Freshwater mollusc assemblages and habitat associations in the Danube River drainage, Hungary

Abstract

ABSTRACT1. Native freshwater mollusc diversity has been declining over the past decades. For developing efficient conservation management plans for molluscs, it is especially important to identify areas with high native biodiversity.2. The River Danube is one of the most important freshwater ecosystems in Europe and should receive special attention. The main objective of this work was to characterize the composition, diversity and conservation status of freshwater molluscs occurring in the Hungarian Danube River Drainage in five river habitat types (main channel of the Rivers Danube and Tisza, side channels of River Danube, tributaries of Rivers Danube and Tisza).3. In total, 53 mollusc species were identified including 10 invasive species and 12 species of conservation concern. The main determining factors of mollusc composition were sediment characteristics, current velocity and oxygen content. Nitrate-nitrogen, ammonium-nitrogen, and calcium content also play a key role.4. Overall, density, species richness and diversity showed significant differences between habitat types. The highest diversity values were detected in the side channels, but the highest proportion of threatened species was observed in the tributaries. The highest number and proportion of invasive species was detected in the main channel of the Danube. Most of the recorded invasive species were previously documented in side channels and the adjacent wetlands, but did not invade the tributaries.5. Tributaries may provide refuges for native molluscs and could be considered as 'source' populations, which may be critically important in the regional maintenance of threatened species. Tributaries are still less disturbed and less invaded; and should be given priority in future conservation management plans.

Invasive Chinese pond mussel Sinanodonta woodiana threatens native mussel reproduction by inducing cross‐resistance of host fish

“…, ). This species has been observed living in sympatry with native mussel species, such as the painter's mussel Unio pictorum (Linnaeus 1758), the thick‐shelled river mussel Unio crassus (Philipsson, 1788) , the swollen river mussel Unio tumidus (Philipsson, 1788) , the depressed river mussel Pseudanodonta complanata (Rossmässler, 1835), A. anatina , and other mollusc species in the silt–clay substrate of lowland areas of the Danube River (Bódis et al, , ; Paunovic et al, ). The habitat preferences of S. woodiana are similar to those of several native freshwater mussels, which can further increase the risk of host competition with native unionid species.…”

“…It is most commonly observed in lowland freshwater environments, such as ponds, oxbow lakes, canals located on floodplains, and rivers that are slowly to moderately moving (0.05 to 0.3 m s −1 ), on muddy sediments where other native unionids are commonly present (Beran, 2008;Kraszewski & Zdanowski, 2007;Sarkany-Kiss et al, 2000). This species has been observed living in sympatry with native mussel species, such as the painter's mussel Unio pictorum (Linnaeus 1758), the thick-shelled river mussel Unio crassus (Philipsson, 1788), the swollen river mussel Unio tumidus (Philipsson, 1788), the depressed river mussel Pseudanodonta complanata (Rossmässler, 1835), A. anatina, and other mollusc species in the silt-clay substrate of lowland areas of the Danube River (Bódis et al, 2011(Bódis et al, , 2016Paunovic et al, 2006). The habitat preferences of S. woodiana are similar to those of several native freshwater mussels, which can further increase the risk of host competition with native unionid species.…”

“…Sinanodonta woodiana is native to two river basins in China, the Yangtze and Amur rivers, where it was primarily located before its expansion to different parts of the world, including Southeast Asia, Europe, North America, and the Caribbean (Kraszewski, ; Watters, ; Zieritz et al, ). This species is spreading quickly throughout European waters and has reached high densities in many rivers and standing water bodies, such as the Cris/Koros River basin in Romania and Hungary (Sarkany‐Kiss, ; Sarkany‐Kiss, Sirbu, & Hulea, ), Lake Balaton in Hungary (Benkő‐Kiss, Ferincz, Kováts, & Paulovits, ), the Danube and Tisza rivers in Hungary (Bódis, Tóth, & Sousa, , ), lowland rivers in Serbia (Paunovic, Csányi, Simic, Stojanovic, & Cakic, ) and the Czech Republic (Douda, Vrtílek, Slavík, & Reichard, ), channels with soft substrate in Italy (Cappelletti, Cianfanelli, Beltrami, & Ciutti, ), inter‐basin waterways in the Iberian peninsula (Pou‐Rovira et al . , ), and warmer water bodies in Poland (Kraszewski & Zdanowski, ).…”

The influence of the landscape structure within buffer zones, catchment land use and instream environmental variables on mollusc communities in a medium‐sized lowland river

“…the lower Havel River (Germany) (von Oheimb et al 2007). The Krąpiel River supports fewer alien mollusc species than very large rivers in terms of catchment area (Bo´dis et al 2012(Bo´dis et al , 2016Piechocki and Szlauer-Łukaszewska 2013).…”

A spatially explicit approach to prioritize protection areas for endangered freshwater mussels

“…In recent decades, severe declines in species richness and the abundance of freshwater mussels have been observed worldwide (Bogan, 1993;Haag, 2012;Howard, Furnish, Box, & Jepsen, 2015;Lydeard et al, 2004). The primary causes of population decline include habitat fragmentation and degradation, water pollution, the introduction of invasive species, and climate change (Bodis, Toth, & Sousa, 2016;Dudgeon et al, 2006;Lydeard et al, 2004;Regnier, Fontaine, & Bouchet, 2009;Strayer et al, 2004;Young & Williams, 1983). The loss of mussel populations may cause long-term ecological consequences to freshwater ecosystems because freshwater mussels often dominate benthic animal biomass in rivers, and provide various ecosystem services such as water filtration, nutrient excretion, and sediment stabilization (Boeker, Lueders, Mueller, Pander, & Geist, 2016;Lummer, Auerswald, & Geist, 2016;Richter, Stoeckl, Denic, & Geist, 2016;Vaughn, 2018).…”