T. G. Stoyko’s research while affiliated with Penza State University and other places

This review summarizes information on the main negative factors affecting the state of floodplain water bodies ecosystems, describes the most common consequences for abiotic and biotic processes, and suggests possible ways to conserve these ecosystems. Evidence of the negative impact of hydraulic construction, embanking of floodplains, channelizing of rivers, agriculture, and other anthropogenic impacts is presented. A special role is played by climate change, which leads to a decrease in flood inundation, drying and overgrowing of water bodies, and their eutrophication. The authors suggest criteria to choose correct indicators that can testify not only to special stages of water body succession (e.g., vegetation) or its trophic status (zooplankton), but also to the long-term effects of anthropogenic and climatic changes. As a recommendation, it is proposed not to consider water bodies separately, but to assess the whole waterscapes and use the change in β-diversity as an indicator. Further conservation strategies can be based on the approaches of the Red List of Ecosystems of the International Union for Conservation of Nature and Natural Resources (IUCN), which will help to draw attention to the problem. The key role for the conservation of floodplain water bodies should be played by territorial protection measures, up to the development of a separate category for small water bodies.

Trematode infection of the second intermediate hosts can lead to changes in their fitness and, as a result, a change in the invasion rate of animal communities. It is especially pronounced during the invasion of parasite species that reduce activity due to the manipulation of hosts through the changes of their morphology and physiology. One of these cases is an anomaly P syndrome hotspot found in some populations of water frogs and toads in Europe caused by the trematode Strigea robusta metacercariae. The occurrence of pathogen and their participation in ecosystems are intrigues questions in the anomaly P phenomenon, as well as the role of planorbid snails that serve as the first intermediate hosts for many trematode species. Herein, we focused on trematodes spectra from planorbid snails and amphibians from the anomaly P hosts with the aim to undetected interactions between the pathways of parasites. Emerging cercariae of 6802 planorbid snails of dominant species (Planorbarius corneus, Planorbis planorbis, and Anisus spp.) were detected by both morphological and molecular methods in seven waterbodies in Privolzhskaya Lesostep Nature Reserve (Russia). A total of 95 sequences of 18 species were received, and 48 sequences were unique and did not present in any genetic databases. The 18 species of trematodes from snails and 14 species of trematodes from amphibian hosts (Pelophylax ridibundus; Ranidae; Anura) were detected. Three species (Echinostoma nasincovae, Tylodelphys circibuteonis and Australapatemon burti) was new for the trematode fauna of the Middle Volga River region and Russia as a whole. Eleven species of parasitic flatworms have amphibians in their life cycles and nine species used amphibians as metacercariae hosts: Echinostoma nasincovae, E. miyagawai, Echinoparyphium recurvatum, Tylodelphys circibuteonis, Neodiplostomum spathula, Paralepoderma cloacicola, Macrodera longicollis, Strigea robusta, and Strigea strigis. The occurrence of trematode species from planorbid mollusks and frogs were compared.

Background. Lace bugs remain an insufficiently studied family of Heteroptera in Penza region. Materials and methods. The material was collected in meadow biotopes on the right bank of Penza reservoir. Other researchers in various regions of the Eastern European forest-steppe revealed these species earlier. Voronezh region is also inhabited by all four species presented in this work. D. longispina has not been recorded in Samara, Orenburg and Saratov regions. Results and conclusions. Four species of lace bugs – Stephanitis pyri, Dictyla rotundata, Oncochila simplex, Derephysia longispina – are registered for the first time in the Penza region.

Abstract. The factors infuencing molluscs distribution in a small steppe stream were investigated to assess the impact of beavers on their diversity and abundance. Twenty stations—in unafected streams, beaver ponds at diferent stages of development, and anthropogenic ponds—were sampled in May 2019 and June 2021. In each pond, a nearshore area of 1 m2 was completely surveyed using a dip net. Twenty-one mollusc species were found. Old and drained beaver ponds were characterized by signifcantly higher species richness. The damming of the river, by both humans and beavers, initially resulted in decreased species diversity, then followed by increased species richness due to increased habitat heterogeneity across the valley. Maximum gamma biodiversity was observed when the river habitats included all types of beaver ponds. When ponds were abandoned, a short-term increase in mollusc biodiversity and abundance was observed. Afterward, channel processes returned the habitats to a lotic state, habitat heterogeneity began to decrease, and mollusc community evenness dropped dramatically. To conserve the mollusc biodiversity of the stream valley, it is necessary for beavers to permanently renew some ponds.

The structure and dynamic of mollusk communities, as well as environmental factors influencing them, were analysed under conditions of small oxbow lakes in the forest-steppe zone (a case of the Khoper river valley, Penza region). 19 species of mollusks were found in the studied water bodies. The oxbows were characterized by relatively low alpha-diversity (number of species 4 ± 2) with relatively high beta-diversity (Jacquard index 0.26 ± 0.18), which is typical for floodplain ecosystems. Lake communities was dominated by Planorbis planorbis (40 %), Lymnaea stagnalis (15 %), Anisus spirorbis (14 %), Lymnaea saridalensis (9 %), Anisus vortex (8 %). The results of our analysis showed that the group of factors that determined the type of water body (stability, light intencity, water temperature, oxygen concentrations) had the greatest impact on the structure of malacocenoses. The seasonal dynamics of mollusk communities was determined by the number of adjoining water bodies, water temperature, and dissolved oxygen concentrations. The number of adjoining oxbows influenced species diversity the most, as well as the total number and biomass – isolation was more favorable for mollusk communities. The factors influencing the highest number of mollusks species (seven) were the light intencity and the presence of fish. Other significant factors were the stability of lakes (five species of mollusks), the number of oxbows and the transparency of the water (four species). Aquatic vegetation positively correlated with only one species – Anisus vortex. Our data suggest that the presence of fish could influence the abundance of Lymnaea saridalensis. The mollusks themselves, apparently, had a positive effect on the number of leeches in water bodies. The most sensitive to the factors were Lymnaea stagnalis, Lymnaea saridalensis, Aplexa turrita, Anisus spirorbis and Anisus leucostoma, the most tolerant were Bathyomphalus crassus, Anisus vortex, Planorbis planorbis, Planorbarius corneus

The mollusk fauna of beaver ponds on small steppe river on the territory of the Privolzhskaya Lesostep nature reserve (Penza oblast) is analyzed. 15 species of mollusks were found. The occurrence of 100% was noted for two species – Planorbarius corneus and Lymnaea stagnalis. The total number of mollusks averaged 59±54.9 ind./m2, biomass – 19.7±4 g/m2. The dominant species was Opisthorchophorus troschelii (45%), the subdominant one was Planorbarius corneus (24%). The relationships between the species richness of aquatic vegetation and the total abundance (R2=0.74) and the abundance of individual species were found – Opisthorchophorus troschelii (R2=0.84) and Physa fontinalis (R2=0.83). Water level fluctuations significantly correlated with the abundance and dominance of Musculium creplini (RS –0.92, p<0.05) and with the dominance of Planorbarius corneus (RS 0.90, p<0.05). The nearby oxbows of the Khoper river differed by a larger species richness (19 species), but the mean species diversity was slightly less (4±2). Differences in mollusk fauna between beaver and natural water bodies were statistically significant. Almost half of mollusk species of beaver ponds were not found in the lakes. Taking into account the disturbed water exchange of oxbow lakes with the river and their gradual degradation, beaver ponds are of great importance for the conservation of biodiversity of freshwater mollusks in the forest-steppe conditions.

The aim of our study was to identify the main abiotic factors that influence the biodiversity of forest-steppe oxbows in limnophase. Experiments were performed in 2016–2017 in Penza oblast, Central Russia. In addition to disturbed water exchange, isolated oxbows experienced such human influence as logging and plowing on watersides, and the construction of roads and mounds. Under those conditions, some water bodies became unstable and temporal, while others remained stable and were relatively unaffected. Higher light intensity in unstable oxbows led to higher plant diversity because of the mass occurrence of helophytes. However, the diversity of hydrophytes in stable oxbows remained higher, which contributed to higher vegetation coverage. This resulted in increased zooplankton diversity, which was also influenced by lower fluctuations in water level and oxygen level. Disturbed water regimes impacted organisms with a full aquatic life cycle (phyto- and zooplankton, fish). The diversity of unstable oxbows decreased due to their isolation from the river and from drying. The absence of fish may positively affect the abundance and biomass of benthos; however, we found no influence on zooplankton. Instability and high fluctuations in water level may lead to the high diversity of organisms that spawn in water. The higher diversity of benthos may also be influenced by the abundance of amphibian larvae which are a necessary food resource. In addition to predation, amphibians are at risk of mass larval mortality because of drying. Although the degradation of oxbows in limnophase is an undesirable consequence of anthropogenic impact, the coexistence of all types of oxbows is necessary to conserve the freshwater biodiversity of forest-steppes.