2014 eurasian watermilfoil mapping survey · ewm mapping survey | lake shamineau | morrison county,...

EWM Mapping Survey | Lake Shamineau | Morrison County, MN | July 2014

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2014 Eurasian Watermilfoil Mapping Survey Lake Shamineau (Morrison County, MN – #49-0127-00) Surveyed July 30, 2014

Surveying, Analysis, and Reporting by: James A. Johnson – Freshwater Scientific Services, LLC Funded by: Lake Shamineau Association – Motley, MN

www.fixmylake.com 18029 83rd Avenue North Maple Grove, MN 55311 [email protected] (651) 336-8696


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Survey & Analysis Methods

EWM Mapping Survey Freshwater Scientific Services, LLC conducted an extensive search of Lake Shamineau on July 30, 2014 to locate and map any beds of invasive Eurasian watermilfoil (Myriophyllum spicatum, hereafter referred to as EWM). This search was conducted by navigating a survey boat slowly along a winding path that roughly covered the littoral area of the lake (Figure 1). As we navigated this path, we visually scanned (using polarized sunglasses) the area within ~30 feet of the boat for EWM. In addition to visual inspection, we also used sonar to locate any plant beds in deeper areas. If sonar readings indicated the presence of a plant bed that was not visible from the surface, we used an underwater video camera or rake tosses to determine if EWM was present. Although the search we conducted was intensive and designed to detect any established patches of EWM in Lake Shamineau, no survey can guarantee detection of all EWM plants in a lake – particularly sparse areas of EWM that are not visible from the surface or that do not stand out as a plant bed on sonar readings.

Date Surveyed July 30, 2014

Surveyed Path Length 25.2 miles

Survey Hours 10.5 hours

Figure 1. Map showing the path surveyed during the July 30, 2014 Lake Shamineau EWM mapping survey.



Point Latitude Longitude

EWM

1

46.263014

-94.631179 2 46.263036 -94.631309 3 46.263167 -94.631600 4 46.263085 -94.631777 5 46.262848 -94.631823 6 46.263544 -94.631523 7 46.263727 -94.631319 8 46.263833 -94.631128 9 46.264565 -94.629795 10 46.264558 -94.628830 11 46.263782 -94.630534

Possible Hybrid Milfoil

1 46.252999 -94.626188 2 46.252548 -94.627873 3 46.252454 -94.627847 4 46.252390 -94.628944

5 46.252397 -94.628910

Purple Loosestrife

1

46.263792

-94.622650 2 46.263797 -94.618899

3 46.255790 -94.592939 4

46.255434

-94.589212

Results Figure 2. Map showing the location of EWM plants, possible hybrid milfoil plants, and invasive purple loosestrife

found during the 2014 Lake Shamineau survey. GPS coordinates for points given in Table 1.

Eurasian watermilfoil (EWM)

Possible Hybrid Milfoil (native × EWM)

Purple Loosestrife (on shore)

Table 1. GPS location of points shown in Figure 2. Note that GPS points for purple loosestrife were recorded immediately offshore from the located plants.



Eurasian Watermilfoil (EWM) The only location where we found invasive EWM plants was in the far northwestern bay of Shamineau Lake, directly north of the public boat launch (Figure 2). EWM growth in this area was confined to shallow near-shore areas (<6 ft) and was very sparse, consisting of only sporadic individual EWM plants interspersed within larger beds of native northern watermilfoil (Myriophyllum sibiricum) and other native plants. We found no dense beds of EWM during the survey, with only a few EWM plants growing to the surface (all in areas shallower than 4 ft). At the time of the survey, EWM did not grow densely enough to impair recreation in the northwest bay, but did appear to have spread southward along shore since the last delineation survey (conducted by the MDNR in 2012). The Lake Shamineau Association should continue to monitor and manage EWM growth in this area (at least annually) to prevent further expansion.

DNR Link: http://www.dnr.state.mn.us/invasives/aquaticplants/milfoil/index.html Hybrid Watermilfoil (EWM x Northern Watermilfoil) Native northern watermilfoil can hybridize (cross-breed) with EWM, leading to plants that are intermediate in appearance and hard to identify definitively without genetic testing. Like EWM, hybrid milfoil can form areas of surface-matted growth that can displace native plants and impair water recreation. Furthermore, hybrid milfoil may react differently than EWM to some herbicide treatments (different timing or dosing may be required for effective control). We found a few areas in in the far southwest portion of the lake (Figure 2) where milfoil plants appeared to have some intermediate characteristics (more surface branching and higher leaflet counts than typically seen in northern watermilfoil). However, without genetic testing, we can not be sure if these patches were hybrid milfoil or just odd-looking northern watermilfoil. The Lake Shamineau Association should track any changes in the amount of surface-matted milfoil growth in this portion of the lake over the coming years and should consider submitting plant samples from this area for genetic testing (link below) if the milfoil plants there begin to form substantial areas of surface-matted growth.

Genetic Testing: http://www.gvsu.edu/wri/thum/milfoil-genetic-identification-services-15.htm Purple Loosestrife (Lythrum salicaria) Although the purpose of our survey was to locate and map any EWM in the lake, we also noted the location of any other invasive aquatic plants that we encountered. The only other invasive that we observed growing in Lake Shamineau was purple loosestrife. This invasive shoreland plant was found in a few isolated locations along the northern shoreline of Lake Shamineau (Figure 2). Although past biocontrol efforts using loosestrife beetles has proven to be very effective for managing large areas of purple loosestrife in MN, the Lake Shamineau Association should consider manual removal of these plants to prevent further expansion.

DNR link: http://www.dnr.state.mn.us/invasives/aquaticplants/purpleloosestrife/index.html



Online Resources & Contacts

Links

Aquatic Invasives in MN http://www.dnr.state.mn.us/invasives/aquatic/index.html Minnesota AIS Grant Programs http://www.dnr.state.mn.us/grants/aquatic_invasive/index.html Minnesota DNR Contacts for AIS and Watercraft Inspection Programs http://www.dnr.state.mn.us/invasives/ais/contacts.html Minnesota Administrative Rules for Aquatic Plant Management https://www.revisor.mn.gov/rules/?id=6280 Minnesota DNR – Aquatic Plant Management Regulations & Permit Application Forms http://www.dnr.state.mn.us/shorelandmgmt/apg/regulations.html Contacts

Christine Jurek Invasive Species Specialist Minnesota DNR [email protected] (320) 255-4279 (ext 232) Chip Welling AIS Management Program Coordinator Minnesota DNR 500 Lafayette Road Box 25 St Paul, MN 55155-4025 [email protected] (651) 259-5149 Steve Enger Aquatic Plant Management Program Coordinator Minnesota DNR 500 Lafayette Road Box 25 St Paul, MN 55155-4025 [email protected] (651) 259-5092

2014 eurasian watermilfoil mapping survey · ewm mapping survey | lake shamineau | morrison county,...

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