Ecophysiological aspects of iron nutrition and domoic acid production in oceanic and coastal diatoms of the genus Pseudo-nitzschia ...

• Main Author: Marchetti, Adrian
• Format: Text
• Language: English
• Published: University of British Columbia 2009
• Subjects: Pacific; Subarctic
• Online Access: https://dx.doi.org/10.14288/1.0092292; https://doi.library.ubc.ca/10.14288/1.0092292

In vast regions of the world's oceans, phytoplankton, in particular diatoms, are growth-limited by low concentrations of the micronutrient, iron. SERIES (Subarctic Ecosystem Response to Iron Enrichment Study) was performed near Ocean Station Papa (144.45°W, 50.20°N) to determine the phytoplankton response to iron enrichment in high nutrient, low chlorophyll (HNLC) waters of the NE subarctic Pacific. Chlorophyll a (chl a) increased 21 times from 0.3 mg m⁻³ to a peak of 6.3 mg m⁻³18 days after the initial addition of iron. Over the duration of the iron-induced phytoplankton bloom, all macronutrient concentrations were drawn down with silicic acid (Si(OH)4) being depleted to low and possibly diatom growth-limiting concentrations due to a >2 Si(OH)₄ : 1 nitrate (NO₃) drawdown ratio in the later stages of the bloom. Microplankton (>20 μm), which initially accounted for 25% of the phytoplankton biomass and increased by a factor of 60 after iron addition, consisted primarily of the pennate diatom genera ...