THE ART AND SCIENCE OF FINDING ZEBRA MUSSELS: A DISCUSSION OF IN-LAKE EARLY
DETECTION SEARCH METHODS IN MINNESOTA
KYLIE CATTOOR, KEEGAN LUND, ALLISON GAMBLE
MINNESOTA DEPARTMENT OF NATURAL RESOURCES
2016 UPPER MIDWEST INVASIVE SPECIES CONFERENCE
OCTOBER 19TH, 2016
LACROSSE, WISCONSIN
ZEBRA MUSSEL LIFE CYCLE
NEW INFESTATIONS INTO A WATERBODY
Potential vectors of spread:
• adults, juveniles, and veligers at variable times of the year
• human pathways: watercraft, docks & lifts
- residual water – limited risk
• connected waters
Detection challenges:
• water clarity (turbidity, water flow, algae)
• substrate (algae coating, muck, silt)
• shade (under rocks, low light, small crevices)
• tiny animals, large waterbodies- potentially localized at low densities
veliger
REPORTING NEW INFESTATIONS IN MN
1. Receive report
• photo or voucher specimen
• general location, date
2. Field inspection
• confirm presence
• lake wide assessment
3. Designate waterbody
4. Potential rapid response
REPORTING NEW INFESTATIONS IN MN
1. Receive report
• photo or voucher specimen
• general location, date
2. Field inspection
• confirm presence
• lake wide assessment
3. Designate waterbody
4. Potential rapid response
REPORTING NEW INFESTATIONS IN MN
1. Receive report
• photo or voucher specimen
• general location, date
2. Field inspection
• confirm presence
• lake wide assessment
3. Designate waterbody
4. Potential rapid response
EARLY DETECTION MONITORING
Photos provided by Minnehaha Creek Watershed District
Methods
• Settlement plates (passive)
- potentially reproducing
- covers large spatial range
- citizen involvement
- cost effective & easy data
collection
EARLY DETECTION MONITORING
Methods
• Settlement plates (passive)
- potentially reproducing
- covers large spatial range
- citizen involvement
- cost effective & easy data
collection
• Veliger tows (active)
- requires high veliger density
- time consuming on large scale
- specialized equipment
- confounding results
Photo provided by MAISRC
Photos provided by Minnehaha Creek Watershed District
EARLY DETECTION MONITORING
Methods
• In-lake searches
- wade v. snorkel v. SCUBA
- quadrat v. transect v. random
FOCUS AT THE ACCESS!
• MCWD early detection monitoring
program
CASE STUDY 1: LAKE INDEPENDENCE, HENNEPIN CO.
Designated infested: September 2014
Reported by: water resource manager
Discovered: public boat launch (juveniles + adults attached
to rock)
Field inspection
• ~2,000/m2 adults on access ramp + underneath dock
• Blue Water Science, 3RP, DNR
• in-lake searches + veliger tows for 29 hours
Rapid response efforts
• barrier containment
• pesticide control (EarthTec QZ & Muriate of Potash) in
2014-2015
• fall 2015: 49 adults outside treatment (12 hour search)
• summer/fall 2016: 3 adults, 2 juveniles (13 hour search)
Designated infested: July 2015
Reported by: lake property owner
Discovered: (?) attached to native, 2 additional reported
Field inspections
• in-lake searches (wade + snorkel) for 15 hours
• 5 DNR staff, no zebra mussels found
More searches…
• fall 2015: 21 hours (snorkel + SCUBA)
• 4 DNR staff, 3 confirmed zebra mussels
• fall dock removal, no zebra mussels reported
CASE STUDY 2: LAKE STELLA, MEEKER CO.
Designated infested: September 2014
Reported by: recreational smorkler
Discovered: 3 juveniles attached to small rocks
Field inspection
• in-lake searches for 30 hours, 13 juveniles found
• Blue Water Science, RCWD, WBLCD staff, WBL volunteers,
DNR
Zebra mussel population monitoring study developed
CASE STUDY 3: WHITE BEAR LAKE, RAMSEY/WASHINGTON CO.
ZEBRA MUSSEL POPULATION MONITORING
Methods
• 4– 50 meter belt transects
• veliger tows (July & August)
• intensive grid (100 x 100 meter)
• settlement plates & dock/lift checks
0
1
2
3
T1 T2 T3 T4
Log
10
zebra
muss
el densi
ty (
# p
er
10 m
2)
Monitoring Station
2015 (Year 1)
2016 (Year 2)
2
300
3
5
2
94
164
70
0
1
2
3
4
10 11 15 18
Log
10
veliger
densi
ty (
# p
er
m3)
Monitoring Station
2015 (Early)
2015 (Late)
2016 (Early)
2016 (Late)
2
33
2,526
256
SAMPLING GRID100 X 100 M QUADRATS 200 RANDOM QUADRATS (2%)
ZM Sampling Grid(100 x 100m)
Zebra Mussel Count
" 0
" 1
" 2
" 3
" 4
" 5
ZM Sampling Grid(Rand 200)
Zebra MusselCount
" 0
" 1 - 5
" 6 - 10
" 11 - 25
" 26 - 50
" 50+
WHAT CAN WE LEARN…
Truly an art and science!
• what is your purpose?
- early detection v. confirmation
• what are your resources?
- time and money
• Early detection monitoring is KEY!
Regardless… low densities are tough to find
Photo provided by MAISRC
Photo provided by MCWD
WHAT CAN WE LEARN…
Just confirming?
• random in-lake searches
– snorkel/wading/SCUBA
– verify infestation extent
Photo provided by MAISRC
Photo provided by MCWD
WHAT CAN WE LEARN…
Early detection efforts
• limited resources
- settlement plates + regular access searches
(get wet)
• search the access (monthly, weekly, daily)
• lakewide surveys (monthly)
- wade/snorkel/SCUBA
- suitable habitat… optimal times of year
(biologically & environmentally)
Photo provided by MAISRC
Photo provided by MCWD
CONTINUING EFFORTS IN MN
Watercraft Inspector Program- MN DNR
• boat access searches
Early detection monitoring
• protocol developed by DNR & MAISRC
Continued partnerships
• U of Minnesota- Extension detectors
• MAISRC
• Other ED programs, e.g. MCWD monitoring program
