Chara horrida (Wahlst 1862) (Charophyta)

Compiled by: Georg Martin, Estonia

1. Description of the habitat/autecology of the species

Chara horrida is mainly found from sheltered locations, in most cases on soft bottom, rarely on muddy or sandy substrates. Depth ranges reach from about 0.5 m down to about 3 m. The species is found from relatively narrow salinity range in the Baltic Sea – between 4.5 and 9 psu.  

2. Distribution (past and present)

While C. horrida occurs rather frequently along the east coast of south and middle Sweden, only single records exist from other regions of the Baltic Sea. The only recent findings outside Swedish waters come from West Estonian Archipelago area and the Aland archipelago.

3. Importance (sub-regional, Baltic-wide, global)

Species is considered to be rare. Its main distribution area is recorded to be the middle and southern part of the Baltic Sea. Outposts can be found in the Netherlands, in northern France and the south coast of Great Britain.

4. Status of threat/decline

A decline of the species has been observed all over the  Baltic Sea. Both in Denmark and Germany the species has totally disappeared from its former locations. The species has not been found recently from its former distribution localities in Finland and many locations in Sweden, despite targeted investigations.

5. Threat/decline factors

Main known factors of threat are eutrophication and coastal engineering. 

6. Options for improvement

Combatting local sources of eutrophication as well as conservation measures, such as restrictions on coastal constructions and dredging, in shallow coastal lagoons and archipelago areas can prevent species from further decline. 

7. References

Blümel C. 2003:  Chara horrida. In Schubert, H., Blindow, I. (eds.), Charophytes of the Baltic Sea, Koeltz Scientific, Koeninstein/Taunus, 113-121.

Olsen S. 1944: Danish charophyta. Chorological, ecological and biological investigations. Kongel. Danske Vid. Selsk., Biol. Skr. 3: 1-240.