Aquatic Plant Control

Transcription

1 Thompson Lake 2015 Annual Nuisance Aquatic Plant Control Report Prepared for: Thompson Lake Improvement Board c/o Livingston County Drain Commissioner's Office 2300 E Grand River Ave. Suite 105 Howell, MI Aquatic Plant Control Prepared by: Progressive AE Mile Road, NE Grand Rapids, MI / January 2016 Project No:

2 Thompson Lake 2015 Annual Nuisance Aquatic Plant Control Report Prepared for: Thompson Lake Improvement Board c/o Livingston County Drain Commissioner's Office 2300 E Grand River Ave. Suite 105 Howell, MI Prepared by: Progressive AE Mile Road, NE Grand Rapids, MI / January 2016 Project No:

3 Table of Contents INTRODUCTION... 1 Project Background... 1 The Importance of Aquatic Plants... 3 Nuisance Aquatic Plants... 4 Nuisance Aquatic Plant Control... 5 Regulation of Aquatic Herbicide Application... 5 METHODS... 6 Aquatic Plant Survey... 6 Aquatic Plant Bio-Volume Mapping... 7 AQUATIC PLANT SURVEY... 8 Plant Species Present... 8 Aquatic Plant Distribution and Bio-Volume... 9 NUISANCE AQUATIC PLANT CONTROL ACTIVITIES SUMMARY OF FINDINGS APPENDIX Appendix A Standard Aquatic Vegetation Summary Appendix B MDEQ Treatment Report Appendix C Harvesting Log Thompson Lake Annual Plant Control Report iii

4 TABLE OF CONTENTS LIST OF TABLES Table 1 Thompson Lake Aquatic Plants, September 10, Table 2 Thompson Lake 2015 Nuisance Aquatic Plant Control Summary LIST OF FIGURES Figure 1 Thompson Lake Location Map... 1 Figure 2 Thompson Lake Depth Contour Map... 2 Figure 3 Benefits of Aquatic Plants... 3 Figure 4 Aquatic Plant Groups Figure 5. Eurasian Milfoil (Myriophyllum spicatum) Figure 6. Starry Stonewort (Nitellopsis obtusa) Figure 7. Nuisance Native Aquatic Plant Growth... 4 Figure 8. Mechanical Harvesting... 5 Figure 9. Application of Aquatic Herbicides... 5 Figure 10. Thompson Lake Aquatic Plant Survey Map... 6 Figure 11. Hydro-Acoustic Survey Read-Out Figure 12. Thompson Lake Aquatic Plant Bio-volume Map, May 12, Figure 13. Thompson Lake aquatic Plant Bio-volume Map, August 12, Figure 14. Thompson Lake Aquatic Plant Bio-volume Map, September 10, Thompson Lake Annual Plant Control Report iv

5 Introduction PROJECT BACKGROUND Thompson Lake is located in Sections 30 and 31 of Oceola Township and in the City of Howell in Livingston County (T3N, R5E; Figure 1). Plant control activities in Thompson Lake are coordinated by Progressive AE under the direction of the Thompson Lake Improvement Board. This report provides an overview of 2015 plant survey results and nuisance aquatic plant control activities. Livingston County Figure 1. Thompson Lake location map. Source: US Geological Survey, Howell 1968 (photorevised 1983); Oak Grove 1968 (photorevised 1975). Thompson Lake Annual Plant Control Report 1

6 INTRODUCTION The construction of a dam at the outlet of Thompson Lake increased the size of the lake and created expansive shallow water area within the lake. Much of the area inundated was formerly wetland which now provides fertile substrate for aquatic plant growth. The original three deep holes within the lake are apparent when viewing a depth contour map of Thompson Lake (Figure 2). Dam N Figure 2. Thompson Lake depth contour map. Thompson Lake Annual Plant Control Report 2

7 INTRODUCTION THE IMPORTANCE OF AQUATIC PLANTS Aquatic plants are an important ecological component of lakes. They produce oxygen during photosynthesis, provide food and habitat for fish, and help stabilize shoreline and bottom sediments (Figure 3). Insects and other invertebrates live on or near aquatic plants, and become food for fish, birds, amphibians, and other wildlife. Plants and algae are the base of the food chain. Lakes with a healthy fishery have a moderate density of aquatic plants. Aquatic plants provide habitat for fish and other aquatic life. Roots and stones absorb wave energy and reduce scouring of the lake bottom. Trees and shrubs prevent erosion and provide habitat. Aquatic plants help to hold sediments in place and improve water clarity. Predator-fish such as pike hide among plants, rocks, and tree roots to sneak up on their prey. Prey-fish such as minnows and small sunfish use aquatic plants to hide from predators. Figure 3. Benefits of aquatic plants. The distribution and abundance of aquatic plants are dependent on several variables, including light penetration, bottom type, temperature, water levels, and the availability of plant nutrients. The term "aquatic plants" includes both the algae and the larger aquatic plants or macrophytes. The macrophytes can be categorized into four groups: the emergent, the floatingleaved, the submersed, and the freefloating (Figure 4). Each plant group provides unique habitat essential for a healthy fishery. Free-floating Submersed Figure 4. Aquatic plant groups. Floating-leaved Emergent Thompson Lake Annual Plant Control Report 3

8 INTRODUCTION NUISANCE AQUATIC PLANTS While aquatic plants are essential for a healthy lake, aquatic plant management may be necessary when exotic, or non-native, species invade a lake, or if native plants grow to nuisance densities. An exotic species is one that is found outside of its natural range. Exotic aquatic plants often have aggressive and invasive growth tendencies. They can quickly out-compete native plants and gain dominance in a lake. Two examples of exotic plant species that are a threat to Michigan lakes include Eurasian milfoil (Myriophyllum spicatum) and starry stonewort (Nitellopsis obtusa). Eurasian milfoil often becomes established early in the growing season and can grow at greater depths than most plants. Eurasian milfoil often forms a thick canopy at the lake surface that can degrade fish habitat and seriously hinder recreational activity (Figure 5). Once introduced into a lake system, Eurasian milfoil may out-compete and displace more desirable plants and become the dominant species. Starry stonewort looks like a rooted plant but it is actually an algae (Figure 6). It was first found in the Detroit River in the 1980s and has since infested hundreds of inland lakes (Brown 2015, Schloesser et al. 1986). Starry stonewort closely resembles the native aquatic plant Chara. However, unlike Chara, which is generally considered to be a beneficial plant, starry stonewort has a tendency to colonize deeper water and can form dense mats several feet thick. Starry stonewort can impede navigation, and quickly displace native plants. Fisheries biologists have expressed concern that starry stonewort may cover valuable fish habitat and spawning areas. At times, native plants can grow to densities that interfere with navigation, swimming, and other recreational lake uses (Figure 7). Figure 5. Eurasian milfoil (Myriophyllum spicatum). Figure 6. Starry stonewort (Nitellopsis obtusa). Figure 7. Nuisance native aquatic plant growth. Progressive AE Progressive AE Progressive AE Thompson Lake Annual Plant Control Report 4

9 INTRODUCTION NUISANCE AQUATIC PLANT CONTROL The objective of a sound aquatic plant management program should be to control the spread of invasive and exotic species while preserving beneficial native plants. Mechanical harvesting (i.e., plant cutting and removal) and chemical herbicide treatments are methods commonly employed to control aquatic plant growth. In certain situations, harvesting is advantageous over herbicide treatments since plants removed from the lake will not sink to the lake bottom and add to the buildup of organic sediments (Figure 8). In addition, some nutrients contained within the plant tissues are removed with the harvested plants. However, mechanical harvesting is non-selective. That is, a harvesting machine will Figure 8. Mechanical harvesting. remove the majority plants in its path, including the beneficial plants as well as the nuisance plants. Harvesting is not recommended when selectivity is required. In addition, attempts to control certain plant types by harvesting alone may not prove entirely effective. This is especially true with Eurasian milfoil (Myriophyllum spicatum) due to the fact that this plant may proliferate and spread via vegetative propagation (small pieces break off, take root, and grow) if the plant is cut. Another common method of nuisance plant control that can be effective is the application of aquatic herbicides (Figure 9). There are two types of herbicides: systemic and contact. Systemic herbicides are taken up by the plant and translocated to the roots, resulting in longer-term control. Contact herbicides only impact the portions of the plant that come into contact with the herbicide. Thus, control with contact herbicides is usually short-lived and milfoil can re-grow within a few weeks. Contact Figure 9. Application of aquatic herbicides. herbicides also tend to be broad-spectrum; they may impact both milfoil and desirable native plants. By contrast, systemic herbicides are selective for milfoil with little or no impact to most native plants. Contact herbicides work relatively quickly while systemic herbicides generally take several weeks to kill the targeted plant. The type of herbicide used in a particular situation is dependent on the plant being targeted, time of year, water use restrictions, area of lake being treated, costs, and other factors. REGULATION OF AQUATIC HERBICIDE APPLICATION In Michigan, aquatic herbicide use is regulated under Part 33, Aquatic Nuisance Control, of the Natural Resources and Environmental Protection Act, PA 451 of Prior to herbicide treatments, a permit must be acquired from the Michigan Department of Environmental Quality (MDEQ). MDEQ regulates the type, dose rate, and location within the lake where herbicides may be applied. Progressive AE Progressive AE Thompson Lake Annual Plant Control Report 5

10 Methods AQUATIC PLANT SURVEY Aquatic plants in Thompson Lake were surveyed in accordance with Michigan Department of Environmental Quality (MDEQ) Procedures for Aquatic Vegetation Surveys. With these procedures, the lake shoreline is divided into sections, and the type and relative abundance of all plants species present in each section of the lake are recorded. GPS waypoints were established around the shoreline to guide the survey and to delineate the survey sections (Figure 10) Legend 84 85! 10! 20! GPS Waypoint Location ! ! 40! ! 52! ! ! ! 25!20! 5! ! 20! ! N Figure 10. Thompson Lake aquatic plant survey map. Thompson Lake Annual Plant Control Report 6

11 METHODS Plant densities were estimated in accordance with MDEQ procedures as follows: (a) = found: one or two plants of a species found at a site, equivalent to less than 2% of the total site surface area. (b) = sparse: scattered distribution of a species at a site, equivalent to between 2% and 20% of the total site surface area. (c) = common: common distribution of a species where the species is easily found at a site, equivalent to between 21% and 60% of the total site surface area. (d) = dense: dense distribution of a species where the species is present in considerable quantities throughout a site, equivalent to greater than 60% of the total site surface area. Data for each individual assessment section was recorded, compiled and tabulated to evaluate the relative abundance of all plant species in Thompson Lake. AQUATIC PLANT BIO-VOLUME MAPPING Early, mid-season, and late-season hydro-acoustic surveys were conducted along the shoreline of Thompson Lake to create maps of plant bio-volume, i.e., the height of plants in the water column. Data was collected using a Lowrance HDS 9 and processed by Navico BioBase. A bio-volume measurement of 50% indicates plants occupy one-half of the water column (Figure 11). In addition to plant height, bio-volume mapping is useful for simply determining the locations of plant beds. Figure 11. Hydro-acoustic survey read-out. Left: Navigation track (red line) and vegetation bio-volume (multi-color). Right: hydro-acoustic profile. Thompson Lake Annual Plant Control Report 7

12 Aquatic Plant Survey PLANT SPECIES PRESENT On September 10, 2015, there were 23 aquatic plant species present in Thompson Lake (Table 1). Four were exotic species (Eurasian milfoil, starry stonewort, curly-leaf pondweed, and purple loosestrife) and the remainder were native plants. The standard aquatic vegetation summary sheet, prepared in accordance with MDEQ Procedures for Aquatic Vegetation Surveys, is included in Appendix A. TABLE 1 THOMPSON LAKE AQUATIC PLANTS September 10, 2015 Percent of Sites Common Name Scientific Name Group Where Present Naiad Najas sp. Submersed 84 Eurasian milfoil Myriophyllum spicatum Submersed 82 Thin-leaf pondweed Potamogeton sp. Submersed 46 Flat-stem pondweed Potamogeton zosteriformis Submersed 38 Starry stonewort Nitellopsis obtusa Submersed 31 Chara Chara sp. Submersed 27 Large-leaf pondweed Potamogeton amplifolius Submersed 26 Water stargrass Heteranthera dubia Submersed 26 Sago pondweed Stuckenia pectinata Submersed 23 Curly-leaf pondweed Potamogeton crispus Submersed 14 Coontail Ceratophyllum demersum Submersed 14 Richardson s pondweed Potamogeton richardsonii Submersed 5 American pondweed Potamogeton americanus Submersed 3 Illinois pondweed Potamogeton illinoensis Submersed 1 Wild celery Vallisneria americana Submersed 1 Bladderwort Utricularia vulgaris Submersed 1 White waterlily Nymphaea odorata Floating-leaved 50 Yellow waterlily Nuphar sp. Floating-leaved 2 Floating-leaf pondweed Potamogeton natans Floating-leaved 1 Purple loosestrife Lythrum salicaria Emergent 20 Cattail Typha sp. Emergent 17 Bulrush Scirpus sp. Emergent 5 Swamp loosestrife Decodon verticillatus Emergent 2 Thompson Lake Annual Plant Control Report 8

13 AQUATIC PLANT SURVEY AQUATIC PLANT DISTRIBUTION AND BIO-VOLUME The early, mid- and late-season bio-volume maps are included in Figures 12 through 14. Thurber Dr Howell City Park Lakeside Dr. Butler Blvd Thompson Shore Dr. Percent Bio-volume Lakeview Cemetery Roosevelt St. Indiana Ave Lakeshore Pointe Dr. Mt. Olivet Cemetery Roselane Dr. Chicago Dr. Harvard Dr. Endicott Endicott N 0' 250' 500' Figure 12. Thompson Lake aquatic plant bio-volume map, May 12, Thompson Lake Annual Plant Control Report 9

14 AQUATIC PLANT SURVEY Thurber Dr Howell City Park Lakeside Dr. Butler Blvd Thompson Shore Dr. Percent Bio-volume Lakeview Cemetery Roosevelt St. Indiana Ave Lakeshore Pointe Dr. Mt. Olivet Cemetery Roselane Dr. Chicago Dr. Harvard Dr. Endicott N 0' 250' 500' Figure 13. Thompson Lake aquatic plant bio-volume map, August 12, Grey areas were inaccessible by boat. Thompson Lake Annual Plant Control Report 10

15 AQUATIC PLANT SURVEY Thurber Dr Howell City Park Lakeside Dr. Butler Blvd Thompson Shore Dr. Percent Bio-volume Lakeview Cemetery Roosevelt St. Indiana Ave Lakeshore Pointe Dr. Mt. Olivet Cemetery Roselane Dr. Chicago Dr. Harvard Dr. Endicott N 0' 250' 500' Figure 14. Thompson Lake aquatic plant bio-volume map, September 10, Thompson Lake Annual Plant Control Report 11

16 Nuisance Aquatic Plant Control Activities In 2015, Eurasian milfoil was the target plant for herbicide treatments; harvesting was used to control starry stonewort and nuisance native vegetation (Table 2; Appendix B). TABLE 2 THOMPSON LAKE 2015 NUISANCE AQUATIC PLANT CONTROL SUMMARY Herbicide or Acres Treated Date Target Harvesting or Harvested 6/9/2015 Eurasian milfoil Triclopyr 3 6/9/2015 Eurasian milfoil 2,4-D amine /23/2015 Starry; nuisance native plants Harvesting 35 7/9/2015 Nuisance algae Copper sulfate 0.5 Total 57 On October 7, Eurasian milfoil plants were collected and sent to the laboratory of SePRO, the manufacturer of the aquatic herbicide Sonar (generic name, fluridone), to test how milfoil in Thompson Lake would respond to a Sonar treatment. SePRO reported that "[t]he assay results support that Thompson Lake milfoil have a typical response to Sonar." Thus, it is anticipated that a Sonar (fluridone) treatment should successfully control milfoil in Thompson Lake. Thompson Lake Annual Plant Control Report 12

17 Summary of Findings In 2015, Thompson Lake maintained a good diversity of native aquatic plants but also contained several submersed exotic aquatic plants including Eurasian milfoil, starry stonewort, and curly-leaf pondweed. Bio-volume mapping showed that plants were low-growing early in the season, were moderate in August, and were tallest in September. Fifty-seven acres were treated or harvested in 2015 to control nuisance aquatic plant growth. Plant control successfully maintained native plants while allowing navigation and recreational activities to occur throughout most of the lake during summer. The areas with greatest bio-volume during the September survey included Chicago Drive, Harvard Drive, Thompson Shore Drive, the west end of Roselane Drive, and Lakeshore Point. Bio-volume mapping will be useful in tracking aquatic plant growth over time. Testing in 2015 showed that a Sonar (fluridone) application should successfully control Thompson Lake milfoil. A fluridone application for milfoil control is planned for 2016, pending issuance of a permit from MDEQ. Starry stonewort will be controlled with copper-based herbicides and mechanical harvesting. Harvesting will also be used for control of nuisance native plants. Thompson Lake Annual Plant Control Report 13

18 Appendix A Standard Aquatic Vegetation Summary Thompson Lake Annual Plant Control Report

19 Standard Aquatic Vegetation Summary Sheet Lake Name: Thompson Lake County: Surveyor: Livingston County Rick Buteyn, Garrett Groves Survey Date: Total Number of AVAS Sites: Sep-15 Occurrence per Relative Density for Code Relative Density Calculations Plant Name Density Category Entire Littoral Zone Code No No Plant Name A B C D A x 1 B x10 C x 40 D x 80 Sum % 1 Eurasian milfoil , Eurasian milfoil 2 Curly leaf pondweed Curly leaf pondweed 3 Chara Chara 4 Thinleaf pondweed Thinleaf pondweed 5 Flatstem pondweed Flatstem pondweed 6 Robbins pondweed Robbins pondweed 7 Variable pondweed Variable pondweed 8 Whitestem pondweed Whitestem pondweed 9 Richardson's pondweed Richardson's pondweed 10 Illinois pondweed Illinois pondweed 11 Large leaf pondweed Large leaf pondweed 12 American pondweed American pondweed 13 Floating leaf pondweed Floating leaf pondweed 14 Water stargrass Water stargrass 15 Wild celery Wild celery 16 Sagittaria Sagittaria 17 Northern milfoil Northern milfoil 18 M. verticillatum M. verticillatum 19 M. heterophyllum M. heterophyllum 20 Coontail Coontail 21 Elodea Elodea 22 Utricularia spp Utricularia spp. 23 Bladderwort-mini Bladderwort-mini 24 Buttercup Buttercup 25 Najas spp , , Najas spp. 26 Brittle naiad Brittle naiad 27 Sago pondweed Sago pondweed Nymphaea Nymphaea 31 Nuphar Nuphar 32 Brasenia Brasenia 33 Lemna minor Lemna minor 34 Spirodella Spirodella 35 Watermeal Watermeal 36 Arrowhead Arrowhead 37 Pickerelweed Pickerelweed 38 Arrow arum Arrow arum 39 Cattails Cattails 40 Bulrushes Bulrushes 41 Iris Iris 42 Swamp loosestrife Swamp loosestrife 43 Purple loosestrife Purple loosestrife 44 Starry stonewort Starry stonewort Total: 94.0 P:\ \Civ\Design\Thompson AVAS.xlsx

20 Appendix B MDEQ Treatment Report Thompson Lake Annual Plant Control Report

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25 Appendix C Harvesting Log Thompson Lake Annual Plant Control Report

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