disturbance and fish daniel d. magoulick usgs, arkansas cooperative fish & wildlife research...
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Disturbance and Fish
Daniel D. MagoulickUSGS, Arkansas Cooperative Fish & Wildlife Research Unit, Department of
Biological Sciences, University of Arkansas
Disturbance
• Two ways to define disturbance– Effects on organisms
• “any relatively discrete event that removes organisms and opens up space and other resources that can be used by individuals of the same or different species.” (Townsend and Hildrew 1994)
• Response to event is part of definition– Response must occur
– Difficult to compare among systems
– Physical nature of event• Defined by the nature of their damaging properties, especially
intensity, frequency, predictability, spatial extent and temporal duration
• Response to disturbance is examined separately
Types of Disturbance• Pulse – short-term, sharply
delineated– Floods– Non-persistent pollution
• Press – arise sharply, reach constant level– Sedimentation after fire– Dam building– Persistent pollution
• Ramp – steady increase in time, may level off– Drought
Perturbation Types
• Perturbation – combo of cause and effect related to disturbance
Response to Disturbance
• Resistance – ability of the community to avoid displacement by disturbance
• Resilience – ability of community to return to its former state after disturbance
Drought as Disturbance
Two types of Drought
• Seasonal – drying in a particular season(s)– Predictable– Periodic or regular
• Supra-seasonal – drying over multiple seasons– unpredictable
Perturbation Types During Drought
• Seasonal– press disturbance and
response
• Supra-seasonal– Ramp disturbance and
response
Factors Affected by Drought
Questions• What factors are most important in determining fish
and crayfish assemblage structure in drying streams?
• What habitats act as refugia and how does refuge use influence fish and crayfish assemblage structure 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
Questions• What habitats act as refugia during stream drying?
– Hyp: Pools act as refugia Net migration into pools
• Does stream drying lead to a concentration effect?– Hyp: Reduced area and fish migration increase densities in
pool habitats (refugia)– Hyp: Reduced area and fish migration lead to unchanged
densities in riffle/run habitats
Pre-drying Drying Isolation Post-drying
B
A
IB<EB
IA EA IA>EA
IB EBIB=EB=0
IA=EA=0IA<EA
IB>EB
3km
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
YOY Central Stoneroller
20 40 60 80 100 120 1400
20
40
60
80
100
120
20 40 60 80 100 120 1400
20
40
60
80
100
120
20 40 60 80 100 120 1400
20
40
60
80
100
120
20 40 60 80 100 120 1400
20
40
60
80
100
120
Fre
quen
cy
Total length (mm)
Pool
Riffle
July Sept
AUG SEP OCT
0
50
100
150
200
250
JUL AUG SEP
0
50
100
150
200
250
AUG SEP OCT
0
100
200
300
400
JUL AUG SEP
0
100
200
300
400
AUG SEP OCT
0
2
4
6
8
10
12
JUL AUG SEP
0
2
4
6
8
10
12
Month
De
nsity
A
bun
da n
ce
V
ol u
me
2002 2003
Conclusions• Survival rates were low and species-
dependent.
• Refuge habitats are species and size-dependent – Pools Adult creek chubs and central
stonerollers– Riffles YOY central stonerollers and bigeye
shiners
• Reduced habitat area and fish migration led to increased densities
Logitudinal Drying Patterns
• Dowstream drying• Headwaters drying• Mid-reach drying
Questions• How do fish use intermittent streams?• What factors affect fish movement between
mainstem and intermittent tributary?• Can intermittent streams act as spawning and
nursery areas?
MethodsMethods
ResultsResults
59 marked bass59 marked bass
Buffalo RiverBuffalo River324 – 445 mm324 – 445 mm480 – 1000+ g480 – 1000+ g
Bear CreekBear Creek319 – 403 mm319 – 403 mm452 – 1000+ g452 – 1000+ g
Buffalo River residentsBuffalo River residents 2424
Bear Creek residentsBear Creek residents 2323
Using both streamsUsing both streams 1212
Stream-use categoriesStream-use categories
Smallmouth Bass Locations
Smallmouth Bass Movers
Smallmouth Bass Movement
Buffalo
Dis
tan
ce (
km)
0
10
20
30
40
50
Bear Both
n = 26n = 38n = 38
Kernel density estimate (km)Kernel density estimate (km)
CategoryCategory NN 95%95% 90%90% 50%50%
Buffalo Buffalo residentresident 88 0.740.74 AA 0.660.66 AA 0.100.10 AA
Bear Bear residentresident 66 0.280.28 AA 0.280.28 AA 0.030.03 AA
Using bothUsing both 1010 3.253.25 AA 3.253.25 AA 0.050.05 AA
““Summer” Home RangeSummer” Home Range
Kernel density estimate (km)Kernel density estimate (km)
CategoryCategory NN 95%95% 90%90% 50%50%
Buffalo Buffalo residentresident 44 15.4015.40 ABAB 11.1711.17 ABAB 0.220.22 AA
Bear Bear residentresident 44 4.174.17 AA 2.872.87 AA 0.320.32 AA
Using bothUsing both 44 36.3236.32 BB 30.4130.41 BB 0.320.32 AA
““Entire Study” Entire Study” Home RangeHome Range
Conclusions• Smallmouth bass use intermittent portions of
Bear Creek.• Summer drying events appear to limit bass
movement. • Immigration of fish into Bear Creek can be
substantial– Spawning migrations
• Larval fish drift densities are very high in Bear Creek– Substantial in intermittent portion of stream
Otolith MicrochemistryOtolith Microchemistry
What are otoliths?What are otoliths?
Application of Application of microchemistrymicrochemistry
Relationship with waterRelationship with water
Advantages and Advantages and disadvantagesdisadvantages
Elemental DiscriminationElemental Discrimination
Determine temporal stability and spatial variability Determine temporal stability and spatial variability
of elemental signatures in Bear Creek and Buffalo of elemental signatures in Bear Creek and Buffalo
RiverRiver
Associate water chemistry from Bear Creek and the Associate water chemistry from Bear Creek and the Buffalo River with otolith chemistry in resident fishBuffalo River with otolith chemistry in resident fish
Use otoliths to describe previous locations of fish Use otoliths to describe previous locations of fish within Bear Creek and the Buffalo Riverwithin Bear Creek and the Buffalo River
ObjectivesObjectives
MethodsMethods
Collected water samples October 2003 – April Collected water samples October 2003 – April
20052005
Analyzed chemical concentrations of waterAnalyzed chemical concentrations of water
Collected smallmouth bass August 2004Collected smallmouth bass August 2004
Extracted otolithsExtracted otoliths
Otolith AblationOtolith Ablation
Data IntegrationData Integration
[Ba:Ca]water (mmol/mol)0.0 0.2 0.4 0.6 0.8 1.0
[Ba
:Ca
] oto
lith
(mm
ol/m
ol)
0.000
0.005
0.010
0.015
0.020
0.025Buffalo RiverLower BearMiddle BearUpper Bear
r = 0.77; P < 0.0001
[Sr:Ca]water (mmol/mol)
0.0 0.5 1.0 1.5 2.0
[Sr:
Ca
] oto
lith
(mm
ol/m
ol)
0.0
0.2
0.4
0.6
0.8BuffaloLowerMiddleUpper
r = 0.87; P = 0.0002
Element:Ca (mmol/mol) in otolith edgesElement:Ca (mmol/mol) in otolith edges
Sample siteSample site Ba:CaBa:Ca Mg:CaMg:Ca Sr:CaSr:Ca
Buffalo RiverBuffalo River 0.00350.0035 AA 0.0300.030 AA 0.710.71 AA
Lower BearLower Bear 0.00380.0038 AA 0.0280.028 AA 1.031.03 BB
Middle BearMiddle Bear 0.00490.0049 AA 0.0440.044 AA 2.032.03 CC
Upper BearUpper Bear 0.01370.0137 BB 0.0290.029 AA 1.641.64 CC
Middle Bear SMB
Buffalo River
[Sr:
Ca
] oto
lith
(mm
ol/m
ol)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Lower Bear
Middle Bear
N = 10
Lower Bear SMB
Buffalo River[Sr:
Ca
] oto
lith
(mm
ol/m
ol)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Lower Bear
Middle Bear
N = 13
Buffalo River SMB
Middle Bear
[Sr:
Ca
] oto
lith
(mm
ol/m
ol)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Buffalo River
Lower Bear
N = 11
Site fidelity across consecutive summers Site fidelity across consecutive summers
Trace element concentrations in Bear Trace element concentrations in Bear CreekCreek
Useful trace elementsUseful trace elements
Classification of fish to collection sitesClassification of fish to collection sites
DiscussionDiscussion
SurvivalSurvival
Objective: examine and compare bass Objective: examine and compare bass
survival in Bear Creek and Buffalo Riversurvival in Bear Creek and Buffalo River
SurvivalSurvival
White and Burnham 1999White and Burnham 1999
• Kaplan-Meier known fateKaplan-Meier known fate
•5 month cutoff for unknowns5 month cutoff for unknowns
• Examined survival among Examined survival among stream-use categories and stream-use categories and periodsperiods
• AICc to select modelAICc to select model
• Model averagingModel averaging
ŜŜannual annual = (Ŝ= (Ŝ5month5month))55 (Ŝ (Ŝ7month7month)) 7 7
Delta method Delta method var( var(ŜŜannual annual ))
Williams et al. 2002Williams et al. 2002
Annual SurvivalAnnual Survival
ModelModel kk AICc wt.AICc wt. ΔAICc ΔAICc
period + sex + interceptperiod + sex + intercept 44 0.2330.233 0.000.00
periodperiod 33 0.2010.201 0.290.29
groupgroup 33 0.1510.151 0.870.87
period + total lengthperiod + total length 44 0.1420.142 0.980.98
period + groupperiod + group 99 0.1340.134 1.101.10
period + sexperiod + sex 44 0.0710.071 2.402.40
period + length + sexperiod + length + sex 55 0.0500.050 3.103.10
period + length * sexperiod + length * sex 66 0.0170.017 5.205.20
Minimum AICc = 107.38Minimum AICc = 107.38
SurvivalSurvival
SurvivalSurvival
Su
rviv
al R
ate
0.4
0.5
0.6
0.7
0.8
0.9
Buffalo R. residentsBear Cr. residentsUsing both streams
SurvivalSurvival
An
nu
al S
urv
iva
l R
ate
0.0
0.2
0.4
0.6
0.8
1.0
Buffalo R.residents
Bear Cr.residents
Using bothstreams
DiscussionDiscussion
SurvivalSurvival
Angler mortalityAngler mortality
Compared to other estimatesCompared to other estimates
ConclusionsConclusions
Consideration of tributary populationsConsideration of tributary populations
Mainstem quality reflects tributary qualityMainstem quality reflects tributary quality
Water development in tributariesWater development in tributaries
Flow dynamicsFlow dynamics
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