Ebro - Ecology

Ecology

The Ebro Delta Natural Park, with a total surface area of 7,802 ha, was established in 1986 and is of international importance for 8 of its plant species and 69 of its vertebrate fauna. It has some 95 breeding species of birds, is also very important for a wide range of overwintering species, and serves as an essential stopover point for large numbers of migratory birds. The Ebro delta has the world's largest colony of Audouin's Gulls. In 2006 it held a record number of more than 15,000 pairs.

There are concerns about the ecological impact of introduction of foreign species that is almost always a burden, affecting much of the original ecosystem introduced species rapidly caused the extinction of numerous indigenous species. The introduction of American crayfish Procambarus clarkii has resulted in economic losses, introduced elsewhere for cultivation, its success is attributable to its ability to colonise disturbed habitats that would be unsuitable for the edible iberian crayfish. The semiaquatic rodent Myocastor coypus or nutria is presuming to expand in some northwest tributaries of the head damaging crops and protected national parks in Basque Country.

The zebra mussel, an invasive species, is expanding upstream in Ebro waters. Due to its rapid rate of reproduction, the species adversely affects the port underwater machinery as well as that of dams and hydroelectric plants, in addition to competing with native species. Following the introduction of Wels catfish are fishes whose number is in clear and rapid decline. Since its introduction in the reservoir Mequinenza in 1974 - has spread to other parts of the Ebro basin over Ebro and its tributaries, especially river Segre. Some endemics species of iberian barbels, genus Barbus in the Cyprinidae, having once been abundant especially in the Ebro river. Competition and predation by Wels catfish has caused its complete disappearance in the middle channel Ebro around 1990. The ecology of the river also, has now a major development in the amount of aquatic vegetation, seaweed and algae. Barbel species from mountain stream tributary of the Ebro that Wels catfish has not colonized, were not affected.