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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
- inland temporary ponds
The uneven
distribution of sediments deposited by the rivers and the flatness
of the terrain have given rise to multiple depressions of the land
that drain, with some difficulty, waters accumulated when it rains.
Water is held back and eventually evaporates, resulting in temporary
ponds that get flooded during the wet season and dry completely
in summer. Many aquatic species adapted to drought periods colonize
them.
Long ago, the plain was teeming with these ponds, but most of them
were drained between the 18th and 19th centuries. Nowadays only
the remains of what in the past were big ponds, with an extension
of 200 hectares, remain; and its surface is used to grow crops that
need or tolerate high quantities of water such as rice and black
poplar groves or just kept as enclosures. Some examples are the
ponds of Pals, Boada, Ullastret and Bellcaire, all situated in the
Baix Ter plain.
- river
Ter estuary
- strongly
humanized aquatic atmospheres
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