Together with coral reefs and tropical rain forests, marshes are considered the most productive ecosystems on the planet. These natural sanctuaries connect the marine and land ecosystems, favoring an interrelationship among a multitude of living things sharing both habitats, along with other wild life native to this environment.
Marshes are generated by the continuous contact with sea water and fresh water on the silt beds along the course of rivers. The Mape and the Oka Rivers cannot carry any material, so the sediment is deposited at the end of the riverbed. The sea waves stop breaking at Laida, entering the river as a tide and transporting sediments from the sea in the form of sand. As the sea tide meets the river, both rivers release the material and suspended nutrients by depositing the sediment in the intertidal area forming slime, a thin, muddy layer or substratum.
The Cantabrian Holm Oak forest
Aingerubide Oak Grove
San Pedro Cave