Flash Interactive
Produced by the American Museum of Natural History, November 13, 2006.
Visual: Satellite image of the world.
Dead zones are low-oxygen waters that affect marine life. Their numbers are increasing. In these locations, growing cities and farms add nutrients—sewage, pollution, and fertilizer—to the water.
Visual: Close-up satellite image of the Baltic Sea. The swirling green strokes of a phytoplankton bloom are visible on the seaís surface.
In the Baltic Sea, added nutrients and loss of wetlands feed blooms of phytoplankton. Bacteria decomposing the phytoplankton consume oxygen in the water, leaving little for marine life. While no dead zone matches the size and duration of the Balticís, some are growing and lasting longer.