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

Abstract Background 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. New information 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.


Abstract Background
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 2006until 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.

Introduction
The fauna of ground beetles (Carabidae) of the Lower Volga Region is well studied and includes at least 460 species (Kalyuzhnaya et al. 2000, Komarov 2002, Komarov 2020. However, information about their habitat distribution is scant, while data on the development of particular species are almost absent (Matalin and Makarov 2008). Along a gradient of variable natural conditions within the Lower Volga Region, the landscapes surrounding the hyperhaline Lake Elton are very special. Collecting ground beetles and making information on the dynamic abundance (estimated by the number of individuals caught in soil traps per species over a certain period of time) public and available, as well as studies on the demographic structure of local populations of particular species occurrences in the most typical habitats of the Lake Elton Region (Fig.  1), were the main objectives of our work. Fieldwork was carried out in 2006-2007, with the data converted in the Darwin Core format in 2020. Map of the sampling sites in Lake Elton region.

Sampling methods
Study extent: Pitfall traps were set in ten model habitats: six zonal, characteristic of this particular biogeographic area and four azonal, present in a variety of biogeographic areas.

Sampling description:
The demographic structure of the local populations of particular ground beetle species was studied in ten model habitats described above. Plastic pitfall traps of 0.5 l capacity and 95 mm upper diameter containing 4% formalin as a fixative were used. In each habitat, ten traps were arranged along a transect at 10 m intervals. Due to the high daily air temperature and low air humidity, the fixative content was increased to 3/4 of the trap's volume. The traps were set from 10 May 2006 until 10 May 2007 and were checked at 10-day intervals on the 10 , 20 and 30 (31 )  The life cycle of particular species was reconstructed according to the chorological series in each local population. In 'spring breeders', such chronological series are represented by: immature of parental generation after hibernation → mature of parental generation → spent of the parental generation → teneral of a new generation → immature of the new generation prior to hibernation (Figure 1 in Matalin and Makarov 2011). In 'autumn breeders', the chronological series is as follows: teneral of the parental generation → immature of the parental generation prior to aestivation → immature of the parental generation after aestivation → mature of the parental generation → spent of the parental generation prior to hibernation (Figure 1 in Matalin and Makarov 2011). In other 'autumn breeders', the same order of physiological conditions of the adults was observed, but without an aestivation parapause. The dispersal capacities of individual species were estimated according to the condition of hind wings and wing muscles. We recognised macropterous, brachypterous and apterous species (Fig. 12), as well as dimorphic species when in the local population both macro-and brachy-/apterous specimens were found. Moreover, in all species, three states of wing muscles were observed: functional (100% th th th st Figure 11. Sagebrush-grassland desert steppe (line 10) in spring, summer and in autumn.

Geographic coverage
Description: Lake Elton is situated inside the blind drainage Botkul-Bulukhta Desert Depression, which belongs to the Caspian Lowland (Fig. 1). The banks of Lake Elton are located 4.2-9.5 m below sea-level. A strongly-pronounced salt-dome structure is characteristic of this region. The largest salt-domes are located on the eastern (Ulagan Mountain, altitude 68.0 m) and western (Presnyi Liman Hills, altitude 43.6 m) lakesides. Seven rivers discharge into Lake Elton: Khara, Solyanka, Chernavka and Lantsug from the northwest and Karantinka, Bol'shaya and Malaya Smorogda from the southeast (Nekrutkina 2006). All these rivers are characterised by high levels of water mineralisation which range from 0.3 to 35.6 g/l (Gorelov et al. 2006). The study area is located at the borders between several natural-climatic zones. Thus, its landscape-zonal typology is still debated. According to some authors (Safronova 2006), this general area belongs to the steppe zone but, according to others (Sapanov and Gabdullin 2006), to the semi-desert belt. Despite this, desert steppes are typical plant associations in most of the habitats; on salinas in floodplain terraces and in lakeside salt-marshes, hyper-halophilic communities are formed; dense reed-beds occur in the river valleys; in gullies on lakesides, there are trees and shrubs (Safronova 2006 ) sampleSizeValue number of traps, 10 in all cases (Event table) sampleSizeUnit traps (Event table) decimalLatitude Geographic latitude (Event table) decimalLongitude Geographic longitude (Event table) geodeticDatum Geodetic datum, WGS84 in all records (Event table) countryCode Country code, RU in all records (Event table) occurrenceID Unique identifier of a particular observations of each species within a trapping ( Occurrence  ) The name of the lowest or terminal infraspecific epithet of the scientificName coordinateUncertaintyInMetres (Event table) The horizontal distance (in metres) from the given decimalLatitude and decimalLongitude describing the smallest circle containing the whole of the Location.