The accumulation of microplastics in the world oceans is one of the main global problems of the modern world. The Black Sea is the main source of seafood for people from several countries, including Bulgaria. The pollution of the Black sea is a result of various factors, especially anthropogenic. The aim of this study was to determine the presence and accumulation of microplastics in the Black Sea mussel Mytilus galloprovincialis L., 1819, harvested from different locations along the northern Bulgarian Black Sea coast. Within each microplastic morphological group, three size classes were recognized: 100-200 μm, 25-100 μm, and ≤ 25 μm. Microplastics were found in the soft tissues of all studied specimens but in a different ratio of pellets, fibers and fragments. Generally, the pellets were the most often registered particles, followed by irregularly-shaped fragments, whereas fibers were less numerous. The dominant part of the isolated plastics are made of polyethylene (PE), and polyethylene terephthalate (PET). Our results pointed out serious pollution with plastic particles in the Bulgarian Black Sea aquatory, which in the future may seriously affect the health of the mussel population and also human health.

On land, the amphibians interact with the environment in a complex way-even small changes in the physiological conditions may significantly impact the behaviour and vice versa. In ectothermic tetrapods, the transition from inactive to active phase may be related to important changes in their thermal status. We studied the thermal ecology of adult Balkan spadefoots (Pelobates balcanicus Karaman, 1928) in northeastern Bulgaria. These toads spend the daytime buried between 10 and 15 cm in sandy substrates, and emerge after sunset. On the substrate, their thermal energy exchange is defined by the absence of heat flow from the sun. Secondary heat sources, like stored heat and infrared radiation from the soil play an important role for the thermal balance of the active spadefoot toads. At the beginning of their daily activity, we measured substrate temperature (at a depth of 11–12 cm), toad’s surface body temperature, and also provided thermal profiles of the animals and the substrate surface in their microhabitats. In animals which recently emerged from the substrate, the temperature was comparatively higher and was closer to that of the subsoil on the spot. After that, body temperature decreased rapidly and continued to change slowly, in correlation with air temperature. We detected a temperature gradient on the dorsal surface of the toads. On the basis of our measurements and additional data, we discuss the eventual role of air humidity and the effects of surface and skin water evaporation on the water balance and activity of the investigated toads.

The urbanization and the expansion of human settlements led to the adaptation of many animal species to living close to humans, often using buildings for roosting. Panel buildings are particularly attractive to rock-dwelling animals such as swifts, swallows, pigeons, and bats due to their numerous cracks and crevices. The abundance of these structures in Eastern Europe has led to the establishment of numerous bird and bat colonies in the cities. However, the recent renovation and insulation of these buildings, while beneficial to residents, threatens the roosts. Construction workers are sometimes unaware of animal presence and inadvertently destroy nests or colonies. Rapid assessments before renovation are essential to rescue individuals and ensure the planning of alternative roosts for bats and birds. We conducted a pilot survey of 61 residential buildings in five municipalities in Bulgaria: Razgrad, Popovo, Haskovo, Dimitrovgrad, and Bobov Dol, to assess bird and bat biodiversity. We performed field assessments using direct observation, thermal cameras, ultrasonic detection, sunset counts, and endoscopic cameras. The most commonly detected bird species were the house martin, barn swallow, common swifts, the Eurasian jackdaw, pigeons, and sparrows. The most commonly detected bat species were the common pipistrelle, noctule, and Kuhl’s pipistrelle. Additionally, we discuss the specifics of the “soviet-type” buildings as nesting facilities for pigeons and the impact of the pigeons on the “micro ecology” of the blocks. Our study aimed to guide conservation actions and awareness during the expanding renovation efforts of old buildings in Bulgaria.

The Xerotyphlops vermicularis (Merrem, 1820) complex represents small, burrowing snakes that occur from the Balkan Peninsula to Afghanistan and generally they are mostly observed during the springtime. In the present study, we report new records of this snake (10 individuals observed) from Elenite village in coastal Bulgaria. According to current knowledge, they represent the northernmost locality of the species in the Balkan Peninsula. We expand the known distribution of X. vermicularis and help to fill information gaps.