Running beetle as indicators for the management of the Enns- and Johnsbachufer in the NP Gesäuse

The high number of species and the presence of many rare and endangered species are due to the considerable structural diversity of sediment banks. Due to the predominance of blocky and bulky grain sizes, morphologically adapted specialists dominate cavity and column-rich gravel benches and, in the case of Bembidion complanatum, Bembidion conforme and Bembidion longipes, reach stock sizes of supraregional conservation importance. Deviations from the mission statement, on the other hand, concern representatives of the Sandufer specialists. The species to be expected are largely present, but strongly underrepresented in terms of settlement densities. The sharp decline or failure of Bembidion foraminosum, a species once very common in the area, is evident as a particularly drastic example. Daily fluctuations in water levels caused by energy-related measures, mainly caused by the Großsölk power plant, are the most important impediment to the river beetle fauna. While vertically structured gravel banks and their fauna are little affected, they cause significant impairments in the area of shallow shore structures. These are expressed on the one hand in permanent, unpredictable floods and, on the other hand, constipation of cavities as a result of the deposition of fine-grained, muddy sediments. Similar impairments occur as a result of excessive gravel removal in the area of lateral trenches. Thus, despite the presence of extensive and structurally rich habitats, the runetle fauna at Johnsbach in the area of influence of the Langgriesgraben is severely impoverished. Tourism uses are another impediment factor. While rafting and canyoning cannot be expected to have a lasting impact on the fauna under the current intensity of use, the uncontrolled admission of sensitive sediment bank structures could very well lead to the decline of rare and endangered beetle species. Visitor steering measures are therefore proposed for the areas Haslau, Johnsbach estuary, Finstergraben and Schneiderwartgraben. As a summary of the deficit analysis, there is also a need for flux-building measures. These would be suitable in the form of restructurings or expansions, especially in the area of the Johnsbach estuary and at the Enns between Admont and Gesäuse Entrance, to initiate the formation of sandy shore structures. Whether the measures to be implemented would have to promote the target species would have to be reviewed in the foreseeable future in the course of monitoring.