N deposition :: Stoneworts (general)

Latin name: 
Charophytes (general)

Impact Type: Deposition of pollutant

Key Concerns:

Stoneworts are a small group of freshwater and coastal, macroscopic non-vascular plants, which belong to the Class Characeae of the green algae (Chlorophyta) (a number of which are listed in the UKBAP). They mostly occur in calcareous or brackish water. A few species, mostly in the genus Nitella, however can grow in acid water. Charophytes are very sensitive to reductions in light levels associated with increases in phytoplankton caused by eutrophication (Blindow 1992). British and Irish red list charophytes characteristic of oligotrophic or mesotrophic waters are, therefore, potentially threatened by N deposition (Stewart 1996, Stewart 2001).

Additional Comments:

There is no published research on the effects of atmospheric nitrogen deposition in the UK on these species, many of which are endangered and are listed in the UKBAP. While agricultural run off may be a frequent cause of eutrophication, atmospheric nitrogen deposition may be important in some circumstances. 

Critical Load/level: 
Critical Load/ Level

No comparable habitat with established critical load estimate available

References: 
Stewart, N.F. 1996 Stoneworts - connoisseurs of clean water Brittish Wildlife 8 92-99
Species group: 

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