Figure 1.
Krill Abundance Has Dropped 80% in 30 Years
(A) This gravid female is nearly ready to release her eggs.
(B) Krill feed on phytoplankton, indicated by the green color in this specimen's digestive organ.
(Images: Langdon Quetin and Robin Ross, researchers at the Marine Science Institute, University of California, Santa Barbara, and funded by the Office of Polar Programs, National Science Foundation)
Figure 2.
Antarctic Penguins Show Striking Contrasts in Their Relationship to the Sea Ice
(A) Ice-dependent Adélie penguins, at their nesting grounds on Anvers Island, have lost 10,000 breeding pairs since 1975.
(B) Ice-avoiding chinstrap penguins at Anvers Island are increasing in number and range.
(C) Breeding gentoo penguins—an ice-avoiding species that has not inhabited Anvers Island sites for at least 800 years—are turning up at Palmer Station.
(Images: Donna Fraser)
Figure 3.
In 1996, oceanographers Warren White and Ray Peterson identified significant inter-annual variations in the atmospheric pressure at sea level, wind stress, sea surface temperature, and sea-ice extent over the Southern Ocean. They called this system of coupled anomalies the Antarctic Circumpolar Wave. This simplified schematic summarizes the inter-annual variations in sea surface temperature (red, warm; and blue, cold), atmospheric sea-level pressure (bold H and L), meridional wind stress (denoted by τ), and sea ice extent (gray lines), together with the mean course of the Antarctic Circumpolar Current (green). Heavy black arrows depict the general eastward motion of anomalies, while other arrows indicate communications between the circumpolar current and the more northerly subtropical gyres. (Image: Warren White, http://jedac.ucsd.edu/ACW/index_research.html)