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Workshop: Engaging people in conservation of crucian carp through a citizen science approach
No full textThe citizen science project “Save the Crucian carp” (zachrankarase.cz/en/) in Czechia represents a successful example of public engagement in freshwater fish conservation. Initially launched as a passive platform for collecting species presence tips from the general public, it gradually gained momentum. Remarkably, many participants went beyond reporting, becoming actively involved in breeding crucian carp in privately owned ponds. Some even voluntarily paid for genetic testing to verify the purity and lineage of the fish, supporting conservation of the two distinct phylogenetic lineages present in the country. This success story serves as a valuable model that could be replicated in other countries. A key step would be translating and adapting the Czech-language website and outreach materials for international use. In this workshop, our goal is to familiarize you with the potential challenges involved in reaching target audiences, filtering citizen-contributed data, and effectively communicating the project’s objectives. We will also explore strategies for engaging participants meaningfully, such as offering incentives or recognition to ensure sustained and impactful public involvement. Citizen science is gaining momentum in the conservation of freshwater fish species, serving as an effective bridge between professional scientists and target groups within society. Media plays a crucial role in fostering this connection. Developing a user-friendly mobile application supported by an informative website can significantly enhance this engagement. Such platforms facilitate the proper dissemination of information, raise awareness, and simultaneously enable the collection of valuable data from the public
Balancing risks and opportunities in ex situ conservation: host–parasite dynamics of the European weatherfish
No full textThe European weatherfish Misgurnus fossilis, once widespread across Eurasia, is now critically endangered in Flanders (Belgium), prompting the establishment of a captive breeding programme as part of conservation efforts. During rearing, juvenile weatherfish suffered heavy infections from the ectoparasitic flatworm Gyrodactylus fossilis, leading to mortality events. Although G. fossilis is a natural parasite of M. fossilis, high host densities in hatchery conditions facilitated pathological infection intensities, while adult fish maintained at lower densities showed no visible pathology. This suggests that husbandry practices strongly modulate dynamics of this host–parasite system in captivity. To place these observations in a historical context, we screened both captive-bred fish and archival material (1881–1973, i.e. prior to the anthropogenic introduction of Asian congeners in Misgurnus) for ectoparasites. Morphological and molecular characterisation revealed infections of three monopisthocotylan flatworms: G. fossilis, Gyrodactylus misgurni (Gyrodactylidae), and Actinocleidus cruciatus (Dactylogyridae). All represent new records for Belgium, with G. misgurni and A. cruciatus considered native due to their occurrence in historical material. Notably, these parasites’ abundance has declined compared to historical collections, raising concerns about their own conservation status. Since parasites contribute substantially to species-richness, ecosystem functioning, and even the health of their host individuals and populations (e.g., their immunological development and resilience) their co-decline alongside endangered hosts represents a hidden and meaningful dimension of biodiversity loss.Our findings highlight both risks and opportunities associated with parasite conservation in ex situ programmes focused on fishes or other vertebrate hosts. High juvenile stocking densities increased parasite burdens and mortality, while improved husbandry practices allowed stable co-existence of host and parasite populations. This indicates that carefully managed captive breeding facilities may act as refugia not only for M. fossilis but also for its specialist parasites, maintaining ecological interactions and genetic diversity that would otherwise be lost.While parasites are often overlooked or actively eliminated in wildlife management, they play essential roles in ecosystems and represent species of conservation concern in their own right. These results emphasise the possibility of including parasites in conservation planning. For the weatherfish and its parasites, ex situ conservation thus provides an experimental framework for developing integrated strategies that safeguard both host and parasite persistence. Future reintroduction initiatives should therefore consider whether to also re-establish native parasite populations, a decision that requires informed discussion among conservation stakeholders. By demonstrating the feasibility of host–parasite co-conservation, this study advances the idea that conservation programmes can optimise resource allocation while preserving the evolutionary and ecological relationships of multiple species simultaneously.This research was funded by an International Coordination Action grant of the Research Foundation – Flanders (G0ADU24N), by the AfroWetMaP project of the Belgian Federal Science Policy Office (4255-FED-tWIN-G3 program, Prf-2022-049) and by the European Life-program (Life-B4B). We gratefully acknowledge the support of Olivier Pauwels, curator of the vertebrate collections at the Royal Belgian Institute of Natural Sciences
Beyond the Net: Optimizing eDNA Sampling and Analysis for Challenging Muddy Habitats and the Endangered Weatherfish (Misgurnus fossilis)
No full textElusive and endangered species are prime candidates for environmental DNA (eDNA) monitoring (Duarte et al. 2023). The European weatherfish (Misgurnus fossilis) is one such species where traditional fishing methods may not yield conclusive results on its presence/absence. On the other hand, eDNA monitoring is less labour-intensive than conventional methods and may require only a small amount of water if species-specific qPCR/ddPCR markers are utilised (Thomsen et al. 2011, Sigsgaard et al. 2015, Kusanke et al. 2020, Brys et al. 2020). We aim to develop a standardised eDNA protocol that would provide additional information to traditional fishing surveys of Misgurnus . Such surveys are especially challenging in smaller vegetated waterbodies and wetlands in Central Europe where electrofishing, dip-netting, or fish trapping may not be feasible. As such, these wetland habitats are also among the most neglected European habitats despite facing considerable threats (Šmejkal et al. 2025). We are currently testing eDNA field sampling procedures and laboratory analyses that will be functional across all known M. fossilis haplotypes and tailored to the specific challenges of muddy-water habitats (e.g., collection farther from shore without stirring up sediment, clogging of filters after filtering small volumes, qPCR inhibition) and their mosaic distribution across the landscape. The latter poses challenges for large-scale monitoring campaigns where maintaining sample storage and transport at sub-zero temperatures in the field may not be possible. Non-frozen samples may be fixated, however, the use of fixatives increases the risk of contamination, limits the volume sampled (e.g., early fixated samples required 35 ml of fixatives (ethanol and sodium acetate) added to 15 ml of water; Ficetola et al. 2008), and such samples may have significantly lower DNA yields (Kusanke et al. 2020). The issues posed by the ethanol-sodium acetate fixation may be alleviated by using other reagents, such as lysis buffers, which allow eDNA preservation even in extreme conditions, e.g., remote localities in arid African savannas (Schenekar et al. 2024).The optimised protocol should be cost-effective and straightforward enough to be used by citizen science projects. The species-specific markers are primarily optimised to be multiplexed, allowing us to combine multiple markers from a single species to increase the probability of detection (Brys et al. 2023) as well as to simultaneously discriminate other co-occurring fish species, primarily the endangered crucian carp (Carassius carassius) (Šmejkal et al. 2025). Moreover, multiplexing lowers the cost and handling effort of analyses (Jo et al. 2019) and, by decreasing the necessary volume of eDNA sample used per reaction, increases the number of tests that can be performed on a single sample when DNA extraction volumes are low (Wozney and Wilson 2017). Multiplexing also allows for the addition of an inhibition-sensitive internal positive control (IPC). Further markers—such as those specific to invasive species of Misgurnus or Carassius—may be included to provide additional information on the current state of the localities in question. eDNA is a valuable tool for early detection of invaders present even at low densities (Jo et al. 2019, Jerde 2019) and, as such, may aid in monitoring invasive Asian weatherfish species, the spread of which is currently of high concern in Europe. Their early detection is crucial, as once established, the removal of invasive weatherfish is extremely challenging—the fish may remain alive buried in sediment for months even when the affected waterbodies are drained (Cano‐Barbacil et al. 2025)
Establishment of regional action plan for conservation of critically endangered crucian carp in Czechia
No full textThe crucian carp (Carassius carassius) occurs in two highly divergent phylogenetic lineages in Europe:the northern lineage, which is widespread across northern and central-eastern Europe and occurs in the Labe (Elbe) and Odra (Oder) river basins andthe Danubian lineage, which is restricted to the Danube basin.The crucian carp from both phylogenetic lineages are naturally present in Czechia. However, probably due to intensive aquaculture and transfers by recreational anglers, fish from different lineages have become mixed in some areas, or particular phylogenetic lineages have been translocated to other watersheds. Although we cannot rule out natural admixture, the conservation of crucian carp should treat these lineages as separate conservation units. In response, a Regional Action Plan (RAP) was developed to preserve the current distribution of phylogenetic lineages in the Vysočina Region and to prevent further unnatural admixture.A citizen science approach ("Save the crucian carp” project) was used to find the remaining populations. Individual populations identified through citizen tips were selected for systematic site monitoring, and samples were collected for further analyses. The lineage (northern or Danubian) of these populations was evaluated using genetic analyses, and suitable populations for conservation were selected. As part of the RAP, we initiated the repatriation of genetically verified crucian carp populations. We distinguished the two lineages genetically and repatriated the populations to their corresponding locations within their respective watersheds. In total, five and seven northern and Danube populations were identified, respectively and three and five northern and Danube populations were repatriated, respectively, using source fish coming from identified populations. This study provides a comprehensive conservation approach for a declining wetland fish species. Although regionally restricted to the Bohemian-Moravian Highlands, the approach can be applied to other declining wetland species with similar ecology and genetic diversity. The findings emphasize the need for a complex, multi-approach assessment of species threats and highlight the importance of managing conservation actions based on scientific evidence (Suppl. material 1)
Umbra krameri populations of the eastern edge of its areal: occurrence, state and eukaryotic symbionts
No full textThe European mudminnow, Umbra krameri, was a widespread fish in the lower reaches of the Dniester and Danube rivers in the first half of the 20th century. In the Dniester River, it was recorded from the junction of the Dniester and its Turunciuc branch to the estuary. Usually, now this endemic fish is found together with the weather loach Misgurnus fossilis and gibel carp Carassius gibelio. The factors that reduced its population were the construction of the Dubasari hydropower plant upstream in the 1950s and the embankment of the Lower Dniester wetlands to develop irrigated agriculture in the lower reaches of the river. After 1980, the hydrological regime of the Dniester in the spring was influenced by the Dniester hydropower complex in Ukraine, whose regime shapes the hydrology of the lower reaches of the river. Due to this, over the past 25 years, only small populations of this species have remained, recorded in the ditches of the Turunciuc branch near the Cuciurgan lake in the area of the village of Nezavertailovca, and water bodies connected to the Dniester on the border of Moldova and Ukraine south of the village of Palanca. Today, it is not easy to find it. Attempts to populate other suitable biotopes with fry obtained as a result of reproduction in aquariums were unsuccessful. Currently, U. krameri is listed in the Red Data Books of the region as most endangered (Moldova) and vulnerable (Ukraine), respectively. In the parasitologically surveyed individuals, inhabiting the lowers Dniester and Danube rivers basins, 176 species of the eukaryotic commensal/parasitic symbionts were revealed: The diversity of parasites of the Lower Dniester populations is much richer and different, compared with those of the Danube basin: although the populations from the Dniester have a rich community of parasites, some typical „Dniester species” are absent or very rare. Almost all identified species present a novelty for this fish-host and 12 of them were described as previously unknown. The parasite fauna of the examined U. krameri includes 18 host-specific species, one species common with U. limi and 12 species common with Esox lucius. The total prevalence of invasion of fishes was 100%. The maximum number of parasite species for one fish reached 18, and usually 4 - 8. Males were slightly more infested than females. The diversity and abundance of parasites adequately reflect the ecological state of the biotopes, their hydrobiocenosis, as well as the impact of the water hydrologic regime, i.e., the intensity of hydropower plants' water discharges. The infestation of U. krameri with symbionts wasn’t accompanied by fish morbidity or mortality. The parasitological situation of U. krameri populations inhabiting the eastern edge area is unfavourable and tense. The prevalence rate of U. krameri parasites is alarming; it is difficult to assume that such high values of infestation did not cause severe damage and even mortalities among fish. The carriage of many pathogenic parasites by this fish, under certain circumstances, may pose a potential threat to the survival of its unique populations of the Dniester River basin
Ex situ breeding and stocking of the European Weatherfish in Hungary and Romania
No full textThe weatherfish (Misgurnus fossilis) was first successfully bred by our research group in 2010. Since then, an induced spawning protocol combined with in vitro fertilization techniques has been applied, and experiments on sperm cryopreservation have also been conducted in this species. The stages and specific characteristics of embryogenesis and early larval development have been monitored and recorded. Larval growth and survival have been examined under various feeding regimes. It has been revealed that M. fossilis is capable of reproducing through parthenogenesis. Through further propagation of parthenogenetic offspring, F2 individuals exhibiting a unique hexaploid chromosomal structure—unobserved in natural populations—have been produced. In Hungary, approximately 2,000 individuals (both juveniles and sexually mature fish) were released into natural habitats during several stocking cycles between 2009 and 2016. Additionally, more than 16,000 individuals (larvae and juveniles) were reintroduced into the marshlands of the Olt River region in Transylvania (Romania) within the framework of a two-year conservation program. In 2024, we resumed our work related to the propagation of the weatherfish. These results contribute to the development of effective propagation, conservation, and reintroduction protocols for this protected and ecologically significant species
The Alien Invasive Fish Species of Muddy Waters in the Odra River Basin: Current Situation and Future Trends
No full textNon-native invasive fish species pose a significant and growing threat to the biodiversity and ecological stability of the Odra River basin. This abstract examines the current status and future trends of key alien species within the Odra, including the Prussian carp (Carassius gibelio), pumpkinseed sunfish (Lepomis gibbosus), topmouth gudgeon (Pseudorasbora parva), and brown bullhead (Ameiurus nebulosus). Their introduction and spread are primarily driven by human activities, such as intentional stocking for aquaculture and recreational fishing, as well as unintentional transfers. The establishment and success of these species are facilitated by their functional and ecological traits, including resilience to pollution and low-oxygen conditions, strong parental care, and a highly plastic diet. These invasive species are causing significant environmental changes. The topmouth gudgeon has been found in "enormous amounts" in fishponds and severely suppresses zooplankton populations, leading to a substantial decrease in native fish production. Similarly, the Prussian carp has rapidly enlarged its range and can negatively influence indigenous species, such as the native crucian carp (Carassius carassius), by directly competing for food and space. Other species, like the brown bullhead and pumpkinseed, also outcompete native species and prey on their eggs and offspring. Future trends suggest that ongoing human disturbance of natural landscapes and economic activities will continue to facilitate the dispersal and establishment of these species. To combat this, a multi-faceted approach is necessary. Proposed protective measures include restoring natural water retention areas and removing obstacles to enhance fish migration, thereby increasing the resilience of the river ecosystem. Ultimately, the long-term ecological impacts of these invasions necessitate urgent and sustained conservation efforts to protect the native biodiversity of the Odra River basin
Modeling of ferroelectric properties of KNN-based ceramics
No full textReplacement of highly noxious led zirconate titanate based materials in MEMS applications for environmentally safe materials remains an important task. Complex multicomponent doping of KNN ceramics provides for a significant improvement of their ferroelectric properties. The efficiency of different machine learning (ML) methods in the prediction of piezoelectric coefficient of KNN-based ceramics has been analyzed. ML integration allows one to accelerate the development of new materials and identify latent interdependences between their composition, structure, and properties. To understand the mechanisms of relationship between the composition and properties, we used the Sure Independence Screening and Sparsifying Operator (SISSO) method in combination with regression ML methods, such as Support Vector Regression, Ridge, Lasso, Elastic Net, Xtreme Gradient Boosting, Random Forest, Gradient Boosting Regression, and Extreme Tree Regression. The Gradient Boosting Regression (GBR) method proved to be the most efficient in combination with SISSO. The test sampling accuracy reached 81 %, and GBR validation for experimental data delivered a mean absolute error of 26 pC/N
Additions to the Entoloma (Agaricales, Entolomataceae) from China: Description of five species with one new to science
No full textEntoloma is one of the top three genera in species diversity of Agaricomycotina. In this study, five species from Qilian Mountain in China were documented. One new species E. griseopileum belonging to subg. Leptonia was introduced based on morphological and phylogenetic analyses. This new species is characterized by its gray basidiomes with fibrillose pileus and wood-decaying lifestyle. Four known species are E. glaucobasis, E. incanum, and E. verae in subg. Cyanula, and E. fuligineocinereum in subg. Nolanea. All five species are documented with descriptions, photo plates, and molecular data including ITS, LSU, and mtSSU sequences
A honey bee fossil (Hymenoptera, Apidae) from the Late Pliocene to Early Pleistocene Teragi Group, Hyogo Prefecture, Japan: Bridging a gap in Apis evolutionary history
No full textA new fossil honey bee Apis (Apis) aibai sp. nov. was discovered in the Late Pliocene–Early Pleistocene lacustrine deposit in Hyogo Prefecture, Japan. Fossil species are identified based on their distinct forewing venation, thick, lighter-colored abdomens, and hind legs. Honeybee fossils exhibit a highly uneven distribution across time. Fossil species are primarily derived from older Oligocene–Miocene deposits, mostly in Europe and China, while fossils of a few modern species have been recovered from younger Pleistocene and Holocene deposits. Apis (Apis) aibai sp. nov. bridges the gap between older and younger fossil records. Additionally, this species represents the most recent extinct honey bee and the oldest known record of the subgenus Apis