Harald Meimberg

River-floodplain systems are among the most impaired ecosystems globally, with severe impacts on associated biota. A key challenge in restoration is the limited understanding of natural metapopulation dynamics. The aim of the present study is to describe how a near-natural river network shapes the population structure of a limnophilic model fish species, the Southern-Balkan endemic Pelasgus thesproticus . Specifically, we aim to (I) infer population connectivity among floodplain habitats and (II) test environmental resistance driving metapopulation dynamics. Utilizing 30 anonymous nuclear markers and mitochondrial cytochrome b sequences, we genotyped 474 specimens from 13 sites in the Vjosa River system in southern Albania, one of the last free-flowing rivers in Europe. Population structure was inferred using clustering and distance-based approaches. The effects of riverscape properties on population connectivity were tested within a riverscape genetic framework. We found evidence for a strongly connected metapopulation linked to river network structure and flow. Gene flow was primarily directed downstream, and genetic differentiation increased with increasing distance to the mainstem. Restoring suitable habitats and hydrological connectivity are essential targets to re-establish functional metapopulations in impacted river-floodplain systems. Moreover, our study underscores the value of the few remaining near-natural rivers as reference conditions for studying natural ecological processes.

Genotyping by amplicon sequencing (GBAS) is a relatively low‐cost approach for generating genotypic data compared with established genomic methods, making it highly scalable and particularly suitable for large‐scale genetic monitoring projects. However, most existing analytical pipelines are either marker‐specific, insufficiently scalable, or lacking efficient data management systems for the long‐term integration of genotypic information, limiting the full potential of GBAS. Here, we address this gap by introducing GBAS‐GUI ( https://github.com/sonnenbe‐dot/GBAS‐GUI ), a pipeline capable of generating GBAS‐based genotypic data for a wide variety of loci at scale. GBAS‐GUI integrates a graphical user interface with multiple checkpoints to improve accessibility and robustness. It implements multiprocessing architecture and a relational database that links genotypic data with associated sample metadata to enhance scalability and data management. The pipeline further enables marker screening through automated calculation of polymorphism information content (PIC) and implements a strategy to recover homologous genotypic information from paralogous loci with non‐overlapping amplicon length ranges. Using multiple empirical datasets, we demonstrate substantial improvements in processing speed, database management and handling artefacts related to co‐amplification of unspecific regions and duplicates of the same genomic region. We further show that incorporating the full sequence information captured by an amplicon increases marker information content beyond what is achievable with length‐based genotyping alone and expands the analytical versatility of GBAS. Overall, GBAS‐GUI provides a robust, scalable and versatile framework that unlocks the potential of GBAS for large‐scale population genetic and phylogeographic studies.

Oreochromis species are of economic importance in fisheries and aquaculture but threatened by human‐mediated activities. Effective conservation and their sustainable management require genetic monitoring tools that can assess genetic variation across species. Various neutral markers have been used to monitor biodiversity in organisms, but they are limited in cross‐amplification among various taxa. Non‐neutral markers such as Exon‐Primed Intron Crossing (EPIC) not only cross amplify various taxa but also target gene regions that are likely to be involved in adaptive responses to selective pressure. This study therefore developed 50 EPIC markers from Oreochromis niloticus reference genome targeting immune related genes to assess their potential to cross‐amplify Oreochromis species. Genetic diversity, population structure, and differentiation was measured among Oreochromis niloticus , O. jipe , O. esculentus and O. leucostictius species and their respective populations from eleven African water bodies and two aquaculture farms. 45 EPIC markers successfully amplified target regions across the four Oreochromis species. O. niloticus exhibited the highest diversity (He = 0.50), followed by O. jipe (He = 0.29), O. leucostictus (He =0.28) and O. esculentus with the lowest (He = 0.25). The highest differentiation values were observed among populations of different species while the lowest was among farmed O. niloticus . This was supported by AMOVA results that showed highest genetic differentiation among species. Population structure analyses were concordant with species boundaries while showing detailed intraspecific clustering patterns among the O. niloticus populations that reflected geographical origin. The observed genetic diversity, gene flow, and population differentiation confirms the applicability of EPIC markers as molecular tools for monitoring biodiversity and guiding the conservation of Oreochromis species under increasing anthropogenic and environmental pressures.

Background: A 33-year-old pregnant woman experienced ear trauma from contact with a fish while swimming. Afterwards, the woman presented with vertigo and hearing loss. Methods: Clinical examination showed a foreign body (FB) in the middle and inner ear, which was removed surgically under general anesthesia. Postoperative care included antibiotics; the FB was sent to the lab for analysis. Results: Although vertigo resolved after surgical intervention, the woman continued to experience hearing loss and finally experienced deafness. Patient had an unusual mechanism of inner ear trauma. The FB was identified as part of a fish and determined to originate from a fish species of the genus Hemiramphus which is listed as harmless to humans in FishBase. Conclusions: As severe penetration of an FB into the middle and inner ear can lead to serious complications, removal of an FB from the ear requires special competence and should therefore only be performed by specifically skilled professional staff.

Fragmentation of wildlife habitats by anthropogenic landscapes is a common cause of habitat degradation, highlighting the need to increase connectivity to support wildlife populations. This study focuses on the Eastern green lizard (Lacerta viridis) and investigates the effectiveness of a species‐specific established corridor network in allowing lizards to move between isolated habitat sections in a vineyard landscape. Using a non‐invasive photographic capture‐recapture approach, individual movements were tracked to assess sex‐specific patterns and distances covered in adult lizards. The study also provided insight into population parameters such as sex ratio and spatial distribution of the resident green lizard population. Results showed a surplus of male individuals and clustered distributions along the habitats. Both male and female green lizards use the habitat network, with males covering larger distances. The connectivity structures facilitated the movement of males between habitat sections, with some individuals covering distances exceeding 250 m. Hereby, male movement distances correlated with female abundance, which emphasizes the importance of connectivity structures in maintaining population stability. Two parameters correlated to female abundance showed significance in the models. First, the fewer females were detected in a male's core area, the higher the probability that it migrated a long distance. Secondly, a positive correlation existed between males' covered distance and female abundance in their entire activity range. Overall, this research highlights the importance of habitat connectivity measures for natural population dynamics by supporting male lizards to migrate in search of females.

Species syngameons are groups of more than two hybridizing species that form complex hybrid networks. Syngameons facilitate sharing the gene pool among species while maintaining morphological differentiation. In oceanic islands, hybridization is common, and syngameons are expected to be common and play an important role in increasing standing variation in the face of the founder effect associated with the colonization process. The mechanisms of how these syngameons are formed and maintained, the impact islands' geological history has on syngameons, and their evolutionary consequences remain unknown. Using the genus Micromeria (Lamiaceae) in the Canary Islands as an example, we aim to describe the structure of the syngameons and evaluate if it varies across island age, taxa, and genomic region. For this, we used 14 Exon primed intron spanning (EPIC) nuclear markers and 12 chloroplast (cpDNA) markers to conduct phylogenetic and genetic diversity analyses. The results show that species in younger islands have higher genetic diversity and share haplotypes with more taxa than species in older islands. Moreover, widespread taxa have higher intraspecific connectivity than taxa with narrower distributions. These findings suggest that species syngameons are larger and more complex in younger islands and that widespread taxa are key players in maintaining them. This pattern and phylogenetic signal were not consistent across loci and genomic compartments, indicating that different genomic regions may show different perspectives on syngameons dynamics. This study provides evidence that island ontogeny, degree of evolutionary divergence, and species distribution range shape the formation, expansion, and maintenance of syngameons.

DNA barcode databases for marine invertebrates faces significant challenges, with several species revealing taxonomic issues like misidentification, ambiguity or shared barcodes. This highlights the importance of the availability of robust genetic data to resolve taxonomic uncertainties and improve species identification, which in many groups of invertebrates, like crustaceans, is lacking. Based on molecular data from the Cytochrome c oxidase I 5′ gene region (COI) for barcoding, this study highlights some of these challenges by addressing existing taxonomic ambiguities and highlighting the scarcity of genetic data for several of the shore crab genus Pachygrapsus Randall, 1840. As expected, molecular data availability is highly skewed towards taxa more prevalent in the Northern Hemisphere. Our analysis reveals a clear barcoding gap amongst Pachygrapsus species, with average interspecific p-distances of 18.75%, exceeding previously reported values for crustaceans. Furthermore, high intraspecific variation (0.70% average) suggests potential taxonomic issues, particularly within P. gracilis (de Saussure, 1857). East and west Atlantic P. gracilis populations exhibit substantial divergence (3.6% p-distance), raising the possibility of ongoing speciation due to limited gene flow across the Atlantic Ocean. Similarly, populations of P. crassipes in the east and west North Pacific exhibit substantial divergence (3.3% p-distance), which suggests possibly another speciation process. COI barcoding proves effective for species identification within Pachygrapsus and in unravelling intraspecific patterns indicative of cryptic diversity guiding further taxonomic revisions integrating morphological, genetic and ecological data.

Rivers and streams are critical components of ecosystems, providing essential resources and supporting diverse aquatic life. Rivers have different physical and chemical characteristics based on geology, latitude, longitude, and climate. These factors influence the aquatic taxa composition and their sensitivities to ecosystem degradation gradients. Assessing the health of these aquatic ecosystems is vital for effective conservation and management. In recent years, there has been growing interest among East African countries to develop and adapt nationwide frameworks for the assessment of ecological integrity based on benthic macroinvertebrates as bioindicators of streams and rivers. Nevertheless, current initiatives have not resulted in binding policy and standardized protocol. Scholars realize the lack of baseline research in the spatial and temporal variation of abiotic and biotic components of East African Rivers, which are the foundation for development and integration of biomonitoring techniques. This review article explores the commonly used bioassessment techniques applied to river ecological integrity assessment, their strength, challenges, and opportunities in their application in East African contexts. It builds on these findings to propose a systematic pathway that begins at the national level but is standardized towards the development of a comprehensive policy-level bioassessment framework for the Afrotropical region.

Cage fish farming, a recent development in aquaculture, has enhanced fisheries production due to its higher stocking densities than traditional pond and open-water systems. Although it can enhance production, the system can pose biodiversity threats when there is an unintentional or intentional release of stocked fish into the wild. In this review, we examine the expansion of Nile tilapia (Oreochromis niloticus L.) cage aquaculture in Africa and the potential threats that this may have on congeneric Oreochromis species. Threats such as interspecific competition, disease transmission and hybridisation, which are drivers of genetic diversity loss among native fish populations, have been reported. However, most studies have focused on investigating cage fish production, water quality and the associated economics, but research assessing the genetic and ecological impacts imposed by the escaped fish from cages on native species is still limited across African countries. While direct evidence of hybridisation due to cage fish farming is lacking, genetic mixing of Nile tilapia with native Oreochromis species has been reported in some African water bodies. Further, only Egypt, Kenya and Uganda have functional Fisheries and Aquaculture regulations for guiding the aquaculture activities. Thus, there is an urgent need to institute regulatory frameworks that not only provide clear guidelines on aquaculture production but also balance between environmental conservation and economic sustainability

Microsatellites (SSRs) are reliable markers for population genetic analyses but often suffer from null alleles caused by mutations in primer binding sites. Exon‐primed intron‐crossing (EPIC) markers address these limitations and serve as a complementary tool. In this study, we developed SSR and EPIC markers for the green toad ( Bufotes viridis ). We demonstrated their effectiveness using genotyping by high‐throughput amplicon sequencing (GBAS) across urban and rural populations. Marker development followed an established in‐house protocol. We then tested their functionality in singleplex‐PCRs before employing them in multiplex reactions and preparing them for sequencing. We analyzed the resulting data using several variability measures as well as individual‐based clustering methods. From the initial set of 48 markers of each type, 35 SSR and 46 EPIC markers consistently amplified across samples both in singleplex and multiplex assays. Data analysis did not corroborate the expectation of a continuous reduction of diversity in urban populations compared to rural ones. Clustering methods using EPIC markers revealed ecologically coherent results, showing weaker genetic structure in rural environments, whereas the SSRs' signal reflected drift‐induced patterns. Our findings suggest that the green toad exhibits a degree of resilience to urban environments. Furthermore, EPIC markers not only complement SSRs by having fewer null alleles but also provide greater robustness to random drift events. We recommend their combined use, especially in fragmented environments prone to genetic drift, such as urban areas.