Distribution of the Non-native Bryozoan Pectinatella magnifica (Leidy, 1851) in the Danube River

Abstract

The non-native freshwater magnificent bryozoan Pectinatella magnifica (Leidy, 1851) was firstly recorded in the summer of 2011 from the Danube River (side arm Rackevei-Soroksari Duna downstream from Budapest). Despite intensive research along the length of the Danube River between Budapest and Belgrade in 2001-2013, it has not been detected to expand its range. Recently, the species has distributed rapidly in the 900-km-long downstream stretch of the Danube River. The species was found at ten sites, between river kilometres 1586 (Hungary, downstream from Budapest) and 685 (the Romanian-Bulgarian stretch of the Danube River). The highest colony abundance was recorded from the Iron Gate (Derdap) sector that is influenced by the backwater effect of the Iron Gate dams. Our findings reveal the capacity of this bryozoan to spread extremely rapidly and to invade successfully stretches of rivers that are exposed to hydromorphological pressures.