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

Kylie.Cattoor@state.mn.us

Keegan.Lund@state.mn.us

QUESTIONS