Although Jellyfish Lake is the most famous lake with jellyfish in Palau, it is not the only one. In more than 20 marine lakes (small saltwater lakes connected to the sea through limestone fissures) of Palau there is living jellyfish. Five of these lakes have been studied more - the mentioned Jellyfish Lake, Clear Lake, Goby Lake, Uet era Ongael and Uet era Ngermeuangel.
Testing ground for evolution
Each of the marine lakes of Palau has specific set of species occasionaly trapped in lakes by the receding sea 15 - 10 thousand years ago. Some lakes have steeper banks, some are elongated in east-west direction, some in south-north direction. Every such detail leads to different circumstances and consequently - different new species and subspecies of animals.
Some marine lakes of Palau are made even more exotic by the fact that they are meromictic - below the upper layer of marine water there is a layer of "dead", anoxic water separated by a layer of floating microorganisms, including a purple bacteria.
Such unusual monuments of nature serve as excellent "testing ground" for studies of evolution. Thus lately several scientists have made interesting treatises about these lakes. Lucky them (scientists!) - making science in beautiful Palau...
Jellyfish of president Remeliik
Ngermeuangel Lake is deep meromictic marine lake, circa 12 - 15 thousand years old. Area of the lake is approximately 4.3 ha, maximum length circa 290 meters, depth up to 40 meters. This is the deepest meromictic lake in Palau and also the anoxic layer is the deepest one - it starts at 18 meters depth below the circa 1 meter thick layer of purple-sulphur bacteria.
This marine lake has comparatively larger layer of liveable marine water. Most likely this is the reason why in this lake there is a comparatively large population of endemic subspecies of golden jellyfish Mastigias cf. papua remeliiki. It has been named after the Palauan president Haruo Remeliik.
Possibly the comparatively larger depth (or longer adaptation time to life in lake) also saved jellyfish during the heat of the El Niño/La Niña event in late 1990ies - while in Jellyfish Lake jellyfish disappeared (happily only for a while), here the population was less affected than in any other researched jellyfish lake.
Golden jellyfish in this lake has similar daily migration pattern to that of Jellyfish Lake - but here jellyfish does not avoid the shadow. Golden jellyfish of Remeliik is small - diameter does not exceed 14 cm
This lake contains also another species of jellyfish - Aurelia sp. This jellyfish has a well pronounced habit of vertical migration, possibly following the movements of their prey - copepods.
Since late 1990ies Uet era Ngermeuangel is included in some tourist routes, although it is less popular than famous Jellyfish Lake.