Chara tomentosa (L. 1753) (Charophyta)

Compiled by: Georg Martin, Estonia

1 . Description of the habitat/autecology of the species

The species cannot stand wave action and therefore it avoids exposed localities. It occurs in sheltered to very sheltered areas on soft muddy bottoms, in bays, coves and coastal lagoons but also in glades within reedbeds and outside the reed belt in the mainland zone of the archipelago. It is a characteristic species of flads in both Finland and Sweden. The depth distribution mostly falls within the interval of 0.5-3.7 m. C. tomentosa inhabits salinity range from fresh water up to 6.5-7 psu.

2. Distribution (past and present)

This species occurs in the brackish water only in the Baltic Sea. It is common and distributed in all countries bordering the Baltic Sea except for Danish waters. It is more often found north from the Baltic Proper. The former distribution of the species has been much wider in the Baltic sea than today. Tremendous decline in distribution of the species has been recorded in German, Swedish and Finnish waters.

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

Species has great importance as habitat forming element in the shallow sheltered soft-bottom environment.

4. Status of threat/decline

A decline of the distribution of the species is observed almost all over the Baltic Sea area. Recolonisation of the species to the abandoned habitats is very difficult and no recolonisation events of degraded habitats are described for the Baltic Sea so far.

5. Threat/decline factors

Main known factors of threat are eutrophication and mechanical disturbance in form of habitat destruction and habitat disturbance. Activities as boating, dredging and cutting of reeds are described as major threat factors.

6. Options for improvement

Combatting local sources of eutrophication as well as conservation measures (incl. restictions on dredging, engineering etc) in shallow coastal lagoons and archipelago areas can prevent species from further decline. 

7. References

Blindow I. 2000: Distribution of charophytes along the Swedish coast in relation to salinity and eutrophication. Internat. Rev. Hydrobiol. 85: 707-717.

Munsterhjelm R. 1997: The aquatic macrophyte vegetation of flads and gloes, S coast of Finland. Acta Bot. Fenn. 157: 1-68.

Torn K., Martin G., Munsterhjelm R. 2003:  Chara tomentosa. In Schubert, H., Blindow, I. (eds.), Charophytes of the Baltic Sea, Koeltz Scientific, Koeninstein/Taunus, 131-141.

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