A transitional ecosystem between river and sea. An environment of mixed waters.
In the coastal lagoons of the Ebro Delta , freshwater from the Ebro river and saltwater meet, creating an environment with very distinctive characteristics. This process gives rise to a wide variety of intermediate-salinity habitats, where environmental conditions change constantly.
A protected natural space
The Ebro Delta, located in the south-eastern tip of Catalonia, covers an area of approximately 350 km² and is designated a protected natural park. This space constitutes a key habitat both for numerous marine organisms and for a great diversity of aquatic and migratory birds, which use it as a resting, feeding and breeding ground.
Salinity: a challenge for life
Adaptations to a changing environment.
The delta acts as a transition zone between fresh and marine water. As the river flows into the sea, salinity gradually decreases, generating environments with fluctuating salinity that pose a challenge for the organisms that inhabit them.
Species living in this environment have developed effective internal regulation mechanisms, allowing them to withstand significant variations in salinity. Some species do not merely remain in the mixing zone, but make a full transition into freshwater or marine environments throughout their life cycle. This is the case for migratory species, such as the European eel (Anguilla anguilla), an emblematic example of adaptation to this ecosystem.
Most common marine species
Among the marine organisms that inhabit transitional environments, the following stand out:
