In the eastern part of the densely wooded island of ESA-Malki, a member of the archipelago of rocky islands (the state of Palau) is an amazing marine lake, in which he lives a lot of jellyfish. There are only two types of jellyfish are living here - the gold and the moon.
The water in Lake Jellyfish is salty and it is connected with the Pacific Ocean network of cracks and three small tunnels running through the surrounding limestone. Nevertheless, the inhabitants of the lake is completely isolated from the ocean and the living conditions in the lake are quite unlike ocean.
Therefore, the gold and the moon jellyfish that inhabit the lake, are very different from their relatives who live in the lagoon of the ocean just 200 meters away from them.
Here, in the absence of their natural predators of jellyfish multiplied to an incredible quantities. Now the lake covers an area of 0.057 square kilometers of all, and the depth of about 50 m, inhabit nearly 2 million jellyfish. The number of jellyfish is so large that their mass can be seen easily, even from the airplane. This jellyfish is almost completely lost the ability to defend themselves, because over time they have gone stinging cells. Diving enthusiasts can safely swim in the lake and watch the jellyfish, not being afraid to get a nasty burn.
Water in the Lake of the Medusa is clearly divided into two layers - top and bottom. The oxygen content in the upper layer is much larger than the bottom. At a depth of 15 meters of oxygen in the water drops to zero. The upper and lower layers of water in the lake never mix. Tunnels, which connects the lake with the ocean, the influx of small amounts of fresh water only in the upper layer of the lake.
Thus, all the jellyfish and other animals living in the lake, forced to live only in the upper water layer. In the lower anoxic layer of water can survive only a few types of bacteria. The water of the lower layer so much saturated with hydrogen sulfide, ammonia and phosphates, which represents a danger to divers, as a person, being in such a solution, can get serious poisoning directly through the skin.
In 1998, Jellyfish Lake was almost completely lost its main inhabitants - golden jellyfish. By December 1998, their numbers in the lake dropped to almost zero. It is believed that such a sharp decrease in population was associated with exposure to a strong phase of El Niño, during which there is a redistribution of huge masses of warm water from the surface layer of the ocean.
As a result of El Niño, the water temperature in the lake rose a lot, that killed a symbiotic algae, without which the jellyfish can not survive. In 1999, the lake could not find any golden jellyfish, but in January 2000, they again began to appear, and today their number has fully recovered.
Diving in Lake of jellyfish is permitted only with a mask and snorkel, and scuba use is prohibited.
kvalangi banned for two reasons: first, the air bubbles from the scuba fall under the dome of the jellyfish, why they may die, and secondly, SCUBA allows a person to dive to a depth of 15 meters, where the oxygen-free layer.
Mass dive to the bottom layer of the lake is bound to cause mixing of the upper and lower layers of water (which in the wild never happens), and all the lake's ecosystem will be irreversibly compromised, which is fraught with the death of all its inhabitants. In addition, careless divers can get myself fatal poisoning through the skin, while in the lower layer of water saturated with hydrogen sulfide and ammonia.
Of all the inhabitants of the lake a real danger to tourists may represent only grebnistye crocodiles. But they prefer to stay away from people, and all the time there were only one attack, which ended in death.