Jellyfish Lake is a small lake, the highlight of the Rocky Islands archipelago in Palau. At first glance, it is the most ordinary lake, but as soon as you go under water, a person enters another world, a world of royal calm, peace, one gets the impression that nature is meditating here.
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| Jellyfish Lake Palau |
Jellyfish Lake is located in the eastern part of the island of Eil Malk. This is a relatively small lake, the size of which is 460 by 160 meters. The water in the reservoir is brackish, which is quite natural, because the lake is separated from the ocean by a small strip of land, only 200 meters. The depth of the lake is 50 meters, but this turned out to be quite enough for a stunning world to form in it, which attracts divers from all over the world - the kingdom of jellyfish.
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| Jellyfish Lake Palau |
The uniqueness of the lake
More than 15 thousand years ago, as a result of tectonic shifts, coral reefs began to gradually rise from the bottom, forming bizarre coral labyrinths above the surface of the water. At the same time, a large rock collapsed, boulders of which fell into the water, cutting off part of the ocean. Thus, more than 70 small lakes were formed, separated by small areas of land. Several jellyfish ended up in these new reservoirs. Since the jellyfish had no enemies in them, their number grew; in the process of evolution, the inhabitants of these waters lost their stinging cells and became absolutely harmless. This fact attracts a huge number of tourists who want to "talk" with jellyfish at depth.
It is believed that the total number of jellyfish living in this unusual lake reaches two million individuals. The number of jellyfish is so large that their mass can be easily seen, even while on an airplane. However, only two species of jellyfish live in this lake - these are golden (Mastigias papua) and moon (Aurelia sp.) jellyfish. The golden jellyfish has a huge numerical superiority over the lunar one. There are other differences in the body structure of golden jellyfish, due to which some biologists propose to separate these jellyfish into a separate subspecies. The golden jellyfish is a transparent gelatinous body with a golden hue, along the edges of which are small tentacles.
These jellyfish do not reach large sizes. Their maximum size is equal to a soccer ball, and their minimum size is a cherry.
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| Jellyfish Lake Palau |
The water in Jellyfish Lake is divided into two layers: the upper layer and the lower one. The upper layer of water contains much more oxygen than the lower one and at a depth of 15 meters the air content is practically zero, and the most interesting thing is that the upper layer of water never mixes with the lower one. A small influx of fresh water is provided to the upper layer of water through the tunnels connecting the lake to the ocean. The water of the lower layer is saturated with hydrogen sulfide, phosphates and ammonia, in which only a few types of bacteria can survive. For divers, it is undesirable to be in the lower layer, because if you do not have a special underwater wetsuit, you can get very serious poisoning through the skin.
Since jellyfish need oxygen, they try to live in the upper layer of water, but this does not prevent them from making frequent migrations every day, both horizontally and vertically, often descending to the border of the anoxic water layer. It can be said with confidence that the migrations of golden jellyfish are carried out with a special organization and rhythm. Jellyfish all night and until lunch, rise and fall in the upper layer of water to absorb nutrients from it. When morning comes, they move from the western part of the lake to its eastern part, and in the afternoon they again gather in the western side of the lake. Swimming near the surface of the water, jellyfish rotate counterclockwise, which provides excellent lighting to the symbiotic algae living in their body, and the algae, through photosynthesis, convert the sun's energy into sugar,
Moon jellyfish move in the same way as golden jellyfish, but not as organized, although it can be said that their pulsation across the lake is also massive. At night, moon jellyfish catch copepods that are near the surface of the water, which make up most of their diet in the lake.
Some biologists suggest that the migration of jellyfish between the eastern and western parts of the lake is associated with Entacmaea medusivora, which feed on jellyfish. These anemones live near the eastern shore of the lake. Jellyfish tend to avoid shade and stay in the light. By following the most illuminated area, they are better able to avoid encounters with sea anemones that are dangerous to them.
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| Jellyfish Lake Palau |
In 1998, Jellyfish Lake almost completely lost its main inhabitants - golden jellyfish. By December 1998, their numbers in the lake had dropped to almost zero. It is believed that such a sharp decrease in the population was due to the impact of a powerful phase of the El Niño phenomenon, during which huge masses of warm water are redistributed near the surface layer of the ocean.
As a result of El Niño, the temperature of the water in the lake increased greatly, which killed the symbiotic algae, without which the jellyfish cannot survive. In 1999, not a single golden jellyfish could be found in the lake, but in January 2000 they began to appear again, and today their numbers have fully recovered.
Tourists
Picturesque clusters of jellyfish attract a lot of tourists and diving enthusiasts to the lake. It is quite safe to swim among lake jellyfish, as they have almost completely lost their ability to "bite". But still, people with sensitive skin or those suffering from allergies are advised to use protective suits when diving. Diving in the jellyfish lake is allowed only with a mask and snorkel, and scuba diving is prohibited.
Scuba diving is prohibited for two reasons: firstly, air bubbles from scuba gear get under the dome of jellyfish, which can cause them to die; secondly, scuba gear allows a person to dive to a depth of more than 15 meters, where an anoxic layer is located.
Mass immersion in the lower layer of the lake will necessarily cause mixing of the upper and lower layers of water (which never happens in natural conditions), and the entire ecosystem of the lake will be irrevocably damaged, which is fraught with death for all its inhabitants. In addition, a careless diver himself can get fatal poisoning through the skin, being in the lower layer of water saturated with hydrogen sulfide and ammonia.
Of all the inhabitants of the lake, only combed crocodiles can pose a real danger to tourists. But they themselves prefer to stay away from people, and only one fatal attack has been recorded in all the time.