Ecologia Balkanica

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https://doi.uni-plovdiv.bg/handle/store/4

p-ISSN: 1314-0213 / e-ISSN: 1313-9940

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Influence of in vitro cultivation factors on micropropagation and alkaloid determination of Convolvulus persicus L.
(Plovdiv University Press "Paisii Hilendarski", 2026-01-25) Doycheva, Iva; Doncheva, Tsvetelina; Philipov, Stefan
Convolvulus persicus L. is a critically endangered species native to Bulgaria. Studying the conditions for its in vitro cultivation is important for its ex-situ conservation. A number of factors influence the growth, development, and multiplication of in vitro plants. In this study, the effects of several medium components - including the type of gelling agent, the quantity of macrosalts, activated charcoal supplementation, and plant growth regulators - were investigated to determine the most suitable conditions for the in vitro cultivation of the species. The effects of explant type and culture vessels were also examined. The type of gelling agent (Gelrite) and the explant significantly affected culture growth. Culture vessels and plant growth regulators had a smaller influence, while the effect of activated charcoal depended on its combination with the other factors. The quantity of macrosalts did not influence plant growth in vitro. A phytochemical analysis of the alkaloid content of Convolvulus persicus was conducted for the first time. The phytochemical analysis revealed that three alkaloids - nicotine, tropinone, and Nmethylpyrrolidinyl-cuscohygrine - were biosynthesized by C. persicus at two developmental stages. Nicotine was identified as the major alkaloid in the species.
Influence of the urban environment on the metabolic activity and functional diversity of phyllospheric microbial communities in linden trees
(Plovdiv University Press "Paisii Hilendarski", 2026-01-25) Dimitrova, Katya; Spasov, Spas; Bogdanov, Nikolov; Shilev, Stefan; Petrova, Slaveya
It has been shown that microorganisms associated with the crown of trees (phyllosphere) can improve their ability to purify the air from pollutants. On the one hand, this is due to the metabolites released by the microorganisms that stimulate the development of trees and their resistance to stress, and on the other hand, the microorganisms themselves also are able to degrade some of the atmospheric pollutants. The aim of the present study was to assess the influence of the urban environment on the metabolic activity and functional diversity of microbial communities in the phyllosphere of linden trees, planted in four experimental plots within the city of Plovdiv (Bulgaria). Each plot is characterized by different anthropogenic load, thus allowing for detection of potential specificity of microbial metabolism. A total of 12 saplings of Tilia tomentosa Moench were planted (3 individuals per plot) and leaf samples were collected after 3-month period in the urban environment. Biolog EcoPlate™ of the BIOLOG system (Biolog, Hayward, CA, USA) was used for estimation of metabolic activity of microbial communities, associated with linden trees. The epiphytic communities isolated from leaf samples of Plot 4 (lowest degree of urbanization) showed the highest average-well color development (AWCD) and substrates` metabolic activity. It was found that microorganisms in the two more strongly affected by the traffic locations (Plot 1 and Plot 3) have a higher rate of carbohydrate assimilation and a lower rate of phenolic compounds assimilation compared to the other two locations. Most of the analyzed functional indices showed higher biodiversity and better distribution of substrate utilization in the epiphytic microflora of the leaves of trees planted on Plot 4 (lowest urbanization intensity).
Breeding density and habitat preferences of the European Turtle Dove Streptopelia turtur Linnaeus, 1758 (Columbiformes: Columbidae) in Bulgaria: preliminary results
(Plovdiv University Press "Paisii Hilendarski", 2026-01-15) Gruychev, Gradimir; Stoyanov, Stoyan; Angelov, Evlogi; Mihaylov, Hristo
We conducted country-wide surveys from 15 May to 31 July 2022 to quantify singing males’ population size and habitat-specific density of Turtle Dove (Streptopelia turtur). We applied point counts at survey stations situated in 11 plot locations systematically distributed across the country. The average Turtle Dove’s density was estimated as 10.1 singing birds per 1 km2 (λ = 10.084, SE = 0.674, 95% CI: 8.846 – 11.496). The mean detection probability (p) was 0.115 (95% CI: 0.105 – 0.126), and the scale parameter of half-normal detection function was 120 m (σ = 119.74 m, SE = 3.53, 95% CI: 113.03 – 126.86). The effective radius was 169.33 m (95% CI: 159.84 – 179.37). The Turtle Dove densities were influenced by altitude with lower densities in higher elevations. The number of singing males increased from May to July. The abundance was influenced by habitat type and land cover, and it was positively correlated with tree height and shrub height measured around sampling points. The highest densities were recorded around stubbles, sunflower crops, and in a mixture of agricultural land cover, although their importance was insignificant. The density of singing males was higher in open areas, in oak and mixed deciduous forests, and in Paliurus communities as well.
Prevalence of opportunistic pathogenic Gram-negative bacteria from the Enterobacteriaceae family in the cloacal microflora of Testudo graeca and Testudo hermanni – a pilot study
(Plovdiv University Press "Paisii Hilendarski", 2025-12-08) Popova, Steliyana; Lazarkevich, Irina; Engibarov, Stephan; Mitova, Simona; Lalovska, Iva
Reptiles can harbour a variety of zoonotic bacteria in their gut, often asymptomatically. In this study, we report our preliminary data on the occurrence of opportunistic pathogenic Gram-negative bacteria in the cloacal microbiota of tortoises housed in the Rescue, Rehabilitation and Breeding Center in Banya village, Burgas District. A total of 24 healthy adult individuals were sampled: 12 spur-thighed tortoises (Testudo graeca) and 12 Hermann’s tortoises (Testudo hermanni), with equal numbers of each gender. Representatives of 7 genera from Enterobacteriaceae family, known as causative agents of rare but serious infections both in humans and animals, have been identified. The most common bacteria were Klebsiella spp., Salmonella enterica, Citrobacter braakii and Enterobacter cloacae, detected in over 75% of the individuals sampled. Morganella morganii, Pantoaea agglomerans and Escherichia coli were found less frequently, in 20% - 30% of individuals. No significant difference in bacterial load between tortoise species or between sexes was found. The high prevalence of opportunistic pathogens that tortoises host may pose a potential health risk, so strict hygiene practices are recommended when handling animals.
Floating platform for continuous monitoring of surface water quality
(Plovdiv University Press "Paisii Hilendarski", 2025-12-11) Popov, Rumen; Tokmakov, Dimitar; Petrova, Slaveya; Nikolov, Bogdan
Monitoring the quality of river water in real time is critical for protecting aquatic life, public health, and the sustainability of our freshwater resources. A Floating Online Monitoring System enables continuous, remote measurement of key water parameters—like pH, dissolved oxygen (DO), turbidity, and contaminants—right at the water’s surface. For this purpose, an automatic, remote measuring station was developed, intended for installation on the floating platform. It is designed for not only collecting and archiving information about the ecological situation along the river, but also periodically forwards the data to a communication server.
Performance evaluation and cross-validation of low-cost particulate matter sensors for environmental research
(Plovdiv University Press "Paisii Hilendarski", 2025-12-10) Terziyski. Atanas; Kochev, Nikolay; Tenev, Stoyan; Georgieva, Svetlanna
Particulate monitoring data plays a vital role in supporting analysis, policymaking, and citizen initiatives, especially in areas related to ecology, air quality, public health, and overall quality of life. However, traditional regulatory monitoring systems are expensive and have drawbacks: they do not provide real-time data and cover only a limited number of official locations. As an alternative, low-cost monitoring devices are increasingly being used, but concerns remain regarding their accuracy and the reliability of the data they produce. As part of efforts to validate low-cost monitoring approaches, this work presents the design, implementation, and ongoing development of a low-cost, sensor-based air quality monitoring system dedicated to monitoring fine particulate matter (PM) and other atmospheric indicators within the METER.AC network. The system integrates multiple devices with various sensors, such as Honeywell HPMA115S0, Sensirion SEN55, and related SEN series, along with GPS modules for precise timestamp and geolocation. Data acquisition is synchronized and automated via UNIX shell scripts, which extract, convert, and process measurement data into structured CSV files containing parameters like PM1, PM2.5, PM10, temperature, humidity, etc. Fluke 985 Particle Counter is a high-quality professional device used as an independent benchmark for crossvalidation, providing particle counts for sizes: 0.3, 0.5, 1.0, 2.0, 5.0, and 10.0 µm. Measurement data are collected at 10-minute intervals and uploaded to a public visualization platform, where interactive graphs and summaries are generated. Also, this study aims to approximate the mass of airborne particulate matter based on particle size distribution derived from the FLUKE device output. On the basis of particle counts, the underlying particle size distribution is estimated with regression models.
AI-supported counselor training for socio-ecological resilience
(Plovdiv University Press "Paisii Hilendarski", 2025-12-10) Manolov, Manol
As higher education experiences rapid technological advancements, the integration of intelligent technologies and generative artificial intelligence into counselor training presents a practical approach to bridging the gap between theoretical knowledge and practical application, while also promoting environmentally sustainable, low-resource, paperless instructional methods. This research introduces an AI-enhanced instructional ecosystem for counseling psychology, which combines HeyGen to simulate therapeutic sessions, Canva for organizing and delivering interactive content, and ChatGPT combined with Designrr to produce customizable, digital workbooks. Prior studies suggest that embedding large language models within course design enhances transversal skills such as critical thinking, structured reasoning, and professional communication; avatar-based storytelling and simulations increase engagement, retention, and analytical depth in university contexts; and personalized digital workbooks support knowledge organization and higher-order cognitive processing. The evaluation used a design-oriented approach that examined workflow usability and material efficiency (e.g., paper savings) for the Canva–HeyGen–Designrr algorithm. Ecologically, the workflow explicitlyprepares trainees to identify and address uncertainty-related eco-anxiety and climate distress through targeted simulations and structured reflective prompts, while its fully digital infrastructure reduces paper consumption by replacing printed vignettes, supervision materials, and journals with reusable electronic resources. The findings suggest that AI-supported, environmentally sustainable training can simultaneously enhance counseling competencies and promote sustainable educational practices, if the energy consumption associated with AI technologies is appropriately monitored and managed within program implementation.
IoT framework for environmental monitoring in Strandzha Nature Park
(Plovdiv University Press "Paisii Hilendarski", 2025-11-22) Tokmakov, Dimitar; Bekyarova-Tokmakova, Anna; Asenov, Stanislav; Shotarova, Snezha; Lyubomirov, Slavi
Environmental monitoring plays a critical role in preserving biodiversity and ensuring sustainable management of protected areas. However, traditional monitoring approaches often lack efficiency, precision, and real-time responsiveness. This paper introduces an innovative Internet of Things (IoT) framework specifically designed for environmental monitoring in Strandja Nature Park—a region of significant ecological value located in Bulgaria. The proposed framework integrates advanced sensing technologies, low-power wide-area network (LPWAN) communications (LoRaWAN), and cloud-based analytics to enable real-time tracking of environmental parameters, including air quality, soil moisture, temperature, humidity, and wildlife presence. A practical deployment of the IoT system demonstrates enhanced capabilities in data acquisition, coverage, energy efficiency, and early detection of ecological disturbances. The results highlight significant improvements over conventional methods in terms of accuracy, data granularity, and cost-effectiveness. Ultimately, this framework provides valuable insights for proactive environmental management, paving the way toward a more comprehensive, sustainable, and technologically advanced approach to biodiversity conservation in protected natural regions.
Ecologo-taxonomic investigations of fungi on Dragoica Mountain Ridge (Forebalkan) in Bulgaria
(Plovdiv University Press "Paisii Hilendarski", 2025-11-29) Lacheva, Maria; Radoukova, Tzenka
A list of lignicolous and terricolous fungi recorded on Dragoica mountain ridge is given in this article. Here are presented a total of 169 species, mainly from Ascomycota and Basidiomycota, and the largest part of them belong to the orders: Agaricales, Boletales, Hymenochaetales, Polyporales and Russulales. Of these fungi 76 species are reported for the first time from the Forebalkan floristic region, and for 93 species are reported new localities from the Forebalkan floristic region. Eight (8) species includes in the Red List of Fungi in Bulgaria: Agaricus macrocarpus, Amanita caesarea, A. vittadinii, Discina ancilis, Hericium coralloides, Lenzites warnieri, Tuber aestivum and Tulostoma fimbriatum. The research was conducted in different habitats: beech-oak forest, oak forest, beech- hornbeam forest, azonal vegetation and the shrubs along the Batulska river, Panega river and Malki Iskar river, in meadows and pastures. Of the fungi species registered, 95 are lignicolous and 74 are terricolous. Most of lignicolous species are saprobionts (80) and 15 species are parasites. From terricolous fungi, there are 44 mycorrhizal and 30 saprobionts. Some of the species such as Clavaria fumosa, Geastrum schmidelii, Hygrocybe punicea, Leccinum quercinum, Mycena aetites, M. bulbosa, Lepiota erminea and Vuilleminia cystidiata could be highlighted as rare. Other species such as Armillaria mellea, Bovista plumbea, Lactarius piperatus, Cantharellus cibarius, Marasmius oreades, Russula cyanoxantha, Trametes hirsuta, Xerulla radicata, etc. are abundant in certain periods of the year. The xerothermic species – Leucopaxillus lepistoides deserve special attention.
Continuous integrated monitoring of meteorological conditions and air quality dynamics in the urban core of Plovdiv, Bulgaria
(Plovdiv University Press "Paisii Hilendarski", 2025-12-01) Paskaleva, Vesselina; Terzyiski, Atanas; Tenev, Stoyan; Kochev, Nikolay
This study provides a comprehensive three-year analysis (2023–2025) of meteorological conditions and air quality parameters in the city of Plovdiv, Bulgaria. The research examines the interactions between temperature, humidity, precipitation, wind characteristics, and fine particulate matter concentrations (PM₂.₅), with the goal of improving the understanding of local atmospheric dynamics and pollution patterns. Recorded temperatures ranged from −7.0°C to 40.4°C. The highest pollution episodes were consistently observed during the coldest months, largely due to intensified household heating combined with reduced atmospheric dispersion under stable winter conditions. Wind speed and direction analyses revealed a significant influence on pollutant dispersion, with lower wind speeds promoting the accumulation of airborne particles, particularly in the city’s low-lying zones. Precipitation intensity varied considerably across the study period, with the most intense events reaching up to 94.73 mm/h. These episodes were associated with temporary reductions in airborne particle concentrations due to effective washout processes. Overall, the results demonstrate a strong interdependence between meteorological variability and air pollution dynamics in Plovdiv.
Preparation and investigation of curcumin-containing PLA composite films for food packaging application
(Plovdiv University Press "Paisii Hilendarski", 2025-12-10) Viraneva, Asya; Grigorov, Aleksandar; Yovcheva, Temenuzhka
Polylactic acid (PLA) is a biocompatible and biodegradable natural polymer known as a promising biopolymer that can be used for food packaging due to its good physical and physicochemical properties. This biopolymer possesses excellent thermal processability, good oxygen barrier capacity, and complete biodegradability, and it is one of the materials used as a food packaging material. PLA has a significant potential for optimizing physical properties through material modifications, including in combination with natural additives as different polyphenols. Polyphenols are a class of naturally occurring compounds found in plants, which exhibit a wide range of beneficial properties, including antioxidant, anti-inflammatory, and antimicrobial activities. In the present paper PLA PLA-based composite films with incorporated polyphenol curcumin with different concentrations were investigated. PLA composite films were prepared using a solution casting method. The films obtained were charged in a corona discharge. The electret properties of the charged samples were studied. The possible surface potential decay mechanisms responsible for the electret’s behavior were discussed. It was established that the surface potential decay depends on the corona polarity and the type of films.
Reintroduced Saker Falcons (Falco cherrug Gray, 1834) are dependent on European ground squirrels during the breeding period in Bulgaria
(Plovdiv University Press "Paisii Hilendarski", 2025-12-11) Georgiev, Dilian; Petrov, Rusko; Andonova, Yana; Klisurov, Ivaylo; Angelov, Ivaylo; Stamenov, Anton; Gradinarov, Dimitar; Arkumarev, Volen
This study examines the diet of the reintroduced Saker Falcon (Falco cherrug) population in Bulgaria. By combining food-remain analysis, visual observations, and camera-trap monitoring, we documented 144 prey items taken by Saker Falcons during the 2020, 2024, and 2025 breeding seasons. The analysis revealed a pronounced dietary specialization: the European ground squirrel (Spermophilus citellus) was the overwhelmingly dominant prey, representing 80.56% of all identified occurrences (N=144). Other rodent species accounted for 8.3% of the food items and birds represented 10.42% of the food items. The pronounced dependence on S. citellus underscores its essential role in the diet of the falcons. Consequently, conservation efforts should prioritize the protection and restoration of pasture systems, and the recovery of declining ground squirrel populations.
An AI-powered knowledge base for scientific abstracts: a case study on environmental DNA (eDNA) in biomonitoring
(Plovdiv University Press "Paisii Hilendarski", 2025-12-05) Baev, Vesselin; Gecheva, Gana
Environmental DNA (eDNA) refers to genetic material shed by organisms into their environment, such as water, soil, or air. As a non-invasive biomonitoring method, eDNA has revolutionized biodiversity assessment by enabling the detection of species presence without direct observation or capture. This approach is especially critical for tracking invasive, elusive, or endangered species and monitoring ecosystem changes due to climate or anthropogenic pressures. Over the past decade, a growing body of scientific literature has explored eDNA applications, resulting in a fragmented but rich landscape of domain-specific knowledge. Navigating this information is increasingly challenging for researchers and policymakers. To address this, we developed BioTrace, an AI-powered knowledge base designed to support conversational exploration of scientific abstracts focused on eDNA in biodiversity monitoring. BioTrace leverages a Retrieval-Augmented Generation (RAG) architecture, integrating the mistral-saba-24b large language model via the Groq API for ultra-fast, low-latency inference. Scientific abstracts are indexed using a vector store, and retrieved passages are reranked using the all-MiniLM-L6-v2 model to improve answer relevance. Users can query the system in natural language and receive grounded, context-aware responses that synthesize findings across multiple studies. So far, the knowledge base includes more than 4000 abstracts on eDNA studies. This work demonstrates the potential of large language models (LLMs) to distil scientific literature into accessible, structured knowledge. BioTrace empowers users with real-time, interpretable insights into eDNA research, serving as a blueprint for future AI-based tools in ecological and environmental sciences.
Onopordum acanthium (Linnaeus, 1753) seeds from Southern Bulgaria: A promising natural source of lipid-soluble bioactive components
(Plovdiv University Press "Paisii Hilendarski", 2025-12-03) Petkova, Zhana; Teneva, Olga; Antova, Ginka; Angelova-Romova, Maria; Andonova, Tsvetelina; Dimitrova-Dyulgerova, Ivanka
The current study aimed to evaluate the chemical and lipid composition of seeds of Onopordum acanthium grown in South Bulgaria. The seeds were characterised with a high amount of carbohydrates (56.76%), and similar contents of proteins (16.05%) and glyceride oil (16.45%). The share of dietary fiber was very high, at 38.4%, and that of the ash content was 3.42%. The chemical composition of the seeds determined their good energy value, which was 439 kcal/100 g. The glyceride oil was rich in lipid-soluble bioactive components – unsaponifiable matter (2.70%), sterols (0.69%), tocopherols (172.50 mg/kg), and phospholipids (0.36%), as well as in various essential fatty acids, linoleic acid being the predominant one (69.3%). The other fatty acids found in high amounts were oleic (21.4%) and palmitic (5.3%) acids. The main sterols identified in the seed oil were β-sitosterol (62.2%), followed by stigmasterol (21.7%) and campesterol (8.6%). Two tocopherols were detected in the fraction: γ-tocopherol (74.7%) and αtocopherol (25.3%), while the predominant phospholipids were phosphatidylinositol (33.7%), phosphatidylcholine (13.1%), phosphatidylserine (12.9%), and phosphatidylethanolamine (11.9%). Important lipid indices were also calculated for O. acanthium seed oil – index of atherogenicity (0.0625), index of thrombogenicity (0.1735), hypocholesterolaemic/hypercholesterolaemic (HH) ratio (16.83), peroxidability index (70.64), and oxidation stability index (0.78). These characterristics depicted the health benefits and oxidative stability of the examined glyceride oil, determining its potential implementation in functional foods, nutraceuticals, and therapeutic formulations.
Fungal diversity in Mediterranean and sub-Mediterranean plant communities of Strandzha Mountain, Bulgaria
(Plovdiv University Press "Paisii Hilendarski", 2025-12-29) Lacheva, Maria; Radoukova, Tzenka
The present study reports 131 larger fungi in Mediterranean and sub-Mediterranean plant communities of Mt Strandzha floristic region. Of these, sixty-nine (69) species are reported for the first time from Mt Strandzha floristic region. New localities on sixty-two (62) macrofungi are also reported. The predominant part of species belongs to the class Agaricomycetes (127 species), other part belongs to the Pezizomycetes (4 species). Seven species (Agaricus macrocarpus, Amanita caesarea, A. vittadinii, Clathrus ruber, Chlorophillum agaricoides, Geastrum triplex and Poronia punctata) are included in the Red List of fungi in Bulgaria and Red Data Book of the Republic of Bulgaria. Five of them (Agaricus macrocarpus, Amanita vittadinii, Chlorophillum agaricoides, Geastrum triplex and Poronia punctata) are new to this floristic region. Myriostoma coliforme is rare and threatened in Bulgaria and Europe. The following rare, steppe, xerothermic and thermophilous fungi (Agaricus comtulus, A. cupreobrunneus, Chlorophyllum agaricoides, Entoloma incanum, Geastrum corollinum, G. pectinatum, G. striatum, Geopora arenicola, Hygrocybe virginea, Lepiota erminea, Leucopaxillus lepistoides and Myriostoma coliforme) deserve special attention. In addition, new collections of some threatened, rare, and lesser-known species are also included. The aim of the paper is to enrich the information about fungal diversity of the Mt Strandzha floristic region, which area is important for conservation of the fungal diversity in Bulgaria.
In silico methods for mutagenicity prediction
(Plovdiv University Press "Paisii Hilendarski", 2025-12-04) Paskaleva, Vesselina; Cokova, Gergana
This research presents a thorough exploratory data analysis to develop an in silico model for mutagenicity prediction, contributing to Safe-by-Design strategies. Using a publicly available dataset, chemical structures were encoded via a range of molecular fingerprints and descriptors. Multiple machine learning algorithms—including k-nearest neighbors, support vector machines, and random forest—were assessed. Performance was validated through 10- fold cross-validation and further tested on an external dataset. Random Forest emerged as the most effective method, achieving a cross-validation MCC of 0.68. The in-house models showed competitive performance relative to existing publicly available tools.
Forest fires in Bulgaria - communication, coordination and coherence
(Plovdiv University Press "Paisii Hilendarski", 2025-12-20) Stoyanov, Todor
In recent years, forest fires have become a pan-European problem. Although mainly the Mediterranean countries are affected, large fires have also been observed in the Czech Republic, Bulgaria, Germany, Slovenia and many other countries. Most EU Member States have more burnt areas than average in the period 2013-2022. The risk of forest fires has spread to areas that were not previously at risk and extends far beyond the Mediterranean region. This is causing huge social, environmental, climatic and economic losses across Europe. The risk of forest fires expected to increase further due to climate change. Forest fires are catastrophic events that require rapid, accurate, and collaborative prevention and response. Effective communica-tion, coordination, and coherence among stakeholders are crucial to save lives, protect ecosys-tems, and minimize economic loss. Therefore, horizontal and vertical coordination, commu-nication and coherence of fire prevention and control measures should be improved. The aim of the present study is to analyze the legally established order for horizontal and vertical coordination, communication and coherence of forest fire prevention and control measures in Bulgaria, to identify shortcomings and to propose improvements.
Evaluating heavy metal pollution and health risks in river systems using Random Forest and XGBoost: Evidence from the Shkumbin River
(Plovdiv University Press "Paisii Hilendarski", 2025-12-19) Shyti, Bederiana; Basha, Lule; Bekteshi, Lirim
Surface water contamination by heavy metals poses significant ecological and health risks due to their persistence, bioaccumulation, and toxicity. This research evaluated the concentrations of cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), lead (Pb), and zinc (Zn) in river water samples and assessed their impact on the Heavy Metal Pollution Index (HPI). Descriptive statistics revealed substantial variation among sampling sites, with HPI values ranging from 2.15 to 21.94. Although Cd and Pb were generally present in low concentrations, their localized maxima indicated potential hot spots of contamination, whereas Fe and Zn showed higher overall levels. To identify the most influential predictors of HPI, two machine learning regression models, Random Forest (RF) and Extreme Gradient Boosting (XGBoost), were implemented. The RF model explained more than 90% of the variance in HPI, with Cd, Zn, and Cr emerging as the most critical contributors. The XGBoost model achieved even higher predictive accuracy (R² = 0.998, RMSE = 0.76), confirming Cd and Cr as dominant predictors, together accounting for nearly 80% of the model’s explanatory power. These findings highlight the pivotal role of Cd and Cr in shaping HPI dynamics and demonstrate the utility of ensemble learning methods for environmental monitoring and risk assessment.
Can photography be employed to analyze the diet of the Lesser Kestrel (Falco naumanni Fleischere 1818)?
(Plovdiv University Press "Paisii Hilendarski", 2025-12-10) Dalakchieva, Svetla; Popova, Aleksandra; Gradev, Gradimir; Yaneva, Stiliyana
Understanding the dietary composition of the Lesser Kestrel (Falco naumanni) is crucial for effective conservation, particularly in regions such as Bulgaria, where the species has recently been reintroduced. This study examines the feasibility of photography and videography as noninvasive methods for dietary analysis of this small colonial falcon. A total of 275 photographs and videos depicting feeding behavior were reviewed, 85 from Bulgaria and 190 from Türkiye. Prey items were identified and classified into major taxonomic categories. In both countries, insects dominated the diet (44.71% in Bulgaria, 52.11% in Türkiye), with Orthoptera being the most frequently consumed group (>90% of insect prey). Additional prey included small mammals, reptiles, millipedes, and birds, with notable regional differences in their proportions. The findings closely align with previous indirect studies (e.g., pellet analysis), validating the effectiveness of photographic methods. The study demonstrates that photography represents a valuable complementary tool for studying the diet of Lesser Kestrels, offering minimal disturbance and potential for citizen science applications. This approach enables large-scale data collection and supports long-term ecological monitoring and conservation management of the Lesser Kestrel in Bulgaria
Resistance of 3D - printed PVA filaments to bacterial degradation
(Plovdiv University Press "Paisii Hilendarski", 2025-11-20) Bashev, Anton; Assenov, Stanislav
This study systematically evaluates the resistance of 3D-printed PVA filaments (Bambu Lab) to bacterial biodegradation and their potential antimicrobial activity against two widespread environmental strains: Bacillus subtilis (Gram-positive) and Pseudomonas aeruginosa (Gram-negative). Using the standardized agar diffusion method, a 15% PVA solution was tested against a positive control (gentamicin). The results showed no inhibition zones around the PVA samples for either bacterial strain, which clearly confirmed the lack of statistically significant antimicrobial activity (p > 0.05). These findings unambiguously demonstrate that under the experimental conditions, the 3D-printed PVA material not only lacks bactericidal or bacteriostatic properties but also exhibits resistance to the metabolism of the test microorganisms. From an engineering and ecological perspective, this implies that although PVA is water-soluble, its ultimate biodegradation in nature may be slow and inefficient in the absence of specialized microbial consortia. Consequently, the widespread use of PVA in 3D printing could contribute to its accumulation in soil and aquatic ecosystems. This highlights the need for a re-evaluation of its environmental compatibility and the development of improved composite formulations or end of life management strategies aimed at ensuring true biodegradability.

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