result of the pollution, heavy metals have also been detected in some commercially important fish in the river. , 19 fish species in the river basin were recognized as threatened. Other animals The Magdalena River and its valley crosses a wide variety of ecosystems, like páramo in its headwaters, dry forest in the upper part of its valley, rainforest in its middle course, and swamps and wetlands in its lower course. The spectacled caiman, green iguana and brown pelican are abundant in these ecosystems but other animal species like the West Indian manatee, Magdalena tinamou, Todd's parakeet, American crocodile, Colombian slider, Magdalena River turtle, Dahl's toad-headed turtle and red-footed tortoise are in danger of extinction. In addition, there is a possible risk posed by invasive hippopotamus. Originally imported by Pablo Escobar, these hippopotami became feral following his demise, and have since expanded beyond their original home on Hacienda Napoles into nearby regions of the Magdalena River. History Due to its geographical position in the north of South America, the Magdalena River was since precolumbian times a route towards the interior of present-day Colombia and Ecuador. Several Carib-speaking peoples such as the Panche and the Yariguí ascended through the western bank of the river, while its eastern portion was inhabited by the Muisca civilization, which called the river Yuma. Likewise, the Spanish conquistadores who arrived to today's Colombia early in the 16th century used the river to push to the wild and mountainous inland after Rodrigo de Bastidas discovered and named the river on April 1, 1501. During the Spanish colonization of the Americas, the river was the only transport link communicating Bogotá with the Caribbean Sea port Cartagena de Indias and thus with Europe. The Magdalena Campaign of Pierre Labatut and Simón Bolívar took place along the Magdalena River. In 1825, the Congress of Colombia awarded a concession to establish steam navigation in the Magdalena River to Juan Bernardo Elbers, but his company closed shortly after. By 1845, steamboats regularly travelled on the river until 1961, when the last steamers ceased operation. In mass media Much of the film Love in the Time of Cholera takes place in the historic, walled city of Cartagena in Colombia. Some screenshots showed the Magdalena River and the Sierra Nevada de Santa Marta mountain range. The General in His Labyrinth, by Gabriel García Márquez, is a fictionalized account of the final voyage of Simón