M. -R.  . D. Magomedov’s research while affiliated with Dagestan Scientific Center of the Russian Academy of Sciences and other places

The north periphery of the Persian leopard range is situated in the Russian Caucasus, where leopards were exterminated by humans in the 1950s. Currently, the Persian leopard is returning to the Caucasus Mountain area and relevant habitat suitability for this species is in demand. In this study, we have mapped the habitats in the Chechen Republic area due to a lack of data from the 1980s onwards. We used remote sensing (RS) datasets, combined them with geobotanical and zoological field surveys data, and assessed the potential habitats of the main mammal species connected with leopards’ ecologically (preys and competitors) using machine learning approaches, such as supervised classification and modeling. The main material for the study is an up-to-date map of habitat types, based on multi-seasonal Sentinel-2 satellite imagery and field geobotanical data. Zoological field data were combined with environmental raster datasets covering the eco system properties and the effect of various factors (relief, climate, anthropogenic factors, etc.) on the probability of foraging, migration, nomadism, and hiding conditions for the studied species. Based on this infor mation, habitat suitability modeling was conducted for leopard prey and competitor species (tur, bezoar goat, chamois, wild boar, roe deer, hare, badger, jackal, wolf, and bear). The suitability maps for each species were used to produce an integrated final map, taking into account the weighted impact of each species on the leopard’s habitat. A preliminary ecological network assessment was performed by overlay the habitat type map with the integrated suitability map. This investigation fully estimates the suitable area for the restoration of leopard grouping in the territory of Chechnya and its characteristics.

Aim. When assessing the degree of transformation and openness of the territory for invasive species, a description of the current state of their biological diversity should be made taking into account the diversity index of adventitious species. Discussion. The problem of intensification of biological invasions has now become one of the world's most acute problems. Biological invasions of alien species have acquired such a scale that by now it is almost impossible to find terrestrial or aquatic ecosystems, wherever adventitious organisms are found. In practice, a number of categories and indices of diversity are used to assess biological diversity, and the methods of their measurement and analysis are also different. But all of them operate with almost two indicators – the number of species and their relative abundance – quantitative parameters, without taking into account modern qualitative changes in species in the composition of ecosystems. Results. It is proposed to introduce additional estimates of the share of adventitious species (the "adventiousness index") in the assessments of total biodiversity, which are necessary to solve a whole range of practical tasks. They give an idea of the state of ecosystems at the moment in a certain area, serve as the basis for the development of a management system for individual species, are necessary to assess the suitability of potential habitats for reintroduction and etc.

The aim of this research was to assess the scale and determine the possible reasons of the death of Caspian seals (Pusa caspica), that were washed up by a storm on the coast of the Republic of Dagestan in early December 2020. The corpses of seals were found on the Dagestan coast from the mouth of the Terek River to the southern outskirts of Derbent, in total about 205 km long. The main methods of collecting material were: accounting of dead seals in open (not overgrown with vegetation) coastal areas, measurements and pathoanatomic autopsies of corpses, sampling of internal organs and tissues of animals for histological, virological, helminthological and toxicological studies. Simultaneously with the onshore work, observations of seals and registration of hydro- meteorological parameters in the coastal waters of the Republic of Dagestan were carried out by two research vessels of the Caspian branch of the Federal Research Institute for Fishery and Oceanography («KaspNIRH»): «Caspian Explorer» and «Hydrobiologist». As a result, 12 coastal sites with a total length of 49.2 km were surveyed, where 313 corpses of dead seals were registered; the average density was 12.27 ± 2.16 specimens/km. The total number of dead seals in December 2020 was estimated at 2,515 ± 443 individuals. Adult females predominated among the dead animals, most of which were pregnant. The corpses showed no signs of infectious diseases or exhaustion. Judging by their condition, the death of animals occurred during the first two decades of November, at some distance from the shore. Conclusion: Basing on the data collected, infectious diseases, helminthiasis, intoxication, accident by catch in the fishing gears, and the impact of an underwater shock wave were excluded from the possible reasons of the death of seals. Acute asphyxia as a result of local release of natural gas, which could form above the sea surface a polluted lens of air unsuitable for breathing, was recognized as the most likely cause of the seals death.