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.
and coastal lagoons
- coastal freshwater ponds
Coastal freshwater ponds are located next to the sea but receive
freshwater from irrigation ditches. They are, usually, old streams
separated from the river but that still carry a sometimes imperceptible
amount of water. The Ter
Vell and Basses
d’en Coll ponds are a good example.
Marine influence is also felt in these ponds. During stormy weather
seawater penetrates into the area significantly increasing salinity
levels; but after the storm continuous influx of freshwater results
in a decrease in salinity levels. Freshwater influx is changes quite
a bit because the irrigation ditches are used to irrigate crops
and therefore, influx depends more on crop irrigation than on the
Nutrients from fertilisers and other human activities seep into
the ponds. They also receive partially (or not at all) purified
sewage water. Irregularity in the influx of water, organic matter
and nutrients are the main causes the quality of water and the ecological
estate of the ponds is not the one desired.
profile of the Basses d'en Coll
- inland temporary
humanized aquatic atmospheres