High-resolution color variations of Weichselian loess-palaeosol sequences in the Dnieper River basin (Ukraine)

<p>High-resolution colour analyses of key loess-soil sequences (LPSs) in the Ukrainian part of Dnieper River basin - one of the major European rivers and the largest river in the borderland between Central and Eastern Europe. The subject of the study were LPSs from the Last Glaciation with a thickness of up to 10 meters. The aim of our studies is to reconstruct the Upper Pleistocene paleogeographic transformations recorded in the Dnieper LPSs.</p><p>In our study area the causative geomorphological agent was dust was blown away by wind from the exposed surfaces rich in loose fine-grained material (e.g. from a wide valley of a big river) and deposited on the land surface as silt covers of different thickness and spatial extent; in warm (interphase, interstadial) periods of the Weichselian it was fixed by vegetation and was the parent rock for the successively developing soils of different pedogenesis types. In the Last Glaciation the zone of long (~1000 km) and generally sub-meridional valley of the Dnieper River was located in the peri- and extraglacial zone and characterized by strong spatial climate gradient depending on the distance from the ice sheet extent. In our times this river flows across several vegetation-landscape zones (forest→forest-steppe→steppe).</p><p>The spectrophotometer made it possible to carry out colour analyses of individual units distinguished within LPSs, taking into account a number of parameters such as: CIELAB color space variables L* (luminance, i.e. lightness [0-100]), a* (>0: red, < 0: green), and b* (>0: yellow, < 0: blue), derived parameters like the Redness Index (RI) and the RGB variables (min., max, average). The analysed LPSs showed relatively high variability of the above mentioned parameters reflecting activity of sedimentation processes (=primary loess) as well as pedogenic changes (soil horizons of different stratigraphic rank) and slope transformations (reworked material). The results of these analyses (presented mainly as curve lines and heatmaps) specify characteristics of environmental conditions of individual litho- and pedostratigraphic units. The advantage of the analysed parameters is their high sensitivity reflecting variability of environmental parameters having global, but also regional or even just local significance.</p><p>Research carried out as part of the grant of National Science Centre, Poland as the project no. 2018/31/B/ST10/01507 entitled “Global, regional and local factors determining the palaeoclimatic and palaeoenvironmental record in the Ukrainian loess-soil sequences along the Dnieper River Valley - from the proximal areas to the distal periglacial zone”.</p>

Distribution of epiphytic algae on macrophytes of various ecological groups (the case study of water bodies in the Dnieper River basin)

The generalization and analysis of original data have shown that the nature of epiphytic algae distribution on higher aquatic plants, representing different ecological groups, is very similar in various types of numerous water bodies in the Dnieper River basin. Their species richness and values of quantitative indices were mostly higher on submerged plants compared to plants of other ecological groups. The number of epiphytic algae species was 1.1-1.7 times higher on submerged plants compared to that on half-submerged plants and 1.6-3.1 times higher compared to plants with floating leaves. The taxonomic structure and species composition of epiphyton were very similar on half-submerged and submerged plants and moderately similar on plants with floating leaves compared to macrophytes of other ecological groups. It is emphasized that the specificity of epiphytic algae distribution on macrophytes of various ecological groups should be taken into account when performing monitoring and assessment of the ecological status of water bodies by the bioindication method.

Variation in morphological characters of the dice snake Natrix tessellata (Reptilia, Colubridae) in the Central and Southern Dnieper River Area

The dice snake Natrix tessellata (Laurenti, 1768) is one of the common snake species in the Southern Palaearctic and North Africa. In the Central and Southern Dnieper River basin the dice snake is one of the most numerous and characteristic species. Relative isolation and the varying influence of environmental factors are known to be a motive force behind epigenetic divergence between populations. In populations of N. tessellata this divergence can be manifest in the form of morphometric and phenetic peculiarities. Research into these parameters of dice snake populations in terms of anthropogenic influence on habitats along a latitude gradient is essential. In the Central and Southern parts of the Dnieper River basin such studies are of great importance for the monitoring of populations and for further indicative purposes. The aim of our study is to characterize the morphometric features of N. tessellata in this area and to determine the variability of these parameters in the snake populations under varying intensities of anthropogenic influence. The snakes were collected in 2013–2016 from the territory adjacent to the Prydniprovska Thermal Power Plant, from the Maiorova gully (Maiorka village, Dnipropetrovsk region) and the National Nature Park “Velykyi Lug” (Zaporizhia region). The following morphometric parameters were recorded: snout-vent length (SVL), tail length (TL), the number of ventral scales (V), and the number of subcaudal scales (SBC), the number of scale rows at mid-body (MBS), the number of supralabial scales (SLS), the number of temporal scales (TS), and the number of postocular scales (POS). All the tested parameters generally correspond to the limits known for this species from the literature. Nevertheless , some geographic peculiarities in variability of the tail length and number of subcaudal scales were identified. According to data from the literature, the southern populations of the dice snake are distinguished by an increase in the number of subcaudal scales . The studied dice snake populations were characterized by some sexual dimorphism in the snout-vent length, tail length and the number of subcaudal scales. A higher percentage of bilateral asymmetry in snakes from the population close to the Prydniprovska TPP was found. Such changes are usually considered to be an indicator of a certain destabilization of the embryogenesis.