11C2
Mountain streams and fast-flowing rivers
Relationships with habitat classifications. EUNIS: C2.21 Epirhithral and metarhithral streams, C2.22 Hyporhithral streams; PAL. CLASS. 24.12 Epirhitral and metarhitral streams, 24.13 Hyporhithral streams; HD 92/43: 3260 Water courses of plain to montane levels with the Ranunculion fluitantis and Callitricho-Batrachion vegetation.
Conservation status. BDA, HD.
Category. Vulnerable [VU – A1, 2 B2 C1 D2 E1 F2 G2 H2 I J L3].
General characteristics. Upper parts of rivers and mountain streams that occur between 800 up to 2800 m alt., where the speed of the water flow is above 1 m/s. These are running water bodies from I to III river order according to the concept of the river continuum. The bottom and the banks are covered by rocks or stones of different size, rarely by gravel, sand or clay deposits. The temperature is low throughout the year, between 0 and 6–8°C. The acidity of the water is close to neutral (pH 6,8–7,4). The high oxygen content (8–10 mg/dm3) is a result mainly of physical aeration. The water maximum is in spring when the snow melts and the minimum is during autumn and winter. This tendency is much stronger in karst areas in N Pirin Mts., West and Central Balkan Range, where possibly the surface water disappears during the minimum period. These streams start from glacial lakes where a biological drift of plankton limnobionts and benthos reobionts is observed. Insect zoobenthos prevails in the water drift.
Characteristic taxa.
- Plants: Algae: Nostoc spp. Vascular plants occur mainly at the outflow place of the glacial lakes where clayey deposits accumulate – most frequent are Ranunculus aquatilis, Sparganium angustifolium and the moss Fontinalis antipyretica.
- Animals: Crustacea: Paracyclops fimbriatus, Attheyela wierzeiskii, A. crassa, Bryocamptus zschokkei; Turbellaria: Crenobia alpine; larvae of Diptera from fam. Simulidae such as Prosimulium spp., Cnetha spp. and fam. Chironomidae (Cryptochironomus spp.); larvae of Ephemeroptera (Baetis alpinus, B. muticus, B. rhodani, Rhithrogena spp., Ecdyonurus carpaticus), and of Plecoptera like Nemoura pirinensis, N. bulgarica, Perla spp., Leuctra spp.; rotifers (Lecane spp., Keratella spp.) survive at large distances in such streams. A typical inhabitant of such areas is the brown trout (Salmo trutta fario).
Distribution in Bulgaria. Rila Mts., N and C Pirin Mts., W and C Rhodopi Mts., W and C Balkan Range, Vitosha, Plana, Zemenska Mts.
Conservation importance. The habitat is important for the regulation and maintenance of the underground waters and the soil humidity of the surrounding terrestrial ecosystems. It is also the habitat of rare and endangered invertebrates and some annelids. The bats Myotis mystacinus, M. nattereri, M. daubentonii, Nyctalus noctula, Hypsugo savii, Pipistrellus pipistrellus, and Barbastella barbastellus are very active above the water during the summers.
Threats. Erosion of the banks; organic pollution and other sources of pollution (metals, plastics, food waste); construction and exploitation of chalets, hotels, ski tracks; construction of water catchments; mountain stock breeding. Deforestation of the lake catchments increases erosion.
Conservation measures taken. The habitat is included in Annex № 1 of BDA. Considerable parts of this habitat type are within protected areas – Rila, Pirin and Central Balkan National Parks, Vitosha Nature Park, etc. and in sites from the European Ecological Network NATURA 2000.
Conservation measures needed. Efficient control of the construction of water purifying facilities in the mountain chalet and resorts that release their wastes in such streams; limitation of the tourist access in areas of the most vulnerable water bodies; prohibition of the construction of ski tracks in areas of distribution of these streams and strict control on the water quantities that are being lead away for industrial and household needs. Conservation and restoration activities in the most affected regions: a typical example is Banderitsa River below Banderishka Polyana locality in N Pirin Mts.
References. Kovachev 2000; Kozuharov 2006; Stoichev1996; Vannote et al. 1980; Videnova et al. 2000.
Authors: Jordan Uzunov, Dimitar Kozhuharov
