Permanent non-tidal, smooth-flowing watercourse

This habitat includes permanent watercourses with non-turbulent water and their associated pelagic and benthic animal, algal and plant communities. The habitat includes slow-flowing rivers, streams, brooks, rivulets, rills and also relatively fast-flowing rivers with laminar flow. The bed is typically composed of sand or mud. Features of the river bed, uncovered by low water or permanently emerging, such as sand or mud islands and bars are treated as littoral zone (C3) and are not included in this habitat. This habitat includes stretches of streams and river at mid and low-altitude with an average flow velocity below 0.2 m/sec. Main physical differences between this habitat type and C.2.2b (Permanent non-tidal, fast, turbulent watercourses of plains and mountain regions with Ranunculus ssp.) are the lower flow velocity and the smaller grain size of the sediments. These two habitats may be related as segments of the same stream or river. The water is mesotrophic and buffered.

The vegetation is mainly constituted by rooted and floating Euro-Asiatic macrophytes, mainly with potamid, batrachid and utricularid growth forms, which belong to the Potamogetonion and Batrachion fluitantis communities. Potamid vegetation can be accompanied in slowly flowing parts of the river bed by nymphaeid species such as Nymphaea alba and Nuphar lutea. Also amphibian macrophytes may occur in this habitat with their aquatic form. Vegetation cover of the habitat, usually, does not exceed 30% of the total area of a river stretch.

Indicators of good quality:

• Morphologically unaltered river bed and banks
• Natural hydrological regime
• Avoid of dominance of algae and floating algae beds (FLAB)
• No or limited formation of floating mats of organic residuals
• No or limited occurrence of exotic species
• Limited extension of nymphaeid vegetation or species indicating high eutrophication

Synthesis of Red List assessment

Confidence in the assessment

Pressures and threats