South Orkney Islands, Antarctica
Salt Water Ecosystems
Key Facts and Details About The South Orkney Islands
Signy Island is an important breeding ground for the large penguin populations of the South Orkney Islands archipelago. Rapidly warming temperatures, an associated decrease in sea ice, and shifts in the abundance of predator species are causing declines in krill, the small, shrimplike crustacean that now constitutes the bulk of the diet for Adélie and chinstrap penguins. Continued reductions in sea ice may threaten the penguins' ability to thrive in the South Orkney Islands.
- The Orcadas research station near Signy Island has recorded a warming in the average surface air temperature of about 3.6° F (2° C) since 1942—more than double the average warming the Earth has experienced during the last century.
- In response to rising temperatures, declining sea ice, and other factors, krill density in the South Orkney Islands region has declined by up to 50 percent since 1976.
- From 1987 to 2004, the number of breeding Adélie and chinstrap penguins declined by or over 47 percent and around 22 percent, respectively.
Key Impacts on Saltwater Ecosystems from Global Warming
- Forced migrations. Cold-water species are on the move, seeking cooler, deeper, or higher-latitude waters, while warm-water species are moving to places formerly too cold for their survival.
- Disease. Scientists are detecting marine diseases, such as lobster-shell disease, in waters historically thought to be too cold. There is some indication that higher ocean temperatures—between 86 and 95° Fahrenheit (30 to 35° Celsius)—promote optimal growth of several coral pathogens.
- Coral bleaching. As seawater temperatures rise above the range that corals can tolerate, they are expelling their symbiotic algae and exposing white skeletons—a process known as bleaching.
- Harm to wetlands. Coastal wetlands, salt marshes, and mangroves are highly vulnerable to inundation as sea levels rise, unless they can migrate inland unimpeded. More frequent droughts in upland and coastal areas may also reduce the flow of freshwater into these brackish ecosystems, contributing to marsh dieback and shoreline retreat. Freshwater from melting land ice and extreme rainfall—the results of global warming—dilutes salinity levels near shore, potentially disrupting the delicate balance among creatures in these productive waters.
What The Future Holds
Changes at the poles have both local and global implications. The retreat of glaciers and shrinking of the Greenland ice sheet in the Arctic, for example, is predicted to cause significant sea-level rise, changes in the salinity of our oceans, and altered feedback loops that will make the Arctic warm up even faster. Organizations like the Intergovernmental Panel on Climate Change (IPCC) and the International Arctic Science Committee play a critical role in advancing the science related to polar areas.