Editing Antarctic Circumpolar Current (section)

== Phytoplankton ==
[[File:S2004341153052.L2 HCHL.MalvinasCurrent.jpg|thumb|The [[Falkland Current]] transports nutrient-rich cold waters from the ACC north toward the [[Brazil–Malvinas Confluence]]. Phytoplankton chlorophyll concentration are shown in blue (lower concentrations) and yellow (higher concentrations).]]
Antarctic sea ice cycles seasonally, in February–March the amount of sea ice is lowest, and in August–September the sea ice is at its greatest extent.<ref>{{Harvnb|Geerts|1998}}</ref> Ice levels have been monitored by satellite since 1973. Upwelling of deep water under the sea ice brings substantial amounts of nutrients. As the ice melts, the melt water provides stability and the critical depth is well below the mixing depth, which allows for a positive net [[primary production]].<ref name="Miller-2004">{{Harvnb|Miller|2004|p=219}}</ref> As the sea ice recedes epontic algae dominate the first phase of the bloom, and a strong bloom dominate by diatoms follows the ice melt south.<ref name="Miller-2004" />

Another phytoplankton bloom occurs more to the north near the [[Antarctic Convergence]], here nutrients are present from [[thermohaline circulation]]. Phytoplankton blooms are dominated by diatoms and grazed by copepods in the open ocean, and by krill closer to the continent. Diatom production continues through the summer, and populations of krill are sustained, bringing large numbers of [[cetacean]]s, [[cephalopod]]s, seals, birds, and fish to the area.<ref name="Miller-2004" />

Phytoplankton blooms are believed to be limited by irradiance in the austral (southern hemisphere) spring, and by biologically available iron in the summer.<ref>{{Harvnb|Peloquin|Smith|2007}}</ref> Much of the biology in the area occurs along the major fronts of the current, the Subtropical, Subantarctic, and the Antarctic Polar fronts, these are areas associated with well defined temperature changes.<ref>{{cite web |url=http://disc.sci.gsfc.nasa.gov/education-and-outreach/additional/science-focus/locus/tutorials/module6.shtml |title=The Southern Ocean |publisher=GES DISC: Goddard Earth Sciences, Data & Information Services Center |date=May 2012 |access-date=13 August 2012 |archive-url=https://web.archive.org/web/20150518090656/http://disc.sci.gsfc.nasa.gov/education-and-outreach/additional/science-focus/locus/tutorials/module6.shtml |archive-date=18 May 2015  }}</ref> Size and distribution of phytoplankton are also related to fronts. Microphytoplankton (>20&nbsp;μm) are found at fronts and at sea ice boundaries, while [[nanophytoplankton]] (<20&nbsp;μm) are found between fronts.<ref name="Knox-2007">{{Harvnb|Knox|2007|p=23}}</ref>

Studies of phytoplankton stocks in the southern sea have shown that the Antarctic Circumpolar Current is dominated by diatoms, while the [[Weddell Sea]] has abundant [[coccolithophorid]]s and silicoflagellates. Surveys of the SW Indian Ocean have shown phytoplankton group variation based on their location relative to the Polar Front, with [[diatom]]s dominating South of the front, and dinoflagellates and [[flagellates]] in higher populations North of the front.<ref name="Knox-2007" />

Some research has been conducted on Antarctic phytoplankton as a [[carbon sink]]. Areas of open water left from ice melt are good areas for phytoplankton blooms. The phytoplankton takes carbon from the atmosphere during photosynthesis. As the blooms die and sink, the carbon can be stored in sediments for thousands of years. This natural carbon sink is estimated to remove 3.5&nbsp;million tonnes from the ocean each year. 3.5&nbsp;million tonnes of carbon taken from the ocean and atmosphere is equivalent to 12.8&nbsp;million tonnes of carbon dioxide.<ref>{{Harvnb|Peck|Barnes|Cook|Fleming|2010}}</ref>