Limnology and Freshwater Biology

Subaquatic landscapes of Kenon Lake – the cooling reservoir of Chita TPP-1

Shoydokov A.B., Matafonov P.V. — Tue, 22 Apr 2025 00:00:00 +0800

Natural-technical systems are changing under the influence of climate and anthropogenic activities. Understanding the functioning of such systems is necessary in order to manage them and predict their development. The functioning of cooling reservoirs depends on climatic changes, changes in the level regime and the thermal effect of water discharge from thermal power plants. Understanding the geoecological situation in the bottom subsystem of a cooling reservoir is possible based on its study using a landscape approach. This approach is just beginning to be applied to the study of reservoirs. The purpose of the study was to identify and map the subaquatic landscapes of the main part of Kenon Lake. Six facies have been identified in the cooling reservoir of the Chita TPP-1. Facies differed in the type of bottom sediments, the presence of vegetation, the species composition of zoobenthos, as well as their quantitative and qualitative indicators. Facies are grouped into two types of landscapes. They differed in depth, type of sediments and composition of benthic invertebrates. The heated waters from Chita TPP-1 cause the formation of subaquatic landscapes in the northwestern and western parts of Kenon Lake. The results of the study show the current state of the main part of the subaquatic landscapes of Kenon Lake, formed under the influence of natural and natural-technical factors. It gives the opportunity to use geoinformation systems to analyze changes in the subaquatic landscapes and assess the geoecological situation in the bottom subsystem of the Kenon Lake.

Scanning microscopy of the oral appendages of Epischura baikalensis females (Copepoda,Calanoida)

Zaidykov I.Yu., Naumova E.Yu. — Tue, 22 Apr 2025 00:00:00 +0800

To date, there are difficulties in understanding the mechanism of capture of small particles, such as picoplankton, by representatives of Copepoda during feeding. In this regard, the morphology of oral appendages in Epischura baikalensis Sars 1900 (Copepoda, Calanoida) was studied using scanning electron microscopy (SEM). We obtained using scanning electron microscopy (SEM) some photographs of the mouth area of the endemic crustacean from Lake Baikal. Lobes of the labrum and labium, densely pubescent with long setae were described. The labrum and labium form a chamber around the esophagus, into which some pores open. It is assumed that through these pores, digestive enzymes are released into the oral cavity, contributing to the formation of a food lump. The article describes the peculiarities of the method of obtaining SEM preparations of E. baikalensis and discusses the role of the morphology of all oral appendages in the capture of food particles, including objects 1-4 μm in size.

Length-weight relationships and condition factors of Mormyridae species in the Niger River: implications for conservation and management

Souley S.M.N., Harouna M., Ado M.I., Youssoufa I. — Tue, 22 Apr 2025 00:00:00 +0800

The length-weight relationship and condition factor of the ten most abundant Mormyridae species in the Niger River at Niamey were examined from August to November 2023. The species assessed were Mormyrus rume, Campylomormyrus tamandua, Pollimyrus isidori, Brienomyrus niger, Hyperopisus bebe, Mormyrus macrophthalmus, Mormyrops anguilloides, Brevimyrus niger, Mormyrops oudoti, Cyphomyrus Psittacus, and Marcusenius cyprinoides. Analysis of their length-weight relationships revealed “b” values ranging from 2.08 to 2.87, suggesting negative allometric growth across all species. Condition factor (k) values varied from 1.22 ± 0.31 for H. bebe to 10.48 ± 2.83 for M. cyprinoides, with no significant differences in average condition factors among the species. These findings highlight the potential vulnerability of Mormyridae species to environmental changes and anthropogenic pressures, emphasizing the need for targeted conservation measures. The results underscore the importance of sustainable fisheries management practices to preserve biodiversity and ensure the long-term productivity of the Niger River ecosystem. The observed negative allometric growth patterns indicate that environmental conditions may be suboptimal for these species, potentially due to factors such as habitat degradation, water quality issues, or overfishing. Addressing these challenges through habitat restoration and regulatory measures could enhance the resilience of fish populations and support sustainable fisheries.

Genetic diversity of members of the genus Acinetobacter (Proteobacteria) from the intestine of Baikal omul Coregonus migratorius (Georgi, 1775)

Tue, 22 Apr 2025 00:00:00 +0800

For the first time, we analyzed genetic diversity of members of the genus Acinetobacter (Moraxellaceae, Pseudomonadales, and Gammaproteobacteria) in the intestinal microbial communities of Baikal omul from the Selenga population. The entire data array obtained through high-throughput sequencing contained 2.9% of the 16S rRNA gene sequences (18 amplicon sequence variants) belonging to the genus Acinetobacter. Phylogenetic analysis revealed that the used 16S rRNA gene fragment did not resolve the taxonomic identification to species level. Despite the formation of stable clusters, they contained different species of the genus. The presence of opportunistic species, such as A. lwoffii, A. johnsonii, and A. pittii, among the detected Acinetobacter and the absence of signs of disease in fish indicates favorable environmental parameters of the Baikal omul habitat on the wintering grounds in the pelagic zone of Lake Baikal.

Amphipods (Crustacea: Amphipoda) of Lake Ladoga

Barbashova M.A., Trifonova M.S. — Tue, 22 Apr 2025 00:00:00 +0800

Surveys conducted between 2019 and 2023 identified six out of the eight known amphipod species in Lake Ladoga, including two native (Monoporeia affinis and Pallaseopsis quadrispinosa) and four invasive taxa (Gmelinoides fasciatus, Micruropus possolskii, Pontogammarus robustoides, and Chelicorophium curvispinum). Two additional species (Gammaracanthus lacustris and Gammarus lacustris) remain rare in the lake and were not recorded in our samples during the study period. Spatial analysis highlighted distinct distribution patterns: native relict amphipods exhibited lower abundance in northern deep-water areas compared to southern regions, while invasive species dominated the littoral zone in terms of biomass. Monoporeia affinis reached densities of up to 21.26 g/m² in open waters, whereas Gmelinoides fasciatus prevailed in littoral habitats (31.32 g/m²). The Ponto-Caspian invaders Pontogammarus robustoides and Chelicorophium curvispinum remained restricted to Volkhov Bay, though C. curvispinum expanded its range within the bay. Notably, Micruropus possolskii demonstrated active northward and southward dispersal, with maximum biomass recorded along the western coast and Petrokrepost Bay (18.39 g/m²). These findings suggest that M. possolskii is likely to colonize the entire littoral zone of Lake Ladoga — Europe’s largest lake — and potentially spread to connected water bodies.