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