Observational approaches to vertical movements of predators and prey in relation to physical/chemical structures

Transcription

1 Observational approaches to vertical movements of predators and prey in relation to physical/chemical structures Martin Biuw Norwegian Polar Institute, Tromsø, Norway MEOP Marine Mammals Exploring the Oceans Pole to Pole

2 What are the objectives? How do marine top predators interact with their environment? How do they respond to environmental variability in space and time? Which costs and benefits are associated with different foraging strategies? Short-term: Foraging success Changes in body condition Detailed data Long-term: Long time series Survival Reproductive success

3 Scales of study of vertical movements Inter-dive variations in target depths Track diurnal movements of prey Follow depth contours Switching between e.g. pelagic and benthic prey Behavioural responses to prey availability and energetic demands Intra-dive changes in depth Descent and ascent rates Drift rates Physiological consequences of foraging performance

4 Which kinds of observations do we need? Individual: Movements, diving, feeding events, body condition etc. Environmental: prey density, nutrients, chlorophyll.. Biological Chlorophyll, nutrients.. In-situ Remote Temperature, salinity, light, currents.. SST, SSH, sea ice, winds, currents Physical

5 Representative onboard instruments Accelerometer/D-tag High resolution (> 1Hz) Non-expendable Time Depth Recorder Medium resolution ( 1 Hz) Non-expendable (must be recovered) Can currently measure: Satellite linked Expendable Location only Compressed data Behaviour: Depth, duration, speed, 3D movements & orientation, (noise) Environment: T, (noise, prey density) Physiology: Body condition (proxy?) Behaviour: Depth, duration, speed Environment: T, light level Physiology: Body condition (proxy) Heart rate Stomach temp. Behaviour: Depth, duration, speed Environment: T, S, density, fluoro. Physiology: Body condition (proxy)

6 Level of detail Detail vs. Coverage The future Accelerometers, cameras, acoustics Increasing battery life & memory capacity Advanced compression algorithms, Argos bandwidth improvements, GSM (coastal), Iridium? (global) Time-depth recorders (Non-expendable) Increasing battery On-board life & memory capacity compression allow transmission of data Argos location-only transmitters (Expendable) Time/space coverage of recording

7 Size and energy constraints define limits I m a laid back kinda guy, but there are limits

8 Observations of predator behaviour and body condition indices Movements Diving Feeding events Buoyancy Body mass

9 Where do they go? What is it like there? How well do they do there? How does this affect how well they will do on land?

10 Growing datasets on animal movements Southern elephant seal tracks accumulated over the past 2 decades

11 TDR data and diving behaviour at several timescales Feeding Entire One Dive track day trip bout

12 Vertical migrations of krill and jellyfish Krill and jellyfish vertical migrations in Lurefjorden, Norway, measured by bottom mounted 38 khz echosounder, cabled to shore.

13 Synchronized and unsynchronized vertical movements Zooplankton movements in the High Arctic using moored ADCP Cottier et al. 2006, Limnol. Oceanogr. 51(6)

14 School structure, movement and size/biomass estimation of Antarctic krill (Euphausia superba) Combining multibeam sonar and multi-frequency echosounder data Latest commercial technology Need big ships Big wallets Commercial interest from industry Korneliussen et al. 2009, ICES J. Mar. Sci 66(6)

15 Depth (m) SEALCAM: predator-borne camera Example: Antarctic fur seals feeding on Antarctic krill Conspecifics Capture events Krill illuminated by flash at night Abundance and biomass? Time 15:00 15:15 15:30 15:45 16:00 16:15 16:30 16:45 17:00 0 Depth 19 m Depth m Integration with diving behaviour allows detailed examination of foraging behaviour

16 Descent/ascent rates and buoyancy? Differences between descent and ascent rates is related to buoyant force, which is largely influenced by relative lipid content Experimentally adjusted buoyancy of Northern elephant seals Natural variations in buoyancy of grey seals Webb et al. J. Exp. Biol. (1998) 201, Beck et al. J. Exp. Biol. (2000) 203,

17 Drift dives as index of body condition Speed Depth Drift rate (cm/s) Time t d Indirect measure of condition change over time Jan Feb Mar Apr May Biuw et al. J. Exp. Biol. (2003)

18 Daily change in drift rate (cm s -2 ) Identification of hotspots using change in drift rate + - Biuw et al. 2007, Proc. Nat. Acad. Sci. 104(34)

19 Accelerometry and sperm whale buoyancy - Stroking - Gliding High lipid Low lipid Miller et al. J. Exp. Biol. (2004) 207,

20 Accelerometry and Baikal seal buoyancy Watanabe et al. J. Exp. Biol. (2006) 209,

21 Accelerometry and seabird mass gain Is dominant wing beat frequency related to foraging success? Stroke frequency (Estimated body mass) Sato et al. J. Exp. Biol. (2006) 211, 58-65

22 Can we get mass AND lipid gain from accelerometry? Descent B) Drift a A m seal C d 0.5 sw v 2 sin( pitch) g ( sw seal 1). C) Ascent Drifting Simulated acceleration for fat vs. lean and heavy vs. light animals Buoyancy differences can be resolved at slow accelerations during drift phases Ascent Mass differences can be resolved at higher accelerations during descent and ascent phases.

23 Animal-borne in situ observations of ocean properties

24 What can I do for you?

25 First prototypes deployed on a beluga whale in Svalbard

26 Conductivity-Temperature-Depth Satellite Relay Data Logger Conductivity sensor Pressure sensor Battery Temperature sensor Comm. port

27 Overcoming Argos bandwidth constraints Hybrid compression method: 10 levels selected at pre-defined pressures (depends on maximum pressure at bottom of profile) 10 additional points selected by broken stick algorithm Flexible setup allows customisation Choice of animals add to flexibility

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29 Southern Elephant Seals as Oceanographic Samplers ~80 seals over 3 seasons ( ) Circumpolar coverage during winter migrations 1-2 temperature-salinity profiles/day High-resolution data set also within ice

30 High data return in under-sampled regions

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32 TOPP northern elephant seals 0 Temperature 22 7 seals tracked during 2-3 month summer feeding migrations

33 Argo Argo + seals Merging datasets

34 Merging datasets Charrassin et al. 2008, Proc. Nat. Acad. Sci. 105(33)

35 Seasonal frontal dynamics from subsurface data (Argo + SEaOS) PF and SACCF are coupled west of South Georgia? Interaction / coupling of all fronts north of South Georgia? In-situ data, not model output

36 Delayed-mode quality control SRDLs are calibrated before deployment, but recalibrations often cannot be done because of the necessity of recapturing an animal. Direct comparisons of SRDL measurements with those measured by shipboard highresolution CTDs or Argo floats. Mapping a set of calibrated data by objective analysis to the SRDL position. S(t) Boehme & Send. DSR II (2005), Owen & Wong (2008)

37 Illustration of data recovery and reconstitution Example 1: Argos CTD tag on Southern elephant seal Dive Temperature: profiles + Original Interpolated Haulouts measurements section

38 Illustration of data recovery and reconstitution Example 1: Argos CTD tag on Southern elephant seal Temperature Salinity

39 Daily change in drift rate (cm s -2 ) Identification of hotspots using change in drift rate + - Biuw et al. 2007, Proc. Nat. Acad. Sci. 104(34)

40 Habitat characterisation using in-situ oceanography Observations: Red surfaces correspond to areas of increasing drift rates (i.e. increasing lipid reserves) Predictions: Areas of feeding and increase in fat reserves overlaid on typical latitudinal section from historical data Biuw et al. 2007, Proc. Nat. Acad. Sci. 104(34) Predictions use only T and S, NOT location or depth!

41 Eléphant de mer Antarctique Moving from physics to primary production In-situ measurements of hydrographic properties and chlorophyll (fluorometry) from a southern elephant seal. Note the high chlorophyll concentrations associated with the Antarctic Divergence. Kerguelen Antarctica Guinet et al.

42 Antarctic soujourn Southbound Before sea-ice With sea-ice Kerguelen Northbound Chlorophyll (μg l -1 ) Kerguelen Temperature ( C)

43 Animals in the Global Ocean Observing System?

44 Animals in the Global Ocean Observing System?

45 What can we do? Examine detailed individual behaviour in many marine vertebrate predator species Measure prey ingestion rates & capture events Estimate changes in condition resulting from feeding Measure ocean physics and subsurface chlorophyll What can we not (yet) do? Long-term records of predator-prey interactions Long-term detailed 3D behaviour and accurate body condition Currently no other environmental parameters beyond T, S and fluorometry Long-term acoustic monitoring of the immediate environment..

46 OO 09 CWPs related to animal tagging and ocean observation New insights into Southern Ocean physical and biological processes revealed by instrumented elephant seals. Charrassin J.-B., F. Roquet, Y.H. Park, F. Bailleul, C. Guinet, M. Meredith, K. Nicholls, S. Thorpe, B. McDonald, D. Costa,Y. Tremblay, M. Goebel, M. Muelbert, M. N. Bester, J. Plötz, H. Bornemann, R. Timmermann, M. Hindell, A. Meijers, R.C. Coleman, I.C. Field, C. R. McMahon, S. Rintoul, S. Sokolov, L. Boehme, M. Fedak, P. Lovell, M. Biuw, O.A. Nøst, K.M. Kovacs, C. Lydersen. Biologging in the Global Ocean Observing System. Boehme L., Kovacs K., Lydersen C., Nøst O.A., Biuw M., Charrassin, J.-B, Roquet F., Guinet C., Meredith M., Nicholls K, Thorpe S., Costa, D, Block B., Hammil M., Stenson G., Muelbert M., Bester M., Plötz J., Bornemann H., Hindell, M.; Rintoul, S., Fedak, M.. & Lovell. P. TOPP: Using Electronic tags to monitor the movements, behaviour and habitats of marine vertebrates. Costa D.P., Block, B.A., & Bograd, S. Additional contribution: On the validation of hydrographic data collected by instrumented elephant seals. Roquet F., Charrassin J.-B., Park Y.H, Marchand S., Reverdin G., & C. Guinet