Detecting Ecotones

1
Detecting Ecotones Modeling Fish Distribution
along Freshwater Gradients of Lake Ontario
Nuanchan Singkran
2
?Objectives

• ? Detect ecotone formation on freshwater
  gradients using biotic and non-biotic indicators.
  
• Determine ecotone function on fish assemblage
  distribution along a freshwater gradient.
• Model abundance distribution of selected fish
  species along freshwater gradients.

Ecotone definition A zone of transition in
physical and biological conditions from different
habitats.
3
?Hypotheses approaches
Fish species compositions
Habitat variables
Abrupt change
Turnover rate (Beta A)
Repeated measure 2-way ANOVA
DCA
Ecotone
flux of fish habitat variables
Habitat B
Habitat A
Functions aggregator mediator soft barrier hard
barrier
4
?Study gradients Summer 02
4
8
5
7
3
1
6
2
6
7
5
Sterling 16.3 km
4
2
3
Floodwood 18.6 km
1
8
5
?Results ST gradient (02)
Jun, Beta A 2.1
Jul, Beta A 12.6
Aug, Beta A 12.8
6
?Results FL gradient (02)
Jun, Beta A 6.3
Jul, Beta A 4.8
Aug, Beta A 5.4
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?Study gradient Summer 04
Summer 04 (TL 28.2 km)
Summer 02 (TL 18.6 km)
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?Results FL gradient (02 04)
Summer 02
Summer 04
9
?Ecotone function FL gradient (04)
16.1
9.7
51.6
22.6
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?Abundance Exchange Model (AEM)

• ? Parameter estimation calibration FL gradient
• Validation ST gradient
• Selected species YP, BG, LP, BM, FTD
• Habitat variables
• -Dynamic variables
• ?water depth ?water temperature ?current
  velocity
• ?aquatic plants ?algae ?woody debris
• -Static variables (substrate types)
• ?mud ?sand ?gravel-cobble ?rock-bedrock

11
?Conceptual model
12
? Fish abundance exchange equation
akn (1-aHPn)/t aHPn habitat preference of
adult fish in habitat n f(Yn)
rb(An)(1-Yn/Cy) rb birth fraction of fish in
growing season rd death fraction of fish in
winter Cy carry capacity of having offspring z
very small no. (e.g., 10-6)
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?Results
Yellow perch
Population dynamics in time
14
?Results
Abundance distribution in space
15
?Results
Abundance distribution in space time
16
?Model validation ST
Abundance distribution in space
17
?Model validation ST
Abundance distribution in space time
18
?Conclusion
AEM
Turnover rate (Beta A)
Rk
depth temp velocity plants algae wood
Ecotone
Sd-Gb-Rk
flux of fish habitat variables
Habitat B
Habitat A
Aggregator Mediator Soft barrier Hard barrier
Md
Gradient
19
M.B. Bain
P.J. Sullivan
D.P. Loucks
L.W. Lion
A.H. Schatz
C.E. Kraft
Acknowledgment
T. Bell
E. Fleisig
M. Brown
K. Hahn
R. Gavin
B. Carr
J. Murphy T. Kumasawa J. Fang E. Sobo
E.Deimezis
K. Arend
M. Meixler
G. Eckerlin
K. Mills