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)

Mean chlorophyll-a, 0 – 50 m

Analysis of variance

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 11

Slide 12

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.

Slide 14

Lipid accumulation window hypothesis:
Step 2 - Temporal Filter

Lipid accumulation window hypothesis:
Step 3 - Emergence Timing linked to Entry
Emergence survival linked to entry and Env.

Anticosti Gyre climatology

Slide 20

Slide 21

Slide 22

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


	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


	Onset
	Photoperiod (Miller et al., 1991)
	Temperature (Niehoff & Hirche, 2005)
	Food availability (Hind et al., 2000)
	Lipid accumulation (hormonal link?) (Irigoien, 2004)


	No single observed environmental cue explains dormancy patterns
	Dormancy entry and emergence occur over a broad range of times, both among individuals and years


	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