This document discusses the complexity of Antarctic pelagic food webs. It notes that the traditional view of a simple krill-centered food chain is an oversimplification, as food webs vary spatially and temporally. Different techniques like gut content analysis, stable isotopes, DNA barcoding are used to identify trophic links between species. While krill remain an important base of the food web, other species like copepods and lanternfish may play a more significant role than previously thought under certain conditions. The document advocates for a better understanding of Antarctic food webs through modeling and considering various sources of uncertainty.

1. Polar Foodwebs
Antarctic Pelagic Foodwebs
Anton Van de Putte
Royal Belgian Institute for Natural Sciences
www.biodiversity.aq

2. Who am I
• Zoologist
• PhD on the ecology and evolution
of Southern Ocean fish
• Science Officer Biodiversity.aq

3. ‘Classical view’
• a spatial homogeneous and simple food chain
• Krill centred
© Philipp Assmy © Volker Siegel © Ulrich Peter

4. Temporal and spatial heterogeneity
AADC, Ben Raymond through
share.biodiversity.aq
Chla, summer Temperature , winter Temperature , summer

5. Pelagic Bioregions
Grant et al., 2006

6. Antarctic ecosystems are changing
Atkinson et al. 2008

7. Antarctic Polar Front
Grant et al., 2006
e.g. Rodhouse & White, 1995

8. Shelf Zone
Grant et al., 2006
e.g. Thomas & Greene, 1998

9. Marginal Ice zone
Grant et al., 2006
e.g. Hopkins et al., 1993

10. Identify trophic links
• Gut content analysis
– snapshot
• Stable isotopes/Fatty acid composition
– Integrated over time
• Barcoding/high throughput sequencing
– snapshot
Deagle 2009, Brown et al.
2012, O'Rorke et al. 2012

11. Barcoding/high throughput
sequencing
• Barcoding: use of
‘standardised’ sequence
– COI, 16S..
– Still requires different
primers
• High throughput
sequencing
– High volume of data
– Semi quantitative
Suz Bateson, University of Guelph

12. Quantify various trophic levels
• Energetic content
• Abundance/Biomass
• Productivity

13. Energy Content
Van de Putte, 2008

14. Occurrence
• Krill base
– occurrence/length frequency
• SCAR-Marbin
– Marine biodiversity
• Biodiversity.aq
– Marine & terrestrial biodiversity

15. Understand food webs
• Modelling
– Distribution
• GLM, GAM, BRT…
– Foodweb
• Eg ecopath
Flores et
al. 2008
Hill et al.
2012

16. Example of a project structure

17. Questioning the Krill importance
• Copepods
– same biomass
– more productive
• Lanternfish
– biomass
underestimated
– High energy content
• Under certain
circumstances
important
alternative

18. Interesting reads
• Atkinson, A., Siegel, V., Pakhomov, E., Rothery, P., 2004. Long-term decline in krill stock and increase in salps within the Southern
Ocean. Nature 432 (7013), 100-103.
• Barrera-Oro, E., 2002. The role of fish in the Antarctic marine food web: differences between inshore and offshore waters in the
southern Scotia Arc and west Antarctic Peninsula. Antarctic Science 14 (4), 293-309
• BROWN, D. S., JARMAN, S. N. and SYMONDSON, W. O. C. (2012), Pyrosequencing of prey DNA in reptile faeces: analysis of earthworm
consumption by slow worms. Molecular Ecology Resources, 12: 259–266. doi: 10.1111/j.1755-0998.2011.03098.x
• DEAGLE, B. E., KIRKWOOD, R. and JARMAN, S. N. (2009), Analysis of Australian fur seal diet by pyrosequencing prey DNA in faeces.
Molecular Ecology, 18: 2022–2038. doi: 10.1111/j.1365-294X.2009.04158.x
• Flores, H., Van de Putte, A. P., Volker, S., Pakhomov, E.A., Van Franeker J.A., Meesters, E., Volckaert, F.A.M., 2008. Distribution,
abundance and ecological relevance of pelagic fish in the Lazarev Sea, Southern Ocean. Marine Ecology Progress Series.
• Grant, S., Constable, A., Raymond, B., Doust, S., 2006. Bioregionalisation of the Southern Ocean: Report of Exports Workshop. WWF-
Australia and ACR CRC, Hobart, September 2006.
• Hill et al. 2012 A Foodweb Model to explore uncerteinties in the South Georgia shelf Pelagic Ecosystem. Deep Sea Research II, 59-60,
237-252.
• Hopkins, T.L., Ainley, D.G., Torres, J.J., Lancraft, T.M., 1993. Trophic structure in open waters of the marginal ice zone in the Scotia-
Weddell confluence region during spring (1983). Polar Biology 13 (6), 389-397.
• O'Rorke R, Lavery S, Chow S, Takeyama H, Tsai P, et al. (2012) Determining the Diet of Larvae of Western Rock Lobster (Panulirus
cygnus) Using High-Throughput DNA Sequencing Techniques. PLoS ONE 7(8): e42757. doi:10.1371/journal.pone.0042757
• Rodhouse, P.G., White, M.G., 1995. Cephalopods occupy the ecological niche of epipelagic fish in the Antarctic Polar Frontal Zone.
Biological Bulletin 189 (2), 77-80.
• Thomas, P.B., Green, K., 1988. Distribution of Euphausia crystallorophias within Prydz Bay and its importance to inshore the marine
ecosystem. Polar Biology 8, 327-331.