This lagoon is the end result of an ancient open-pit mining exploitation site and currently stands as an extraordinary ecological niche where flora and fauna species interact in a particular manner. The high value of these species is paramount in the overall understanding of the Terva River Valley biodiversity.
The Lagoon of Brejo site includes wetlands, common alder and grey willow trees that are considered priority conservation habitats in Portugal. These refer to woodlands dominated by common alder wood (Alnus glutinosa), grey willows (Salix atrocinerea) and a signi cant quantity of birch trees (Betula alba). In a mosaic pattern with these woodlands are small areas dominated by sphagnum and an abundance of acidophilus reeds of J.acutiforus, J. conglomeratus and/ or Juncus effusus.
In terms of fauna, the lagoon is recognized as the area with the highest number of identi ed species, which is revealing of its high speci c value. Some examples are the green sandpiper (Tringa achropus), the mallard (Anas platyrhynchos), the common moorhen (Galinula chloropus), the red squirrel (Sciunus vulgaris) and the re salamander (Salamandra salamandra).