Lake Eğirdir

Eğirdir (Turkish: Eğirdir Gölü, formerly Eğridir) is a lake in the Lakes Region of Turkey. The town of Eğirdir lies near its southern end, 107 kilometers (66 miles) north of Antalya. With an area of 482 square kilometres (186 sq mi) it is the fourth largest lake in Turkey, and the second largest freshwater lake.

Name

The town and the lake were formerly called Eğridir, a Turkish pronunciation of the town's old Greek name Akrotiri. Eğridir means "it is crooked" in Turkish, so to remove the negative connotations, in the mid-1980s the "i" and the "r" were transposed in a new official name, thus creating Eğirdir, a name that evokes spinning and flowers, although many people in Turkey still call both the town and the lake by its former name.

History

Lake Eğirdir must have existed in ancient times, since coins from the nearby city of Parlaos have been found with ships on them, but no clear references to the lake have been found in ancient texts, and its ancient name is unknown. A number of ancient settlements have been located around the lake: places whose names are known were Eğirdir itself (historically known as Akroterion), Parlaos, Malos, and Prostanna; and places whose ancient names are not known were at the ruin sites of Bedre, Ghaziri, and Ertokuş Han, as well as on Yeşil Ada. (Based on its modern name, Bedre – now known as Gökçe – may have been called "Petra" in ancient times.) In the 14th century, Ibn Batutta mentioned merchant shipping on the lake at Eğirdir (or Akrīdūr, as he called the city in Arabic).

Hydrology

Lake Eğirdir is fed by about 40 different springs, some of which are intermittent, and also by rainfall within its 3,309-km2 drainage basin. The main streams which feed Lake Eğirdir are the Pupa, the Hoyran, the Yalvaç, and the Çay. Besides evaporation, water exits Lake Eğirdir either by flowing out through the Kovada Canal into Lake Kovada, by draining out into one of the about 20 natural ponors that exist at the bottom of the lake, or by being pumped out through one of the 11 irrigation pumps built around the lake. The average retention time for water in the lake is 2.5 to 3 years.

The lake has an average depth of 7 m and a maximum depth of 13 m. Significant fluctuations in Lake Eğirdir's water level are not uncommon. It has a total volume of 4,000 cubic hectometres (140 billion cubic feet), of which 1,000 cubic hectometres (35 billion cubic feet) is drawn off for irrigation, drinking water, or other human uses. Approximately 45,000 hectares are irrigated by waters drawn from the lake. There is no thermal stratification in the lake.

A strait called the Hoyran Boğazı divides Lake Eğirdir into two parts: the larger Eğirdir Gölü proper and the smaller Hoyran Gölü.

Islands

Lake Eğirdir has two islands, connected to the mainland by a long causeway into the town of Eğirdir:

Can Ada (meaning "Life Island") the smaller of the two islands.

Yeşil Ada ("Green Island," formerly known as Nis) - until 1923, was home to a Greek community living in stone and timber houses.

Fish

Beginning with Karekin Deveciyan's Türkiye'de Balık ve Balıkçılık in 1915, a total of 15 different fish species have been recorded in Lake Eğirdir. Of these, 7 are endemic species that still inhabit the lake, 2 are endemic species that are now locally extinct, 4 are introduced species, 1 is of uncertain origin but is native to the area, and 1 is of unknown status but likely an exotic species. Introduction of invasive species since the 1950s, along with overfishing, has caused significant disruption in the local ecosystem. The first major change came in 1955, when the non-native pike perch, which preys on other fish, was intentionally introduced to the lake. The reason was that the lake's native fish were not very economically valuable for commercial fishing. The population dynamics of the lake's ecosystem "rapidly collapsed", and two endemic species became locally extinct. Since then, other exotic species have been introduced to the lake, such as the omnivorous Prussian carp by 1996 and the plankton- and fish-eating big-scale sand smelt by 2003.

Endemic species:

Eurasian carp (Cyprinus carpio): its numbers have decreased significantly due to overfishing, habitat loss, and invasive species.

Eğirdir barb (Capoeta pestai): since 1955, predation from the pike perch drove this fish's numbers to critically endangered status, but in the 2000s it started to reappear in small numbers as pike perch numbers dropped. According to Küçük et al., it survived because "a small creek flowing into the lake forms a shelter and breeding ground".

Ereğli minnow (Hemigrammocapoeta kemali: According to Küçük et al., this fish's first recording in Lake Eğirdir was in 1950 by Curt Kosswig, who incorrectly identified it as Tylognathus klatti. In any case, it has not been seen since 1958; it was presumably hunted to extinction by the pike perch.

Kavinne (Pseudophoxinus handlirschi): native to the lake and its basin, it was last fished in 1960. There are no official records, but based on interviews with local fishermen it seems to have gone extinct by the early 1970s. It inhabited the lake's pelagic zone and was formerly a significant source of commercial fishing.

Eğirdir minnow (Pseudophoxinus egridiri): According to Küçük et al., P. egridiri should be classified as distinct from other Pseudophoxinus species because it has a different number of scales and vertebrae. It developed a different niche than P. handlirschi, and they lived in different habitats. Now, P. egridiri is critically endangered; it mainly exists in the cold-water streams feeding the lake, such as the Karaot region and Yalvaç Creek. Habitat loss and pollution due to drought are major threats to this species.

Baltic vimba (Vimba vimba): called "asıl akbalık" by Deveciyan in 1915, it has been fished on a modest scale. According to Küçük et al., its numbers declined during the 2000s.