lake and landscape features shaping aquatic macrophyte
TRANSCRIPT
Lake and Landscape Features Shaping Aquatic Macrophyte Communities in the Undisturbed Lakes of Isle Royale National Park, Michigan, USA
Angela De Palma-Dow Kendra S.Cheruvelil
Michigan State University
East Lansing, MI
1
What are aquatic macrophytes?
2
Background and Introduction
3
Macrophyte communities in lakes: Habitat structural complexity
Shelter refuge from predators
Shoreline & sediment stabilization
Oxygen production
Nutrient cycling
e.g., Sousa, Thomas & Murphy 2011, Mastrantuono & Mancinelli 2005; Scheffer 1998; Lodge 1985
4
5
Why we care: High macrophyte production in ecosystems
From: Wetzel 2001
Native macrophyte communities: Repositories for biodiversity
Natural inventories
Rare & threatened species
Range, distribution and DNA
Essential to gauge changes over time
Climate changes & shifts
Introduction of invasive species
Natural variation of communities
- succession, herbivory, seasonal patterns
e.g., Giller et al. 2004; MI Natural Features Inventory; MEA 2005; O’Hare 2012.
7
How do we measure macrophyte communities?
8
Measuring macrophyte communities Richness (# species)
9
Measuring macrophyte communities Richness (# species) Diversity (richness + abundance)
10
Measuring macrophyte communities Richness (# species) Diversity (richness + abundance) Structure (growth form)
11
What shapes macrophyte communities?
12
Shaping macrophyte communities 1) Introductions / dispersal of species - Physical aquatic connections 2) Establishment and growth - Lake and landscape features
13
Research question: What shapes the inland lake macrophyte communities on Isle Royale National Park?
1) Introductions and dispersal potential 2) Establishment and growth potential
e.g. Kissoon et al 2013;Akasaka & Takamura 2012; O’Hare et al. 2012; Sousa, Thomas &Murphy 2011, Leibold et al. 2004
14
Expectations: Introduction and dispersal potential
Few macrophyte studies • Disturbed, altered, engineered or invaded systems
• Richness higher in connected ponds • Lakes close together had similar community composition
Need for more information • Natural, undisturbed, protected lakes
(e.g. Akasaka & Takamura 2012; O’hare et al. 2012; Dahlgren & Ehrlen 2005; Larson et al. 1995; Van Geest et al. 2003) 15
Credit: Thomas Kitchin & Vict / All Canada Photos / SuperStock
Expectations: Establishment and growth potential LOTS of studies
• Increased lake area = higher richness • Irregular lake shape = higher richness • Increased clarity = higher richness &
diversity
Less studied
• Water color • Sediment nutrients • Macrophyte diversity & structure
Need for more information • Natural, undisturbed, protected lakes
SDF = 1
SDF =50
16
Vestergaard and San-Jensen 2000
Macrophyte communities on Isle Royale…
17
http://www.noaanews.noaa.gov/stories2011 18
USGS 1968
• Reference condition of native communities • Pre-invasion status • Home to rare / threatened species • Macrophytes serve as food & habitat to
island wildlife
Why Isle Royale?
C: B. Bergman and J. Bump 2011
Methods
20
Approach: Comparative field study 15 inland lakes
• Sampled summers 2012 & 2013
• Relatively deep (>2m)
• Relatively permanent
Predictors: Dispersal & introduction potential
1. Surface hydrologic connectivity
• # of Inflows • # of Outflows • Position in lake chain
(e.g. Yannarell & Triplett 2005; Soranno et al 1999; Kratz 1997)
2. Lake characteristics
• Lake Area, Watershed Area
• Max Depth
• SDF (lake shape)
• Water & sediment chemistry
– NH4, TP, Alkalinity
• Water Color
• Water Clarity (Secchi disk)
Predictors: Establishment & growth
(e.g. Capers et al. 2009; Hakanson & Boulion 2002)
Response macrophyte variables
• Richness – Number of species in lake
• Diversity (e.g. Chiarucci et al 2011)
– Shannon Evenness Index emphasizes rarity
– Inverse Simpson Index emphasizes commonality
• Structure: % Growth form Emergent Submersed Floating leaf
24
Methods: Macrophyte sampling
Snorkel surveys of each lake:
• Four quadrants
• (4) 50m transects
– 8 quadrats (0.5 m 2)
• Each quadrat
– Est. % occurrence
– Use Braun-Blanquet cover classes (1964)
25
Methods: Macrophyte sampling
• Richness : all species encountered = present
• Diversity: calculated from % occurrence
• Structure: % Growth form calculated from richness values
26
Methods: Statistical analysis
Richness
Diversity - Shannon Evenness Index
Diversity - Inverse Simpson Index
1. Calculate macrophyte metrics
3. Determine dispersal vs.
establishment ID most important & recurring predictors
Partial least square regression (PLSR)
• Consolidate predictors into components
• Use components in regression
• One PLSR for each response variable
2. Model macrophyte metrics as function
of predictors
27
Results
28
Results: Macrophyte Richness
25 24
21 20
17 17 16 15 13
24 22
19
13 12
9
0
5
10
15
20
25
30
Ric
hn
ess
(#
of
spe
cie
s )
Connected Lakes
Isolated Lakes
29
Results: Macrophyte Diversity
Lake Name Shannon Evenness
(rare) Lake name
Inverse Simpson (common)
Feldtman 0.42 Least diverse
Feldtman 1.69 Benson 0.60 Benson 3.13 Ojibway 0.61 Ojibway 3.15 LeSage 0.73 LeSage 3.85 Beaver 0.74 Desor 4.49
Livermore 0.75 Livermore 4.63 Angelworm 0.78 Beaver 5.31
Otter 0.79 Angelworm 5.97 Mason 0.81 Patterson 7.21 Richie 0.82 Richie 7.24 Desor 0.83 McDonald 7.88 Ahmik 0.83 Mason 8.05
Patterson 0.84 Ahmik 8.22 McDonald 0.84
Most diverse Otter 8.26
Chickenbone 0.87 Chickenbone 10.16
MEAN 0.8 MEAN 5.9 SD 0.1 SD 2.3
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Results: Macrophyte Diversity
Lake Name Shannon Evenness
(rare) Lake name
Inverse Simpson (common)
Feldtman 0.42 Least diverse
Feldtman 1.69 Benson 0.60 Benson 3.13 Ojibway 0.61 Ojibway 3.15 LeSage 0.73 LeSage 3.85 Beaver 0.74 Desor 4.49
Livermore 0.75 Livermore 4.63 Angelworm 0.78 Beaver 5.31
Otter 0.79 Angelworm 5.97 Mason 0.81 Patterson 7.21 Richie 0.82 Richie 7.24 Desor 0.83 McDonald 7.88 Ahmik 0.83 Mason 8.05
Patterson 0.84 Ahmik 8.22 McDonald 0.84
Most diverse Otter 8.26
Chickenbone 0.87 Chickenbone 10.16
MEAN 0.8 MEAN 5.9 SD 0.1 SD 2.3
31
Results: Structure - % Growth Form
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Ric
hie
Ch
icke
nb
on
e
Ott
er
Mas
on
Ah
mik
Live
rmo
re
Ojib
way
Bea
ver
Pat
ters
on
An
gelw
orm
McD
on
ald
Ben
son
LeSa
ge
Feld
tman
Des
or
Am
ou
nt
of
gro
wth
typ
e in
lake
FloatingLeaf
Emergent
Submersed
32
Inflow
Lake Area
SDF
Secchi Depth
TP, Water
-0.30
-0.20
-0.10
0.00
0.10
0.20
0.30
0.40
Dir
ect
ion
an
d e
ffe
ct c
orr
ect
ed
pro
po
rtio
n o
f va
riat
ion
exp
lain
ed
by
vari
able
Example Results: Most important variables for explaining variation in response variable
33
(>15%)
% Variation seen in Y from X (First component only)
Connectivity Metrics
Lake and Landscape Metrics
Chemistry
Results: Macrophyte Richness
# inflow SDF
TP, Water
-0.30
-0.20
-0.10
0.00
0.10
0.20
0.30
0.40
Dir
ect
ion
an
d e
ffe
ct c
orr
ect
ed
pro
po
rtio
n o
f va
riat
ion
exp
lain
ed
by
vari
able
50% variation, p < 0.001 Chain Location
# inflow
# outflow
Depth Max
Lake Area
SDF
Watershed Area
Alkalinity
Water Color
Secchi Depth
NH4, Water
TP, Water
TP, Sediment
34
Alkalinity
TP, Sediment -0.30
-0.20
-0.10
0.00
0.10
0.20
0.30
0.40 Shannon Evenness (rare): 60% variation, p<0.001 Chain Location
# inflow
# outflow
Depth Max
Lake Area
SDF
Watershed Area
Alkalinity
Water Color
Secchi Depth
NH4, Water
TP, Water
TP, Sediment
Alkalinity
-0.30
-0.20
-0.10
0.00
0.10
0.20
0.30
0.40Simpson Inverse (common): 56% variation, p<0.001
Results: Macrophyte diversity D
ire
ctio
n a
nd
eff
ect
co
rre
cte
d p
rop
ort
ion
of
vari
atio
n e
xpla
ined
by
vari
able
fo
r co
mp
on
ent
1
35
Results: Structure (% growth form) D
ire
ctio
n a
nd
eff
ect
co
rre
cte
d p
rop
ort
ion
of
vari
atio
n e
xpla
ined
by
vari
able
fo
r co
mp
on
ent
1
Chain Location
# outflow
Lake Area -0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
Titl
e
Emergent: 57% variation, p<0.01
# outflow
TP, Water
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4Floating Leaf: 56% variation, p<0.001
Lake Area
Water Color -0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
Submersed: 43% variation, p<0.01
36
37
Discussion and Conclusions
Summary: What shapes the inland
lake macrophyte communities on Isle Royale National Park?
• Intro/dispersal AND Establishment / growth
• Predictors differ by macrophyte metric
– Richness
– Diversity
– Structure
38
0
5
10
15
20
25
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0 50 100 150 200 250
Shan
no
n E
ven
ne
ss
Ric
hn
ess
Total Phosphorous (ug/L)
Shannon Eveness (Sediment TP) Lake Richness (Water TP)
Discussion: Species Richness, diversity and Phosphorous
39
0
5
10
15
20
25
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0 50 100 150 200 250
Shan
no
n E
ven
ne
ss
Ric
hn
ess
Total Phosphorous (ug/L)
Shannon Eveness (Sediment TP) Lake Richness (Water TP)
Mainland Michigan CLMP TP range
Discussion: Species Richness, diversity and Phosphorous
40
Discussion: Species diversity and alkalinity
41 e.g. Vestergaard & Sand-Jenson 2000
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0 50 100 150 200
Inve
rse
Sim
pso
n
Shan
no
n E
ven
ne
ss
Alkainity in CaCo3 ppm
Shannon Eveness Inverse Simpson
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0 50 100 150 200
Inve
rse
Sim
pso
n
Shan
no
n E
ven
ne
ss
Alkalinity in CaCo3 ppm
Shannon Eveness Inverse Simpson Mainland Michigan STORET & DNR (1979-2004)
Discussion: Species diversity and alkalinity
42 e.g. Vestergaard & Sand-Jenson 2000
Discussion: Significance of comparing Isle Royale to other lakes
• Relatively undisturbed lakes vs. areas where we have most information
– Invasive presence
– Shoreline development
• Influence of natural connectivity
– No boating traffic
– Reference conditions
43
Conclusions
• Macrophyte communities shaped by both introduction/dispersal and establishment/growth “shaper” variables
– Include dispersal (connectivity) in future studies
• Multiple response metrics are important (richness, diversity, structure)
– Characterize different aspects of communities
– Shaped by lake, landscape, and connectivity variables
• Sample sediment nutrients and water color 44
Thank you!
Field and Lab Techs Kim Schoch
Sarah Schaffer Charlotte Lee
Jennifer Hollen Hannah Meiklejohn
Kaitlin Clark Haley Sisson
Rachel Mistak Stephen Rivard
Committee Members and
Analysis support Kendra Cheruvelil
Garret Crow Kim Scribner
Paul Bourdeau
Limnology Lab at Michigan State University!
National Park Service Staff Mark Romanski, Paul Brown, Val Martin & Erin Leinart Additional Support: Dr. Joe Bump & Brenda Bergman (Mich Tech)
MiCorps’ Jo Latimore
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Thank you!
Questions?
46
47
0
2
4
6
8
10
12
14
16
18
20
0 2 4 6 8 10 12
Ric
hn
ess
an
d S
imp
son
Div
ers
ity
Chl-A Concentrations mg m-3
Richness Simpson
Simpson R2=0.19 P= 0.46
Richness R2=0.11 P= 0.59
Did we do a good job of sampling the diversity in the communities?
48
Generally, could have sampled more lakes but, as we get to the 12th and the 14th lake, the error bars on the curve are getting smaller, meaning that a plateau is close and probably would be more defined had we sampled a few more lakes. We know that these lakes had high numbers of rare species (ex: we found at least one species that was only found in one or two lakes).
Accuracy assessment results
• Would my diversity metrics results differ if I sampled my lakes based on size and not uniformly?
• Ex. Richie lake instead of 4 transect, sampled 8 transects
49
How similar or dis-similar are these communities? Bray-Curtis clustering for both the plant species found in each lake and lake type based on environmental variables
50
Feldtman Benson Richie
Desor Angelworm
Chickenbone Otter
Ojibway LeSage Mason
Patterson Ahmik
McDonald Beaver Livermore
0.3 0.5 0.7 0.9
Ma
cro
ph
yte
Ab
un
dan
ce
Bray-Curtis dissimilarity
Feldtman Chickenbone Livermore
Desor Richie
Angelworm LeSage
Beaver McDonald
Mason Ojibway Benson Otter
Ahmik Patterson
0.0 0.2 0.4
Pre
dic
tors
Bray-Curtis dissimilarity