i2
Secondary spread of invasive aquatic plants depends on survival time during air exposure
Susan Knight1
Lindsey Bruckerhoff2
John Havel2
1‐University of Wisconsin 2‐Missouri State University, Slide 1
i2
Wordy title?
Nice pic of Susan!
itsguest, 2/11/2013
i3
Invasive aquatic plants are widespread and damaging to lakes Slide 2
i3
made pics a bit bigger since you have the space
itsguest, 2/11/2013
i4
Two invasive aquatic plants are prevalent in Wisconsin
Eurasian water‐milfoil (EWM)
Myriophylum spicatum
635 lakes
Curlyleaf pondweed (CLP)
Potamogeton crispus
485 lakes
Wisconsin DNR SWIMS data for 2010, maps courtesy of A. Latzka
Slide 3
i4
I am happy to see better distribution maps! Thank you Latzka!
itsguest, 2/11/2013
i5
Some boats carry hitchhikers.
Aquatic plants (Johnstone et al. 1985) Zebra mussels (Johnson et al. 2001)
Zooplankton (Havel and Stelzleni‐
Schwent 2000)
Snails and other invertebrates (Rothlisberger et al. 2010)
Rothlisberger et al. 2010 Fisheries 35: 121
Slide 4
i5
I increased the contrast in the plot so it can be seen a little better, although still a little blurred
itsguest, 2/11/2013
Factors controlling secondary spread
Encounter
Carry
Colonization
Most boaters visit multiple lakes.
0.3
N = 800 interviews
Number of Boaters 0.25
0.2
0.15
0.1
0.05
0
1
2
3
4
5
6
7
8
9
10
>10
Number of Waterbodies Visited
Summer 2011 Wisconsin data
B. Beardmore, pers. com.
Boats are out of water for short periods.
50
Number of Boat Trips (%)
45
N = 2,936 trips
(800 interviews)
40
35
30
25
20
15
10
5
0
1
2‐4
5‐14
15‐30
>30
Days in Between Boat Trips
Summer 2011 Wisconsin data
B. Beardmore, pers. com.
Factors Controlling Secondary Spread
Encounter
Carry
Colonization
Experiments:
Survival time out of water by species and size of “wad”.
Field experiments at UW Trout Lake Station
9 experiments during summer, 2011 & 2012
Strict procedures for containment
i6
During each experiment:
Fresh collection
Isolation Cut stems to 20 cm
Measure apical tip length
Dry to different time endpoints (n=10 ea)
Rehydrate and grow 1‐2 weeks
Re‐measure apical tip length
“Alive” = significant positive growth
Slide 11
i6
What do you mean by isolation? Maybe say sorting or leave out?
itsguest, 2/11/2013
Weather for drying was mild and humid
100
2012
40
80
30
60
20
40
10
20
0
June
0
July
August
Relative Humidity (%)
Temperature (°C)
50
Temperature during rehydration depended on our method.
Temperatre (C)
2011 40
35
30
25
20
15
10
5
June
July
August
2012
40
Temperature (°C)
35
30
25
20
15
10
5
June
July
CLP stems exhibited positive growth up to 18hr of drying. EWM stems exhibited positive growth up to 24hr of exposure. Coiling experiments
Coiled EWM exhibited growth up to 3 days of air exposure. 2012
What life history stages can be transported?
Eurasian watermilfoil
Curlyleaf pondweed
turion
CLP turion experiment
After air drying 2 weeks, 10% of turions sprouted (vs. 50% in control).
Conclusions
• Under mesic summer conditions, single stems of EWM and CLP can survive about 1 day out of water.
• Coiling plants extends the survival time of EWM to 3 days.
• Many boaters visit multiple lakes during these time intervals.
• The dormant turions of CLP can likely survive much longer periods out of water and are produced at a time when boating activity is high.
Acknowledgments
Funding
Wisconsin DNR
Technical assistance
Coauthors Trout Lake Station students & staff
Boater data
Ben Beardmore
seknight@wisc.edu