Hybrid Milfoil: Coming to a Lake Near You?

Post by Sara Fox, Aquatic Invasive Species Outreach Assistant, University of Wisconsin-Extension. This post was originally featured on the UW-Sea Grant Blog. 

This summer, while water skiing in Waukesha County, Wisconsin, I recall taking a massive wipeout. I remember expecting to feel the painful sting after hitting the water, similar to that of a belly flop. Instead, I landed on a cushion of plants. I looked around and found myself floating on top of a giant mat of milfoil!

If you’re a Wisconsin lake user, patches of milfoil probably aren’t new to you. However, a new milfoil hybrid combines genes of native and invasive species and may be a cause for concern on some Wisconsin lakes.

Wisconsin has many native milfoil species that provide cover and sometimes food for fish, invertebrates and aquatic insects. Milfoil species such as northern or whorled watermilfoil are native to Wisconsin and have contributed to lake ecosystems for a long time. More recently, in the early 1960s an invasive milfoil species called Eurasian watermilfoil was discovered in Dane County and since has spread to over 800 lakes in Wisconsin.

A diver surfaces through a heavy infestation of Eurasian watermilfoil.

As its name suggests, Eurasian watermilfoil is native to Europe, Asia and North Africa. Like many other plants, Eurasian watermilfoil grows up to the surface to access sunlight. Yet, unlike many other plants, it doesn’t stop at the surface; it grows across the surface, causing dense mats of vegetation that can get tangled in boat propellers and block sunlight from native plants below.

Eurasian watermilfoil can spread quickly and efficiently, primarily because of its ability to produce adventitious roots after fragmenting. This means that if you cut a strand of Eurasian watermilfoil into ten pieces, each piece could sprout new roots and become its own plant.

Treatment options for lakes that contain Eurasian watermilfoil differ by lake and vary by levels of efficacy, cost, benefits, and drawbacks. Attempted treatments have included: chemical application, manual hand pulling and use of biological control weevils.

Even more recently, a hybrid milfoil has evolved on some lakes in Wisconsin and it might be a big deal. The hybrid (sometimes referred to as a “super milfoil”) is a genetic cross between native northern watermilfoil and invasive Eurasian watermilfoil. It exhibits characteristics similar to both northern and Eurasian watermilfoil and genetic testing is often needed to verify its presence.

A possible hybrid species collected and pressed in Jefferson County, Wisconsin.

The hybrid species hasn’t caused any verified negative effects to lake ecosystems that differ from Eurasian watermilfoil, but it’s potential to cause trouble for lake users in coming years makes it worth keeping an eye on. For example, state biologists have observed that the hybrid may be harder to control using the chemical application methods we use to treat Eurasian watermilfoil. Specifically, in some cases, it has shown a reduced sensitivity to  2, 4-D and fluridone. (It’s important to note that if your lake hasn’t seen success treating for Eurasian watermilfoil it doesn’t necessarily mean you have the hybrid.)

Additionally, the hybrid’s growing habits seem to have a competitive advantage over both its parents. Expect more information on the hybrid’s behavior soon from organizations conducting research such as the University of Minnesota Aquatic Invasive Species Research Center and the Wisconsin DNR Aquatic Plant Management Program.

If you’re worried about hybrid milfoil making its way into a lake you care about, don’t panic! There are preventative measures individual lake users can take to make sure hybrid milfoil–and every other aquatic invasive species–doesn’t enter a new waterbody:

  • INSPECT your boat, trailer and equipment.
  • REMOVE any attached aquatic plants or animals (before launching, after loading and before transporting on a public highway)
  • DRAIN all water from boats, motors and all equipment
  • NEVER MOVE live fish or plants away from a waterbody.
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Starry Stonewort: Up-And-Coming AIS of Wisconsin

Post by Bradley Steckart, Waukesha and Washington County AIS Coordinator; adapted by Sara Fox, UW-Extension

Starry Stonewort (Nitellopsis obtusa) has made a name for itself in Wisconsin as a well-known invasive species. Questions surrounding its unknown impacts and the viability of its reproductive bulbils have researchers, scientists, and volunteers interested in this relatively new invader. N. obtusa is a prohibited aquatic invasive species currently present in four Wisconsin counties. Here’s what you need to know about starry stonewort: 

What is it?

Starry stonewort is a freshwater macroalgae native to Europe and western Asia. While it is classified as invasive in the Midwest, it is listed as endangered in its native habitat. You might confuse starry stonewort with native stonewort (Chara spp.) or muskgrass (Nitella spp.) and pondweeds such as sago pondweed. 

You can identify starry stonewort by it’s bright green branches that grow in whorls of 4-6 around the stem. It is named after its small, white, star-shaped reproductive structures called bulbils. These bulbils reside 1-3 inches deep in the sediment and act as an anchor for the alga. Starry stonewort is dioecious, meaning that male and female reproductive structures grow on seperate algal stalks. Currently, only males are present in the United States indicating that reproduction is only occurring asexually by bulbil production.

The star-shaped reproductive structure of starry stonewort is called a bulbil. Credit – Paul Skawinski

How might it affect me?

Like many other invasive species, starry stonewort holds potential to outcompete native vegetation and alter the ecosystem of the waterbody where it is introduced. Starry stonewort grows into dense vegetative mats that can interfere with recreational water activities like tubing or water skiing. Large patches of starry stonewort may also threaten fish spawning habitat. However, those impacts are inferred from the impacts of other invasive aquatic plants. The specific effects of starry stonewort on fisheries is largely unknown and is currently under investigation by leading scientists.

As always, it is beneficial to take preventative measures to avoid spreading starry stonewort and other aquatic invasive species to and from your lake.

Starry stonewort can outcompete native plant species in a waterbody. Credit – Paul Skawinski

What does this mean for Wisconsin Lakes?

Manual and chemical control methods have been used to treat starry stonewort with varying success. However, boaters and anglers can take individual action to prevent the spread by following Wisconsin DNR AIS prevention steps:

INSPECT your watercraft vehicles and trailers for plant fragments upon exit and entrance to a waterbody. Pay special attention to anchors and footwear where bulbils might reside. Hunters should make sure to inspect duck decoys and blinds.

DRAIN water from your boat. This includes livewells, motors, and bait containers filled with water from the waterbody you’re exiting.

REMOVE all attached plants from your watercraft vehicles and trailers.

NEVER MOVE plants or water among waterbodies. Not only is this effective, but enforced by Wisconsin law.

For more information on starry stonewort, check out WDNR or UWEX Lakes resources.

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Lakes and Rivers Grant Story Map

Ever wonder where DNR grants go? Wonder no longer! Ben Kort (GIS Specialist) and Ali Mikulyuk (Statewide Rivers, Lakes Grant Coordinator), of the Water Quality Program’s Lakes and Rivers Section, recently finished an online story map to provide detailed information to the public on the state’s Rivers and Lakes Grant Program. This story map tool is an interactive tool created with ArcGIS Online that displays projects funded by the department’s Surface Water Grant program in 2018. This story map is a great way for people to learn about projects funded statewide that protect and/or improve their favorite lake or river.

There are 211 projects located in 62 Wisconsin counties depicted on the map, representing $6.2 million dollars in local or regional funding to improve water quality, reduce runoff, create aquatic habitat, and target aquatic invasive species. This new interactive map, provides a visual representation of the work funded by the program’s grant dollars. You can filter the map by grant type, county, and legislative area and find information about the department’s grant funding programs and supported projects.

Explore the story map and learn more about the Surface Water Grants Program.

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Protecting Wisconsin’s Hunting Tradition

Post by Jeanne Scherer, AIS Outreach Specialist for UW-Extension and Wisconsin Department of Natural Resources; adapted by Sara Fox 

As summer winds down and a hint of color change is showing up in the leaves, Wisconsin’s hunters prepare to take to the waters for the 2018 waterfowl hunting season on opening weekend, September 29-30. This season marks the third year of Waterfowl Hunter Aquatic Invasive Species (AIS) Outreach efforts, where teams of DNR staff, statewide AIS Partners and volunteers station themselves at access points to talk to hunters about what they can do to stop the spread of AIS. You may have encountered AIS outreach at hunting sites before. This year, watch for volunteers and partners at the Mead Wildlife Area, Big Muskego, Horicon Marsh, along the Mississippi River, and in multiple counties across the state.

Waterfowl Hunter AIS outreach is modeled after the successful Clean Boats Clean Waters (CBCW) program that reaches boaters all summer long at boat landings in Wisconsin.  Waterfowl inspectors will conduct a hunting version of the CBCW survey and talk with them about specific aspects of duck hunting that risk AIS movement. Mud, for example, can hide seeds, the bulbils of starry stonewort, and the eggs or larvae of tiny invaders like spiny waterfleas. A threat of particular concern to the hunters is the faucet snail. These snails carry intestinal flukes that can kill thousands of ducks if they eat them.

AIS can get stuck in hunting gear, like this starry stonewort on a decoy. Credit- Brad Steckart.

Hunters who talk with inspectors are given a collectible bird band stamped with the Stop Aquatic Hitchhikers logo as a thank you for taking action to protect their favorite hunting sites. Since the hunters traditionally wear their duck bands as a collectible, the band also serves as a reminder to stop the spread of AIS.

Duck bands with the SAH! logo serve as a reminder to stop the spread of AIS.

Just a few minutes of preventative action can protect our hunting tradition for generations to come. Before launching into and leaving a waterbody, hunters must:

Inspect waders, boats, trailers, motors and hunting equipment, including boots, blinds and dogs.

Remove all plants, animals and mud.

Drain all water from decoys, boats, motors, livewells and other hunting equipment.

Never move plants or live fish away from a water body.

A special consideration for waterfowl hunters is to remove all seed heads and roots when using vegetation for your duck blinds. It is important to note that it is illegal to use phragmites in counties where the plant is listed as prohibited by NR40, in general these counties include the western half of Wisconsin.

For more information contact Jeanne Scherer, AIS Outreach Specialist, at jeanne.scherer@ces.uwex.edu.

For more information about aquatic invasive species, including where they are prohibited and restricted, in Wisconsin, visit this WDNR webpage.

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