The status of the Danube River sediment regime and morphology as a basis for future basin management

The marbled crayfish, Procambarus fallax f. virginalis, is a taxon widely available in the aquarium pet trade, which has been introduced to open waters in several European countries and in Madagascar. Recent studies confirmed this parthenogenetically reproducing crayfish as a high-risk invasive species, and vector of the crayfish plague pathogen, Aphanomyces astaci. It has been first discovered in Slovakia in 2010, but the status of the local population was not studied since then. Due to enlarged sampling area around the first report and one locality, where we presupposed the crayfish occurrence, we identified new marbled crayfish populations. Here, we report presence of three newly established marbled crayfish populations in Slovakia. Two populations are located critically close to the Váh River, a major tributary of the Danube River; one of them being directly connected to the Váh River via a side channel during occasional floods. The third established marbled crayfish population was found at the mouth of a thermal stream flowing into the Nitra River, a tributary of the Váh River. In this stream, crayfish coexist with other exotic fish and gastropod species of aquarium origin. We presume that the reported localities may serve as a source for further expansion of the marbled crayfish in the mid-part of the Danube catchment. Floods, active dispersal (including overland), passive dispersal by zoochory or anthropogenic translocations are among the major drivers facilitating the marbled crayfish colonization. We have not detected the crayfish plague pathogen in any of the studied populations. However, if spreading further, the marbled crayfish will encounter established populations of crayfish plague carriers in the Danube River, in which case they may acquire the pathogen by horizontal transmission and contribute to spread of this disease to indigenous European crayfish species.

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Microbiological and Physico-Chemical Parameters of the Danube River (Romanian–Bulgarian Sector) with Ichthyofaunal Diversity

10.20944/preprints202101.0051.v1 ◽

2021 ◽

Author(s):

Mădălina-Andreea Ivan ◽

Carmen Curuțiu ◽

Nicolai Craciun ◽

Valentin Jujea ◽

Cristian-Emilian Pop

Keyword(s):

Point Sources ◽

Danube River ◽

Current Status ◽

Water Stream ◽

The Danube River ◽

Pollution Levels ◽

Physico Chemical ◽

The Status ◽

Point And Diffuse Sources ◽

Agricultural Areas

Water and water habitats are essential to life and to the wellness of the communities that rely on them, as the Danube river is subject to human impact and vice versa, periodic surveys are required to determine the status of its pollution levels. In this work we used known microbiological indicators as well as physico-chemical ones to assess the ecotoxicological status of the Danube river from eleven locations partially forming the “Romanian–Bulgarian Danube Sector”. Most of the microbial communities found, and their densities, could be explained by point and diffuse sources scattered along the sector such as discharged household and farm wastewater, as well as nearby agricultural areas where fertilizers have been used and then leaked in the water stream during rainfalls. However, microbial data on non-point sources that lead to diffuse pollution of surface waters could be linked to such parameters and furthermore shown a slight correlation with the current status of fish communities.

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Managing the world's most international river: the Danube River Basin

Marine and Freshwater Research ◽

10.1071/mf09229 ◽

2010 ◽

Vol 61 (7) ◽

pp. 736 ◽

Cited By ~ 37

Author(s):

Nike Sommerwerk ◽

Jürg Bloesch ◽

Momir Paunović ◽

Christian Baumgartner ◽

Markus Venohr ◽

...

Keyword(s):

River Basin ◽

Science Policy ◽

Expert Knowledge ◽

River Basin Management ◽

Danube River ◽

Basin Management ◽

Transboundary River ◽

The Danube River ◽

Transboundary River Basin ◽

Danube River Basin

Transboundary river-basin management is a challenging task emerging from lack of on-site expert knowledge, high administrative and socioeconomic complexity, various stakeholder interests, and difficulties enforcing international and national law. Therefore, an efficient ‘science–policy interface’ is a crucial ingredient for the successful development and implementation of adequate management strategies. The Danube River Basin (DRB) drains areas of 19 countries with different cultural, political, and environmental legacies. The European Water Framework Directive (WFD) has provided the guiding legal instrument for DRB management since 2000, supported by several multilateral agreements. The International Commission for the Protection of the Danube River (ICPDR) is responsible for the implementation of the WFD in the DRB. It stimulates management-oriented research and coordinates the various activities of the contracting parties and observers, including those of many NGOs and stakeholders. The development of the first DRB Management Plan in 2009 constituted a milestone of cooperation among scientific, political, and public organisations. Key stressors and pressures have been identified, a new basin-wide monitoring network has been established, and numerous conservation and restoration sites have been designated. A major challenge in DRB management will be to establish synergies among the competing interests of navigation, hydropower production, flood protection and nature conservation. This paper examines the strengths and weaknesses of DRB science–policy interactions and outlines future strategies for sustainable development of the DRB as a template for transboundary river basin management.

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