Rumsey, S. Scripps Institution of Oceanography, srumsey@ucsd.edu

 
VARIABILITY IN LARVAL DEVELOPMENT AND LARVAL STAGE-STRUCTURE OF EUPHAUSIA PACIFICA IN THE SOUTHERN CALIFORNIA BIGHT
 
Recruitment of Euphausia pacifica exhibits considerable intra/interannual variability. The extent to which this variability is driven by heterogeneity in the developmental regime of larvae has yet to be established. Life-history modelling suggests that developmental variability during the egg, and furcilia I-II stages is crucial in determining overall larval survivorship. These results highlight the importance of the timing/location of egg release in determining egg viability and subsequent recruitment. Indirect developmental pathways during the furcilia I-II stages may also be associated with diminished recruitment success. E. pacifica was sampled in the Southern California Bight to assess the predictions of the models. MOCNESS and CTD-fluorometer transects were taken across persistent SST fronts identified from AVHRR data. Samples show that spawning was restricted in depth relative to the distribution of females, suggesting the vertical location of egg release was in response to specific physical-biological cues. Differences in furcilia I-II developmental pathways among stations were also noted. The association of such developmental variability and larval stage-structure with in situ physical-biological conditions is discussed. Models hindcasted time-series of egg input and stage-specific mortality. The results of these models provide a context for evaluating environmental heterogeneity in forcing the observed variability in larval development and stage-structure.
 
Day: Thursday, Feb. 4
Time: 12:15 - 12:30pm
Location: Hilton of Santa Fe
 
Code: SS04TH1215H