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6 result(s) for "Raev, Ivan"
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Virgin forests in Romania and Bulgaria: results of two national inventory projects and their implications for protection
Despite extensive forest destruction in the Middle Ages and later intensive commercial forest management, remnants of virgin forests remained spared in some Central, Eastern and South-Eastern European countries. These virgin forests are the last examples of original forests in this part of Europe. That is why their protection becomes an important issue of current European forestry and nature protection policy. But the knowledge about the location and the area of virgin forests in these countries is incomplete up till now. This article has the prime goal to present a conceptual framework what virgin forests might be (“A conceptual framework for defining of virgin forests” section). Based on this framework, a working methodology has been tested in Bulgaria and Romania (“Results of the two national projects in Romania and in Bulgaria” section and further). For this reason two projects have been carried out by the Royal Dutch Society of Nature Conservation (KNNV) in close co-operation with the Forestry Institutes in Romania and in Bulgaria. The results of these projects are described in general terms and further analysis in the future is necessary to describe specific features like forest structure and spatial heterogeneity of these forests. Based on the results of the inventory, principles of sustainable protection and management of the mapped virgin forests were defined and described in the research reports. The usefulness of the inventory became evident already during the EU pre-accession period of both countries while preparing the NATURA 2000 network. The remaining virgin forests of temperate Europe are an inexhaustible source of ecological information about biodiversity, structure, natural processes and overall functioning of undisturbed forest ecosystems. Their research will reveal information which can be used for ecological restoration of man-made forests which are degraded through intensive forestry practices over the last centuries. The last virgin forests of temperate Europe represent an irreplaceable part of the natural capital of Europe and are worth to be protected by law. Their last remnants in South-Eastern and Eastern Europe are endangered by commercial activities. A full inventory of remaining virgin forests in all countries of temperate Europe is a matter of highest urgency. A representative selection of virgin forest sites should be declared by UNESCO as World Heritage Sites.
Spatial Distribution and Genetic Diversity of Turbot (Scophthalmus maximus, Linnaeus, 1758) in Bulgarian Black Sea Waters Relative to Fishing Pressure and Their Abiotic Environment
The present study examined the genetic diversity and spatial distribution of turbot (Scophthalmus maximus), an economically important species on the Bulgarian Black Sea coast. Maximum entropy (MaxEnt) modeling software Version 3.4.4. was utilized to develop a habitat suitability model for S. maximus in the Bulgarian Black Sea region. Data collected via demersal and pelagic surveys and genetic sampling from 2017 to 2021 were utilized to link species occurrence localities with selected abiotic factors. Our findings showed that the species’ habitat preferences are strongly influenced by temperature and dissolved oxygen, and projections based on simplified climatic scenarios indicated potential distribution shifts and a substantial reduction in reproduction habitats in the northern region. The assessment of genetic diversity was based on mtDNA COIII sequencing; MtDNA revealed a low level of polymorphism in all analyzed populations. The extensive fishing pressure may have increased the likelihood of genetic and population bottlenecks and a consequent decline in genetic diversity in the Shabla, Nesebar, and Tsarevo populations. The Tajima’s D values for the latter indicated that turbot underwent a bottleneck followed by rapid population expansion. Our findings are essential for the conservation and effective management of S. maximus stocks in the region.
Genetic diversity and morphological characterisation of three turbot (Scophthalmus maximus L., 1758) populations along the Bulgarian Black Sea coast
Turbot ( Scophthalmus maximus L., 1758) is a valuable commercial fish species classified as endangered. The conservation and sustainability of the turbot populations require knowledge of the population’s genetic structure and constant monitoring of its biodiversity. The present study was performed to evaluate the population structure of turbot along the Bulgarian Black Sea coast using seven pairs of microsatellites, two mitochondrial DNA (COIII and CR) and 23 morphological (15 morphometric and 8 meristic) markers. A total of 72 specimens at three locations were genotyped and 59 alleles were identified. The observed number of alleles of microsatellites was more than the effective number of alleles. The overall mean values of observed (Ho) and expected heterogeneity (He) were 0.638 and 0.685. A high rate of migration between turbot populations (overall mean of Nm = 17.484), with the maximum value (19.498) between Shabla and Nesebar locations, was observed. This result corresponded to the low level of genetic differentiation amongst these populations (overall mean Fst = 0.014), but there was no correlation between genetic and geographical distance. A high level of genetic diversity in the populations was also observed. The average Garza-Williamson M index value for all populations was low (0.359), suggesting a reduction in genetic variation due to a founder effect or a genetic bottleneck. Concerning mitochondrial DNA, a total number of 17 haplotypes for COIII and 41 haplotypes for CR were identified. The mitochondrial DNA control region showed patterns with high haplotype diversity and very low nucleotide diversity, indicating a significant number of closely-related haplotypes and suggesting that this population may have undergone a recent expansion. Tajima’s D test and Fu’s FS test suggested recent population growth. Pairwise Fst values were very low. The admixture and lack of genetic structuring found pointed to the populations analysed probably belonging to the same genetic unit. Therefore, a proper understanding and a sound knowledge of the level and distribution of genetic diversity in turbot is an important prerequisite for successful sustainable development and conservation strategies to preserve their evolutionary potential.
Effects of anthropogenic and environmental stressors on the current status of red mullet (Mullus barbatus L., 1758) populations inhabiting the Bulgarian Black Sea waters
The red mullet ( Mullus barbatus Linnaeus, 1758) is a keynote species for the Bulgarian Black Sea ecosystem and fisheries; nevertheless, existing knowledge on population status is very scarce. The present study was intended to assess the health status and adaptive potential of M. barbatus populations inhabiting the Bulgarian waters of the Black Sea. Our findings revealed that populations of M. barbatus are exposed to a variety of anthropogenic and environmental stressors. The species’ status was assessed using representative genetic, morphological, biochemical and chemical biomarkers from specimens obtained in the research area’s northern and southern regions. Based on mtDNA markers, genetic analysis revealed low haplotype and nucleotide diversity, typically observed in overexploited or “threatened” populations. Examining the morphology of the specimens revealed no discernible pattern of differentiation. Except for aluminium and chrome, metal and PAH concentrations in fish were below the regulatory thresholds. The specimens from the southern region ingested more microplastics than those from the northern region. The majority of specimens collected from the southern region also exhibited elevated levels of oxidative stress and decreased antioxidant defence, which can be interpreted as an early indication that they had reached the limits of their adaptive potential. Further research on the composite effects of the stressogenic environment on the Black Sea biota are critically needed, as well as the introduction of new indicators and thresholds at molecular and cellular levels for adequate monitoring of both the ecological state of the marine environment and its biota.
Fostering diffusion of scientific contents of national society cardiovascular journals: the new ESC search engine
uropean Society of Cardiology (ESC) National Society Cardiovascular Journals (NSCJs) are high-quality biomedical journals focused on cardiovascular diseases. The Editors´ Network of the ESC devises editorial initiatives aimed at improving the scientific quality and diffusion of NSCJ. In this article we will discuss on the importance of the Internet, electronic editions and open access strategies on scientific publishing. Finally, we will propose a new editorial initiative based on a novel electronic tool on the ESC web-page that may further help to increase the dissemination of contents and visibility of NSCJs. The National Society Cardiovascular Journals (NSCJs) of the European Society of Cardiology (ESC) are high-quality biomedical journals devoted to publishing original research and educative material on cardiovascular diseases. These journals officially belong to the corresponding ESC National Cardiac Societies. Many of them have achieved major international recognition, are included in most important bibliometric databases, and have made major scientific impact. Some NSCJs offer full-text English content and are freely available in electronic editions. However, NSCJs are largely heterogeneous and some of them are only published in local languages with a limited visibility. The main goal of biomedical journals is to publish high-quality scientific information. To achieve this goal, journals should compete for the best research carried out in their field, the 'prestige' of the journal being the main driver to attract original contributions. In turn, a journal's prestige is based on credibility, diffusion and scientific impact. To ensure that the scientific process is fully respected, journals rely in the 'peer review' system. This process not only allows the editors to select the best possible material for publication, but also assures the readers that the quality of the information follows the highest scientific standards. In fact, the process significantly improves the final quality of manuscripts eventually published. Once an article is definitely accepted for publication, the journal should guarantee its expedited publication and widespread diffusion among the scientific community. The Editors' Network of the ESC provides a unique platform for devising editorial initiatives aimed to improve the scientific quality, and facilitate diffusion of the contents of NSCJs. Herein we will discuss the importance of the internet and electronic editions in scientific publishing. We will also review the growing relevance of open access (OA) strategies. Last but not least, we will propose a new initiative based on a novel electronic tool that may further help to increase the diffusion, dissemination and overall visibility of NSCJs. This tool, located on the ESC website, should foster collaboration among the different NSCJs and also broaden exposure from diverse scientific sites and ESC official journals. Hopefully, this will help to further expand the scientific impact of European cardiovascular research.