Michelle Nault

Wisconsin Department of Natural Resources

Michelle.Nault@Wisconsin.gov

Starry Stonewort A new aquatic invader in Wisconsin

Photo: Paul Skawinski

What is starry stonewort? • Starry stonewort (Nitellopsis obtusa) is a member of the

Characeae family.

• Characeae are green algae that can range in size from centimeters to meters, and are found throughout the world.

• Not a vascular plant like most our aquatic plant species.

Native Range • Native to Europe and Asia

• Endangered species in the United Kingdom and Japan

Non-Native Range

• First documented in St. Lawrence River in 1978; likely transported via international ballast water

• Documented in lower Michigan inland lakes in the mid-2000s.

• First documented in Wisconsin (Waukesha Co.) in September 2014.

• Currently known from Indiana, Michigan (Lower), Minnesota, New York, Ohio, Pennsylvania, Vermont, Wisconsin, and Ontario, Canada.

Starry stonewort distribution

Starry Stonewort (Nitellopsis obtusa)

First discovered in Little Muskego Lake, Waukesha Co. – Fall 2014

Now known in 6 Wisconsin Lakes & Sturgeon Bay area

Little Muskego, Waukesha Co. Big Muskego, Waukesha Co.

Long, Racine Co.

Pike, Silver, Green, Washington Co.

Sturgeon Bay, Door Co.

Green Bay/Lake Michigan Distribution

• First reported to WDNR by a lake management consultant conducting an aquatic plant survey out on the Sturgeon Bay Channel (Door Co.)

• Verified by WDNR and the New York Botanical Garden

• WDNR conducted rapid assessment of public access locations surrounding the initial report

• Monitoring consisted of random rake tosses via shore off piers, docks, boat launches, beaches, etc.

Green Bay/Lake Michigan Distribution

Ecology

• Macroalgae species that can grow up to ~7 ft (2 meters) tall

• Anchored to the sediments with clear filaments called rhizoids, which resemble fishing line

• Can persist under the ice in St. Lawrence River

• In Detroit River, first appears in July with peak biomass in September, and declines beginning in November

Habitat

• Occupies a broad range of habitats

• Occurs in lakes, ponds, and slow-moving water bodies

• Can colonize shallow to deep waters up to at least 20 feet (6.1 meters); tolerant of low light conditions

• Particularly thrives in alkaline, stagnant to slow-moving waters with moderate to high levels of nutrients and calcium

Reproduction

• Fragmentation of the stem

• Specialized structures called bulbils – star-shaped

– creamy white

– less than 1/3-inch (~1 cm)

• Only male starry stonewort has been found in North America. – No sexual reproduction

Photo credit: Robin Sleith

Dispersal

• Primarily moved by boats, trailers, & anchors

• Waterfowl not believed to be source of dispersal due to lack of sexual reproduction (zygotes).

Impacts

• Impacts of starry stonewort are largely unknown – primarily anecdotal and not science based

How might starry stonewort affect a lake?

• May outcompete native aquatic plants

• Thick “meadows” may alter habitat and prevent fish from spawning

• May become a navigational nuisance in shallow waters (< 6 feet)

Photo: Paul Skawinski

Identification

• Related to many native macroalgae

in Wisconsin – Chara (10+ species)

– Nitella (9+ species)

– Tolypella (2 species)

– Lychnothamnus (1 species)

• Can be difficult to distinguish non-native starry stonewort from these native species

Identification

Starry stonewort Nitellopsis obtusa Nitella flexilis Chara globularis Chara contraria

Large compared to most of its native relatives

Photos: Paul Skawinski

Identification Retains its shape when held out of water

Starry stonewort Nitellopsis obtusa

Chara contraria

Identification Smooth stem – no bumps or ridges

Starry stonewort Nitellopsis obtusa

Identification Starry stonewort Nitellopsis obtusa Nitella mucronata

Branchlet divides into equal-length parts

Branchlet has a short uneven bract coming off

the side

Identification

Starry stonewort Nitellopsis obtusa

Branchlet has a short bract coming off the

side

Bract cell

Identification

• Starry stonewort produces distinct star-shaped bulbils

Nitellopsis obtusa (starry stonewort)

Identification

• Most native macroalgae do not produce bulbils; Chara aspera produces round bulbils

Chara aspera

Identification Horned pondweed

(Zannichellia palustris) VS.

NATIVE

Starry stonewort

(Nitellopsis obtusa)

Identification Sago pondweed

(Stuckenia pectinata) VS.

NATIVE

Starry stonewort

(Nitellopsis obtusa)

Management Options

• Management of starry stonewort has been largely unsuccessful in other states

• Chemical herbicide treatments (i.e. copper sulfate, hydrothol) – may provide temporary nuisance relief, but does not

kill the entire plant – generally non-selective and may impact native species

• Physical control – hand-removal, DASH, dredging, mechanical harvesting

• Drawdown? • No known biocontrol methods • “Wait and see” • Eradication in not a realistic goal

Next Steps • Prevent the further spread of starry stonewort within

Lake Michigan and potentially to inland lakes.

• Search for starry stonewort at nearby heavily used lakes.

• Assess the population at newly discovered sites to determine appropriate management.

• Engage local stakeholders in management planning and education/outreach activities (i.e. CBCW).

• If management occurs, collect quantitative data to assess efficacy and longevity of control

• Work with other states and partners to learn and adaptively manage starry stonewort.

How can we stop the spread of AIS? • Wisconsin State Law

requires that prior to leaving a boat launch, you must:

Inspect boats, trailers and equipment, including anchors and other places that accumulate sediment

Remove all attached aquatic plants, animals and mud

Drain all water from boats, vehicles and equipment

Never move plants or live fish away from a water body

What can marinas do to help? • Educate customers via personal interactions and

appropriately placed signage on the AIS prevention steps they should take to minimize spread

• Always perform the AIS prevention steps when moving watercrafts for customers

• When servicing a watercraft, always perform the AIS prevention steps before test launching it

• Provide a hot water, high pressure wash to customers who are moving boats that have been slipped throughout the season

• Keep boat launch areas free of floating vegetation and other debris which could get caught on trailers

• Report any newly discovered invasive or suspicious plants/animals to local WDNR staff

Acknowledgements Mary Gansberg

Paul Skawinski

Tim Plude

Becca Klemme

Bob Wakeman

Maureen Ferry

Amy Kretlow

Libby Hess

Jeremy Bates

Susan Eichelkraut

Craig Helker

Kari Hagenow

Tim Campbell

Jenny Seifert

Dr. Ken Karol

Brad Steckart

Onterra LLC

Discussion

Michelle Nault

Northern Lake Michigan Basin Aquatic Invasive Species Coordinator

2984 Shawano Ave.

Green Bay, WI 54313

Michelle.Nault@Wisconsin.gov

920-662-5110