Should lake managers worry about all invasive species? A...
41
Should lake managers worry about all invasive species? A case study on European frogbit Bin Zhu, Ph.D. 05/21/2016 MACOLAP/NECNALMS Conference
Transcript of Should lake managers worry about all invasive species? A...
Should lake managers worry
about all invasive species?
A case study on European frogbit
Bin Zhu, Ph.D.
05/21/2016
MACOLAP/NECNALMS Conference
Definition
• Invasive species are any species or other viable biological material (including its seeds, eggs, spores) that is transported into an ecosystem beyond its historic range, either intentionally or accidentally, and reproduces and spreads rapidly into new locations, causing economic or environmental harm or harm to human health.
• Synonyms for invasive species: introduced, foreign, exotic, alien, nonnative,
immigrant and transplants.(http://www.anstaskforce.gov/ans.php)
0
5
10
15
20
25
30
35
Pre-1839
1840-1859
1860-1879
1880-1899
1900-1919
1920-1939
1940-1959
1960-1979
1980-2007
Nu
mb
er
of
Sp
eci
es
Biological Invasion
(Source: New York Sea Grant)
(Source: New York Sea Grant)
Invasion Vectors
Commercial Ship (14 Months’ Activity)
Ballast Dump
Ballast Load (Source: New York Sea Grant)
(Grigorovich et al., 2003)
Impacts of Invasive Species
• Invasive Species – over 120 billion
annually (Pimentel 1999)
• Zebra/Quagga Mussels- $1.5 Billion
1989-2006 (NANSC 2006)
• Aquatic Plants - $1-10 billion /yr(Rockwell 2003)
– Purple loosestrife - $45 Million/yr(Congressional Research Service 1999)
European Frogbit
(Hydrocharis morsus-ranae)
• Free floating annually
• Originated from Eurasia
• First introduced to Ottawa from
Switzerland in 1932
• It escaped to the Rideau Canal
system in 1939
• Spread rapidly by means of water,
birds, boats, and human (Catling et
al. 2003).
Invasion in North America
(Modified from Catlings et al. 2003)
•Reproduces via stolons and winter buds
•Up to 100 buds/plant
•High density: 512 plantlets/m2 in Oneida Lake
•Dissolved oxygen (DO) as low as 1.9 mg/L (Zhu
et al. 2008)
Should We Worry about it?
Michigan DNR
Objectives
1. Determine what factors contributing their invasive success
2. Assess the ecological impacts of European frogbit;
3. Evaluate impacts of two physical methods - hand pulling and shading
4. Gauge the effectiveness of hand pulling and shading as well as biological control using snails
Objectives
1. Determine what factors contributing their invasive success
2. Assess the ecological impacts of European frogbit;
3. Evaluate impacts of two physical methods - hand pulling and shading
4. Gauge the effectiveness of hand pulling and shading as well as biological control using snails
Fulton, NY Salmon River
Ausible Point Perch River
**. Correlation is significant at the 0.01 level (2-tailed).
*. Correlation is significant at the 0.05 level (2-tailed).
Important Factors
Plant Presence
Elev. T Cond TDS DO pH Wind TP TKN NO3- TN
Pearson Correlation
-0.117 0.126 0.211 0.244 -.403** -0.235 -.840** -0.109 0.221 -.308* 0.054
Sig. (2-tailed) 0.44 0.399 0.155 0.098 0.005 0.113 0.000 0.467 0.136 0.035 0.72
N 46 47 47 47 47 47 47 47 47 47 47
Effects of Global Warming and Eutrophication
• Factorial Designs in growth chamber
– Two temperatures (25 and 30 oC)
– Two TP concentrations (19 and 36 µg/L, nearshore oligotrophic and mesotrophic lakes)
– Five replicates
• Plant Parts: leaf, stem, root, base and stolon
• ANOVA
AA
A
A
A
A A
AAB
AA
A
A B
AA A
A B
A
0
3
6
9
12
15
18
Leaf Stem Stolon Base Root
Num
bers
LT-LP LT-HP HT-LP HT-HP
A AA
A
A A A
A
AB A A
B
B AA
AB
0
5
10
15
20
25
30
35
Leaf Area Stem Length Stolon Length Root LengthPar
amet
er V
alue
(cm
2or
cm
)
LT-LP LT-HP HT-LP HT-HP
A
AA
AA
A
ABA
AB
AB
A
BCA
AB
ABC
A
CA
B
C
0
20
40
60
80
Leaf Stem Base Stolon Root
Bio
mas
s (m
g)
LT-LP LT-HP HT-LP HT-HP
(Zhu et al. 2008. JAPM)
Summary I
• The most important factors may be:
– Temperature
– Wind exposure
– (Nitrate and DO)
• Higher temperature tended to stimulate plant growth.
• TP did not have any significant effects on plant growth, suggesting European frogbit grows similarly in mesotrophic and oligotrophic lakes.
Objectives
1. Determine what factors contributing their invasive success
2. Assess the ecological impacts of European frogbit;
3. Evaluate impacts of two physical methods - hand pulling and shading
4. Gauge the effectiveness of hand pulling and shading as well as biological control using snails
Field Experiments in Oneida Lake
Untreated Hand pulling
Shading
Plant Absent
Measured Parameters
• Dissolved oxygen and pH
• Total phosphorus (TP), soluble reactive
phosphate (SRP), nitrate
• Chlorophyll a
• Zooplankton
• macroinvertebrates
• Submerged macrophytes
0
1
2
3
4
5
6
7
6/15 6/29 7/13 7/27 8/11
Co
nce
ntr
atio
n (
mg
/L)
Dissolved Oxygen HandpullingShadePlant ControlOpen Water
0
0.02
0.04
0.06
0.08
0.1
6/15 6/29 7/13 7/27 8/11 9/20
Co
nce
ntr
atio
n (
mg
/L)
Soluble Reactive Phosphorous (SRP)
0
0.02
0.04
0.06
0.08
0.1
6/15 6/29 7/13 7/27 8/11 9/20
Co
nce
ntr
atio
n (
mg
/L) Nitrates (N)
0
5
10
15
20
25
30
6/15 6/29 7/13 7/27 8/11 9/20
Co
nce
ntr
atio
n (
mg
/L)
Chlorophyll a
Hand pulling
Shade
Untreated
Plant Absent
Water Chemistry and Phytoplankton
0%
20%
40%
60%
80%
100%
6/15
/200
9
6/29
/200
9
7/13
/200
9
7/27
/200
9
8/11
/200
9
9/20
/200
9
Per
cen
t Ab
un
dn
ace
(#/L
) Plant AbsentDiaphanasoma
Bosmina
Graptoberis
Polyphemus
Ceriodaphnia
Chydorus
Daphnia
Zooplankton Abundance
0%
20%
40%
60%
80%
100%
6/15
/200
9
6/29
/200
9
7/13
/200
9
7/27
/200
9
8/11
/200
9
9/20
/200
9
Per
cen
t Ab
un
dan
ce (
#/L
) Untreated
0%
20%
40%
60%
80%
100%
6/15
/200
9
6/29
/200
9
7/13
/200
9
7/27
/200
9
8/11
/200
9
9/20
/200
9Per
cen
t Ab
un
dan
ce (
#/L
) Hand pullingDiaphanasoma
Bosmina
Graptoberis
Polyphemus
Ceriodaphnia
Chydorus
Daphnia 0%
20%
40%
60%
80%
100%
6/15
/200
9
6/29
/200
9
7/13
/200
9
7/27
/200
9
8/11
/200
9
9/20
/200
9
Per
cen
t Ab
un
dan
ce (
#/L
) Shade
Hand pulling
Shade
Plant Absent
Untreated
Zooplankton Density
Macroinvertebrates
Ekman dredge
(Zhu et al. 2015 FWS)
Hester-
Dendy
Sampler
(Zhu et al. 2015 FWS)
Control Methods Effects
(Zhu et al. 2015 FWS)
Submerged Macrophytes
0
5
10
15
20
25
30
35
40
45
50
Den
sity
(g
/m2 )
Plant AbsentJune
September
0
5
10
15
20
25
30
35
40
45
50
Den
sity
(g
/m2 )
UntreatedJune
September
0
5
10
15
20
25
30
35
40
45
50
Den
sity
(g
/m2 )
Hand PullingJune
September
0
5
10
15
20
25
30
35
40
45
50
Den
sity
(g
/m2 )
ShadeJune
September
Effects of
Shading on
Plants
(Zhu et al. 2014 PLOS One)
Summary II
• European frogbit did not show significant impacts on water chemistry and phytoplankton.
• More zooplanktons and more diversed surface invertebrates are found in European frogbit beds.
• European frogbit had negative impacts on submerged macrophytes.
• Hand pulling did not affect the ecosystem but shading had negative impacts on invertebrates and plants.
• Conclusion: European frogbit has mixed effects!
Objectives
1. Determine what factors contributing their invasive success
2. Assess the ecological impacts of European frogbit;
3. Evaluate impacts of two physical methods - hand pulling and shading
4. Gauge the effectiveness of hand pulling and shading as well as biological control using snails
Effectiveness of Control Methods
0
1
2
3
4
5
6
7
Open Water Plant Control Hand Pulling Shade
Bio
mas
s (g
/m2 )
Plant Absent Untreated
Effectiveness of Hand Pulling
0
5
10
15
20
25
30
35
Date 6/18 Date 6/23 Date 7/8 Date 7/27
Fro
gb
itB
iom
ass
(g
/m2)
Handpull
Control
Hand Pulling
Untreated
Effectiveness of Shading
(Zhu et al. 2014 PLOS One)
Effectiveness of Snail Feeding
(Zhu 2014 JAPM)
Summary III
• Snails don’t control this plant.
• Both hand pulling and shading could be viable
options for controlling and eradicating
invasive European frogbit.
• Hand pulling is preferable than shading.
Take-home Messages
• A clear definition of invasive species when we speak.
• Addition of some species may not represent any real
harm and might not be considered invasive.
• Some species capable of causing harm are not
necessarily harmful in all cases / may have benefits.
• Some control may be needed to avoid serious harm, but
the level of control needed may be low.
• Early detection and rapid response are necessary to best
management
• Monitoring the plant community of lakes is strongly
encouraged.
Acknowledgement
• Cornell University
– Dr. Lars G. Rudstam
– James Kopco
• Hobart and Williams Smith Colleges
– Dr. Meghan Brown
– Nathan Burtch
– Samuel Georgian
– Michael Ellis
– Meredith Eppers
– Bryan Harris
– Bethany Bashaw
– Joseph Sullivan
• University of Hartford
– Kelly Fancher
– Cora Ottaviani
• New York Great Lakes Protection Fund
• New York Great Lakes Protection Fund (small program)
• Andrew W. Mellon Foundation
• University of Hartford Coffin Grant
• University of Hartford Dean’s Research Fund
