Uet era Ngermeuangel

Testing ground for evolution

Each of the marine lakes of Palau has a specific set of species occasionally trapped in lakes by the receding sea 15 – 10 thousand years ago. Some lakes have steeper banks, some are elongated in the east-west direction, some in a 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 a deep meromictic marine lake, some 12 – 15 thousand years old. The area of the lake is approximately 4.3 ha, maximum length roughly 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 approximately 1-meter thick layer of purple-sulfur bacteria.

This marine lake has a 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 live in the lake) also saved jellyfish during the heat of the El Niño/La Niña event in the late 1990s – 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 have a similar daily migration pattern to that of Jellyfish Lake – but here jellyfish do 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 the late 1990s Uet era Ngermeuangel is included in some tourist routes, although it is less popular than famous Jellyfish Lake.

References

1. Coral Reef Research Foundation, Marine Lakes Research Accessed 08.02.10.
2. Jellyfish swarms, tourists, and the Christ-child, Mike N. Dawson, Laura E. Martin, Lolita K. Penland. Hydrobiologia 451: 131-144, 2001. Accessed 08.02.10.
3. Five new subspecies of Mastigias (Scyphozoa: Rhizostomeae: Mastiigidae) from marine lakes, Palau, Micronesia, Michael N. Dawson. Journal of Marine Biological Association, U.K. 2005., 85., 679-694. Accessed 08.02.10.