population dynamics dan magoulick arkansas cooperative fish & wildlife research unit department...
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Population Dynamics
Dan Magoulick
Arkansas Cooperative Fish & Wildlife Research Unit
Department of Biological Sciences
University of Arkansas - Fayetteville
Questions
• What factors are most important in determining fish assemblage structure in drying streams?
• What are the effects of predation in drying stream pools?
• What habitats act as refugia and how does refuge use influence fish assemblage structure in drying streams?
• What are the source – sink dynamics in drying streams?
Pre-drying Drying Isolation Post-drying
B
A
IB<EB
IA EA IA>EA
IB EBIB=EB=0
IA=EA=0IA<EA
IB>EB
0
0.1
0.2
0.3
0.4
0.5
0.6
August September
CR
C A
pp
aren
t S
est
imat
es
Pool Riffle
CRC Transition Probabilities
00.050.1
0.150.2
0.250.3
0.35
0.40.450.5
August September
CR
C T
ran
siti
on
Pro
bab
ilit
ies
Pool to Riffle Riffle to Pool
0
50
100
150
200
250
300
350
400
450
July August September
CR
C P
op
ula
tio
n E
stim
ates
Pool Riffle
Central s toneroller
0
0.2
0.4
0.6
0.8
1
July Septem ber
Su
rviv
al R
ate
Pool Rif f le
Central Stoneroller
0
0.2
0.4
0.6
0.8
1
1.2
July Septem ber
Mo
vem
ent
Rat
ePool Rif f le
Central Stoneroller
0200400
600800
100012001400
160018002000
June August October
Po
pu
lati
on
Est
imat
ePool Riff le
Bigeye shiner
0
0.2
0.4
0.6
0.8
1
1.2
July August Septem ber October
Su
rviv
al R
ate
Pool Riffle
Bigeye shiner
0
0.10.2
0.30.4
0.5
0.60.7
0.80.9
1
July August Septem ber October
Mo
vem
ent
Rat
ePool Rif f le
Bigeye shiner
0
200
400
600
800
1000
1200
1400
1600
June July August Septem ber October
Po
pu
lati
on
Est
imat
es
Pool Rif f le
Conclusions• Survival rates in these systems are low and
species-dependent.– S similar between habitats for central stonerollers.– S pools<riffles but both decreased over time.
• Habitat migration rates related to survival.• Pools are important refuge habitats for some fish
species (e.g. central stonerollers).• Reduced habitat area and fish migration can lead to
increased densities which may impact population and community dynamics