Inventory of aquatic plants in the Danube Delta: a pilot study in Romania
The Danube Delta is one of the largest delta areas of the world and its water bodies belong to many different types, ranging from fast-flowing large channels to still oxbow and flood plain lakes. The Tulcea arm, Sf. Gheorghe arm, Sulina arm, Litcov channel, the Old Danube, and the Magearu channel were chosen as study reaches where survey units were placed. 36 species were found to be closely associated with the water bodies and their littoral reaches. The highest number of species was found in the Magearu channel, whereas in the large channels used for large ship navigation, only a few species were detected. The highest plant mass was also detected in channels with predominately Ientic conditions, and in channels with considerable water flow the plant mass was low. Some channels like Litcov were dominated by amphibious species such as Mentha aquatica. In the Old Danube Ceratophyllum demersum was ubiquitous, but it was rather unexpected to find Salvinia natans and Lemna minor as the most frequent species in the structured littoral of the large navigable channels. The original findings indicate that too little is still known of the abundance and distribution pattern of aquatic plants in the water bodies of the Danube Delta.