ICES Journal of Marine Science: Journal du Conseil Advance Access originally published online on December 13, 2007
ICES Journal of Marine Science: Journal du Conseil 2008 65(3):339-350; doi:10.1093/icesjms/fsm171
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Characteristics of Calanus finmarchicus dormancy patterns in the Northwest Atlantic
1 Department of Fisheries and Oceans, Bedford Institute of Oceanography, PO Box 1006, Dartmouth, NS, Canada B2Y 4A2
2 NOAA, Southwest Fisheries Science Center, 1352 Lighthouse Avenue, Pacific Grove, CA 93950-2097, USA
3 School of Marine Sciences, University of Maine, and Gulf of Maine Research Institute, 350 Commercial Street, Portland, ME 04101, USA
4 Department of Fisheries and Oceans, Northwest Atlantic Fisheries Centre, PO Box 5667, St John's, NF, Canada A1C 5X1
5 Department of Fisheries and Oceans, Institut Maurice Lamontagne, 850 Route de la Mer, CP 1000, Mont-Joli, QC, Canada G5H 3Z4
6 Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, USA
Correspondence to C. L. Johnson: tel: +1 902 4260753; fax: +1 902 4269388; e-mail: JohnsonC{at}mar.dfo-mpo.gc.ca
Johnson, C. L., Leising, A. W., Runge, J. A., Head, E. J. H., Pepin, P., Plourde, S., and Durbin, E. G. 2008. Characteristics of Calanus finmarchicus dormancy patterns in the Northwest Atlantic. – ICES Journal of Marine Science, 65: 339–350.Demographic time-series from four fixed stations in the Northwest Atlantic Ocean demonstrate variable timing of entry into and emergence from dormancy in subpopulations of the planktonic copepod Calanus finmarchicus. A proxy for timing of entry was established as the date each year when the proportion of the fifth copepodid stage (CV) in the subpopulation rose to half its overall climatological maximum CV proportion at that station. The proxy for timing of emergence at each station was set as the first date when adults were more than 10% of the total abundance of copepodid stages. An alternate emergence proxy date was determined by back-calculating the spawning dates of the first early copepodid stages appearing in spring, using a stage-structured, individual-based model. No single environmental cue (photoperiod, surface temperature, or average surface-layer chlorophyll a concentration) consistently explained entry or emergence dates across all stations. 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, moult, and undergo early stages of gonad maturation.
Keywords: Atlantic zonal monitoring programme, Calanus finmarchicus, copepod population dynamics, diapause, dormancy, individual-based model, lipids
Received 7 July 2007; accepted 19 September 2007; advance access publication 13 December 2007.