Effects of climate variability on Calanus dormancy patterns and population dynamics in the Northwest Atlantic

J.A. Runge, A. Leising, and C. Johnson

Demographic time series from four fixed stations in the northwest Atlantic Ocean show variable timing of entry into and emergence from dormancy in subpopulations of the planktonic copepod, Calanus finmarchicus. Among hypotheses put forward to explain dormancy in Calanus species, we cannot eliminate the lipid accumulation window hypothesis for onset of dormancy or a lipid-modulated endogenous timer controlling dormancy duration. The fundamental premise of these hypotheses is that individuals can only enter dormancy if their food and temperature history allows them to accumulate sufficient lipid to endure overwintering, molt and undergo early stages of gonad maturation. We have incorporated this concept into a 1-D Calanus life cycle IBM model. The model reproduces the climatological demography of C. finmarchicus data from the Gulf of St Lawernce, C. pacificus data from the San Diego trough and C. marshallae data from the coastal Oregon upwelling zone.

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