Emilia Varadinova

• Assoc. prof. at South-West University "Neofit Rilski" Institute of Biodiversity and Ecosystem research - Bulgarian Academy of Science

Freshwater macroinvertebrates are a diverse group and play key ecological roles, including accelerating nutrient cycling, filtering water, controlling primary producers, and providing food for predators. Their differences in tolerances and short generation times manifest in rapid community responses to change. Macroinvertebrate community compositio...

This paper presented the effect of the activity of the coal fired power plants "Repub-lika" and "Bobov dol" in Bulgaria and the influence of the wastewaters discharge on the ecological status of Razmetanitsa River (Struma River catchment-West Aegean region) and Sokolitsa River (Maritsa River catchment, East Aegean region). The data of the biologica...

The aim of this paper is to compare the taxonomic composition and species diversity of the macrozoobenthos in Maritsa River (Bulgaria) and Han River (South Korea). Samples were collected at 15 selected sites in each river, including some of their main tributaries in 2020 and 2021. The number of the taxa recorded in Maritsa River was more than twice...

The aim of the study was to identify the current taxonomic composition and dominant structure of the macrozoobenthos in the Maritsa River and estuarine zones of its main tributaries (Chepelarska, Sazliyka, Stryama and Topolnitsa). The samples were collected from 15 sites in August and September 2020. The total number of the identified taxa was 165...

Owing to a long history of anthropogenic pressures, freshwater ecosystems are among the most vulnerable to biodiversity loss¹. Mitigation measures, including wastewater treatment and hydromorphological restoration, have aimed to improve environmental quality and foster the recovery of freshwater biodiversity². Here, using 1,816 time series of fresh...

The importance of adequate biological assessments of rivers based on aquatic assemblages is essential to establish recovery measures. Macrophyte and macroinvertebrate communities react differently in time and in response strength to diverse stressors. Our hypothesis was that each group response is a result of specific and combined abiotic factors a...

The present study provides data on the trophic structure of the benthic macroinvertebrate communities in mountainous and semi-mountainous small streams and river sections belonging to Mesta, Struma and Vardar River catchments from 7th Ecoregion. The benthic macroinvertebrates were assigned to seven Functional Feeding Groups. We analyzed their troph...

Rivers are the main resource for water supply in Bulgaria and South Korea, thus the ecological status of the running water bodies is important for the ecosystem integrity, as well as for the health and life standard of the population in both countries. This study presents and compares the water management policies, the water legislations and the sy...

A survey of macrozoobenthos in selected standing water bodies situated in mountain areas of Bulgaria was carried out. The study was conducted in the summer of 2020 (July-August) at one lake (Trevisto Lake – Rhodopes Mts.) and eight reservoirs (Ognyanovo – Sredna Gora Mts.; Bebresh, Hristo Smirnenski and Yovkovtsi (two sites) – Balkan Mts.; Belmeken...

The results showed a trend of a steady change in the values of the hydrological and physical-chemical parameters of the aquatic environment in a 40-year period. The processes of water flow decreasing and water temperature increasing during both high and low water periods could be a probable result of the climate change. These changes in water regim...

A survey of the macrozoobenthos communities in the Maritsa River (South Bulgaria) was carried out in the summer of 2021. Benthic samples were collected and physicochemical parameters (water temperature, pH, conductivity, dissolved oxygen and nutrients) were measured at 15 sites located on the main river and its tributary system. The studied sites b...

New data on the distribution of the Asian alien species Branchiura sowerbyi (Oligochaeta: Naididae) were reported for Bulgaria. During the period 2012-2020, the species was found in 40 lotic and lentic water bodies (17 rivers and 23 reservoirs and lakes). Eight new inhabited water bodies of different types (4 reservoirs , 2 natural lakes and 2 rive...

Three representative areas (two in the range of the Buhovo mine and one near the village of Katina) located in Western Bulgaria and a part of the Balkan Mountains uranium deposit were sampled between 2015 and 2016. Physical and chemical parameters of the soil, such as moisture content, temperature, pH, organic matter, and texture, were measured at...

Long-term trends of the ecological status assessed by biological quality element macrozoobenthos, of the transboundary Mesta River (South Bulgaria) during the period 1978-2020 were analyzed. Macrozoobenthos samples were taken and physico-chemical parameters were measured twice at 7 sites situated on the main river and its tributaries during the low...

The study aimed to analyse the representativeness of the monitoring sites for the ecological status assessment of running water bodies through an example of a model systems: Chetirka (Logodashka) River and its tributaries Gabrovska and Leshtinska River as well as the section of the Struma River after the Chetirka inflow. Hydrobiological (benthologi...

Two decades after the first record of the invasive mussel Corbicula fluminea (Müller, 1774) in Bulgaria in 2001, it has been found in many surface lotic and standing waters in the Bulgarian Danube River Basin. The aim of the current study is to report the finding of C. fluminea in lotic environment of the East Aegean water basin in Bulgaria. Six ne...

The aim of the study was to identify the current taxonomic composition and dominant structure of the macrozoobenthos in the Maritsa River and estuarine zones of its main tributaries (Chepelarska, Sazliyka, Stryama and Topolnitsa). The samples were collected from 15 sites in August and September 2020. The total number of the identified taxa was 165...

The study presents results on diversity and geographical distribution of the orders Ephemeroptera, Ple-coptera and Trichoptera (EPT) in eight mountain tributaries of Struma River. The EPT benthic fauna was studied for the first time in the Otovitsa and Mochura Rivers. The research was performed in August 2020 at nine localities within the Struma Ri...

Ecosystems of karst springs are insufficiently studied in Bulgaria. This study was focused on bottom macroinvertebrate assemblages from this river type. Their taxonomic diversity, community structure and habitat preferences in relation with the environmental factors were examined. During the summer of 2020, seven rivers originating from karst sprin...

Intermittent rivers and ephemeral streams drain more than 50% of the land surface on Earth. Yet, their ecology remains insufficiently understood. In Bulgaria, temporary rivers are typically small- or medium-sized rivers (national type R14), flowing in areas with subMediterranean climate. We present the first data focused explicitly on macrozoobenth...

Eutrophication impact on key aquatic communities (phytoplankton, macrophytes and macrozoobenthos) was studied in three standing water bodies in Bulgaria (Kardzhali, Koprinka and Batak). The reservoirs had a high summer nutrient level and were between eu- and hypertrophic category. In the meso-eutrophic condition the highest number of phytoplankton...

Seasonal impact on the ecological status assessment through macrozoobenthos in representative lentic water bodies (lakes and dams) situated at Ecoregion 7 Eastern Balkans (South Bulgaria) was made. Data from twelve standing water bodies during three seasons (summer 2018, autumn 2018 and spring 2019) were analysed. The Total number of taxa index sho...

The study presents the current ecological status assessment of the Bulgarian part of the Strumeshnitsa River, its tributary Luda Mara River, and the Struma river, in the section after the Strumeshnitsa River influx. The study was conducted in the summer of 2015. Six representative sampling sites situated at three rivers were selected. Biological (b...

Тhe present study was focused on the influence of heterogeneity of the bottom substrate and the amount of organic carbon in sediments on the riverine macrozoobentos trophic structure. The benthic and sediment samples were taken in the spring and autumn of 2011 and 2012 from four Bulgarian rivers – Mesta, Vit, Tundzha and Veleka, situated at three d...

The national legislation on surface waters characterization (Regulation N4/2012) was applied for the lotic ecosystems in Torfeno Branishte (Vladayska and Boyanska Rivers) and Bistrishko Branishte Reserves (Bistritsa and Yanchovska Rivers) in view of ecological status assessment. Water samples were collected and analysed both for physicochemical ele...

The Batova Valley is protected in the sense of the requirements of the Habitats and Birds Directives and the Biodiversity Act. European environmental agency developed in the 2000 year Directive 2000/60/EC for a mutual strategy of European Council countries, for prevention and protection of waters. Criteria for assessment of surface water bodies bas...

The trophic structure of macrozoobenthos in 50 of the largest standing water bodies (lakes and reservoirs) in Bulgaria was studied. Two-year benthic sampling from 11 lakes and 39 reservoirs, belonging to 15 national types of standing water bodies were taken. The analysis of the taxonomic composition and the abundance of functional feeding groups sh...

Surveys on benthic macroinvertebrate communities of ten standing water bodies (Bezbog, Kalin, Choklyovo marsh, Bistraka, Dospat, Stoykovtsi, Drenov dol, Pchelina, Dolna Dikanya, Dyakovo) were conducted in the period July-August 2018. They were chosen to represent natural (lakes) characterized with reference conditions as well as artificial and heav...

The book is written to summarize the results of the WEMA project „Mapping and Assessment of Ecosystem Services of Wetlands in Bulgaria“. The project was implemented by the Institute of Biodiversity and Ecosystem Research at the Bulgarian Academy of Sciences (IBER‐BAS) and was accomplished with the financial support of the BG03 Program „Biodiversity...

Книгата е написана с цел да се обобщят резултатите от проект „Картиране и оценка на екосистемните услуги във влажните зони на България“ (WEMA). Проектът беше изпълнен от Института по биоразнообразие и екосистемни изследвания при БАН (ИБЕИ- БАН) и е осъществен с финансовата подкрепа на Програма BG03 „Биологично разнообразие и екосистеми“, по Финансо...

Aphelocheirus aestivalis is a stenobiotic species with low dispersion ability. It is the only member of the family Aphelocheiridae found in most of Europe. Hydromorphological changes and water pollution threaten its subpopulations. Considering the vulnerability of the species, more accurate data about its occurrence and geographic distribution are...

The functional feeding groups of the riverine macrozoobenthos are studied in two ecoregions (East Balkan and Pontic Province) and two catchment basins (Aegean and Black Sea) in Bulgaria. Totally, 83 benthic samples from 40 sites situated at 35 rivers, which belong to ten types of water bodies are analysed for establishing site-specific referent con...

The book is written to summarize the results of the WEMA project „Mapping and Assessment of Ecosystem Services of Wetlands in Bulgaria“. The project was implemented by the Institute of Biodiversity and Ecosystem Research at the Bulgarian Academy of Sciences (IBER‐BAS) and was accomplished with the financial support of the BG03 Program „Biodiversity...

Atanasovsko Lake (7.200 ha, Southeast Bulgaria) incorporates diverse habitats and lies along the Europe's second largest migration route, Via Pontica. The dynamics of environmental conditions, factors controlling water quality and ecological status (water chemical parameters and biological quality elements) were studied for three years. The key fac...

10 Trophic structure of benthic macroinvertebrates in three different types of running water 11 bodies subjected to varying degrees of anthropogenic pressure was analyzed. A seasonal 12 survey was conducted at the three Bulgarian rivers during 2011. An adapted version of the 13 multi-habitat sampling method was applied along with measuring physical...

Species diversity and distribution of benthic macroinvertebrates in 51 of the largest Bulgarian natural lakes and reservoirs were studied in 2011 and (or) 2012. This work presents the first comprehensive faunistic composition of Bulgarian standing water bodies. The up-to-date check-list includes 297 taxa belonging to 22 systematic groups. These inc...

The water quality, physico-chemical and the ecological state assessment of the water bodies of the trans- boundary Mesta River during the period 2009-2010 were discussed. The MDS analysis illustrated that similarities between species composition of the macrozoobenthos at the studied sites are based on the level of the anthropogenic impact rather...

KERAKOVA, M., M. IHTIMANSKA and E. VARADINOVA, 2013. Application of trophic indices in ecological state assessment of riverine water bodies. Bulg. J. Agric. Sci., Supplement 2, 19: 277–281 Benhtosological data from 39 potentially referent sites situated on 33 Bulgarian rivers are used for this study. Functional feeding group distribution and the ma...

The Lower Danube, being an important navigable way, is recognized as a heavily modified water body according to the Water Framework Directive criteria. The riparian zone is subjected to various anthropo- genic pressures, such as discharge of organic substances and nutrients, continuity interruption, sediments and gravel abstraction, rip-rap armo...

A comparison of the Irish Quality Rating System (Q-Scheme) and the Bulgarian version of the scheme was made for two different ecoregions. A total of 16 macroinvertebrate samples were taken from 11 rivers and their tributaries in Ireland and Bulgaria. Eight of the sites were situated on six rivers flowing into the Black Sea. Eight samples were taken...

The article represents recent data of the first complex study on the oligochaete fauna from the main river courses in the Pirin Mountain, SW Bulgaria. Samples were taken from 18 streams and rivers but aquatic oligochaets were found only in 10 of them. A total of 125 specimens were identified and assigned to 16 taxa, 11 of them identified to the spe...

The stone crayfish Austropotamobius torrentium is one of the three native crayfish species occuring in Bulgaria (the other two are Astacus astacus and Astacus leptodactylus), which is protected by many European and national laws. In comparison with other European countries little is known about the population status of stone crayfish in Bulgaria. T...

The present study was conducted to establish the seasonal changes of the macrozoobenthic communities in different habitats, within the Srebarna Lake, during the period 2009-2011. The lowest value of the total abundance was recorded during the spring of 2011 in the central open water body, where unfavorable environmental conditions were recorded. In...

The Lower Danube, being an important navigable way, is recognized as a heavily modified water body according to the Water Framework Directive criteria. The riparian zone is subjected to various anthropogenic pressures, such as discharge of organic substances and nutrients, continuity interruption, sediments and gravel abstraction, rip-rap armoring,...

Complex investigations of the Blagoevgradska Bistritsa River, left tributary of the trans-boundary Struma River, were carried out in the summer of 2008. Seven representative sites were sampled. Physico-chemical parameters such as water temperature, pH, oxygen concentration, oxygen saturation, conductivity, nitrates and phosphates were measured. The...

Studies of the species diversity and abundance of the aquatic Oligochaeta fauna as a part of macrozoobenthic communities survey was conducted in 15 lentic water bodies in Bulgaria. Studied sites referred to the ecoregions 7 (Eastern Balkan) and 12 (Pontic/Danubian Province) and belong to different types of stagnant water bodies, according Bulgarian...

The water quality, physico-chemical and the ecological state assessment of the water bodies of the transboundary Mesta River during the period 2009-2010 were discussed. The MDS analysis illustrated that similarities between species composition of the macrozoobenthos at the studied sites are based on the level of the anthropogenic impact rather than...

This work focuses on an integrated approach for lake ecological status assessment, elaborated according to the requirements of the European Water Framework Directive (WFD). Data from five lowland and semi-mountain lakes in Bulgaria (Southeast Europe) collected from two years (2011-2012) form the basis for an integrated assessment and the definition...

This paper presents the results of species content and structure of the macroinvertebrate communities alongside Tundzha River (South-East Bulgaria) and some of its tributaries for two periods of investigations: 1987 and 2009. The changes of macrozoobenthos community in Tundzha River are not just related with appearance or disappearance of the speci...

The ‘normative definitions’ of ecological water quality classes given by the Water Framework Directive (WFD) are narrative descriptions of the conditions present in water bodies of different qualities relative to reference conditions found in unimpacted sites. Defining the type-specific reference conditions for water bodies and finding biological m...

Thе biodiversity of aquatic communities (macrozoobenthos, zooplankton and fish) in 5 of Smolyanski and 2 of Chairski landslide lakes was studied in spring and summer of 2010. A total of 19 taxa of different taxonomic level of macrozoobenthos and zooplankton were reported for the first time in the studied lakes. The enriched list included 4 new p...

The first record of Branchiura sowerbyi in Bulgaria was in 1964 at a fish farm on Belene Island (576-560 R. km) in the Danube River. During the last 50 years this species has become established downstream to the 530 R. km of the Danube River and has spread rapidly upstream of nearly all the Danube tributaries. Nowadays the distribution of this spec...

Development of the taxonomic composition of bottom macroinvertebrate fauna in Srebarna Lake Re- serve is studied with a view to the changes in the environment after its reconnection with Danube River. A regime switching in the succession of the bottom invertebrate community in Srebarna Lake occurs expressed by considerable changes of its species...

Hildenbrandia rivularis, a rarely found red algal species and one of the few red algae that occur in freshwaters, has been recorded for the eighth time in Bulgaria. In 2011 during phyto- and macrozoobenthos sampling along Tundzha river, on submerged cobbles and pebbles of the river near Gavrailovo village (close to the city of Sliven), variable in...

Development of the taxonomic composition of bottom macroinvertebrate fauna in Srebarna Lake Reserve is studied with a view to the changes in the environment after its reconnection with Danube River. A regime switching in the succession of the bottom invertebrate community in Srebarna Lake occurs expressed by considerable changes of its species comp...

The multi-habitat sampling method (adapted version), combining the techniques according to the AQEM/ STAR methodology, EN 27828:1994, EN ISO 5667-1:2006/AC: 2007, EN ISO 5667-3:2003/AC: 2007, EN 28265:1994, was developed in compliance with type-specific river conditions in Bulgaria. A number of specifics with the original sampling method were defin...

We present progress towards developing a qualitativ e reasoning model of sustainable development issues i n the River Mesta, Bulgaria, following a standardized framework for conceptual description of QR case studies. Using the QR ontology, we have organized our expert knowledge about biological and physical processes in the stream as well as impact...

The recovery processes of the benthic invertebrate communities and improving availability of the bottom habitats of the Srebarna Biosphere Reserve is discussed. After the construction of the connecting canal (1994-1995), the bottom invertebrates were found to be represented during the whole vegetation period, and the species diversity is getting hi...

A survey on the composition, abundance of macroinvertebrates and application of some biological water quality indices at 36 sites in the West Aegean Sea River Basin District and the East Aegean Sea River Basin District was carried out as a part of a broad study on supplemental water quality survey. Totally 239 macroinvertebrate taxa belonging to 21...

Successful transfer and uptake of qualitative reasoning technology for modelling and simulation in a variety of domains has been hampered by the lack of a structured methodology to support formalisation of ideas. We present a framework that structures and supports the capture of conceptual knowledge about system behaviour using a qualitative reason...

Practicability of the new Integral index of the organic pollution degree (IT) based on functional feeding groups (FFG) of the macrozoobenthos was tested for assessment of the ecological status of the Mesta river. Dynamic balance of the proportion of two functional feeding groups - shredders (SH) and deposit feeders (DF) can be indicative for the fo...

The dynamics of the functional feeding groups (FFGs) of the bottom invertebrate communities was studied in relation to flow parameters (discharge, cross section area, mean current velocity and water depth) at three selected sites within the system of the River Mesta. Pearson's correlation coefficient was used for initial estimation of correspondenc...