05C1
Shallow drying-up water bodies with floating vegetation
Relationships with habitat classifications. EUNIS: C1.341 Shallow-water floating communities; PAL. CLASS: 22.432 Shallow-water floating communities.
Conservation status. None.
Category. Endangered [EN – C1 D3 E2 F2 G2 H2 L1].
General characteristics. This habitat type includes mainly eutrophic, riverside, flooded areas, marshes and temporary small swamps that most often dry up in summer. They are typical for the valleys of the large rivers, particularly in their lower parts – the Danube, Osam river (Obnova village), Vit and Iskar rivers, Maritsa river (Plovdiv and Haskovo regions), Toundzha river, Struma river (Petrich lowland), the periphery of large swamps in W Bulgaria – Aldomirovsko and Dragomansko swamps; swamps near Sofia (Kazichene and Novi Iskar villages); in Strandzha Mts. and at the southern Black Sea coast; Forebalkan (Veliko Tarnovo and Lovech regions); northern Black Sea coast and Dobrudzha area (Chair Gyol and Chair Harman localities), East Rhodopi Mts. Flooded areas and marshes used to be widely distributed in the past but after the redirection of the river beds and construction of the dykes and draining activities their distribution in Bulgaria decreased considerably. Usually these water bodies appear when the water in the rivers and swamps is high, in April – May. The water stays until the end of June or beginning of July, but soon dries up and most of the water bodies are completely dry at the beginning of the summer. However, this time is enough for the development of floating coenoses of hydrophytes when the water is 0.30–0.50 m deep. These are coenoses of Callitriche cophocarpa, C. stagnalis, Elatine alsinastrum, Ludwigia palustris, Ranunculus aquatilis, R. penicillatus, and R. trichophyllus. This habitat type used to be very typical for the flooded areas along Iskar river in Sofia lowland. In the marshes near Kazichene village coenoses of Hottonia palustris used to develop – a species extinct from the Bulgarian flora today. Together with the species typical for this habitat type some other hygro- and hydrophytes like Lemna minor, L. trisulca, Phragmites australis, and Sparganium emersum also occur. They make complexes with the coenoses mentioned above, especially in the larger swamps in which the water retreats only from the periphery while in the inner part of the swamps it remains throughout the whole year.
Characteristic taxa.
- Vascular plants: Alisma plantago-aquatica, Callitriche cophocarpa, C. stagnalis, Ceratophyllum demersum, Elatine alsinastrum, Hottonia palustris, Lemna minor, L. trisulca, Ludwigia palustris, Oenanthe aquatica, Phragmites australis, Ranunculus aquatilis, R. penicillatus, R. trichophyllus, Rorippa amphibia, Sagittaria sagittifolia, Sparganium erectum, Typha latifolia.
- Animals: Invertebrates – Rotifera: Brachionus calyciflorus, Keratella cochlearis, Polyarthra dolychoptera, P. vulgaris; Crustacea: Alona spp., Acanthocyclops robustus, Attheyella crassa, A. wierzeiskii, Bosmina spp., Bryocamptus spp., Canthocamptus staphylinus, Diacyclops bisetosus, Eucyclops serrulatus, Megacyclops viridis; Nematoda: Dorylaimus stagnalis; Diptera: Chironomus gr.; Vertebates: reptiles – pectinate tritons.
Distribution in Bulgaria. Throughout Bulgaria, mainly in the lowlands and the karst areas, up to 1000 m alt. Such water bodies are numerous in the Danubian Plain (along the Danube, Iskar, Osam, Yantra, Vit rivers, etc.), Thracian Lowland (mainly along Maritsa river, in the lower part of the valley), Toundzha Hilly Country, Znepole region (the swamps near Dragoman town and Aldomirovtsi village), Sofia region (the flooded areas along Iskar river), Strandzha Mts. (along Veleka and Rezovska rivers), East Rhodopi Mts., Black Sea coast, the valley of Struma river (Petrich-Sandanski lowland), Forebalkan (Lovech, Gabrovo, Tarnovo regions).
Conservation importance. The shallow-water, drying-up water bodies with floating vegetation are among the habitats whose area and distribution have been most drastically reduced in Bulgaria. Some rare, endangered and protected species occur in these coenoses like Callitriche stagnalis, Elatine alsinastrum, Hottonia palustris, Ludwigia palustris. The flying imagos of water insects, mainly from the family Chironomidae constitute a very good feeding resource for the bats Myotis daubentonii, Nyctalus noctula, Pipistrellus pipistrellus.
Threats. Draining of the riverside swamps and lakes, hydro-meliorative activities along the rivers (dykes, draining), drying up as a result of the general aridisation of the climate, accumulation of dead plant material, extraction of gravel and sand, pollution from waste waters and household waste, use of fertilizers and pesticides in the neighbouring arable lands, watering of surrounding lands.
Conservation measures taken. Some of the localities are within existing protected areas – Srebarna Managed Nature Reserve, Persina Nature Park, Shablensko Ezero (lake) and Durankulashko Ezero (lake) Protected Sites and sites from the European Ecological Network NATURA 2000. This habitat type is under restoration in Dragoman swamp.
Conservation measures needed. Overcoming of the negative public attitude towards swamps, restoration of already drained marshes and flooded areas, restoration of the water regime of the still existing swamps, termination of the large hydro-meliorative activities along the rivers, restoration of the old riverbeds.
References. Jordanoff 1931.
Authors: Rossen Tzonev, Vladimir Valchev
