New data on the morphology of Achnanthes brevipes (Bacillariophyta)

This electron microscopy study of Achnanthes brevipes from mineralized tributaries (Solyanka, Chernavka, Khara) of the hyperhaline Lake Elton (Volgograd Region) provides new data on the variability of quantitative diagnostic characteristics (valve length, number of striae and areolae in 10 μm). Based on the original and published data, a refined diagnosis of A. brevipes is proposed. It is very similar to A. longipes in valve shape and quantitative characteristics, but striae are multi-row in the latter species and single-row in A. brevipes. A short note about the nomenclature status of A. brevipes is given.

Benthos Algae Communities of Saline Rivers in the Lake Elton Basin: Taxonomic and Quantitative Structure

For the first time, an assessment was given of the taxonomic and quantitative structure of the phytobenthos of seven saline rivers in the basin of the hypersaline lake Elton (Volgograd Region). Main types of algacenoses developing on substrates were revealed, namely: diatom phytobenthos, communities of diatoms with cyanoprokaryotes, cyanobacterial films and mats, and epiphyton. The phytobenthos consists of local, mosaic-distributed communities with a small similarity of their species composition. The algacenosis structure is determined by Bacillariophyta (with the predominance of species of the genus Navicula) and Cyanoprokaryota (of the genera Phormidium, Leptolyngbya, and Geitlerinema). The abundance and biomass values vary widely, reaching their highest values (109,834–417,472 mln cells/m2 and 523.6–567.6 g/m2 ) in cyanobacterial communities of mesohaline rivers with their salinity up to 16–19 g/L. Mineralization as a factor influencing the structure of communities, most rigidly acts in the estuarine sections of rivers, by controlling the composition of the dominant species. For critical salinity values (> 70 g/L), characteristic structural transformations of communities by the type of replacement of planktonic and benthic Bacillariophyta and Cyanoprokaryota by planktonic Chlorophyta (of the Dunaliella genus) and picoplankton were established.

Carabid beetles of the environs of Lake Elton: fauna, population dynamics, demography

The present paper includes the results of a year-round pitfall trapping survey of ground beetles in the region of Lake Elton, Volgograd Area, Russia. The main objectives of the project lie in studying the local fauna of Carabidae in the Lake Elton region, as well as their demographic structure and dispersal potential of the local populations of particular carabid species. A total of ten model habitats: six zonal (characteristic of that particular biogeographic area) and four azonal (present in a variety of biogeographical areas) were studied. In each model habitat, ten pitfall traps were set from 10 May 2006 until 10 May 2007 and were checked at 10-day intervals except for the period with negative temperatures (from 1 November 2006 until 31 March 2007). During the period of observation, 51,314 specimens of Carabidae, belonging to 149 species, were trapped. The resulting sampling-event dataset includes 24,291 plot-based observations (= sampling events), some of them containing zero records of particular species in a certain habitat and time. This is the first sampling-event dataset of a year-round pitfall trapping survey (from May 2006 until May 2007) of ground-beetle communities and the demographic structure of local populations of particular species in the Lake Elton region, Volgograd Area, Russia.