Annual report 2005-06.indd - Antarctic Climate and Ecosystems ...

antarctic marine ecosystemsof field data and models will be used topredict the effects of ecosystem changeson harvested species and the food web.This work will also be used in combinationwith credible models of fishery dynamicsto promote more effective management ofmarine living resources.OverviewMost marine life is found in the surface mixedlayer of the ocean, typically to about 200 metresdeep, where light from above and nutrients frombelow provide the foundations of productivity.Many of the vertebrate species (e.g., whales,seals and penguins) of the Antarctic region areof high conservation value and depend primarilyon Antarctic krill for food. The current inabilityto predict the effects of environmental changeson their populations makes it difficult for bodiessuch as the Commission for the Conservationof Antarctic Marine Living Resources (CCAMLR)and the International Whaling Commission(IWC) to establish sound long-term managementstrategies.Australian research has already highlightedthe structure and dynamics of the krill-basedSouthern Ocean ecosystem. Much of thisresearch has led to the adoption by CCAMLR,to which Australia is a signatory, of manyprecautionary proposals for managementof biological resources around Antarctica.CCAMLR manages the krill harvest, which is theAntarctic’s largest fishery and the one with thegreatest potential to impact widely on the foodweb in the region. The krill fishery is projected toexpand into one of the world’s largest fisheries,yet the effects of climate change on krill stocks,and on the species dependent on krill (seabirds,penguins, seals and whales), are unknown.The ACE CRC is examining the predictedenvironmental changes and their implicationsfor sustainable management of SouthernOcean fisheries and the marine life protectedthrough CCAMLR. During the first two years,we developed a framework for elaboratingecosystem models of the Southern Oceanand created conceptual ecological modelsfor key taxa, including krill, in the Antarcticmarine food web. We also analysed large-scaledatasets of ice and ocean colour to elaboratean empirical model of primary production in thesea ice zone of eastern Antarctica and madesubstantial progress in developing under-icesensing capability to measure in situ chlorophyllabundance in the sea ice zone.Key achievements 2005-06• Completion of BROKE-West Survey: TheBROKE-West expedition surveyed more than1 million square kilometres of the SouthernOcean, gathering data on krill populationsand physical oceanographic properties.• Proposal for multidisciplinary sea ice studyin 2007: A 30-day early season cruise wasapproved by both the Physical Sciencesand the Life Sciences Antarctic ResearchAssessment Committee (ARAC).• Sea ice algal distribution: A conceptual modelfor large-scale sea ice algal distribution wasdeveloped.• Krill population model: A spatially-structuredkrill population model based on empiricalmeasurements was developed for thesouthwest Atlantic.• Physical regionalisation of the SouthernOcean: Methods have been developed toassist in compartmentalising the ecosystemmodels as well as for providing a foundationfor reviewing the biological diversity in theSouthern Ocean.Plans for 2006-07• Testing of optical sensor (hyperspectralradiometer) for remote and non-invasivedetermination of ice algae distribution(Polarstern cruise).• Coordination of multidisciplinary sea icecruise (September 2007).• Scoping out the development of the fullycoupledbiophysical model.• Completion of the physical regionalisation ofthe Southern Ocean.• Further development of components ofa Southern Ocean ecosystem model,particularly model linkages between thephysical environment and krill productivity.• Analysis and publication of BROKE-Westresults.Antarctic Climate & Ecosystems CRC - Annual Report 2005-06 37