On line: Habitat Paper n. 23: Lagoons, estuaries and deltas. A border between rivers and sea.

Delta, lagoons, estuaries, three environments produced by the close interactions between the rivers and the sea. Environments that require to the living organisms to make difficult adjustments to the incessant alternation of conditions partly continental and partly marine.

In this unique band of transition between land and sea, plants compete with green algae for the domain role of submerged vegetation. The population of these environments is composite, both and in its aquatic component , and in what colonizes the banks.

There are species of marine origin, but able to tolerate low salinity and variable water . Few species such as eel and sturgeon, alternate their lives between sea and river, crossing lagoons and deltas during their migrations. The most conspicuous aspect of the fauna of these environments is water fowl, especially numerous during the winter when the ponds are filled with the migratory stopping here before moving to their breeding areas.

Fragile, as is typical in transition environments, delta, estuaries and lagoons have profoundly been influenced by the massive urbanization of the coasts, which led to a drastic reduction of the tipical saltmarsh formations. What survives of the original population must now compete with a growing number of alien species that enter into competition for living space.

Free download of the paper (PDF format) at the link of Italian Ministry of Enviroonment:

http://www.minambiente.it/opencms/opencms/archivio/biblioteca/protezione_natura/qh23.zip