Starry stonewort: A new aquatic
invasive species in Minnesota
Dan Larkin
April 15, 2016
Photo: Dan Larkin
Overview
• Introduction to starry stonewort
• Applied research on starry stonewort
– Risk assessment
– Control
• Takeaways
– Identification
– Citizen science opportunities
Photo: Dan Larkin
Starry stonewort
Nitellopsis obtusa
• New AIS in Minnesota
• Charophyte (green
algae)
Photo: Paul Skawinski
Starry stonewort
• Native to Europe, Asia
– Endangered in Japan
– Special concern in UK
(JNCC 2010,
Kato et al. 2014)
Photo: Scott Brown
Starry stonewort
• Closely related to
stoneworts /
muskgrasses native
to Minnesota
McCourt et al.
1996
Chara aspera C. contraria Nitella flexilis
Starry stonewort
• Relatively new invader
• Quickly gaining ground
• Increasing concern for AIS management
Starry stonewort
• Relatively new invader
• Quickly gaining ground
• Increasing concern for AIS management
Starry stonewort
• Relatively new invader
• Quickly gaining ground
• Increasing concern for AIS management
Starry stonewort
• Relatively new invader
• Quickly gaining ground
• Increasing concern for AIS management
Starry stonewort
• Lake Koronis (Stearns Co.)
Photos: Google Earth
Starry stonewort
• Reported as highly
invasive in some areas
• Reductions in plant
diversity
• Potential impacts to
spawning habitats
(Pullman and Crawford
2010, Sleith et al. 2015) Photo: Paul Skawinski
Starry stonewort
Michigan
• 128 lakes
• e.g., L. Houghton
– 0 – 3,000 acres in 5y (M. Heilman pers. comm.)
– Frequency nearly
tripled 2013–2015 (Progressive AE)
Photo: Google Earth
Starry stonewort
• How at risk is Minnesota?
• What can we do?
– Limited ecological knowledge
– Limited control toolkit
– High uncertainty
Photo: Dan Larkin
Invasion process
Prevention
Species
absent
Eradication
Rare,
localized
Containment
Rapidly
increasing
Long-term
management
Widespread and
abundant
Invasion stage
(time→)
Ab
un
da
nc
e
Invasion process
Prevention
Species
absent
Eradication
Rare,
localized
Containment
Rapidly
increasing
Long-term
management
Widespread and
abundant
Invasion stage
(time→)
Ab
un
da
nc
e
curlyleaf
pondweed
hydrilla
Invasion process
Prevention
Species
absent
Eradication
Rare,
localized
Containment
Rapidly
increasing
Long-term
management
Widespread and
abundant
Invasion stage
(time→)
Ab
un
da
nc
e
starry
stonewort
×
Invasion process
Prevention
Species
absent
Eradication
Rare,
localized
Containment
Rapidly
increasing
Long-term
management
Widespread and
abundant
Invasion stage
(time→)
Ab
un
da
nc
e
starry
stonewort
Little impact so far
But high uncertainty
about the future
×
Overview
• Introduction to starry stonewort
• Applied research on starry stonewort
– Risk assessment
– Control
• Takeaways
– Identification
– Citizen science opportunities
Photo: Dan Larkin
Risk assessment
• Ecological niche modeling
– Collaboration with Nick Phelps (MAISRC /
Vet Med) and postdoc Luis Escobar
Risk assessment
• Ecological niche modeling – Occurrences from native and invaded ranges
– Model distribution in relation to climate and environmental data
– Predict potential for range expansion
http://www.unil.ch/
Risk assessment
• Ecological niche modeling
Escobar et al. In review
Risk assessment
• Ecological niche modeling
– Exploiting “novel” climate niche in invaded range
Escobar et al. In review
Risk assessment
• Predictions of suitable habitat
Escobar et al. In review
Risk assessment
• As-yet uninvaded areas (Mid-Atlantic, Great Plains, Intermountain West) potential high suitability
Escobar et al. In review
Risk assessment
• Minnesota may have limited suitability
Escobar et al. In review
Next steps
• Investigate these
predictions through:
– Finer-scale risk
assessment for MN lakes
– Climate tolerance
experiments
– Desiccation tests
Figure: DH Montgomery, Pioneer Press
Scaling down to MN lakes
• Chemistry of SSW lakes:
– Fairly clear/low-nutrient
• Oligo-meso to mesotrophic
(S. Brown, MLSA)
– Alkaline (Sleith et al. 2015)
– High calcium carbonate
(Fuller & Taricska 2011)
• Positive feedbacks? (Kufel
& Kufel 2002)
Charophyte meadow in Poland Photo: Piotr Panek
Scaling down to MN lakes
• Chemistry of SSW lakes:
– Fairly clear/low-nutrient
• Oligo-meso to mesotrophic
(S. Brown, MLSA)
– Alkaline (Sleith et al. 2015)
– High calcium carbonate
(Fuller & Taricska 2011)
• Positive feedbacks? (Kufel
& Kufel 2002)
What lakes is it found in now?
What are physiochemical conditions of these lakes?
Which Minnesota lakes overlap with these conditions?
Scaling down to MN lakes
• Chemistry of SSW lakes:
– Fairly clear/low-nutrient
• Oligo-meso to mesotrophic
(S. Brown, MLSA)
– Alkaline (Sleith et al. 2015)
– High calcium carbonate
(Fuller & Taricska 2011)
• Positive feedbacks? (Kufel
& Kufel 2002)
What lakes is it found in now?
What are environmental conditions of these lakes?
Which Minnesota lakes overlap with these conditions?
Scaling down to MN lakes
• Chemistry of SSW lakes:
– Fairly clear/low-nutrient
• Oligo-meso to mesotrophic
(S. Brown, MLSA)
– Alkaline (Sleith et al. 2015)
– High calcium carbonate
(Fuller & Taricska 2011)
• Positive feedbacks? (Kufel
& Kufel 2002)
What lakes is it found in now?
What are environmental conditions of these lakes?
Which Minnesota lakes overlap with these conditions?
Climate tolerance
• Testing climate predictions
– Correlative models
– Nature full of surprises
– Is MN climate limiting for
starry stonewort?
Escobar et al. In review
Climate tolerance
• Growth experiments
– Culture starry stonewort
in new MAISRC lab
– Mimic winter conditions
predicted to be range-
limiting
• Duration
• Photoperiod
• Light quality
Climate tolerance
• Current and
future climate
– Typical
– Severe
– Mild
– Variable
(Hellmann et al. 2008, US
EPA 2008, NOAA 2016) Photo: MAISRC Facebook
Spread risk
• Dioecious, only males
identified in U.S. to date
• Spread by fragments
and “bulbils”
• Concentrated near
accesses / high-use
areas
Sleith et al. (2015)
Spread risk
• Unintentional human
movement fragments
and bulbils
• If contaminated boat…
how long does material
stay viable?
Photo: NYS DEC
Spread risk
Desiccation trials
• Undergrad Carli Wagner
• Environmentally controlled chambers
• Still able to grow after 12h, 24h, 2d, 5d….?
• Different materials
– Fragments
– Bulbils
– Different sized clumps
Photo: Milwaukee Journal Sentinel
Spread risk
Desiccation trials
• Different materials
– Fragments
– Bulbils
– Different sized clumps
Photo: Milwaukee Journal Sentinel
Overview
• Introduction to starry stonewort
• Applied research on starry stonewort
– Risk assessment
– Control
• Takeaways
– Identification
– Citizen science opportunities
Photo: Dan Larkin
Control
• Difficult to control
starry stonewort
– “Haircut” w/ dead
upper but live lower
parts, able to resprout
Pullman and Crawford 2010
Control
• Difficult to control
starry stonewort
– “Seedbank” of bulbils
left behind
– Herbicide sensitivity of
bulbils unknown
Photo: www.mymuskegonow.com/
Control
• Testing sensitivity of
plants and bulbils to
different herbicides
Photo: www.mymuskegonow.com/
Control
• Testing sensitivity of
plants and bulbils to
different herbicides
– Small-scale, high-
replication assays
Photo: MAISRC Facebook
Control
• Testing sensitivity of
plants and bulbils to
different herbicides
– Small-scale, high-
replication assays
• Chelated copper
formulations
• Non-copper herbicides
(diquat, alkylamine
endothall)
Photo: MAISRC Facebook
Control
• Testing sensitivity of
plants and bulbils to
different herbicides
– Larger-scale, more
realistic tests of
promising treatments
Photo: NOAA NCCOS
Control
• Testing non-target
effects on native
charophytes and
vascular plants
Photos: Ville Karvinen, articulo.mercadolibre.com.ec/,
Gary Fleming, C. B. Hellquist)
Extension
• Starry stonewort
working group (June)
– Bringing together
experts from around the
country
Photo: Dan Larkin
Extension
• Starry stonewort
working group (June)
– Synthesizing what is
known: ecology,
impacts, management
– Setting research
agenda Photo: Dan Larkin
Extension
• Starry stonewort
working group (June)
– Synthesizing what is
known: ecology,
impacts, management
– Setting research
agenda
Overview
• Introduction to starry stonewort
• Applied research on starry stonewort
– Risk assessment
– Control
• Takeaways
– Identification
– Citizen science opportunities
Photo: Dan Larkin
Identification
• May grow dense, tall
– Can have robust,
plant-like appearance
underwater
Photo: Paul Skawinski
Identification
• May grow dense, tall
– Can form thick mats
Photos: Dan Larkin,
Minnesota DNR
Identification
• Whorls of 4-6
long branchlets
Photo: Paul Skawinski
Identification
• Small, star-
shaped bulbils
Photos, L-R: Dan Larkin, MN DNR, Paul Skawinski
Volunteer/citizen science opportunities
AIS Detectors AIS Trackers
AIS Detectors program
• Front line for AIS early
detection
• Network of trained
volunteers
• Watershed focus
Sue Galatowitsch (MAISRC Director) and
Eleanor Burkett (Extension Educator)
AIS Trackers program
• Monitoring AIS
population changes in
response to
management
• Use findings to guide
AIS management
Photo: Dan Larkin
Acknowledgments
• Funding: Environment and Natural Resources
Trust Fund
• Collaborators: Luis Escobar, Nick Phelps,
Huijie Qiao
• Undergraduate researcher: Carli Wagner
Photo: Dan Larkin
For more information
MAISRC
• http://www.maisrc.umn.edu
• Sign up for our newsletter
• Follow @AISResearchMN on Twitter
• And like us on Facebook!
Koronis Lake Association (see Kevin Farnum)
• Starry stonewort public information meeting
• Presentation by Prof. John Rodgers, Clemson University
• April 26, 2016 at 7:00 PM
• Paynesville High School Auditorium