Danube Delta Biosphere Reserve
The Danube Delta maintains its enormous biodiversity in a better state than most other deltas in Europe, even in the world. It contains a greater range of habitat types, lower and higher plants, invertebrates and vertebrates than all other deltas in Europe. Many of the species that live within the delta are unique to it, these include plants and animals. The static freshwater ecosystems provide the base for the food chain in much of the delta. The contribution they make spills over in canals, rivers and other moving waters. Protozoa, micro-algae, algae and macrophytes are the primary producers, on which zooplankton, oligochaetes, molluscs, insects, fish, amphibia, reptiles, birds and mammals feed in ascending order within the food chain. Imbalances in some seasons have allowed some components like blue/green algae to thrive, to the detriment of macrophytes and many of the animals that depend on plant life. Inevitably, the more adaptable fish species (roach, crucian carp and perch) have survived then thrived, at the expense of species like pike, zander and common carp (Cyprinus carpio). Terrestrial ecosystems have suffered less than aquatic ones, because they are less easy to pollute and over fish. Exploitation by grazing, arable cropping, forestry, reed cutting is limited to areas where this is possible and in much of the delta these potentially damaging activities are impossible.