Meeting Abstract

P1.171  Friday, Jan. 4  Identifying markers of preparation for dormancy and the terminal molt in Calanus finmarchicus BAUMGARTNER, MF; TARRANT, AM*; LYSIAK, NSJ; HANSEN, BH; ARUDA, AM; ALTIN, D; NORDTUG, T; OLSEN, AJ; Woods Hole Oceanographic Institution; Woods Hole Oceanographic Institution; Woods Hole Oceanographic Institution; SINTEF, Trondheim Norway; Woods Hole Oceanographic Institution; BioTrix, Trondheim Norway; SINTEF, Trondheim Norway; Norwegian Univ. Science and Tech., Trondheim Norway atarrant@whoi.edu

Calanus finmarchicus is an oceanic calanoid copepod that can enter dormancy during the last juvenile stage (fifth copepodid, C5) of development. In many locations, a portion of the population enters dormancy, while the remainder skips dormancy and molts into adults. Regulation of Calanus dormancy is poorly understood, and dormancy cannot be initiated reliably in the laboratory. To gain insight into Calanus dormancy, we sampled C5 copepodids from Trondheim Fjord, Norway every other day from May 1 to June 11, 2012. Unlike many heterogeneous oceanic populations, most individuals from this high-latitude fjord population are predicted to enter dormancy with relative synchronicity. As expected, we primarily observed early-stage individuals (C2-C4) during early May and C4-C5 individuals during June. The C5 copepodids were overwhelmingly in pre-apolysis molt phases, consistent with animals preparing for dormancy rather than proceeding directly toward the terminal molt and adulthood. We are using Illumina-based transcriptional profiling to compare gene expression patterns between early- and late-developing C5 copepodids with the goal of identifying a molecular signature of preparation for dormancy. We also collected laboratory-reared copepods on the day of molting from the C4 to the C5 stage. We sampled these animals daily throughout the C5 stage and monitored their within-stage molt phase, gonad maturation, and oil sac size. Transcriptional profiling is also being conducted on these cultured animals to identify genes that are diagnostic of progression toward the terminal molt and adulthood.