Different types of environments resulting from the dynamic equilibrium between the sea, the river and freshwater can be found in the Baix Ter plain. The interaction between the sea, the river and the sediments it carries has given rise to a wide variety of ecosystems, with very subtle variations in the duration of floods, depth, salinity, nutrient content or type of substrate. The variety of environments and the diversity of organisms that can be found in them are two of the most important ecological aspects of the area. A description of the main aquatic ecosystems found in the Baix Ter follow.


- marshlands and coastal lagoons
- coastal freshwater ponds


- springs

Scattered throughout the alluvial plain we find deep, circular ponds filled with underground water. They are usually formed by landslides that leave on the open the phreatic levels and result in water surfacing. Although years ago these ponds abounded most of them have now disappeared. The best preserved ones can be found in Pals.
Since their water comes from underground its levels and composition varies very little and the nutrient content is very low; they are clean and clear waters in which herbaceous beds of submerged macrophytes (aquatic plants that require clear waters in order to grow) thrive.

Ullals de Pals

- inland temporary ponds
- river Ter estuary
- strongly humanized aquatic atmospheres