Lake Ohrid

Lake Ohrid (Macedonian: Охридско Езеро, transliterated: Ohridsko Ezero; Albanian: Liqeni i Ohrit) straddles the mountainous border between the southwestern region of the Republic of Macedonia and eastern Albania. It is one of Europe’s deepest and according to most experts the oldest lake in Europe, preserving a unique aquatic ecosystem with more than 200 endemic species that is of worldwide importance.[1] The importance of the lake was further emphasized when it was declared a World Heritage site by UNESCO in 1979. However, human activity on the lake shores and in its catchment area is resulting in the ecosystem coming under stress.

Lake Ohrid is the deepest lake of the Balkans, with a maximum depth of 288 m (940 ft) and a mean depth of 155 m (508 ft). It covers an area of 358 km² (138 sq mi), containing an estimated 55.4 km³ of water. It is 30.4 km long by 14.8 km wide at its maximum extent with a shoreline length of 87.53 km, shared between the Republic of Macedonia (56.02 km) and Albania (31.51 km).

While Lake Ohrid is special as such, by far the most spectacular quality is its impressive endemism. Similar to Lake Baikal or Lake Tanganyika, Lake Ohrid harbors endemic species covering the whole food-chain, from phytoplankton and sestile algae (20 species; e.g., Cyclotella fottii), over plant species (2 species; e.g., Chara ohridana), zooplankton (5 species; e.g., Cyclops ochridanus), cyprinid fish (8 species; e.g., Pachychilon pictus), to predatory fish (2 trout species; Ohrid trout Salmo letnica and "Belvica" Acantholingua ohridana) and finally its diverse endemic bottom fauna (176 species; e.g. Ochridagammarus solidus), with particularly large endemism among crustaceans, molluscs, sponges and planarians. Whereas the endemic species list cited above is based on morphological and ecological characteristics, some recent applications of molecular genetic techniques underline the difference of the fauna from common European taxa, as well as the old age of the lake.

Quite remarkably, exotic species do not seem to be a major issue in Lake Ohrid, although they have been recorded in small populations for several decades or exist in nearby rivers or lakes. The reason lies very probably in the ideal adaptation of the endemic species to the specific conditions in the lake, such as low nutrient availability, good living conditions in greater depth thanks to high water transparency and oxygen content, as well as subaquatic spring inflows supplying cool and oxygen-rich water.

Despite the exceptionally high level of endemism in Lake Ohrid (for example, ten of the seventeen identified fish species and as much as 80% of its molluscan fauna is endemic), a significant number of non-endemic species is found in Lake Ohrid. This includes species, which are mobile (e.g., via water birds) or migratory, such as the European eel.

The lakeshore reed beds and wetlands provide critical habitat for hundreds of thousands of wintering water birds, including rare and threatened species such as the Dalmatian Pelican, Ferruginous Duck, Swan, Spotted Eagle, and Eastern Imperial Eagle.

There are three cities on the lake's shores: Ohrid and Struga on the Macedonian side; Pogradec in Albania. There are also several fishing villages, although tourism is now a more significant part of their income. The catchment area of the lake has a population of around 170,000 people, with 131,000 people living directly at the lake shore (43,000 in Albania and 88,000 in the Republic of Macedonia). The population in the catchment has increased greatly by 100,000 people in the last half century, putting the lake's fragile ecosystem under pressure. The historic monuments, as well as the pristine lake environment make the area around Lake Ohrid a prime site for tourism. In the 1980s more than 200’000 national and international tourists went on a literal pilgrimage to the Macedonian lake side every year.