Present address: Metropolitan Water District of Southern California, 700 Moreno Avenue, La Verne, California 91750, USA.
MASS SEXUAL REPRODUCTION IN THE TOXIGENIC DIATOMS PSEUDO-NITZSCHIA AUSTRALIS AND P. PUNGENS (BACILLARIOPHYCEAE) ON THE WASHINGTON COAST, USA1
Version of Record online: 28 DEC 2009
© 2009 Phycological Society of America
Journal of Phycology
Volume 46, Issue 1, pages 41–52, February 2010
How to Cite
Holtermann, K. E., Bates, S. S., Trainer, V. L., Odell, A. and Virginia Armbrust, E. (2010), MASS SEXUAL REPRODUCTION IN THE TOXIGENIC DIATOMS PSEUDO-NITZSCHIA AUSTRALIS AND P. PUNGENS (BACILLARIOPHYCEAE) ON THE WASHINGTON COAST, USA. Journal of Phycology, 46: 41–52. doi: 10.1111/j.1529-8817.2009.00792.x
Received 30 September 2008. Accepted 21 August 2009.
- Issue online: 20 JAN 2010
- Version of Record online: 28 DEC 2009
- domoic acid;
- P. australis;
- P. pungens;
- sexual reproduction;
- Washington State
Sexual reproduction is documented for the first time in field populations of the pennate diatoms Pseudo-nitzschia australis Freng. and P. pungens (Grunow ex Cleve) Hasle (var. cingulata Villac and hybrids between var. cingulata and var. pungens). A bloom dominated by these species began on June 26, 2006, along Kalaloch Beach, Washington, USA, coincident with a drop in the Si(OH)4:NO3 ratio to below two. Multimodal size distributions were detected for both species, and synchronous auxosporulation occurred within the smallest size class during a 3-week window. Auxospores and initial cells created a new class of large cells, and cells in the intermediate size classes increased in abundance during auxosporulation. Mating cells of both species were attached to colonies of surf-zone diatoms. Paired gametangia, gametes, zygotes, auxospores, and large initial cells were found. Auxosporulation began first for P. pungens (June 30), apparently once a critical, high cell concentration was reached, followed by P. australis (July 5), when the total Pseudo-nitzschia cell concentration reached 929,000 cells · L−1. Low frequencies of auxosporulation occurred throughout the bloom but increased 4-fold for P. australis and 3-fold for P. pungens when macronutrients were reduced to low levels on July 11. A 2-year life cycle was estimated for P. australis and 3 years for P. pungens, both with annual auxosporulation. Domoic acid (DA) in razor clams reached a maximum of 38 μg DA · g−1 on July 18. A significant relationship existed between the percent of cells within the new size range and DA concentrations in razor clams on the same beach.