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Antarctic coastal foodwebs: ecological redundancy, generalism and potential responses to environmental change

Antarctic coastal foodwebs: ecological redundancy, generalism and potential responses to environmental change
Jonathan S. Stark

Authors

Jonathan S Stark, GJ Johnstone
Terrestrial and Nearshore Ecosystems Theme, Australian Antarctic Division, Channel Hwy, Kingston Tas 7050

G Dunshea
Ecological Marine Services, PO Box 197, Fremantle WA 6959

C Gillies
Earthwatch, 126 Bank Street, South Melbourne, VIC 3205

Abstract

Antarctic coastal foodwebs were studied using gut content analysis, stable isotopes and DNA-based diet techniques, providing trophic data over different timescales, resulting in the most comprehensive description of these foodwebs yet undertaken. Stable isotope (SI) analysis revealed Antarctic nearshore foodwebs were of comparable trophic length and complexity to other regions. Carbon signatures were distinct between different communities of primary producers and macroalgae was a major carbon source along with phytoplankton but sea ice algae was less important than expected. Molecular analysis of the diets of large benthic predators (fish, starfish, molluscs) via pyrosequencing showed a range of ecological niches from extreme generalist to specialised diets. Generalists displayed a diverse diet with plasticity prevalent in abundant predators. This may reflect an advantageous foraging strategy given the ephemeral and highly seasonal nature of primary production in this ecosystem or it could be attributable to the large degree of spatial heterogeneity in community structure. Network analysis indicated connectivity among generalist predator diets at relatively few prey taxa. One of the main predators in coastal ecosystems, the fish Trematomus bernachii, showed evidence of spatial differences in diet relating to availability of prey items over a regional scale. DNA-based diet techniques showed considerable potential as a tool for regional scale biodiversity assessment to complement existing biodiversity sampling techniques for the study of ecosystems that are difficult to sample by other means, like the Antarctic nearshore. Antarctic food webs posses some features that make them susceptible to climate change (e.g. diet specialisation), but in other aspects they are potentially very resilient (generalism, ecological redundancy).

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Key dates

  • 11th June 2013
    Registrations close
  • 21st June 2013
    Registrations at the AAD open for staff
  • 24th June 2013
    Registrations at the venue open
  • 24th June 2013
    Conference commences
  • 26th June 2013
    Conference concludes

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This page was last modified on 23 September 2013.