|The Dead Sea has such a high saline content |
that pillars of salt form near its banks.
Lying on the border of Israel and Jordan, the Dead Sea is a one of the best-known examples of a hypersaline lake. With a salinity of 33.7 percent, it is more than ten times saltier that the ocean. And at 377 meters deep, it’s also the world’s deepest hypersaline lake.
The Jordan River used to feed fresh water into the Dead Sea, but in the 1950s it was diverted to supply drinking water to Israel and Jordan instead. This lowered the lake’s water level, and it continues to drop more each year. Water levels have fallen by more than 25 meters over the last 40 years. Since the basin has no outlet, water only escapes by evaporation, leaving behind salt and other minerals. Over time, this made the Dead Sea much saltier than ocean water.
Fish can’t survive in the Dead Sea, but it’s not totally lifeless. Extremophiles—organisms adapted to live in extreme conditions such as high temperature or salinity—do live in the Dead Sea. Salt-loving microbes known as halophiles can survive and thrive in the lake.
In 2010, researchers from Ben-Gurion University found several giant craters at depths of 30 meters spewing fresh water and brimming with bacteria at the bottom of the otherwise barren lake. The craters were covered with thick layers of a new microbial species that live near fresh water plumes that shoot from underwater springs.
Reaching the springs is a bit of a challenge. Divers carry about 40 kg of weight to lower their buoyancy enough to sink, since the salty water is so dense it makes you float. They also must wear full face masks to protect their eyes and mouths. Getting Dead Sea water in your eyes could cause blindness and swallowing it would cause choking and possibly suffocation.
The bacteria they found were similar to what you’d find living in a regular saltwater ocean. These bacteria use both sunlight and sulfides to survive. Not only have the organisms evolved in such a harsh environment, the bacteria can cope with sudden changes in salinity as fresh water and saltwater currents swirl around the springs.
Normally, highly salt-adapted bacteria die when placed in fresh water, and fresh water bacteria die when they come in contact with salt water. Researchers claim that being able to live in both environments is something very unexpected and deserves further study.