Site-specific Factors Affecting Productivity Of An Upper Trophic … · David Irons Dan Roby Evelyn...
Transcript of Site-specific Factors Affecting Productivity Of An Upper Trophic … · David Irons Dan Roby Evelyn...
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APEX
Alaska
Predator
Ecosystem Experiment
Rob SuryanPat Jodice
David Irons Dan Roby Evelyn Brown
Site-specific Factors Affecting Productivity Of An Upper Trophic Level Marine Predator:
Bottom-up, Top-down, And Mismatch EffectsOn Reproduction In A Colonial Seabird
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Breeding Success & Prey Abundance
Total prey abundance(m2/km2)
0 10 20 30 40 50 60
fledg
lings
/ ne
st
0.0
0.2
0.4
0.6
0.8SB95 SB96
SB97SB98
SB99
EI95EI96
EI97
EI98EI99
NI96
NI97
NI98
NI99
SI95
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Alaska
Prince William Sound
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Reasons for Study
Regime Shift in the Gulf of Alaska
Exxon ValdezOil Spill
Anderson and Piatt. 1999. Mar. Ecol. Progr. Ser. 189:117-123
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Black-legged Kittiwakes
Egg Chick Fledgling24 days 37 days
Chick Provisioning = 2 to 4+ meals/day
Adult Foraging Range = 5 to 60 km(Range < 1 to > 100km)
(1-3) (1-3)
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Shoup Bay
N. Icy Bay
Eleanor I.
Seal I.
Gulf of Alaska
Prince William Sound
Study Areas
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.
Eleanor & Seal Isles.~500 pairs
Shoup Bay~7,000 pairs
N. Icy Bay~1,800 pairs
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Reproductive Success & Diets
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Energy Density of Forage Fishes
myc
t.
herr
ing
sala
cape
lin
gunn
el
prkl
bck.
scul
pin
pollo
ck
Ene
rgy
dens
ity (k
J / g
wet
mas
s)
0
1
2
3
4
5
6
7
8
9lipid AFLDM
Energy Density of YOY < 1+-yr-old
1+-yr-old
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Kittiwake Diet and Growth –Experimental Feeding
Days14 16 18 20 22 24 26 28 30
Bod
y M
ass
(g)
100
150
200
250
300
350
400
Diet = Pacific Herring
Diet = Walleye Pollock
Kitt
iwak
e
Romano et al.
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Monitoring Foraging Activities
TransmitterAttachment
Data LoggerAt Colony
Tracking by Boat
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Foraging Trips
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% m
ass
0
20
40
60
80
100
Herring Sand lance Capelin Other
79 293 268 224 121 26 67 129 22 18 70 60
nosurv
a)
nodata
nosurv
Diets
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Preferential Selection of Prey Type
Herring Sand lance
Selection Similar to Availability (P > 0.05)
Significant Positive or Negative Selection (P < 0.05)
Bi
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% o
f oto
liths
0
20
40
60
80
100
'95 '96 '97 '98 '99 '95* '96 '97 '98 '99 '95 '96 '97 '98 '99
YOY 1-yr-old 1+ & 2-yr-old
Shoup Bay Eleanor Island N. Icy Bay
0
35 56 42 89 43 5 7 36 7 14 34b)
nosurv
nodata
nosurv
Age Classes of Forage Fish in Kittiwake Diets
96 % of Sand lance were YOY
Herring
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% AGE ONE HERRING IN DIET0 20 40 60 80 100
0
20
40
60
80
100
INDEX OF PREY ABUNDANCE (SCHOOLS/KM)0.0 0.2 0.4 0.6 0.8
30405060708090
100
% YOY HERRING AND YOY SAND LANCE IN DIET0 20 40 60 80 100
% F
EE
DIN
G O
CC
UR
ING
IN F
EE
DIN
G F
LOC
KS
0
20
40
60
80
100
a
b
c
r2 = 0.2796P = 0.1778
r2 = 0.7395P = 0.0007
r2 = 0.7881P = 0.0003
Prey Type and Feeding Flock Use
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Feeding Frequency vs. Productivity
Energy provisioning rate (kJ nest-1 day-1)100 200 300 400 500 600 700
0.0
0.2
0.4
0.6
0.8BA
BA
BACH CH
ELEL
EL
EL
GUGU
GU
GU
IC
IC
ICSH SH
SHSH
SH
R2= 0.48
Pro
duct
ivity
(fled
glin
gs /
nest
)
meal delivery rate * meal size * energy density
Jodice et al. 2000
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Forage Fish Sampling
Clupea pallasi Ammodytes hexapterus
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Forage Fish Abundance(surface area density [m2/km2])
Surfa
ce a
rea
dens
ity (m
2 /km
2 )
0
10
20
30
40
50
60
'95 '96 '97 '98 '99Shoup Bay Eleanor Island N. Icy Bay
'95* '96 '97 '98 '99 '95 '96 '97 '98 '99
nodata
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Location
North Central South
Phyt
opla
nkto
n ab
unda
nce
(ml /
m2 )
0
2
4
6
8
10
12
1994 1995 1996 1997 1998 1999
Phytoplankton Abundance
Data courtesy of Prince William Sound Aquaculture Corporation
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020406080
100
YOY
1 yr old
1+ and 2 yr old
1989 1990 1995 1996 1997 1998-0.2
-0.1
0
0.1
0.2
0.3
Shoup Bay
00.20.40.60.8
1
Hydroacoustic Data - Juvenile HerringBiomass Density
Kittiwake Diets - Ages of Herring Consumed
Kittiwake Reproductive Success(relative to 6-yr mean)
A
B
C
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Forage Fish Distribution
Brown and Moreland 2000
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Response to Weekly Fluctuations in Prey Abundance
1 2 3 4 5
Dur
atio
n (h
rs) &
No.
0
2
4
6
8
1 2 3 4 5
Trip duration No. of trips per day
Herring
Sand lance
% O
ccur
renc
e
0
20
40
60
80
100m
2 /km
2
0
5
10
406080
100
0
5
10
15
20
Week of chick-rearing
1 2 3 4 5 1 2 3 4 5
15 31 66
39 66 5163 85
56
3357
3740 12 19 28 34
26
16 16
14 11 2025
22
20 16 28 3229 23 17
2231 34
31 28
a b c
d e f g
h ji k
1997 1998 19991996
Age-1 YOY Age-1 YOYHerring:
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G ro w th
Age (d ays)0 5 10 15 20 25 30 35
g
0
100
200
300
400
500
1999199819971996
0 1 2 3 4 5Dur
atio
n (h
rs) &
No.
02468
W e e k o f c h ic k -re a r in g
0 1 2 3 4 5 0 1 2 3 4 5 0 1 2 3 4 5
% O
ccur
renc
e
02 04 06 08 0
1 0 0
T r ip d u ra t io n N o . o f tr ip s p e r d a y
H e rr in g S a n d la n c e1996 1997 1998 1999
Age-1 YOY Age-1 YOY
(YOY)
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Chick Survival and Growth
Bet
a su
rviv
al
0.00
0.25
0.50
0.75
1.00
Chi
ck g
row
th (g
/d)
12
13
14
15
16
17
18
Nea
r-fle
dgin
g m
ass (
g)
360
370
380
390
400
410
420
a
b
c
'95 '96 '97 '98 '99Shoup Bay Eleanor Island N. Icy Bay
'95* '96 '97 '98 '99 '95 '96 '97 '98 '99
40
25 3633
19
nosurv
14
2726
15
13 26 25
70 94
73
6787
3463
67
31
nodata
nohatch
2353
47
1634
44
2951
45
26
2812 24
nodata
nodata
nosurv
nohatch
nohatch
nodata
nosurv
nosurv
Beta ChickSurvival
Chick Growth
FledgingMass
-
Bet
a su
rviv
al
0.00
0.25
0.50
0.75
1.00
Chi
ck g
row
th (g
/d)
12
13
14
15
16
17
18
Nea
r-fle
dgin
g m
ass (
g)
360
370
380
390
400
410
420
a
b
c
'95 '96 '97 '98 '99Shoup Bay Eleanor Island N. Icy Bay
'95*'96 '97 '98 '99 '95 '96 '97 '98 '99
40
25 3633
19
nosurv
14
2726
15
13 26 25
70 94
73
6787
3463
67
31
nodata
nohatch
2353
47
1634
44
2951
45
26
2812 24
nodata
nodata
nosurv
nohatch
nohatch
nodata
nosurv
nosurv
Beta ChickSurvival
Chick Growth
FledgingMass
Surfa
ce a
rea
dens
ity (m
2 /km
2 )
0
1 0
2 0
3 0
4 0
5 0
6 0
'9 5 '9 6 '9 7 '9 8 '9 9S h o u p B a y E le a n o r I s la n d N . I c y B a y
'9 5 * '9 6 '9 7 '9 8 '9 9 '9 5 '9 6 '9 7 '9 8 '9 9
n od a ta
Forage Fish Abundance
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Foraging Trip DurationChick-rearing
Dur
atio
0
1
2
3
4
5
6
7
'95 '96 '97 '98 '99 '95 '96 '97 '98 '99 '95 '96 '97 '98 '99
b
Shoup Bay Eleanor Island No. Icy Bay
1716
2532
34
716
16
11
9
19 12
nodata
nosurv
nosurv
Dur
atio
n (h
rs)
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Kittiwake Productivity
Eleanor Island Icy BayShoup Bay
'95 '96 '97 '98 '99 '95 '96 '97 '98 '99 '96 '97 '98 '99
Pro
duct
ivity
(c
hick
s fle
dged
/ ne
st s
truct
ure)
0.00
0.25
0.50
0.75
1.00
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Factors Affecting Chick Growth and Provisioning Rate
Foraging trip duration (hrs)2 3 4 5 6
Nes
tling
gro
wth
(g/d
)
13
14
15
16
17
18
Log 1-yr-old herring abundance index(m2/km2)
-1 0 1 2For
agin
g tr
ip d
urat
ion
(hrs
)
2
3
4
5
6
SBSB
SBSB
SB
EIEI
EI NI
NI NI
r2 = 0.57, F = 14.04, P = 0.003
Feeding rate is very important Effect of prey abundance varies with colony & prey type
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Top Down EffectsEgg and Nest Predators:
Primary: Bald Eagle, Common Raven, Peregrine Falcon Opportunists: Glaucous-winged Gulls, Northwestern Crow,
Black-billed Magpie
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Top Down Effects
Predation Rate and Predator Swamping:Example of intensity: 2 hr period = 36 eggs taken at Shoup Bayand 14 eggs taken at N. Icy Bay. Falcons observed taking up to6 chicks per day.
At 3 chicks per day 1 falcon pair could remove > 50% of chicks at Eleanor Island, but only 10% of chicks at N. Icy Bay and 3% at Shoup Bay.
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Multiple Linear Regression Analysis
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Independent VariablesLaying & Incubation Nestling
Lower Trophic Level Processes
Phytoplankton abundance X
Phytoplankton abundance in year t-1* X
Timing of peak phytoplankton abund. X
Spring SST (March to May) X
SST May X
SST June X
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Total prey abundance X
Herring abundance X
Sand lance abundance X X
Capelin abundance X
1-yr-old herring abundance index* X X
1-yr-old herring and sand lance abundance index*
X X
Independent VariablesLaying & Incubation Nestling
Prey Abundance
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Independent VariablesLaying & Incubation Nestling
Colony Effect, Prey Consumptionand Foraging Effort
Colony size X X
% mass of herring X
% mass of sand lance X
% mass of capelin X
% mass of 1-yr-old herring X
Age class of herring X
Foraging trip duration X X
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Dependent Variables
Fledging success
(% of chicks fledged)
Mean clutch size
Laying success(% of nests with > 1
egg)
Egg laying
Near-fledging mass
Beta chick survival
Hatching success
(% of eggs hatched)
Nestling growthMedian hatch date
NestlingIncubation
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Ind. Variable Coeff Std. Error t value Pr(>|t|) (Intercept) -60.1906 27.9667 -2.1522 0.0977
Year 0.0422 0.0140 3.0054 0.0397Size 0.0004 0.0000 8.5458 0.0010Dur -1.9430 0.0691 -28.1085 0.0000
lPr1yrHerr -5.7378 0.1994 -28.7791 0.0000Size:lPr1yrHerr 0.0001 0.0000 6.5023 0.0029
Size:Dur -0.0001 0.0000 -14.7983 0.0001lPr1yrHerr:Dur 1.4904 0.0542 27.5194 0.0000
MLR ResultsNestling Growth = Dependent Variable
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Functional Response Curves(Cairns 1987)
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Breeding Success vs. Prey Abundance
1-yr-old herring abundance(m2/km2)
0 2 4 6 8 100.0
0.2
0.4
0.6
0.8
a)
b)
Total prey abundance(m2/km2)
0 10 20 30 40 50 60
Bre
edin
g su
cces
s(fl
eglin
gs/n
est)
0.0
0.2
0.4
0.6
0.8
Seal Island
Shoup Bay
Eleanor Island
N. Icy Bay
y = 0.01 + 0.70(1 - e-0.81x)r2 = 0.39
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1-yr-old herring abundance(m2/km2)
0 5 10 15 20 25
Nes
tling
gro
wth
(g/d
ay)
13
14
15
16
17
18
Seal Island
Shoup Bay
Eleanor Island
N. Icy Bayy = 14.50 + 2.36(1 - e-0.39x)r2 = 0.24
Growth vs. Age-1 Herring Abundance
Relationship is independent of direct top-down effects
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ConclusionsBottom-up & Colony Specific Effects
Geographic distribution and abundanceAge classEnergy density (kJ/g)*
Important characteristics of Kittiwake Prey
Feeding frequency (trip duration)Energy density of prey
Important factors affecting Chick Survival and Growth
Shoup Bay: 1-yr-old herring critical for maximum productivityN. Icy Bay and Eleanor Island: can maintain high feeding
frequency with YOY fish
Colony-specific Kittiwake-Prey Relationships
Prey AbundanceAge-class of prey (capture time, feeding flock use)
Important factors affecting Foraging Trip Duration
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ConclusionsTiming Mismatch and Top-Down Effects
Age 1 fish available early in breeding seasonYOY sand lance available early but availability limited
Forage Fishes – timing of arrival and peak abundanceEarly Season
YOY HerringYOY sand lance more available
Late Season
Predators that specialize on kittiwake coloniesReduced availability of alternative preyPredator swamping at large colonies
Top-Down Control
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Kittiwakes
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FundingExxon Valdez Oil Spill Trustee Council U.S. Fish and Wildlife Service
Special thanks toJeb Benson, Max Kaufman, Teresa Sauer
Aerial SurveysTim Veenstra (pilot) & Stephanie Moreland (observer)
Prey I.D.Kathy Turco & Greg Golet
Field CrewsJill Anthony, Matt Becker, Brenda Bilotta, Jared
Gerstein, James Hall, Bill Henry, Stephanie Holzwarth, Amy Kaplan, Laura Kennedy, Jonel Kiesau, Christopher Kuntzch, Kurt Lenington, Casey Lott, Chris May, Kristen Mosher, Laura Minich, Tim Meehan, Eva-Marie Muecke, Kyle Payton, Kim Raum-Suryan, Cynthia Restrepo, Janet Rothermel, John Ryder, Ruth Smith, Greg Spencer, Caroline Van Hemert, Tansy Wagner, James Weldy, Sean Wolfe
Acknowledgments