10C2
Streams and small rivers with macrophytic vegetation of plain to mountain levels
Relationships with habitat classifications. EUNIS: C2.1A Mesotrophic vegetation of spring brooks, C2.1B Eutrophic vegetation of spring brooks; Pal. Class.: 24.43 Mesotrophic river vegetation, 24.44 Eutrophic river vegetation; HD 92/43: 3260 Water courses of plain to mountain levels with the Ranunculion fluitantis and Callitricho-Batrachion vegetation.
Conservation status. BDA, HD.
Category. Endangered [EN – A1, 2 B2 C1 D2 E2 F2 G2 H2 I L2].
General characteristics. This habitat type encompasses parts of rivers and streams where the speed of the running water is usually below 1 m/s. They occur in areas at and below 800 m altitude in the mountain foothills and lowlands. These are running water bodies from river order IV to VI according to the concept of river continuum. The bottom and the banks are covered by clay or muddy-clay, rarely gravel-sand, deposits. These sediments provide the environment for a number of macrophytes to develop, mainly representatives of the genera Potamogeton spp., Callitriche spp., Berula erecta, Mentha aquatica, Ranunculus trichophyllus, Zannichellia palustris,and in the the coastal area also Sparganium erectum, Typha latifolia, etc. The winter temperature is low, 6–8°C, and higher in summers - above 15°C. The acidity is close to neutral or slightly alkaline (6,8–7,8 pH). Both physical and biogenic aeration exist. The oxygen composition varies according to the speed of the river flow and to the presence of photosynthesizing organisms. A pronounced spring maximum of the water level is observed during the period of snow melting and the minimum is during the autumn-winter period. It is possible that surface water is absent in autumn in some parts of these water bodies. This tendency is very strong in karst areas. Oligochaete-insect zoobenthos prevails. These are meso-to eutrophic waters that are often rich in allochthonous organic material.
Characteristic taxa.
- Vascular plants: Berula erecta, Callitriche spp., Mentha aquatica, Myriophyllum spicatum, Potamogeton crispus, P. nodosus, P. pectinatus, P. pusillus, P. trichoides, Sparganium erectum, Typha latifolia, Zannichellia palustris.
- Animals: Oligochaeta: Branchiura sowerbyi, Tubifex tubifex, Limnodrilus spp. Larvae of different insects, mainly Diptera, like Chironomus gr. thummi, C.gr. plumosus, Asellus aquaticus.
Distribution in Bulgaria. Southern parts of the Danubian Plain, Forebalkan, Sofia and Pernik lowlands, West Frontier Mountains; typical parts of Palakaria, Blato, Konska, Panega, Kamenitsa, Rachene, Negovanka, Chernelka and Byala Reka rivers.
Conservation importance. The habitat is important for the regulation and maintenance of the underground waters and humidity of the surrounding terrestrial ecosystems.
Threats. Organic pollution from the neighbouring urban areas and industrial enterprises; use of the rivers for watering; redirection of the riverbeds and construction of dykes; extraction of sand, clay and stones; building of small water power stations.
Conservation measures taken. The habitat is in Annex № 1 of BDA. Some of the localities are within protected areas: Chernelka and Karlukovski Karst Nature Monuments and in sites of the European Ecological Network NATURA 2000.
Conservation measures needed. To include parts of the localities of this habitat type in protected areas; restoration activities.
References. Vannote et al. 1980.
Authors: Rossen Tzonev, Dimitar Kozhuharov
