Centre for Marine Biodiversity and Biotechnology Away Day 2012. Presentation by Susan Gallon on Southern elephant seals: A top predator of the southern ocean and a useful vehicle to study its environment

1. Southern elephant seals: A top predator of the southern
ocean and a useful vehicle to study its environment
Susan Gallon

2. Southern elephant seals
(Mirounga leonina)
Largest pinniped species (♂ 1500-3000 Kg, ♀ 400-600 Kg)
Extremely sexually dimorphic: male up to 10 times larger
than adult female
Long (up to 2 hours), deep (up to 2500 m) and nearly continuous
diving at sea (90 % diving)
2 annual migrations from their breeding and molting sites
Major consumers of Southern Ocean biomass

3. 1- INVESTIGATING FORAGING STRATEGIES
Study site:
Elephant Island (61°S 55°W)
29 southern elephant seals (5 PM SA
♂, 20 PM ♀ and 4 PR ♀)
Whisker SI analyses
15N a proxy for the trophic position of
predator
13C a proxy for foraging habitat
Satellite tags (SMRU, St Andrews, UK)
To track individual seals at sea and
monitor their diving behaviour
State Space Models (SSM) were used to
infer foraging areas during seals’ migration.
In these foraging areas we calculated:
dive duration, dive depth, diel
migration, shelf foraging and benthic
foraging

4. 1- INVESTIGATING FORAGING STRATEGIES

5. 1- INVESTIGATING FORAGING STRATEGIES
Satellite tracked animals and kernel density of foraging area

6. 1- INVESTIGATING FORAGING STRATEGIES
13C 15N 13C 15N
F203-262 F203-262 F255-263 F255-263
-18 14 -18 14
0 2 4 6 8 10 12 0 2 4 6 8 10 12
13.5 13.5
-19 13 -19 13
12.5 12.5
-20 -20
12 12
11.5 11.5
-21 -21
11 11
-22 10.5 -22 10.5
10 10
-23 9.5 -23 9.5
9 9
-24 0 2 4 6 8 10 12 -24 0 2 4 6 8 10 12
F255-263 F255-263
F203-262 F203-262 -18 14
0 2 4 6 8 10 12
-18 14 13.5
0 2 4 6 8 10 12 -19 13
13.5
-19 13 12.5
-20
12.5
12
-20 11.5
12 -21
11
11.5
-21
-22 10.5
11
10
-22 10.5
-23 9.5
10
-23 9
9.5
-24 0 2 4 6 8 10 12
9
-24 0 2 4 6 8 10 12
F203-262 F203-262
-18 14
13C 15N
0 2 4 6 8 10 12
13.5
-19 13
12.5
-20 F229-265 F229-265
12
-18 14
11.5
-21 0 2 4 6 8 10 12
13.5
11
-19 13
-22 10.5
12.5
10 -20
-23 12
9.5
11.5
9 -21
-24 0 2 4 6 8 10 12 11
-22 10.5
10
Samples taken in November 2008 and 2009 and January 2009 for -23 9.5
9
F203-262 -24 0 2 4 6 8 10 12
Samples taken in January 2008 and 2009 for F255-263 and F229-265 F229-265 F229-265
-18 14
0 2 4 6 8 10 12
13.5
-19
13
12.5
-20
12
-21 11.5
11
-22 10.5
10
-23
9.5
9
-24
0 2 4 6 8 10 12

7. 1- INVESTIGATING FORAGING STRATEGIES
13C 15N 13C 15N
F203-262 F203-262 F255-263 F255-263
-18 14 -18 14
0 2 4 6 8 10 12 0 2 4 6 8 10 12
13.5 13.5
-19 13 -19 13
12.5 12.5
-20 -20
12 12
11.5 11.5
-21 -21
11 11
-22 10.5 -22 10.5
10 10
-23 9.5 -23 9.5
9 9
-24 0 2 4 6 8 10 12 -24 0 2 4 6 8 10 12
F255-263 F255-263
F203-262 F203-262 -18 14
0 2 4 6 8 10 12
-18 14 13.5
0 2 4 6 8 10 12 -19 13
13.5
-19 13 12.5
-20
12
Similar profiles in consecutive years
12.5
-20 11.5
12 -21
11
11.5
-21
-22 10.5
11
10
 fidelity to foraging area and prey
-22 10.5
-23 9.5
10
-23 9
9.5
-24 0 2 4 6 8 10 12
9
-24 0 2 4 6 8 10 12
F203-262 F203-262
-18 14
13C 15N
0 2 4 6 8 10 12
13.5
-19 13
12.5
-20 F229-265 F229-265
12
-18 14
11.5
-21 0 2 4 6 8 10 12
13.5
11
-19 13
-22 10.5
12.5
10 -20
-23 12
9.5
11.5
9 -21
-24 0 2 4 6 8 10 12 11
-22 10.5
10
Samples taken in November 2008 and 2009 and January 2009 for -23 9.5
9
F203-262 -24 0 2 4 6 8 10 12
Samples taken in January 2008 and 2009 for F255-263 and F229-265 F229-265 F229-265
-18 14
0 2 4 6 8 10 12
13.5
-19
13
12.5
-20
12
-21 11.5
11
-22 10.5
10
-23
9.5
9
-24
0 2 4 6 8 10 12

8. 1- INVESTIGATING FORAGING STRATEGIES
13C 15N
F256 F256
-18 14
0 2 4 6 8 10 12 13.5
-19 13
12.5
-20
12
11.5
-21
11
-22 10.5
10
-23 9.5
9
-24 0 2 4 6 8 10 12
WAP: Feed on the shelf, some benthic dives, lower 13C and higher 15N
F292-293 F292-293
-18 14
0 2 4 6 8 10 12
13.5
-19 13
12.5
-20
12
11.5
-21
11
-22 10.5
10
-23 9.5
9
-24 0 2 4 6 8 10 12
OPEN WATER: No shelf, no benthic dives, higher 13C and lower 15N
F209 F209
-18 14
0 2 4 6 8 10 12
13.5
-19 13
12.5
-20
12
11.5
-21
11
-22 10.5
10
-23 9.5
9
-24 0 2 4 6 8 10 12
MIXED: Shelf, benthic dives, open water, mixed 13C and 15N values

9. 1- INVESTIGATING FORAGING STRATEGIES
13C 15N
F256 F256
-18 14
0 2 4 6 8 10 12 13.5
-19 13
12.5
-20
12
11.5
-21
11
-22 10.5
10
-23 9.5
9
-24 0 2 4 6 8 10 12
WAP: Feed on the shelf, some benthic dives, lower 13C and higher 15N
F292-293 F292-293
Different C and N profiles
-18 14
0 2 4 6 8 10 12
13.5
-19 13
12.5
-20
 Different isotopic signature for seals
12
11.5
-21
11
-22 10.5
10
feeding in different geographic areas
-23 9.5
9
-24 0 2 4 6 8 10 12
OPEN WATER: No shelf, no benthic dives, higher 13C and lower 15N
F209 F209
-18 14
0 2 4 6 8 10 12
13.5
-19 13
12.5
-20
12
11.5
-21
11
-22 10.5
10
-23 9.5
9
-24 0 2 4 6 8 10 12
MIXED: Shelf, benthic dives, open water, mixed 13C and 15N values

10. 1- INVESTIGATING FORAGING STRATEGIES
13C 15N
13C 15N
F252 F252
-18 14
0 2 4 6 8 10 12
13.5
-19 13
12.5
-20
12
11.5
-21
11
-22 10.5
10
-23 9.5
9
-24 0 2 4 6 8 10 12

11. 1- INVESTIGATING FORAGING STRATEGIES
13C 15N
F261 F261
-18 14
0 2 4 6 8 10 12
13.5
-19 13
12.5
-20
12
11.5
-21
11
-22 10.5
10
-23 9.5
9
-24 0 2 4 6 8 10 12
Similar C profile but different N profile 15
13C N
Seals (from same gender and age class)
F252 F252
that forage in same habitat feed on prey
-18
-19
0 2 4 6 8 10 12
14
13.5
13
12.5
from different trophic level
-20
12
11.5
-21
11
-22 10.5
10
Why? How?
-23
-24
9.5
9
0 2 4 6 8 10 12

13. 2- IDENTIFYING FORAGING EVENT
Translocation study:
Kerguelen Island (49°S 69°E)
3 adult female southern elephant seals
(T3, T4 and T5)
Satellite tags (SMRU, St Andrews, UK):
Provided an estimate of the location of
the animal at sea and on land
Accelerometer tags
(Loggend, CNRS, France):
Placed on neck of the animal to detect
feeding event
2-D accelerations (heave and surge) at
8 Hz (T4 and T5) and 16 Hz (T3)
Depth sensor at 1 Hz

14. 2- IDENTIFYING FORAGING EVENT
Heave
Surge
400 m
Static acceleration gravity or pitch
Dynamic acceleration movements of the seals resulting from either stroking
and/or rapid head movements

15. 2- IDENTIFYING FORAGING EVENT
Heave
Surge
Threshold
400 m
Matlab (version 7.0.1) Low pass filter to extract static (gravitational) acceleration
Feeding event acceleration spikes over the threshold
Feeding dive acceleration profiles with more than one spike present in both the
surge and heave axes

16. 2- IDENTIFYING FORAGING EVENT

17. Climate
Ocean resources
Demography
Oceanographers Biologists
Oceanographic Distribution and
conditions availability of prey
- Temperature - Prey species
- Salinity - Prey encounter
- Fluorescence - Foraging efficiency
- Dissolve oxygen - Life history

18. 3- FUTURE WORK

21. 4- Merging expertise
It may be possible to use seal tracking data to locate deep-sea coral habitats
and furthermore to use bio-logging equipment attached to seals as platforms
for ocean sensors to relay physical ocean data (e.g. salinity, temperature) from
the areas they frequent. These physical data may be in turn be used to better
identify and protect cold water coral habitats.

22. Thank you