isotopic tracking of marine mammals in coastal and pelagic ... · isotopic tracking of marine...

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