During the three decades following the publication of the first comprehensive monograph on the European mudminnow ( Umbra krameri Walbaum, 1792), knowledge of the species’ biology, distribution, genetics, ecology, and conservation has expanded substantially. In several countries, a dynamic distribution pattern has become apparent, with many local populations seemingly disappearing while new populations continue to be documented. However, many of these newly recorded occurrences likely represent previously overlooked remnant populations rather than genuine range expansions. Despite the uncertainty associated with detectability, the overall distribution pattern of U. krameri clearly reflects a large-scale process of range contraction and habitat fragmentation across most of its native range. Recent phylogeographic and population genetic studies have fundamentally improved understanding of the species by revealing pronounced drainage-based structuring, limited contemporary gene flow, and the existence of distinct evolutionarily significant units (ESUs). At the same time, the development of genomic resources, complete mitogenome assemblies, and environmental DNA (eDNA) approaches has created entirely new opportunities for monitoring and conservation. Numerous studies have also advanced knowledge of habitat use, trophic ecology, population dynamics, and conservation management, while conservation breeding and translocation programs have been initiated in several countries across the species’ range. Considering the threats affecting the species, together with the documented population declines and numerous local extinctions, its current IUCN Red List status should be reassessed and upgraded from Vulnerable to Endangered, or possibly even Critically Endangered.

Floodplain specialist fishes have undergone disproportionate declines across Europe due to river regulation and groundwater alteration. The European mudminnow ( Umbra krameri ), now Critically Endangered in Austria, persists naturally in only two isolated populations (Fadenbach, Jesuitenbach). Field surveys were combined with microsatellite analyses to assess population structure and genetic diversity in both wild populations and in four ex situ stocks established from Fadenbach. Wild populations were strongly differentiated, indicating prolonged isolation without contemporary gene flow. Despite marked demographic fluctuations and recent habitat desiccation, both populations retained moderate levels of heterozygosity and showed no significant signal of a recent bottleneck. Whereas the estimated contemporary effective population size was critically low for the Fadenbach population, no robust estimate could be obtained for the Jesuitenbach population. All ex situ populations derived exclusively from Fadenbach and collectively retained their allelic diversity, yet showed significant divergence from one another due to founder effects and drift. These results thus identify two genetically distinct conservation units and reveal acute vulnerability masked by currently stable diversity metrics. Securing U. krameri in Austria will require hydrological restoration of suitable habitats, protection of both wild populations, and coordinated genetic management integrating in situ and ex situ conservation.

The Alpine salamander (Salamandra atra) is a cold-adapted amphibian with low dispersal capacity, endemic to the Alps and Dinarides. Isolated populations at the range’s margins are especially vulnerable to habitat fragmentation and genetic erosion. We investigated the population genetic structure of S. atra in the Koralpe, a biogeographically important mountain range in southeastern Austria. Using mitochondrial DNA, we found that the Koralpe population harbors unique genetic variants not shared with other known populations. Strong genetic differentiation and low connectivity among Koralpe subpopulations, inferred from microsatellites, indicate long-term isolation, likely caused by unsuitable intervening habitats and the species’ limited dispersal capacity. Although the estimated effective population size (Ne = 245) is moderate and no severe genetic bottlenecks were detected, subpopulation sizes are likely small. These findings highlight the conservation value of this peripheral population and support its recognition as a distinct management unit. In situ protection, improved landscape connectivity, and continued (genetic) monitoring are essential for the population’s long-term survival. Given its unique genetic signature and pronounced structuring, targeted conservation measures are critical—especially under increasing pressure from climate change and habitat degradation. Preserving this isolated lineage will contribute to local biodiversity and help safeguard the evolutionary potential of S. atra as a whole.

The European Mudminnow ( Umbra krameri )—a species adapted to slow-flowing, oxygen-poor backwaters and marshes with dense vegetation—was declared extinct in Austria in 1975. However, it has since been rediscovered at two isolated sites: Fadenbach in the Nationalpark Donau-Auen and Jesuitenbach. Captive breeding programs have since been initiated to support reintroduction and safeguard remaining genetic diversity. To inform conservation strategies, we assessed genetic diversity, structure, and effective population sizes (Ne) using polymorphic microsatellite markers. Preliminary results reveal significant genetic differentiation between the two wild populations and between captive stocks and their presumed source in Fadenbach. Overall genetic diversity is low, and Ne estimates suggest a high risk of inbreeding, genetic drift, and further loss of adaptive potential. Although sample sizes are limited, these findings point to critical conservation concerns, especially for the Fadenbach population. Importantly, this study emphasizes the utility of genetic monitoring as a central tool for evidence-based conservation planning—supporting adaptive management, preventing further genetic erosion, and promoting the long-term survival of this critically endangered species in Austria and beyond.