Clear Lake (Palau)
Encyclopedia
Clear Lake is a marine lake located on Eil Malk
island in Palau
. Eil Malk (also Mecherchar) is part of the Rock Islands, a group of small, rocky, mostly uninhabited islands in Palau's Southern Lagoon, between Koror and Peleliu. There are about 70 other marine lakes located throughout the Rock Islands. Clear Lake is notable for endemic subspecies of golden jellyfish and is one of five marine lakes in Palau used for several scientific researches in evolutionary biology the other lakes being Jellyfish Lake
, Goby Lake
, Uet era Ngermeuangel
, Uet era Ongael
.
reef. However the lake is sufficiently isolated and the conditions are different enough that the diversity of species in the lake is greatly reduced from the nearby lagoon. The golden jellyfish Mastigias cf. papua salii and possibly other species in the lake have evolved to be substantially different from their close relatives living in the nearby lagoons.
into two layers, an oxygenated upper layer (mixolimnion) and a lower anoxic layer (monimolimnion). The oxygen concentration in the lake declines from about 6 mg/l at the surface to zero at 16 meters (at the chemocline
) . Stratification is persistent and seasonal mixing does not occur. The lake is one of about 200 saline meromictic
lakes that have been identified in the world. However most of these lakes are of freshwater origin. Permanently stratified marine lakes are unusual, but on Eil Malk and on other nearby islands there are eleven other permanently stratified marine lakes, the most renowned one is Jellyfish Lake
.
Eil Malk
Eil Malk or Mecherchar is the main island of the Mecherchar Islands, an island group of Palau in the Pacific Ocean. In a more narrow sense, just the southeastern peninsula of Mecherchar is called Eil Malk...
island in Palau
Palau
Palau , officially the Republic of Palau , is an island nation in the Pacific Ocean, east of the Philippines and south of Tokyo. In 1978, after three decades as being part of the United Nations trusteeship, Palau chose independence instead of becoming part of the Federated States of Micronesia, a...
. Eil Malk (also Mecherchar) is part of the Rock Islands, a group of small, rocky, mostly uninhabited islands in Palau's Southern Lagoon, between Koror and Peleliu. There are about 70 other marine lakes located throughout the Rock Islands. Clear Lake is notable for endemic subspecies of golden jellyfish and is one of five marine lakes in Palau used for several scientific researches in evolutionary biology the other lakes being Jellyfish Lake
Jellyfish Lake
Jellyfish Lake is a marine lake located on Eil Malk island in Palau. Eil Malk is part of the Rock Islands, a group of small, rocky, mostly uninhabited islands in Palau's Southern Lagoon, between Koror and Peleliu. There are about 70 other marine lakes located throughout the Rock Islands. Jellyfish...
, Goby Lake
Goby Lake
Goby Lake is a marine lake located on Koror island in Palau. There are about 70 other marine lakes located throughout the Rock Islands and Koror...
, Uet era Ngermeuangel
Uet era Ngermeuangel
Uet era Ngermeuangel is a marine lake located on Koror island in Palau. There are about 70 other marine lakes located throughout the Rock Islands and Koror...
, Uet era Ongael
Uet era Ongael
Uet era Ongael is a marine lake located on Ongael island, Koror, in Palau. There are about 70 other marine lakes located throughout the Rock Islands and Koror...
.
Golden jellyfish
Clear Lake is one of the oldest of meromictic marine lakes in Palay and is circa 15,000 - 12,000 years old. It is connected to the ocean through fissures and tunnels in the limestone of ancient MioceneMiocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
reef. However the lake is sufficiently isolated and the conditions are different enough that the diversity of species in the lake is greatly reduced from the nearby lagoon. The golden jellyfish Mastigias cf. papua salii and possibly other species in the lake have evolved to be substantially different from their close relatives living in the nearby lagoons.
Lake stratification
Clear Lake is stratifiedStratification (water)
Water stratification occurs when water masses with different properties - salinity , oxygenation , density , temperature - form layers that act as barriers to water mixing...
into two layers, an oxygenated upper layer (mixolimnion) and a lower anoxic layer (monimolimnion). The oxygen concentration in the lake declines from about 6 mg/l at the surface to zero at 16 meters (at the chemocline
Chemocline
A chemocline is a cline caused by a strong, vertical chemistry gradient within a body of water. A chemocline is analogous to a thermocline, the border at which warmer and cooler waters meet in an ocean, sea, lake, or other body of water...
) . Stratification is persistent and seasonal mixing does not occur. The lake is one of about 200 saline meromictic
Meromictic
A meromictic lake has layers of water that do not intermix. In ordinary, "holomictic" lakes, at least once each year there is a physical mixing of the surface and the deep waters...
lakes that have been identified in the world. However most of these lakes are of freshwater origin. Permanently stratified marine lakes are unusual, but on Eil Malk and on other nearby islands there are eleven other permanently stratified marine lakes, the most renowned one is Jellyfish Lake
Jellyfish Lake
Jellyfish Lake is a marine lake located on Eil Malk island in Palau. Eil Malk is part of the Rock Islands, a group of small, rocky, mostly uninhabited islands in Palau's Southern Lagoon, between Koror and Peleliu. There are about 70 other marine lakes located throughout the Rock Islands. Jellyfish...
.