The evolution and termination of an iron-induced mesoscale bloom in the northeast subarctic

• Main Authors: Philip W. Boyd, Robert Strzepek, Shigenobu Takeda, George Jackson, C. S. Wong, R. Mike Mckay, Cliff Law, Hiroaki Saito, Nelson Sherry, Keith Johnson, Jim Gower, Neelam Ramaiah
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: We also tha; Pacific; Subarctic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.494.3445; http://www.aslo.org/lo/toc/vol_50/issue_6/1872.pdf

We initiated and mapped a diatom bloom in the northeast subarctic Pacific by concurrently adding dissolved iron and the tracer sulfur hexafluoride to a mesoscale patch of high-nitrate, low-chlorophyll waters. The bloom was dominated by pennate diatoms and was monitored for 25 d, which was sufficiently long to observe the evolution and termination of the bloom and most of the decline phase. Fast repetition–rate fluorometry indicated that the diatoms were iron-replete until day 12, followed by a 4–5-d transition to iron limitation. This transition period was characterized by relatively high rates of algal growth and nutrient uptake, which pointed to diatoms using intracel-lularly stored iron. By days 16–17, the bloom was probably limited simultaneously by both iron and silicic acid Acknowledgements