Browsing by Author "Stammerjohn, Sharon E."

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The Impact of a Large-Scale Climate Event on Antarctic Ecosystem Processes
(2016-10) Fountain, Andrew G.; Saba, Grace; Adams, Byron; Doran, Peter T.; Fraser, William; Gooseff, Michael N.; Obryk, Maciej K.; Priscu, John C.; Stammerjohn, Sharon E.; Virginia, Ross A.
Extreme climate and weather events, such as a drought, hurricanes, or ice storms, can strongly imprint ecosystem processing and may alter ecosystem structure. Ecosystems in extreme environments are particularly vulnerable because of their adaptation to severe limitations in energy, water, or nutrients. The vulnerability can be expressed as a relatively long-lasting ecosystem response to a small or brief change in environmental conditions. Such an event occurred in Antarctica and affected two vastly different ecosystems: a marine-dominated coastal system and a terrestrial polar desert. Both sites experienced winds that warmed air temperatures above the 0 degrees C threshold, resulting in extensive snow and ice melt and triggering a series of cascading effects through the ecosystems that are continuing to play out more than a decade later. This highlights the sensitivity of Antarctic ecosystems to warming events, which should occur more frequently in the future with global climate warming.
Responses of Antarctic Marine and Freshwater Ecosystems to Changing Ice Conditions
(2016-10) Obryk, Maciej K.; Doran, Peter T.; Friedlaender, Ari S.; Gooseff, Michael N.; Morgan-Kiss, Rachael M.; Priscu, John C.; Schofield, Oscar; Stammerjohn, Sharon E.; Steinberg, Deborah K.; Ducklow, Hugh W.
Polar regions are warming more rapidly than lower latitudes, and climate models predict that this trend will continue into the coming decades. Despite these observations and predictions, relatively little is known about how polar ecosystems have responded and will continue to respond to this change. Two Long-Term Ecological Research (LTER) sites, located in contrasting environments in Antarctica, have been studying marine and aquatic terrestrial ecosystems for more than two decades. We use data from these research areas to show that the extent and thickness of ice covers are highly sensitive to short- and long-term climate variation and that this variation significantly influences ecosystem processes in these respective environments. Declining sea-ice extent and duration diminishes phytoplankton blooms as a consequence of reduced water stratification, whereas the thinning of lake-ice cover enhances phytoplankton blooms because of increased penetrating light into the water column. Both responses have cascading effects on upper trophic levels.