Effects of hydraulic engineering restoration measures on invasive gobies in a large river (Danube, Austria)

Abstract

Invasive gobies can have severe detrimental effects on local fish communities, however, direct methods for population control are often insufficient (i.e. fishing) or not feasible (i.e. poisoning). Indirect methods, such as habitat modifications in the course of restoration programs, appear promising but are poorly studied. In this study, we investigate the effects of different restoration measures on the abundance and occurrence of non-native gobies in the main stem of a free-flowing section of the Danube and attempt to disentangle these measures from general large-scale trends by applying a Before-After-Control-Impact design. We found three invasive goby species (racer, bighead, and round goby) in the sampling area, partly with very high abundances. Four to six years after the installation, the measures had negative (riprap removal), neutral (side arm reconnection), or positive (groyne field adaptations) effects on goby abundances. We conclude that the impact of the measures depends on the type of intervention, is species-specific, and is largely related to substrate composition. Independent from the effect of the measures, abundances of bighead and round goby dropped in the project and reference sections after the pre-survey. This general decline probably indicates a stabilization phase of the goby populations on a lower level, but may also be influenced by a major flood event. Nevertheless, our results indicate a high potential of shoreline modifications for invasive species control, calling for considering and incorporating them in river restoration programs.

Water level induced changes of habitat quality determine fish community composition in restored and modified riverbanks of a large alpine river

“…Fishes are known to be fast colonizers of new aquatic habitats if those are fully connected, particularly when living conditions change seasonally (Pander et al, 2015b;Pires et al, 1999). Considering the abiotic differences between habitats and particularly seasons and results derived from lowland rivers (Erös et al, 2008;Meulenbroek et al, 2018;Ramler & Keckeis, 2020), a large difference in overall fish community composition between CP, BR, and RR as well as a strong seasonal change of community composition was expected. Surprisingly only the latter was observed in this alpine river and the strong seasonal differences detected were mainly attributed to higher spe- matching the observed times of spawning and subsequent larval drift (Nagel et al, 2021).…”

Flow, force, behaviour: assessment of a prototype hydraulic barrier for invasive fish

“…The round goby is a very successful aquatic invasive species that has populated numerous North American and European aquatic habitats (Kornis et al, 2012;Adrian-Kalchhauser et al, 2020). The upstream range expansion of this species into ecologically valuable headwaters is a severe environmental threat, that can lead to important and irreversible ecosystem impacts (Phillips et al, 2003;Myles-Gonzalez et al, 2015;Ramler and Keckeis, 2020;S ˇlapansky ´et al, 2020). Ensuring the passage of native species and impeding the passage of invasive species over river obstacles is a major challenge for decision makers and requires advances in integrated interdisciplinary research (Rahel and McLaughlin, 2018).…”

Regional Allocation Design and Efficiency Improvement of Rural Water Conservancy Project in China

“…Meanwhile, many scholars have analyzed the financing mode and management mechanism in the rural water conservancy construction in specific region. [3][4] From the perspective of view, the research can be divided into macro and micro levels.…”