Benthic diatoms from the littoral zone of Southern Brittany

Estuaries and brackish waters


In estuaries, salty swamps and most of the brackish waters generally, the salinity can vary more or less quickly, as a result of the tide, of the pluviometry and of periods of sunshine. The species which live in these waters thus have to be euryhaline, that is that they have to support, daily or not, variations of salinity, sometimes of big amplitude. These species, more or less euryhaline, have three origins. Some ones are generally met in sea (¨euryhaline marine species¨); others are present usually in freshwaters (¨euryhaline freshwater species¨); some ones (¨brackish species¨) are considered as limited to waters the salinity of which is situated between 0,5 and 30 %o (or in very mineralized continental waters). 
In addition, in samples collected in estuaries, stenohaline marine and freshwater diatom species are also found. However, the fact of finding, after preparation of the samples, frustules or valves of these stenohaline species does not allow to know if they were alive or not in situ. They could have been brought by tidal streams or by brooks. 

The species illustrated below are characteristic of brackish littoral zones.

Marine diatoms 1 : genera Achnanthes to Berkeleya

Marine diatoms 2 : genera Biremis to Diploneis

Marine diatoms 3 : genera Entomoneis to Mastogloia

Marine diatoms 4 : genera Navicula to Trachysphenia

Marine diatoms 5 : the genus Haslea

Euryhaline marine diatoms 1 : genera Achnanthes to Diploneis

Euryhaline marine diatoms 2 : genera Entomoneis to Nitzschia

Euryhaline marine diatoms 3 : genera Opephora to Tryblionella

Brackish marine diatoms 1 : genera Anomoeoneis to Navicula

Brackish marine diatoms 2 : genera Nitzschia to Synedra

Non-identified taxa and genera

Around 80 "freshwater species" are presented on the website Diatoms of the fresh waters.

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