Following recent population-genetic analyses involving additional specimens, we identified an error in the species identification of Macrobrachium specimens collected at Lipót, Hungary. The specimens were originally identified as Macrobrachium nipponense (De Haan, 1849), but additional molecular analyses demonstrated that they belong exclusively to Macrobrachium dayanum (Henderson, 1893). The misidentification most likely resulted from the mislabelling of the sample during laboratory processing. Consequently, the Lipót population should not be considered an occurrence of M. nipponense . Instead, it represents the first documented record of M. dayanum in the country and, based on currently available evidence, its second established population in Europe. The COI sequences originally reported under GenBank accession numbers PQ883994 and PQ883995 correspond to M. nipponense specimens from Passau, Germany, and not to the Lipót material. A new accession number PZ937962 for the M. dayanum specimens from Lipót is provided in this corrigendum.
The invasive pink salmon ( Oncorhynchus gorbuscha Walbaum, 1792) is extending its distribution across the North Atlantic region, and important questions need to be answered in terms of spread, potential impacts, and threats to ecosystems and native species. To find evidence of pink salmon reproduction in Sweden, environmental DNA (eDNA) sampling and electrofishing were conducted in rivers along the Atlantic coastline. Pink salmon were detected in four out of five monitored rivers by use of eDNA from February to May 2024, albeit in low concentrations. No pink salmon were captured by electrofishing, and this method was largely unsuccessful due to flooding events and turbid waters. These findings provide the first indication of juvenile pink salmon presence in Sweden and represent the southernmost recorded eDNA-based detections of possible pink salmon reproduction in Europe and the North Atlantic. Further monitoring and research using eDNA are recommended to gain a comprehensive understanding of the recruitment and establishment of pink salmon in Sweden and other countries in the North Atlantic region.
The parasite fauna of the Chinese sleeper ( Perccottus glenii ), one of the most successful invasive freshwater fish species in Europe, reflects the successive stages of its biological invasion. To assess the ecological integration of this invasive host into recipient ecosystems, it is essential to understand the parasite colonisation processes associated with it. However, data on the molecular diversity of cestode parasites associated with Chinese sleepers in the Danube Delta remain scarce. This study investigated the parasite fauna of Chinese sleepers in the Ukrainian part of the Danube Delta (Vylkove canals) and analysed the genetic diversity of larval cestodes using COX1 mtDNA, 28S rDNA, and 18S rDNA markers. Eight parasite taxa were recorded, comprising both co-introduced host-specific parasites ( Gyrodactylus perccotti , Nippotaenia perccotti ) and locally acquired species. Molecular analysis of plerocercoid larvae recovered from fish mesenteries confirmed their identity as Ophiotaenia europaea , clearly distinguishing them from Ophiotaenia saphena concurrently recorded from Pelophylax ridibundus in the same locality. COX1 p-distances between the two species reached 15.4%, consistent with species-level differentiation. Phylogenetic analysis revealed geographic structuring within O. europaea , with Ukrainian specimens grouping more closely with Bulgarian than with Central European sequences. These results confirm the role of the Chinese sleeper as a paratenic host for O. europaea in the Danube Delta and highlight the complexity of cestode transmission pathways associated with this invasive fish.
Water-level regulation (WLR) in hydropower-regulated reservoirs can severely degrade littoral zones, reducing habitat availability, biodiversity, and ecosystem functions. Effective mitigation measures are therefore needed. The lake-in-reservoir (LiR) approach mitigates WLR by creating a partially separated sub-basin within or adjacent to a reservoir to dampen water-level fluctuations, potentially offering refuge for sensitive species and supporting rehabilitation of degraded littoral habitats. This review synthesizes available evidence on LiR implementations, ecological responses, and the factors shaping their performance. A structured literature search identified seven documented LiR implementations in Sweden and Norway, of which five were supported by sufficient data for ecological interpretation. Across cases, LiRs supported more stable and productive littoral habitats, with positive responses observed in macrophytes, invertebrates, fish, and waterbirds. However, outcomes varied among sites, and target species did not always benefit. The evidence base remains limited, geographically restricted, and dominated by short-term monitoring, constraining broader inference. Effectiveness also appears to depend on factors such as reservoir morphology and hydrology, weir design, and biological interactions among species. Despite these limitations, LiRs represent a promising yet underexplored approach for supporting biodiversity and productivity in reservoirs, functioning as a targeted, site-specific rehabilitation measure rather than a substitute for system-level hydrological reform. Further research is needed to evaluate long-term ecological outcomes, assess transferability across systems, and develop design principles to guide future applications.
Abstrac Harmful cyanobacterial blooms are an increasing threat to freshwater ecosystems worldwide; however, the role of macroalgae in regulating these blooms remains poorly understood. This study investigated the effects of Cladophora glomerata and its allelopathic potential on the biomass of Planktothrix agardhii and microcystin concentrations across two growing seasons in the shallow hypertrophic Lake Łekneńskie, Poland. Phenolic content in water strongly correlated with phenols in Cladophora extracts and showed the strongest negative association with cyanobacterial biomass among all tested predictors, although this effect appeared most visible early in the season. Water temperature and P. agardhii biomass were the primary predictors of extracellular microcystins in water. Intracellular microcystins were negatively associated with phenols and positively with chlorides. All effects showed significant seasonal variation. These findings suggest that C. glomerata may be associated with reduced cyanobacterial biomass in an aquatic ecosystem through allelopathic mechanisms, although this potential appears to be dependent on environmental conditions and the phenological stage of development. However, cause-and-effect associations still require experimental confirmation.
