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Isotopic tracking of marine mammals in coastal and
pelagic settings
Paul Koch, Univ. of California, Santa Cruz CA
Seth Newsome, Geophysical Lab, Washington DC
David Aurioles, CICIMAR, La Paz, Baja California Sur
Pisias et al. (QSR, 2001)
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Chlorophyll ConcentrationRed = highest
Magenta = lowest
-21.4
-23 to -24
-21.1-22.9
-19.7-21.9
-20.0
-20.8
-20.7
-24.64‰ drop in zooplankton
-20.4
-23.9
δ13C values at the base of the food web
-20.3
-20.5-20.1
-21.0-20.5
-18.5
3.5
7.07.4
11.2
10.1
10.3
7.8
8.0
2.8
7.26.7
4‰ drop in zooplankton
δ15N values at the base of the food web
Chlorophyll ConcentrationRed = highest
Magenta = lowest
OffshoreMore 12C
Lower Values
NearshoreMore 13C
Higher Values
High LatitudeMore 12C and 14N
Middle LatitudeMore 13C and 15N
Isotopic gradients label feeding zones
δ15N
δ13C
Seals & toothed whales
Big fish
Small fish
Small carnivores &suspension feeders
Phytoplankton
Zooplankton
Harbor seal(Phoca vitulina)
PribilofIslands
Males from AK
San MiguelIsland
Males and femalesfrom CA
Northern fur seal(Callorhinus ursinus)
Burton et al. (Oecologia , 2001)
NearshoreCA Harbor Seal
OffshoreCA N. Fur Seal
NearshoreAK Harbor Seal
OffshoreMale AK N. Fur Seal
13C = -12.4 ± 0.6‰15N = +18.7 ± 1.0‰
13C = -14.5 ± 0.4‰15N = +18.4 ± 0.4‰
13C = -13.7 ± 1.0‰15N = +17.4 ±1 .8‰
13C = -15.7 ± 0.7‰15N = +16.5 ± 1.4‰
Seals as sampling buoys
MigratoryFemale AK N. Fur Seal
13C = -14.9 ± 0.7‰15N = +16.3 ± 1.0‰
Probing Northern elephant seals
(Mirounga angustirostris)
San Benitos
Año Nuevo
Highly migratory, deep-diving, gregarious breeders
Females (600 kg): on shore ~1 winter month to pup, 1 summer month to molt
Males (2000 kg): on shore ~3 winter months to breed, 1 summer month to molt
Expanding north after near extinction in late 19th
century
5
Where do females go to tank up?
Stewart & DeLong(J. of Mammalogy, 1995)
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Pup fur comparison
Aurioles et al. (Marine Mammal Sci., 2006)
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y = -0.803x2 - 22.588x - 140.21
R2 = 0.6855
y = 2.4968x + 54.964
R2 = 0.4966
12.0
12.5
13.0
13.5
14.0
14.5
15.0
15.5
16.0
16.5
17.0
17.5
18.0
18.5
19.0
19.5
20.0
-17.0 -16.5 -16.0 -15.5 -15.0 -14.5 -14.0 -13.5 -13.0 -12.5
San Benito (9, 160)
Ano Nuevo (10, 201)
Poly. (San Benito (9, 160))
Linear (Ano Nuevo (10, 201))
δ1
5N
δ13C
Sub-sampled whiskers
Reasonable agreement with tags
Sorry, had to delete this figure.Showed all elephant seal migration paths forAño Nuevo and San Benitos.
Jason Hassrick (UCSC) & Seth Newsome (CIW)
Tracking data from LeBoeuf et al. (Ecological Monographs, 2000)
Historical Ecology of Northern Fur Seals
Chaluka
KodiakOglodax
Ozette
Hesquiat
Cape Flattery
Seal Rock
Duncan’s Point
San Miguel Island
Moss Landing
Modern versus ancient distributions
Newsome et al.(PNAS, 2007)
Bottom Line: NFS fed offshore in the past. NFS were not highly migratory in the past.
Shemya NFS-15.4/+13.7 Northern NFS
-14.2/+17.3
Southern NFS-13.1/+17.9
Southern HS-11.7/+18.0
Northern HS-11.9/+18.4
Chaluka HS-13.7/+15.8
The Distribution and Ecology of Southern Elephant Seals and Adélie Penguins on the
Holocene Ross Sea Coast
Paul Koch, Univ. of California Santa Cruz
Brenda Hall, Univ. of Maine
Carlo Baroni, Univ. di Pisa
Seth Newsome, Carnegie Inst. of Washington
Maria Salvatore, Univ. di Roma
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-21
-24
-27
<-27
15N
13C
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1. Feeding on the fronts - pelagic
1
3. Feeding on the ice margin - pelagic
2
2. Feeding on the shelves - benthic
3
1
2
2. Feeding on the shelves - benthic
1
2
2. Feeding on the shelves - benthic
Biuw et al. (2007) PNAS
Adélie Penguin
Weddell Seal
Marble Point
Gneiss Point
Spike Cape
Kolich Point
Bernacchi Bay
Explorers Cove
Dunlop Island
Cape Roberts
Depot Island
Cape Ross
Cape Bird
Inexpressible Island
Gondwana Station
Edmonson
Point
Adelie Cove
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Emslie et al. (2007) Geology
Hall et al. (PNAS, 2006)
What does all this mean for elephant seals?
Were they breeding all along the Ross Sea?
6
8
10
12
14
16
18
-25 -24 -23 -22 -21 -20 -19 -18
Inexp Elephant
Inexp Weddell
Inexp Crabeater
Inexp Adélie (mod)
Inexp Adélie
Gond Weddell
13C (‰, PDB)
15N
(‰, Air)
Bone collagen
Inexpressible Is.
GondwanaAdélie Cove
6
8
10
12
14
16
18
-26 -25 -24 -23 -22 -21 -20 -19
Gond Elephant
Edmn Weddell
Inexp Elephant
Inexp Weddell
Inexp Crabeater
Edmn Elephant
South Elephant
13C (‰, PDB)
15N
(‰, Air)
Body Fur
Inexpressible Is.
Gondwana
Edmonson Pt.
Adélie Cove
South
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6
8
10
12
14
16
18
20
22
-26 -24 -22 -20 -18 -16 -14 -12 -10
Gond Elephant
Edmn Weddell
Inexp Elephant
Inexp Weddell
Inexp Crabeater
Edmn Elephant
PV Female
PV Male1
PV Male2
PV Male 3
South Elephant
13
C (‰, PDB)
15
N(‰, Air)
Body Fur
Inexpressible Is.
Gondwana
Edmonson Pt.
Adélie Cove
South
Ross Sea ecology extremely dynamic
Penguins = cool, fast iceElephant Seal = warmer, ice-free beachesElephant seals were feeding (and breeding?) in the Ross SeaLarge area - may have been the dominant breeding locale in
the hemisphere (testing with DNA)
Where are we headed?
Capitalize on tagging efforts - make maps using sealsCompound-specific approaches (space vs. trophic/physiology)
6
8
10
12
14
16
18
-25 -24 -23 -22 -21 -20 -19 -18
Inexp Elephant
Inexp Weddell
Inexp Crabeater
Inexp Adélie (mod)
Inexp Adélie
Gond Weddell
Edmn Weddell
Edmn Adélie
Edmn Adélie (mod)
13C (‰, PDB)
15N
(‰, Air)
Bone collagen
Inexpressible Is.
Gondwana
Edmonson Pt.
Adélie Cove
Subtle decreases with decreasing age
Copyright ©2007 by the National Academy of Sciences
Emslie, Steven D. and Patterson, William P. (2007) Proc. Natl. Acad. Sci. USA 104, 11666-11669
Fig. 2. An {approx}8,000 calyr B.P. record of {delta}15 N and {delta}13C values of Adelie penguin eggshell from Antarctica
Marine δ13C gradients: basin scale
Key factors that vary with region[CO2aq] - δ13C ∝ 1/[CO2]: temperature, growth rate, productivity
δ13CTotal CO2 - upwelling, continental inputs
Physiology - Cell size, fixation pathway
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Goericke & Fry (GBC, 1994)
Marine δ13C gradients: shelf - offshore
Clementz & Koch (Oecologia, 2001)
-30
-25
-20
-15
-10
δ13C
Marine δ15N gradients: basin scale
Key factors that affect regional δ15N values
[NO3]: δ15N ∝ 1/[NO3]: vertical mixing delivers limiting nutrients (drives production) and remineralized N
δ15NNO3 - vertical mixing (deep ocean ≈ 5‰), denitrification (15N-enriched NO3), atmospheric inputs
Physiology - N2 fixation (≈0‰) vs. uptake of NO3 or NH4
Recommended