Notes
Slide Show
Outline
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Development of the Lipid Accumulation Window hypothesis to explain Calanus finmarchicus dormancy
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Data Sources and Collaborators
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Proxies for dormancy entry and exit
  • Entry  (Onset)
    Fifth copepodid (CV) half-max proxy
      Dormant when…
      CV proportion ≥ `x  / 2
      where     `x = average max. CV
    proportion over all years
  • Exit  (Emergence)
    Emergence when…
     1. Adult (CVI) proportion ≥ 0.1
  •       2. Back-calculation from early copepodid appearance, using development time-temperature relationship
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AG: Anticosti Gyre, NW Gulf of St. Lawrence
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Possible dormancy cues
  • Onset
  • Photoperiod
    (Miller et al., 1991)
  • Temperature
    (Niehoff & Hirche, 2005)
  • Food availability
    (Hind et al., 2000)
  • Lipid accumulation (hormonal link?)
    (Irigoien, 2004)
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Climatological temperature at 5 m
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Mean chlorophyll-a, 0 – 50 m
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Analysis of variance
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Conclusions
  • No single observed environmental cue explains dormancy patterns
  • Dormancy entry and emergence occur over a broad range of times, both among individuals and years
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Lipid accumulation window hypothesis:
Step 1:Decision to enter dormancy in stage CV is made in stage CIV.  Criterion is attainment of 30% lipid content by wt.
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Lipid accumulation window hypothesis:
Step 2 - Temporal Filter
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Lipid accumulation window hypothesis:
Step 2 - Temporal Filter
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Lipid accumulation window hypothesis:
Step 3 - Emergence Timing linked to Entry
Emergence survival linked to entry and Env.
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AG
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Anticosti Gyre climatology
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Next Steps
  • Work on parameters for model for C. finmarchicus; development of general set for all of NW Atlantic
  • Test LAW model against C. finmarchicus life cycle data sets in the NW Atlantic. Does the model reproduce variability in individual years?
  • Test refined and alternative hypotheses- Additional conditions required?
  • Examine mechanisms for emergence from dormancy: parameterization of Saumweber and Durbin functions for potential diapause duration
  • Examine influence of climate change scenarios on Calanus life cycle and population dynamics
  • Further testing with time series observations, include measures of lipid levels in CIV and CV