|
|
The Balkan Rivers and Streams ecoregion contains fish and mollusk species that are found only in this ecoregion. Many can be found only in highly localized areas or bodies of water, including caves. Rivers and streams descend from the Balkan Mountains that help define the topography of this region, and flow into the Mediterranean Sea. There is also a vast network of underground rivers here that supports animals specially adapted to the dark conditions underground.
Two features have influenced freshwater life in the Balkans more than anything else: glaciers and limestone. When rivers and lakes in northern Europe were locked in ice during the last Ice Age thousands of years ago, water in the south flowed free. This allowed a large number of aquatic species to survive in the rivers and lakes here compared to northern Europe. Also, the soft limestone that the Balkans are built of allows water that seeps underground to create subterranean "karst" channels, where many aquatic species live. The Balkans region hosts about 200 known snail species. The Sava River alone harbors 103 species, of which 54 live only in this river system. The highly endangered olm (blind salamander) shares its underground home with many endemic invertebrates. The highly endangered Dalmatian barbel gudgeon (a fish) also lives below the surface, but sometimes it frequents rivers above ground. Endemic trout live in the rivers and lakes of this ecoregion, including the ohrid, marbled and belushka trouts, as well as S. dentex. Many other rare and often endangered fish species are endemic to the Balkans Rivers and Streams ecoregion, including Greek brook lamprey, Leuciscus illyricus, and Phoxinellus ghetaldii.
The aftermath of recent human conflicts in this region includes large-scale movements of refugees across the region and pollution originating from bombed industrial sites. Urban, suburban, and agricultural development causes pollution to enter the waterways both above and below ground. Dams have altered the natural flows and available habitats of many of the rivers in this region, and planned projects are expected to continue to drastically change the envrionments in which many native species have evolved. There is great concern about the ability of the many localized endemic species to survive these changes. The ecoregion also includes a large number of introduced species that are believed to harm native species. For example, the introduced brown trout, S. trutta, has bred with the rare native marbled trout, Salmo marmoratus, and has reduced the genetic integrity of the native species.
|
