PROPOSAL FOR THE INCLUSION OF TOP PREDATOR STUDIES IN SO-GLOBEC POLARSTERN CRUISE ANT XVIII-5

SO-GLOBEC winter krill studies
Antarctic Peninsula site
Bellingshausen Sea, Marguerite Bay, May 2001

J.A. van Franeker
ALTERRA (formerly IBN-DLO)
PO Box 167
1790 AD Den Burg (Texel)
The Netherlands
tel. +31-222-369724
fax +31-222-319235
email: J.A.vanFraneker@ibn.dlo.nl

5/11/1999

General considerations on Antarctic top predator studies

Antarctic seabirds and mammals are not uniformly distributed over the Southern Ocean. Spatial, seasonal and other variability in the environment results in strong and rapid responses in the ecosystem up to the highest trophic level. Distribution, abundance and community-structure of top predators reflect underlying physical, chemical and biological processes in the ocean. Such links are present from the very fine to very large scale and studying these in an interdisciplinary framework serves a number of scientific and practical objectives:

• quantifying the role of the top predator community in the Southern Ocean ecosystem(s), for example in terms of overall food-consumption or carbon fluxes
• establishing the nature and consistency of qualitative and quantitative interactions between environmental phenomena (physical, chemical or biological e.g. krill populations) and top predators
• identifying marine areas/zones of major importance to particular (groups of) Antarctic bird or mammal species and their prey-species such as krill
• improving knowledge on pelagic ecology, distribution and population size of individual species Data collected following these objectives on subsequent cruises will increasingly contribute to modelling the role of the Southern Ocean in global cycles such as its interaction with atmospheric CO2 levels (Joint Global Ocean Flux Study JGOFS). In such modelling, top predator dietary information may supply indirect data on the role of intermediate biological levels not easily studied directly. Also, top predator data may be of use to translate fine scale oceanographic results to larger areas. ALTERRA aims to enhance its expertise in this field, by gradually expanding data sets to a wider geographical and seasonal coverage. Focus of interest is the seasonal sea-ice zone, the importance of which is still insufficiently known. Taking part in SO-GLOBEC in Polarstern's ANT XVIII-4 fits extremely well in these wider objectives of ALTERRA.

  SO-GLOBEC and top predator studies

  Krill, Euphausia superba has been selected as the primary target species of Southern Ocean GLOBEC (GLOBEC report nr 7 a). This focus on Antarctic krill includes its habitat, prey, predators and competitors.
  The first "Predator Science Question" in SO-GLOBEC has been formulated as: How does winter distribution and foraging ecology of top predators relate to the distribution and characteristics of the physical environment and prey (Krill)?
  Following ALTERRA's (formerly IBN-DLO) participation in four earlier SO-JGOFS and SO-GLOBEC cruises (see publications) it is proposed that ALTERRA participates in the ANT XVIII-4 cruise to address this question. Much of the earlier studies have focussed on work within the sea-ice zone. Top predator censuses include the recording of fine-scale observations of ice-coverage and ice-characteristics, and thus contribute to the required detailed description of the physical environment. As top predator censuses follow standardized quantitative methods, results are not only significant in a distributional sense, but may also be used to quantitative estimates of their predation effects on local krill populations.

  Considering the time of year and expected cruise design, presence of one experienced observer seems adequate for the purpose of top predator censuses. Censuses will be conducted following standard methods from an outdoor observation post installed on top of the bridge of Polarstern. Depending on the requirements for sea-ice observations on a 24 hour basis, a second observer may be required. This will need to be discussed in planning meetings.

  RELEVANT PUBLICATIONS

  Van Franeker, J.A. 1992. Top predators as indicators for ecosystem events in the confluence zone and marginal ice zone of the Weddell and Scotia seas, Antarctica, November 1988 to January 1989 (EPOS Leg 2). Polar Biol. 12: 93-102.

  Schalk, P.H., Brey, T., Bathmann, U., Arntz, W., Gerdes, D., Dieckmann, G., Ekau, W., Gradinger, R., Plötz, J., Nöthig, E., Schnack-Schiel, S.B., Siegel, V., Smetacek, V.S., & Van Franeker, J.A. 1993. Towards a conceptual model of the Weddell Sea ecosystem, Antarctica, In: Christensen, V. and Pauly, D. (Eds.). Trophic models of aquatic ecosystems. ICLARM Conf. Proc. 26: 323-327.

  Van Franeker, J.A. 1994. A comparison of methods for counting seabirds at sea in the Southern Ocean. J. Field Ornithol. 65(1): 96-108.

  Van Franeker, J.A. 1996. Pelagic distribution and numbers of the Antarctic Petrel Thalassoica antarctica in the Weddell Sea during spring. Polar Biology 16: 565-572.

  Van Franeker, J.A. 1996. Long term studies of Antarctic Fulmarine Petrels and the role of top predators in the Southern Ocean pelagic ecosystem. Circumpolar Journal 11(1/2): 97-102.

  Van Franeker, J.A., Bathmann, U.V., & Mathot, S. 1997. Carbon fluxes to Antarctic top predators. Deep Sea Research II 44(1/2): 435-455.

  Van Franeker, J.A., Gavrilo, M., Mehlum, F., Veit, R.R., & Woehler, E.J. 1999. Distribution and abundance of the Antarctic Petrel. Waterbirds 22(1): ... (in press).

  Van Franeker, J.A., Van den Brink, N.W., Bathmann, U.V., Pollard, R.T., & de Baar, H.J.W. (....). Responses of seabirds, in particular prions (Pachyptila sp.), to small scale processes in the Antarctic Polar Front. Deep Sea Research: accepted.

  further publications of relevance by applicant

  van Franeker, J.A. 1989. Sea ice conditions. in: Hempel, I., P.H. Schalk and V. Smetacek (eds). The Expedition Antarktis VII/3 (EPOS LEG 2) of R.V. "POLARSTERN" in 1988/1989. Berichte zur Polarforschung 65: 10-13.

  van Franeker, J.A. 1989. Seabirds, seals and whales. in: Hempel, I., P.H. Schalk and V. Smetacek (eds). The Expedition Antarktis VII/3 (EPOS LEG 2) of R.V. "POLARSTERN" in 1988/1989. Berichte zur Polarforschung 65: 172-179.

  Ackley, S.F., Eicken, H., van Franeker, J.A., Wadhams, P. 1992. Protocol for ship and airborne observations on the structure, physical properties and coverage of sea ice in the framework of Southern Ocean (SO) JGOFS activities. AWI, Bremerhaven, 9 pp.

  Bathmann, U.V., Scharek, R., Crawford, R., Peeken, I., Bakker, D., van Franeker, J.A. 1994. Phytoplankton spring blooms at the Polar Front and at the ice edge north of the Weddell Sea. EOS, Transactions, A.G.U. 75 (3), Supplement 1994 Ocean Sciences Meeting: 158.

  Smetacek, V., Bathmann, U., van Franeker, J.A., Veth, C. 1994. Spring at the ice edge: Southern Ocean JGOFS cruise of RV "Polarstern". EOS, Transactions, A.G.U. 75(3) Supplement 1994 Ocean Sciences Meeting: 158.

  Van Franeker, J.A. 1994. Top Predators: Seabirds, seals and whales. In: Bathmann, U., Smetacek, V., de Baar, H., Fahrbach, E. & Krause, G. (Eds). The expeditions ANTARKTIS X/6-8 of the Research Vessel "POLARSTERN" in 1992/93. Berichte zur Polarforschung (Reports on Polar Research) No. 135. (AWI, Bremerhaven). pp 23-30.

  Van Franeker, J.A. 1994. Sea-ice cover and icebergs. In: Bathmann, U., Smetacek, V., de Baar, H., Fahrbach, E. & Krause, G. (Eds). The expeditions ANTARKTIS X/6-8 of the Research Vessel "POLARSTERN" in 1992/93. Berichte zur Polarforschung (Reports on Polar Research) No. 135. (AWI, Bremerhaven). pp 17-22.

  van den Brink, N.W., & van Franeker, J.A. 1997. Sea ice observations and icebergs. pp 12-17 in: U.Bathmann, M.Lucas & V.Smetacek (eds). The Expeditions ANTARKTIS XIII/1-2 of the Research Vessel "POLARSTERN" in 1995/96. Berichte zur Polarforschung Nr.221.

  van Franeker, J.A., & van den Brink, N.W. 1997. Censuses of marine birds and mammals. pp 116-121 in: U.Bathmann, M.Lucas & V.Smetacek (eds). The Expeditions ANTARKTIS XIII/1-2 of the Research Vessel "POLARSTERN" in 1995/96. Berichte zur Polarforschung Nr.221.

  Van Franeker, J.A. subm. Censuses of marine birds and mammals during ANT-XVI/3 (Polarstern, 18 March - 9 May 1999, SO-JGOFS & SO-GLOBEC). Berichte zur Polarforschung (submitted).