Could the biggest movers be the biggest losers – clues from ecosystem modelling of whale-krill interactions

Vivitskaia  J.    D.    Tulloch (1,2),    Éva    E.    Plagányi    (2),    Christopher    Brown (3),    Richard    Matear (4),    Anthony    Richardson (2),    Hugh    P.    Possingham (1)


1    ARC Centre of Excellence in Environmental  Decisions, University of Queensland, St Lucia, Brisbane, Queensland, 4072

2    CSIRO Oceans and Atmosphere Flagship, Queensland BioSciences Precinct (QBP), St Lucia, Brisbane, Queensland, 4072

3    Australian Rivers Institute, Griffith University, Nathan, Queensland, Australia

4  CSIRO Oceans and Atmosphere Flagship, GPO Box 1538, Hobart, Tasmania 7004

Reliable       predictions       of       climate       change       impacts       on      harvested      marine       species       such      as       krill       and       their    dependent       predators     are     crucial     for     effective     ecosystem-­‐based     fisheries     management.     In     the     Southern    Hemisphere,       altered     productivity     regimes     are     expected     due     to     climate-­‐induced       changes     in     the     oceans.    Highly         migratory       baleen       whales       may       be       particularly       susceptible       to       these       changes,       due      to       the      close    synchrony     between   their   life   history   and   water   temperature,   and   productivity.   There   is     currently   limited    understanding     of   the   complex   trophic   interactions   between     these   species,   and     their   responses   to     changes    in      the    marine    environment.     We    developed    a    focused    forage    fish    ‘Model    of     Intermediate    Complexity    for    Ecosystem        Assessments’      (MICE)      for      phytoplankton,      krill      and      five      baleen      whales      (Blue,      Fin,      Humpback,    Minke,     Right   whales),   including   predator-­‐prey     feeding   interactions.   We   fitted   the   model   to   available   catch    and       survey     data,     and     account     for     key     uncertainties     to     increase     robustness.     We     included     environmental    forcing    using    outputs    of    existing    global    climate    models    to     predict  primary-­‐productivity    shifts    under    climate    change    for    the    southern    hemisphere,    and    used    the    predicted    patterns    to    evaluate    how    krill    perform    under    alternate      oceanographic       conditions.       We      found       spatial       and       temporal       variability       in       productivity-­‐driven    changes      in      krill      across     the      southern      oceans,      with      consequences      for      future      fisheries      management.      By    modeling      interactions    between    whales    and    changes    in    their     prey,    we    found     differences    between     whale    species      in       bottom-­‐up      forcing       of       spatial       distribution      and      abundance.       With       many       of       the       large       whale    populations        severely      impacted      by      historic      whaling,      this      improved      understanding      of      their      response      to    changes    in    their    prey    from    multiple    could    have    important    implications    for    conservation.

Species on the Move

An International Conference Series

The conference brings together scientists and natural resource managers working in the disciplines of global change, biogeography and evolution, and relevant in contexts of natural resource management, biodiversity management and conservation, and theoretical ecology.

Species responses to climate change is a rapidly evolving research field, however, much of our progress is being made in independent research areas: e.g. understanding the process vs responding to the implications, terrestrial vs marine ecosystems, global meta-analyses vs in depth species-specific approaches. This interdisciplinary conference develops connections between these parallel streams, and across temporal and spatial scales.

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