Regulation of Algal Blooms in Antarctic Shelf Waters by the Release of Iron From Melting Sea Ice

• Published in: Geophysical Research Letters
• Main Authors: Sedwick, Peter N., DiTullio, Giacomo R.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: ODU Digital Commons 1997
• Subjects: Iron; Ross Sea; Algal bloom; Diatom; Sea ice; Phytoplankton; Ice-edge blooms; Antarctic; Manganese; Biogeochemistry; Marine Biology; Oceanography; Antarc*
• Online Access: https://digitalcommons.odu.edu/oeas_fac_pubs/93; https://doi.org/10.1029/97GL02596; https://digitalcommons.odu.edu/context/oeas_fac_pubs/article/1102/viewcontent/Sedwick_1997_Regulation_of_algal_blooms_in_Ant.pdf

During summer 1995-96, we measured iron in the water column and conducted iron-enrichment bottle-incubation experiments at a station in the central Ross Sea (76°30'S, 170°40'W), first, in the presence of melting sea ice, and 17 days later, in ice-free conditions. We observed a striking temporal change in mixed-layer dissolved iron concentrations at this station, from 0.72-2.3 nM with sea ice present, to 0.16-0.17 nM in ice-free conditions. These changes were accompanied doubling of algal (diatom) biomass. Our incubation experiments suggest that conditions were iron-replete in the presence of sea ice, and iron-deficient in the absence of sea ice. We surmise that bioavailability iron was released into seawater from the melting sea ice, stimulating phytoplankton production and the biological removal of dissolved iron from the mixed layer, until iron-limited conditions developed. These observations suggest that the episodic release of bio-available iron from melting sea ice is an important factor regulating phytoplankton production, particularly ice-edge blooms, in seasonally ice-covered Antarctic waters.