Characteristics of Calanus finmarchicus dormancy patterns in the northwest Atlantic

Slide 2

Data sources

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

AG: Anticosti Gyre, NW Gulf of St. Lawrence

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)

Onset of dormancy ANOVA

Climatological temperature at 5 m

Mean chlorophyll-a, 0 – 50 m

Emergence from dormancy ANOVA

Dormancy duration is not related to deep water temperature during dormancy







Dormancy duration is inversely related to surface temperature at onset

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

Slide 13

Calanus IBM overview

Lipid accumulation window hypothesis:
Decision to enter dormancy in stage CV is made in stage CIV.  Criterion is attainment of 30% lipid content by weight

Model objective

Slide 17

Slide 18

Next Steps

	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 metabolic limitation of diapause duration (Saumweber and Durbin, 2006)
	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

Slide 20

Individual-based model