllum verticillatum L. Whorl-leaf watermilfoil Native

14 Native Myriophyllum Western Watermilfoil Myriophyllum hippuroides Kathy Hamel Andian Watermilfoil Myriophyllum quitense Jenifer Parsons Northern Watermilfoil Myriophyllum sibiricum John Madsen Whorled watermilfoil Myriophyllum verticillatum USDA NRCS

15 Northern watermilfoil Myriophyllum sibiricum Komarov Common native in northern United States Occasionally forms a nuisance Circumboreal

16 Eurasian watermilfoil Myriophyllum spicatum L. Nonnative from Eurasia Widespread nuisance-forming invasive (49 US states, southern tier provinces of Canada)

17 Morphological Methods Morphological conditions measured in six segments of each specimen: Stem red or green Apical meristem rounded or flat Leaf tips rounded or flat Internode length Stem thickness Leaf length Leaflet length Leaflet number Northern watermilfoil specimen from Pend Oreille Lake, ID

18 PCR Amplification separated by electrophoresis and sequenced (BGU) Phylogenetic analysis and chloroplast gene sequencing (GVSU) PCR-RFLP (MSU) All three labs used different approaches, with some cross-over verification Genetic Methods

19 Morphological Results Comparison of Boolean characteristics of northern watermilfoil and Eurasian watermilfoil, with a comparison by Fisher's exact test. Fisher's Exact Test Characteristic Northern watermilfoil Eurasian watermilfoil P-value Flat Leaf End No Yes No Yes 4.2% 5.6% 95.8% (23) 94.4% (17) < (1) (1) Flat Apical Meristem No Yes No Yes 83.3% (20) 16.7% (4) 5.6% (1) 94.4% (17) <0.001 Stem Color Green Red Green Red 87.5% (21) 12.5% (3) 72.2% (13) 27.8% (5) 0.256

20 Morphological Results, cont. Comparison of morphological characteristics of northern watermilfoil and Eurasian watermilfoil, with a comparison by T-test Northern watermilfoil Eurasian watermilfoil T-test Variable Mean SE Mean Mean SE Mean p-value Leaflet Number < Leaf Length (mm) Leaflet Length (mm) < Stem thickness (mm) Internode Length (mm)

21 Northern Eurasian Frequency of number of leaflet pairs per leaf for northern watermilfoil (SIB, left) and Eurasian watermilfoil (SPI, right).

22 Northern Watermilfoil (Myriophyllum sibiricum) Native submersed aquatic plant Leaves arranged in whorls of 4 around stem, typically remains rigid when removed from water Leaves have < 12 leaflet pairs Leaf tips are round not flat Reproduces by stem fragments and turions Northern watermilfoil often has longer leaves than Eurasian watermilfoil ID Characteristics: Round leaf tips and < 12 leaflet pairs

23 Eurasian Watermilfoil (Myriophyllum spicatum) Introduced from Europe Submersed evergreen perennial Spreads by root crowns, runners, and fragments Grows in 2 to 15 feet of water, forms surface canopy Leaves are in whorls of 4 around stem ID Characteristics: Flat leaf ends, Flat apical meristem, > 12 leaflet pairs

24 Genetic Analysis Findings All three labs agree that plants identified as northern watermilfoil were northern watermilfoil All three labs agree that plants identified as Eurasian watermilfoil were Eurasian watermilfoil No evidence of hybridization in any samples

25 Eurasian watermilfoil Gets More Complicated Hybridization with M. sibiricum May form a terrestrial form on moist soil and mud flats

26 Habitat Lakes, rivers, reservoirs, ponds, freshwater and brackish estuaries Low to moderate organic content in sediment Fine clay to sand, cobble, and rock crevices in sediment Quiet to high energy zone, rooting below wave wash zone

27 What do plants need? Water Light Carbon dioxide Oxygen Water Nutrients: Nitrogen Phosphorus

28 A Tale of Two Plants CO 2, O 2 Nutrients Water Emergent, Floating Removal of Toxic Gases Submersed

29 Requirements for Growth Light Water attenuates amount of available light, controls depth distribution and growth rate Nutrients For both types of plants, sediment is bulk of source for major limiting nutrients (N, P) of rooted plants Water You re kidding, right? Carbon dioxide Gases diffuse 1,000x more slowly in water, rate of availability limits photosynthesis Oxygen Oxygen may be low for respiration, particularly in roots Temperature/Heat As with all plants, temperature range may limit growth Toxic gases in sediment (methane, sulfate) Floating, emergent plants have a flow-through system for gas exchange A safe place to root Disturbance, water level fluctuation, herbivory may limit growth

30 Comparison between Eurasian watermilfoil and Native Pondweed - Photosynthesis Submersed plant photosynthesis is controlled by light levels Madsen and Boylen 1988

31 Maximum depth of colonization versus light transparency Canfield et al Maximum depth of plant growth is largely controlled by light availability

32 Plant Nutrition Source of Nutrients Water column Sediment Growth-dilution

33 Nutrient Sources: Sediment vs. Water Barko et al. 1991

34 Tissue Concentrations of N and P As the plants grow, nutrient uptake does not keep up with the increasing volume or biomass of the plant resulting in growth dilution of nutrient content in the plants. If growth continues, nutrient Madsen 1991 limitation will eventually occur.

35 Phosphorus and Algae Dillon and Rigler Limnology and Oceanography Vol. 19, No. 5, Increased phosphorus in water leads to more algal growth While some increased algal growth will benefit fish production, too much algae leads to oxygen depletion, fish kills, and odor problems Nutrients will also increase growth of free-floating plants

36 This is Your Lake on Phosphorus: Excessive planktonic and filamentous algae or duckweed is directly related to fertilizing ponds

37 Bicarbonate Uptake Many submersed plants can use bicarbonate as well as dissolved carbon dioxide for photosynthesis. Bicarbonate and carbon dioxide together are known as dissolved inorganic carbon, or DIC Stevenson Limnol. Oceanogr. 33:

38 Inorganic Carbon vs. Photosynthesis Adams et al Limnol. Oceanogr. 23:

39 Relative Abundance EWM versus Trophic Status: Smith and Barko 1990 Oligotrophic Eutrophic

40 Plant Abundance Plant Response to the Environment Approximate Boundary Environmental Gradient

41 EWM Abundance vs. Total Phosphorus Milfoil Abundance Total Phosphorus( gl -1 )

42 EWM Abundance by Trophic Index Milfoil Abundance TrophicIndex

43 EWM Abundance and Alkalinity

44 Salinity and Water Chemistry Up to 33% seawater Softwater to hardwater

45 Nichols and Buchan JAPM

46 Ecological Impacts Reduces oxygen in water beneath canopy Increases internal nutrient loading, phosphorus Shades native plants Alters predator/prey balance

47 Eurasian watermilfoil vs. Native Plants

48

49

50 Why does Eurasian watermilfoil suppress native plants? Various mechanisms have been proposed, including: Ability to use bicarbonate as a photosynthetic carbon source Photosynthetic adaptations High productivity

51 Canopy Formation

52 Madsen et al Vmax vs Km

53 Madsen et al Light Compensation Point vs Km

54 Daily Carbon Balance, Open Water Madsen et al. 1991

55 Daily Carbon Balance, Milfoil Canopy Madsen et al. 1991

56 Invasive Plants and Fish Alter predator/prey balance After time, produces large numbers of stunted, underfed fish Valued by fisherman, not fisheries biologists Concern (though no data) that predatory fish hide in wait in dense vegetation for salmonids

57 Relative Fish Production Aquatic Plants and Predator/Prey Balance Largemouth Bass Sunfish Percent Plant Cover

58 Is this reversible? Does Management do any Good? Since shading is the main mechanism of competition, it is an elastic change and reversible With some management techniques, native plants already present respond positively in year of treatment With less selective techniques, sufficient plant propagules exist for revegetation

59 Selective Management with Herbicides Untreated mesocosm Mesocosm treated with Triclopyr

60

61 Restoration from Benthic Barrier Eichler et al JAPM 33:51-54.

62 Native Plant Restoration from Suction Dredging Eichler et al JAPM 31:

63 Four Life History Types Annual Overwinters by seed only Herbaceous perennial Overwinters by a vegetative propagule Evergreen Perennial Overwinters by green shoot Woody perennial Overwinters as a woody stem Rare in aquatic sites Tuber vegetative propagule Seed Root Crown evergreen perennial

64 Propagation and Spread Reproduction by seed Reproduction by vegetative means Spread by natural causes Spread by humans

65 Propagation Seed Seed set and success Vegetative Autofragment Root Crown Rhizomes Runners

66 Seed Set Eutrophic lakes produce more flowers and higher percentage of seed set than oligotrophic lakes Madsen and Boylen 1989

67 Seed Germination and Environment Madsen et al. 1988

68 In Situ Seed Germination Madsen et al 1988

69 Seed Germination and Burial

70 Drying Period and Seed Germination Eurasian watermilfoil seeds tolerate long periods of drying Hartleb and Madsen 1997

71 Propagation by Seed Large number of seeds are produced by Eurasian watermilfoil Seeds are viable, and germinate underwater Few, if any, seedlings survive to maturity underwater Seed propagation not important in most lakes

72 Vegetative Spread Fragments Runner Rhizome VT DEC

73 Vegetative Propagation: Runners Eurasian watermilfoil overwinters as root crowns a tight mass of growing stems Underground stems may produce new root crowns Erect stem can fall over and form new root crown

74 Vegetative Propagation: Fragments Autofragments formed by plant tend to predominate Allofragments from breakage may also be viable Autofragment production is greatest late in summer Autofragments may overwinter

75 Northern Asexual Spread Peak rhizome spread in August, peak autofragment formation in September Madsen et al. 1988

76 Southern population vegetative spread follows a different pattern based on environmental parameters Colony expanded at rate of 3.8 cm / day Madsen and Smith 1997

77 Invasion Process Introduction Establishment Colony Formation

78 Spread of Melaleuca Campbell, F.T In: J.O. Luken and J.W. Thierot, Assessment and Management of Plant Invasions. Springer, New York

79 Spread of Melaleuca Campbell, F.T In: J.O. Luken and J.W. Thierot, Assessment and Management of Plant Invasions. Springer, New York

80 Spread of Invasive Plants over Time Hobbs and Humphries Conserv. Biol. 9:

81 Hobbs and Humphries Conserv. Biol. 9: Cost of Control vs Time of Intervention

82 Hobbs and Humphries Conserv. Biol. 9: Phases of Invasion vs Manage -ment Priority

83 Natural Dispersal Water movement Wave action Currents Tides Animal carriers

84 Boats are the #1 mode of Eurasian watermilfoil spread in North America Boat launches are the most common site for first infestations in a new lake Boat Launches

85 Where to Check on Boats and Trailers MN DNR

86 Prevention Educational signs at boat launches, marinas Volunteer inspectors to teach on EWM danger Volunteer Plant Survey to watch for EWM in lake Target boat launches! Boats can be cleaned manually without any special equipment

87 Phenology and Growth Eurasian watermilfoil is an evergreen perennial Annual growth cycle varies across country Storage of carbohydrates is key

88 Temperature, Light and Growth Warm, Clear Year Cool, Cloudy Year Biomass (g DW m -2 ) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

89 500 Eurasian watermilfoil phenology varies geographically, interannually, and between lakes Biomass (g DW m -2 ) Biomass (g DW m -2 ) Biomass (g DW m -2 ) Cold Water North Temperate J F M A M J J A S O N D Warm Water North Temperate J F M A M J J A S O N D Warm Water South Temperate 100 J F M A M J J A S O N D

90 Carbohydrate Allocation Owens and Madsen 1998

91 Seasonal Carbohydrate Allocation Owens and Madsen 1998

92 Total Nonstructural Carbohydrate Content Carbohydrate Low Point Low Point Month of the Year

93 Carbohydrate: TNC storage by season

94 Low Points in Carbohydrate Storage of Eurasian watermilfoil Low carbohydrate storage in summer through fall in southern populations of Eurasian watermilfoil Northern populations usually have a distinct low point in early to mid summer Madsen 1997

95 Eurasian watermilfoil Carbohydrate Low Points 5 4 Northern Sites Southern Sites Frequency of Studies Madsen A M J J A S O Month of Year

96 Autofragment Formation Plant produces stem segments through abscission layer formation Timing is typically in fall, in both north and south Madsen et al. 1988

97 Eurasian watermilfoil Management Application Timing of management to coincide with low point Timing of management to prevent autofragment formation Drawdown exploits lack of resistant propagule

98 Conclusion Management goal is maintenance of low invasive plant population with diverse native plant community at most economical cost Before management of invasive plant After management of invasive plant

99 Dr. John D. Madsen Mississippi State University Geosystems Research Institute Box 9627 Mississippi State, MS Ph Fax