Pictures from Google.com https://www.google.com/search?q=Jellyfish+Lake,+Palau&rlz=1C1CHYD_enUS578US579&es_sm=93&tbm=isch&imgil=gItuRMOQX7Nz7M%253A%253BSJDYgwwWmycGIM%253Bhttp%25253A%25252F%25252Fwww.roughguides.com%25252Fphoto%25252Fsnorkeler-jellyfish-lake-rock-islands-palau-micronesia%25252F&source=iu&pf=m&fir=gItuRMOQX7Nz7M%253A%252CSJDYgwwWmycGIM%252C_&biw=1758&bih=810&usg=__cWObGcRe8CNBTGh5IYQtyXL7J6o%3D&ved=0CDQQyjdqFQoTCIG7teO40scCFQjMgAod10wOiw&ei=nNLjVYH9IYiYgwTXmbnYCA#tbm=isch&tbs=rimg%3ACQqhTE_1a2oPJIjgFaYg2LchUNL5RjIVm4mNB86DQPWQ8uoLec0qWEciokp4rci8QN1b_1cqU2ayCSXGq_1KzPngb0k5yoSCQVpiDYtyFQ0Ef59TE1S2s6qKhIJvlGMhWbiY0ER7QnoS2uoLzcqEgnzoNA9ZDy6ghEuv0vq7J3NAyoSCd5zSpYRyKiSEQKltr7o47V-KhIJnityLxA3Vv8RysJwgpx4z5sqEglypTZrIJJcahGwV3IclPaWwioSCb8rM-eBvSTnEX5nexcqWOFV&q=Jellyfish%20Lake%2C%20Palau&imgdii=z5SIdK4jQY-pTM%3A%3Bz5SIdK4jQY-pTM%3A%3BUWUal-M-DbqkdM%3A&imgrc=z5SIdK4jQY-pTM%3A --------------- https://en.wikipedia.org/wiki/Jellyfish_Lake "Fifth 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. Millions of golden jellyfish migrate horizontally across the lake daily. Jellyfish Lake is connected to the ocean through fissures and tunnels in the limestone of an ancient Miocene 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 etpisoni, and possibly other species in the lake have evolved to be substantially different from their close relatives living in the nearby lagoons. Jellyfish Lake is stratified into two layers, an oxygenated upper layer (mixolimnion) and a lower anoxic layer (monimolimnion). The oxygen concentration in the lake declines from about 5 ppm at the surface to zero at 15 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 apparently permanent stratified marine lakes.[1] The stratification of the lake is caused by conditions which prevent or restrict the mixing of water vertically. These conditions include: 1. The lake is surrounded by rock walls and trees which substantially block the wind flow across the lake that would cause mixing. 2. The primary water sources for the lake (rain, runoff and tidal flows through tunnels) are all close to the surface. 3. The lake is in the tropics where seasonal temperature variation is small, and so the temperature inversion that can cause vertical mixing of lakes in temperate zones does not occur. The oxygenated layer extends from the surface to about 15 metres (49 ft). All organisms that require oxygen live in this layer including the jellyfish, a few species of fish and copepods. This layer is somewhat turbid. Visibility is limited to about 5 metres (16 ft). The salinity of this layer down to about 3 metres (9.8 ft) is affected by rain and runoff, and below this, salinity levels are unaffected by freshwater inputs. The lake is connected to the sea via three tunnels that lie near the surface. The tunnels channel tidal water in and out of the lake. Tide levels in the lake are damped to about a third of the lagoon tidal levels. The tidal peaks are delayed from the lagoon tidal peaks by about 1 hour and forty minutes. Biologist William Hamner estimated that about 2.5% of the lake's volume is exchanged during a tidal flow. However, because the tidal water enters at the surface, the lower anoxic layer is largely unaffected by tidal flows.[2] The anoxic layer extends from about 15 metres (49 ft) below the surface to the bottom of the lake. The oxygen concentration in this layer is zero. The hydrogen sulfide concentration rises from about zero at the top of this layer to over 80 mg/liter at the bottom of the lake. The top three meters of this layer contains a dense population of bacteria, at least one species of which is a purple photosynthetic sulfur bacterium. This bacterial layer absorbs all sunlight so that the anoxic layer below the bacterial plate is dark, but transparent. Hamner estimated the visibility to be about 30 meters. The anoxic layer also contains high concentrations of ammonia and phosphate which are almost completely absent from the upper layer. The anoxic layer is potentially dangerous for divers, who can be poisoned through their skin. This risk is mitigated as scuba diving equipment is not allowed in the lake, thus limiting the depths to which individuals may dive.[3] Age of the lake[edit] Jellyfish Lake is around 12,000 years old. This age estimate is based on the depth of the lake (about 30 meters), an estimate of the thickness of the sediment (at least 20 meters[4]) and the rising sea level since the end of the last ice age. About 12,000 years ago, the sea level had risen to the point that sea water began to fill the Jellyfish Lake basin.[5] Golden jellyfish[edit] The golden jellyfish are most closely related to the spotted jellyfish (Mastigias papua) that inhabit the nearby lagoons.[6] They are similar to the spotted jellyfish in that they derive part of their nutrition from symbiotic algae (Zooxanthellae) that live in their tissues and part of their nutrition from captured zooplankton.[7] However, the golden jellyfish are morphologically, physiologically, and behaviourally distinct from the spotted jellyfish. They are easily distinguished from the spotted jellyfish by the almost complete loss of spots on the exumbrella and the almost complete loss of their clubs, an appendage attached to the oral arms.[8] Marine biologist Michael Dawson proposed that the golden jellyfish that inhabit Jellyfish Lake be classified as a subspecies (Mastigias cf. papua etpisoni) of the spotted jellyfish living in the nearby lagoons. The species identification is uncertain (denoted by cf. in the name) because the Mastigias papua local to Palauan lagoons may be only one of several cryptic species that make up the M. papua group, and in the future, the M. papua local to Palau may be identified as a separate species from other M. papua. He also proposed that the jellyfish living in four other Palauan marine lakes were distinctive enough to deserve recognition as unique subspecies.[8] Moon jellyfish[edit] The moon jellyfish were identified as Aurelia aurita by Hamner.[9] However, since the release of that report in 1981, genetic testing has been done on specimens of Aurelia collected from locations throughout the world. The results of that testing indicate in addition to the three named species of Aurelia there are at least six other cryptic species in the Aurelia genus. Three of the cryptic species identified were from Palau. One of these cryptic species is common to four of Palau's marine lakes with jellyfish populations including Jellyfish Lake. [10] Hence, the most accurate designation for the moon jellyfish in Jellyfish Lake (as of February 2001) is Aurelia sp. Despite the close proximity of Palau's moon jellyfish cryptic species, Dawson and Jacobs stated that the molecular data suggested that they had not interbred for millions of years.[10] ================== USGS - http://www.lib.utexas.edu/maps/australia/mecherchar_84.jpg map of Eil Malk or Mecherchar Island, Rock Islands, Palau, West Pacific Ocean, (topographic) 1:25,000 ================= http://visit-palau.com/about-palau/general-information/ Location and Geographic Description 7° 30' North Latitude, 133° 30' East Longitude Offical Languages English and Palauan more info Time Zone When it’s Noon Monday in Palau, it is: Manila 11:00 A.M. Monday Tokyo 12:00 P.M. Monday Sydney 1:00 P.M. Monday Honolulu 5:00 P.M. Sunday Los Angeles 7:00 P.M. Sunday Climate Palau enjoys a pleasantly warm climate all year round with an annual mean temperature of 82° degrees F. (27° C.). Rainfall can occur throughout the year, and the annual average is 150 inches. The average relative humidity is 82%, and although rain falls more frequently between July and October, there is still much sunshine. Typhoons are rare as Palau is located outside the typhoon zone. Currency & Credit Cards The official currency of the Republic is the U.S. Dollar. Visa, JCB, and Master Card are widely accepted at stores and visitor facilities. There are FDIC insured banks and major hotels with limited foreign currency exchange. In addition, Palau has money transfers such as Western Union or through Bank Institution. Tipping Tipping is optional, but appreciated. Immigration, Customs & Health Requirements VISA and PASSPORT Requirements All visitors must have a valid passport not less than 6 months from date of expiration and proof of return arrangements. VISAs are NOT required. 30-days Tourist Visa will be issued upon arrival and may be extended within 7 days in advance with approval of the Chief of Immigration for a fee of US$50.00 before expiration date of the visa. (Note: Maximum of 90 days: 30 days upon arrival plus 2 extensions at US$50.00 fee per extension. After which visitors must exit the country). Citizens of United States of America, Federated States of Micronesia, Republic of the Marshall Islands, Guam, and the Common Wealth of Northern Marianas Islands with valid passports are issued 1 year Visa upon arrival. For more information about extended stay in Palau, please call the Bureau of Immigration at (680) 488 – 2498 or 2678, Mondays to Fridays at the hours 7:30am – 4:30pm or e-mail inquiries to imm@palaunet.com.