Biological change in the Rhine River system:
The biological community of the Rhine River system has changed gradually during the earth history as a consequence of glacial and interglacial periods, by stream captures, and by evolutionary processes. Major human-induced changes probably started in the Roman period.
But it was especially in the 19th and 20th centuries, that river engeneering led to a severe impoverishment of the biological communities. In the 20th century, pollution increased considerably.
During the last decades of this century, the inherited fauna was transformed to a great extent by invasive species, largely from the Ponto-Caspian region. Many original Rhine species have suffered from a severe reduction, but still partly live in affluents. The global climate change is not considered a crucial factor to drive and shape the species turnover.