Biodiversity on 24123 ha
PN-BmB este alcătuit, pe lângă fluviul Dunărea si brațele acestuia, din 7 insule și ostroave mari și 52 de lacuri/iezere temporare sau permanente. Fiecare dintre cele 7 insule reprezinta o entitate geo-morfologica distincta, cu microrelief de lunca distribuit pe o amplitudine altitudinala de 6 m, de la varful de grind pana la fundul de lac. Aceasta variatie altitudinala determina la randul ei o diversitate de habitate acvatice, terestre si mixte caracteristice pentru fiecare insula in parte care este inundata la cote diferite ale Dunarii. De aceea fiecare dintre cele 7 insule reprezinta o atractie particulara.
In the territory of the park were identified 19 types of habitats, of which we mention: willow forests, natural eutrophic lakes, poplars and willows, Typha marshes, bushes (zachog, wicker), Phragmites marshes, wet meadow meadows, meadows steppe. Of the 19 types of habitats identified, in the Small Wetland of Braila, 9 are on the List of Habitats Directive of Fauna and Flora. Of the ecosystems identified here, 50% are natural, 30% are semi-natural and 20% are anthropogenic.
Due to the fact that the territory of the park is subjected each year to periods of flooding and periods of water withdrawal, the two types of ecosystems, terrestrial and aquatic, are interdependent, creating a specific Danube biome. Between these types of ecosystems there is no strict territorial and temporal delimitation, there being a succession and periodic replacement. When the flood is very high, where there was a terrestrial ecosystem, an aquatic one will appear, and during periods of prolonged drought, the aquatic ecosystems will be replaced by some terrestrial ones.
So far, in the system of islands and lakes of Balta Mica of Braila, a number of 218 higher plant species has been identified. The woody species are those characteristic of areas of floodplain, being represented by soft essences, the most widespread being: willow (Salix alba, Salix cinerea, Salix fragilis), poplar (Populus alba, Populus nigra), elm (Ulmus foliacea), small catina (Myricaria germanica), Blackberry (Rubus caesius).
In reed swamps, the most common plant species are: reed (Phragmites australis), parrot (Typha latifolia, Typha angustifolia), Scirpus lacustris, Lythrum salicaria, Galium palustre, Euphorbia palustris, Solanum dulcamara, Sium latifolium, Glyceria maxia palustris, Butomus umbellatus, Iris pseudacorus.
Of the lower plants, the best represented are green, blue and silicon algae, as organisms specific to wetlands, as well as fungi (fungi).
Special vegetation is found on the sands (Tragus racemosus, Cynodon dactylon, etc.).
The characteristics of a wetland in a flood-free regime are also reflected in the ecological structure of the avifauna encountered in the park, of the 206 species of birds, 98 being aquatic and 108 terrestrial.
The highest concentration of aquatic species, but also terrestrial, is reported in the Small Island of Braila, in the area of the Dobrele, Sbenghiosu, Lupoiu, Curcubeu, Gâsca, Jigara, Vulpaşu and Cucova islands and in the Island of Fundu Mare.
Of the nesting, migratory and sedentary species, the presence of which can be considered as special, according to the Birds Directive, we mention: all species: – Tachybaptus ruficollis, the large greble – Podiceps cristatus, Podiceps nigricore, large cormorant – Podiceps nigricore and the small cormorant – Phalacrocorax carbo, Phalacrocorax pygmaeus, Eurassian bittern – Botaurus stellaris, Little bittern – Ixobrychus minutus, night snapper – Nycticorax nycticorax, yellow snapper – Ardeola ralloides, red-tailed pea, Eurasian Spoonbills – Ardea leucorodia, summer swan – Cygnus olor, red headed duck – Anas strepera, Garganey – Anas querquedula, white-eyed pochard – Aythya nyroca , white tailed eagle – Haliaeetus albicilla, the white-cheeked duck – Chlidonias hybridus, Kingfisher – Alcedo atthis, Sand martin – Riparia riparia, European roller – Coracias garrulus.
Other species are only present as winter guests or in the passage: the small diving and the polar diving – the stellate gull, the arctic gull, the winter greble – Podiceps auritus, the common pelican and the crested pelican – Pelecanus onocrotalus, Pelecanus crispus, small brook – Anser albifrons, Anser erythropus, sparrow duck – Acute duck, Duck with moose – Netta rufina, field eagle – Aquila heliaca, fisherman’s pike – Pandion haliaetus, Saker falcon – Falco cherrug, Westwen snowny plover – Charadrius alexandrine, common redshank – Tringa totanus, common tern – Sterna hirundo, foothhills – Merops apiaster.
The alternation between the periods of flood and the periods of drought has also made its mark on the representativeness of mammals in the PN-BmB territory, these having an accidental and aperiodic presence depending on the level of the Danube. So far, a number of 11 mammal species have been observed and identified: Sus scofa– Wild boar, Capreolus capreolus-Deer, Felis silvestris-Wild cat, Nyctereustes procynoides– wild dog, Lepus europaeus – Field rabbit, Vulpes vulpes-Fox, Mustela nivalis – weasel, Mustela putorius – Muskrat, Ondatra zibethica – Bizam, Meles meles-Badger, Lutra lutra – Otter.
All 11 species of mammals are protected by both national and Community legislation (Habitats Directive). Apart from the semi-aquatic species, such as the mackerel and the bison, which find favorable feeding places even when the Danube’s share is high, the other species usually meet when the water level is lower, they swim across the Danube’s arms.
Although they have quite favorable conditions for feeding and breeding in the areas adjacent to the park, when the water level allows them, mammals prefer the territory of the park especially for breeding, because here the pressure of any kind exerted on them is extremely low.
Amphibians and reptiles
Amphibians and reptiles, second-order consumers, are found in both terrestrial and aquatic ecosystems, but the number of species is rather poorly represented. So far, 3 species of reptiles and 8 species of amphibians have been identified, these species being on the lists of strict protection in both national and European legislation:
- Natrix natrix – Grass snake,
- Natrix tesselata-Water snake,
- Emys orbicularis-Water turtle,
- Frog carving-Small lake frog,
- Riding frog-Big lake frog,
- Hyla tree-Brooch,
- Dalmatian frog-Red forest frog,
- Pelobates fuscus-digging frog,
- Bumblebee-Buzzard red,
- Bufo bufo-Brown frog,
- Triturus cristatus-Triton with ridge.
The fish populations are represented by a number of 52 species registered according to the most recent studies carried out during the Danube, of which 24 species are found on the annexes of the European directives and those of the national legislation in force, being strictly protected species.
In the 52 lakes and inland ponds, the extremely rich submerged vegetation is an inexhaustible food source for phytophagous species such as carp (Cyprinus carpio), Danube scum (Alosa pontica).
At the same time, an explosive development of vegetation during times when the water level is lower, can be a danger to all aquatic life. This fact, combined with the high temperatures in summer, can lead to death by asphyxiation of aquatic organisms. One of the factors that contribute to maintaining the ecological balance within the fish populations is given by the presence of the predatory species of which the most known are: Fishbass (Silurus glanis), stingrays (Exos lucius), pike(Stizostedion lucioperca).