Endangered Species in the Danube River Basin
Sturgeons are restricted to bodies of flowing water in the Northern Hemisphere. Their distribution spans the coasts of the Atlantic and the Pacific, the Mediterranean, the Black and Caspian seas, and also to large rivers like the Danube as well as some lakes.
The Atlantic sturgeon (Acipenser sturio) is already extinct, while the Ship sturgeon (Acipenser nudiventris) is close to extinction. The Danube sturgeon (Acipenser gueldenstaedti), the Beluga (Huso Huso) and the Stellate sturgeon (Acipenser stellatus) are highly endangered and extremely rare, while the Starlet (Acipenser ruthenus) is dependent on stocking programmes for survival.
Sturgeons can become very old and are sexually mature at a late age; the Beluga reaches sexually maturity at the age of 15. During the spawning season, from spring to summer, sticky, brownish-green eggs are laid. After 2 weeks, the young sturgeon are ready to feed, and they migrate to the ocean between their 1st and 3rd years.
Great white pelicans
The great white pelican’s main habitat is restricted to the Danube Delta in Romania and Ukraine, although they are also native in Asia and Africa.
They prefer extensive swamps with open waters on lakes, landlocked seas, lagoons and large river deltas. The bodies of water should have plenty of fish and aquatic plant life.
Great white pelicans are sensitive to disturbances in their mating area and flee immediately when approached by humans. It may happen that they abandon mating and no longer incubate due to such disturbances.
70% of all great white pelicans worldwide live in the summer on the 4500 square meter large Danube delta, protected by nature conservation laws.
The great white pelican is classified as rare, there are fewer than 10.000 mating pairs, worldwide. The European mating population encompasses around 4.100 pairs
The beaver was originally the largest rodent in Europe, from France to Northern Mongolia, and from Northern Scandinavia to the Mediterranean. At the beginning of the 20th century, it was close to extinction. At present, more than 1000 beavers live in 2 large areas, namely the Danube-March-Area, and in the Inn-Salzach-Valley.
Beavers are social animals that live monogamously in family groups. Predominantly nocturnal, they do not hibernate, but remain in their dens for weeks at a time.
The beaver prefers slow flowing or stagnant bodies of water rich in riverine vegetation or vast alluvial forests. Their way of chopping down trees is the most well known trait of the beavers. Trees are food, as well as construction material for its spacious castles.
These beaver-constructed-dams are water level regulating, which lessen the effects of floods and droughts on smaller rivers. The living space of a beaver, which in turn provides a habitat for several other animal and plant species, is a labyrinth of dams and canals.
Earthen banks on water bodies are of crucial importance to kingfishers, because they nest in excavated holes. Rivers with bare, steep banks are indispensable, where holes can occur only on non-developed banks during floods.
However, over the past years, it appears that the birds are switching to nesting next to stagnant water, as vertical walls can no longer be found on the banks of rivers because of the man-made changes to river flows.
Kingfishers’ reach sexual maturity at the age of 1. Their average lifespan is only 2 years.
European pond turtle
The European pond turtle is found both Europe-wide and in Northern Africa. On the Danube and the March there are the only a few remaining native populations.
Pond turtles prefer a habitat on still or slow flowing bodies of water, with a muddy bed and an abundance of aquatic plants, i.e. vegetation rich bayous in alluvial forests.
The survival of a population depends on flat lentic regions, which can be warmed by the sun, as well as poor grasslands close to bodies of water with bushy banks, warm groves and sandy hills.
Adult pond turtles are particularly threatened by human disturbances to their habitat, such as: draining of swampland and wetlands, restructuring of bodies of water, urban sprawl and destruction of egg deposition areas.
It often occurs that females are run over by vehicles, while searching for nesting areas. Turtles also fall victim to weirs used for fishing, as they get trapped and inevitably drown.