Hiltz, M. Mount Allison University, hiltzm@is2.dal.ca
Bates, S. S. Fisheries and Oceans Canada, BatesS@mar.dfo-mpo.gc.ca
Kaczmarska, I. Mount Allison University, iehrman@mta.ca

 
EFFECT OF PHOTOPERIOD ON THE SEXUAL REPRODUCTION OF THE PENNATE DIATOM PSEUDO-NITZSCHIA MULTISERIES
 
"Male" and "female" cells from each of two sets of Pseudo-nitzschia multiseries clones (an ontogeneticaly older short-celled and a younger long-celled clone) were individually mixed and grown under different photoperiod regimes (4, 10, 16 hours of light). Vegetative and sexual cells were counted for at last four consequtive days to estimate the relative abundance of gametes, zygotes, auxospores and initial cells. Cell size, which reflects population age, influences sexualization. The short-celled clones had a lower maximum preponderance of gametes (2%) than the long-celled clones (25%), suggesting that the former were nearing the minimal cell length capable of sexualization. A positive correlation was found between photoperiod length and gamete production of the long-celled clones; 58% of variance in gamete production was attributed to photoperiod. Greatest production of auxospores per gamete (92%) occurred in 16 hours of light, while the highest proportion of initial cells (27%) occurred in 10 hours of light, suggesting that the latter photoperiod may be most conducive to sexual reproduction in nature. Our results provide insight into the timing and magnitude of auxosporulation of P. multiseries and the toxicity of cells in the field.
 
Day: Thursday, Feb. 4
Time:
Location: Sweeney Center
 
Code: SS42TH0718S