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

• DOI: 10.4319/lo.2005.50.6.1872
• Publication Date: 2010-07-01T22:15:58Z
• Authors: Philip W. Boyd; Robert Strzepek; Shigenobu Takeda; George Jackson; C. S. Wong; R. Mike McKay; Cliff Law; Hiroshi Kiyosawa; Hiroaki Saito; Nelson Sherry; Keith Johnson; Jim Gower; Neelam Ramaiah
• Keywords: Bloom; Silicic acid; Subarctic climate; Sedimentation; Biogenic silica

We initiated and mapped a diatom bloom in the northeast subarctic Pacific by concurrently adding dissolved iron tracer sulfur hexafluoride to mesoscale patch of high-nitrate, low-chlorophyll waters. The was dominated pennate diatoms monitored for 25 d, which sufficiently long observe evolution termination most decline phase. Fast repetition–rate fluorometry indicated that were iron-replete until day 12, followed 4–5-d transition limitation. This period characterized relatively high rates algal growth nutrient uptake, pointed using intracellularly stored iron. By days 16–17, probably limited simultaneously both silicic acid supply, because low concentrations evident. Modeling simulations, data from our study, provided an estimate critical threshold aggregation. Observed abundances during exceeded this between 13 17. Mass sedimentation aggregates recorded surface-tethered free-drifting sediment traps at 50 m depth on 21. Although controlled availability acid, we cannot rule out role likely triggered onset mass sedimentation. During evidence species succession species-specific aggregation point important links stress initiation