Ivan Traykov | Sofia University "St. Kliment Ohridski" (original) (raw)
Papers by Ivan Traykov
TRAYKOV, I. and A. TOSHEVA, 2015. Trophic state and macrophyte based assessment of the ecological... more TRAYKOV, I. and A. TOSHEVA, 2015. Trophic state and macrophyte based assessment of the ecological status of selected reservoirs in Bulgaria. Bulg. J. Agric. Sci., Supplement 1, 21: 121–125 The objectives of the study were to assess the trophic state and to compare it to the ecological potential of the water bodies according to the macrophyte assemblages within selected reservoirs. The studied reservoirs varied greatly in their trophic status, as well as in species composition and abundance. Sampling was conducted between 2009 and 2014. The concentrations of nutrients and the Carlson’s trophic state indices were used to assess the trophic state of the reservoirs. The trophic state varied between oligo-mesotrophic to hyper-eutrophic, with the majority being eutrophic. A discrepancy between the expected trophic state and the measured one was observed for each water body type. No correlation was observed between the trophic state and the ecological status of the water bodies. Trophic st...
TRAYKOV, I. and M. VLADIMIROVA, 2015. Relationships between trophic state and physicochemical var... more TRAYKOV, I. and M. VLADIMIROVA, 2015. Relationships between trophic state and physicochemical variables of some standing waterbodies on the territory of East-Aegean river Basin directorate, Bulgaria. Bulg. J. Agric. Sci., Supplement 1, 21: 126–136 The objectives of the study were to describe the physicochemical variables and to assess the trophic state of the reservoirs Ovcharitsa, Byal Kladenets, Skalitsa, Zhrebchevo and the fi shponds of Nikolaevo. Sampling was conducted at four occasions between April and August 2013. The concentrations of nutrients and the Carlson’s trophic state indices were used to assess the trophic state of the water bodies. The trophic state spans over several trophic categories – from oligo-mesotrophic to hypertrophic, with majority of the water bodies being eutrophic. Very strong positive correlation was observed between the transparency and the chlorophyl trophic state indices. Weaker, but still strong correlation was observed between the transparency an...
Plants
Upland rivers across Europe still exhibit undisturbed conditions and represent a treasure that we... more Upland rivers across Europe still exhibit undisturbed conditions and represent a treasure that we cannot afford to lose. We hypothesize that the combination of pristine and modified conditions could demonstrate biological responses along the stressor gradients. Thus, the response of aquatic macrophyte communities to anthropogenic stressors along upland rivers in Bulgaria was studied. Six stressors were selected out of 36 parameters grouped into hydromorphological, chemical variables and combined drivers (catchment land use). The stressors strongly affected species richness on the basis of biological type (bryophytes vs. vascular plants) and ecomorphological type (hydrophytes vs. helophytes). Hydrological alteration expressed by the change of the river’s base flow and altered riparian habitats has led to a suppression of bryophytes and a dominance of riverbank plant communities. Seventy-five percent of mountain sites were lacking bryophytes, and the vegetation at semi-mountainous sit...
Acta Zoologica Bulgarica
Three reservoirs are planned to be built in the upper section of the Arda River, Central Rhodope ... more Three reservoirs are planned to be built in the upper section of the Arda River, Central Rhodope Moun-tains, Bulgaria. Pursuant to a decision of the Environment and Waters Ministry relating to the Environ-mental Impact Assessment of the Madan Reservoir, a feasibility study was conducted on the loading and the eutrophication mitigation measures. Nutrient source apportionment modelling, and estimation of instream loads on which such modelling is validated, is made. The level of uncertainty increases when monitoring frequencies are low. In order to illustrate the level of variability that such uncertainty can gen-erate in modelling results, the most likely nutrient load with probable upper and lower boundary levels are calculated to demonstrate the likely possible range of nutrient loads from individual pressures (sources). The results are used to forecast the trophic state of the Madan Reservoir. Source apportionment model-ling should only be used as an indicator of the likely contrib...
The reservoirs are artificial water bodies with strong anthropogenic impact on the dynamics of th... more The reservoirs are artificial water bodies with strong anthropogenic impact on the dynamics of the environmental factors and the biotic interactions. The changes in the exploitation regime of the reservoir determine both the spatial and temporal changes of the environmental factors and the characteristics of the biotic community. The influence of the exploitation regime is illustrated by the changes in the basic environmental factors along the Kardjaly reservoir between 2000 and 2002. The hypolimnetic withdraw of waters and the changes in the water levels had a significant impact on the temperature and the oxygen regimes of the reservoir, the longitudinal gradients of the chemical parameters and as a consequence – on the biological response of the system. The sustaining of the water level above the mean annual level and the lower through-flow of the reservoir in 2002 led to strengthening in the spatial heterogeneity of the numbers and relative abundance of the zooplankton and a simu...
Bulgarian Journal of Agricultural Science
Longitudinal differences in physical and chemical parameters lead to a trophic gradient in the re... more Longitudinal differences in physical and chemical parameters lead to a trophic gradient in the reservoirs. Marked differences in abiotic parameters and trophic response were observed between the riverine and the lacustrine part of Ognyanovo reservoir in relation to nutrients loading. Abundance and species composition of aquatic macrophytes were studied between 2009 and 2012. The observations at each sampling station are based on transect monitoring data. Strong infl uence of water level fl uctuations and seasonal dynamics were observed, which emphasizes the problem of what the proper time is for macrophytes sampling in reservoirs to provide an adequate defi nition of the ecological state in the future. The gathered data are used to produce a map of the macrophytes distribution in the reservoir. Rapid spread of the invasive species Elodea nuttallii is described after it appeared in the reservoir. A multiple point of spreading of E. nuttallii is observed in relation to fi shermen and ...
Bulgarian Journal of Agricultural Science
New information on the distribution of some macrophytes from different types of limnetic water bo... more New information on the distribution of some macrophytes from different types of limnetic water bodies in Bulgaria was presented. The chorological data are related to 9 species: Ceratophyllum demersum, Lemna gibba, Myriophyllum spicatum, Myriophyllum verticilatum, Najas marina, Potamogeton gramineus, Potamogeton pectinatus, Potamogeton perfoliatus, Typha laxmanii.
Bulgarian Journal of Agricultural Science
The impact of single small hydropower plants on the environment is thought to be negligible. Thei... more The impact of single small hydropower plants on the environment is thought to be negligible. Their effect progressively increases with the cascade development of the river basins, thus the cumulative environmental effects of small hydropower reservoirs can have a signifi cant impact on the ecological state of the rivers. We have studied the effect of two small hydropower reservoirs on some parameters of river water quality. The Lakatnik Reservoir and the Svrazhen Reservoir are situated in the middle reaches of the Iskar River, directly one after another. The river water is rich in nutrients and organic substances and carries high amounts of suspended sediments. As it fl ows through the cascade, the river temperature increases, while oxygen concentration, electrical conductivity and suspended sediments decrease, mostly due to the enhanced degradation and transformation of the organic substances in the water. The amount of the phytoplankton depends on the residence time and the amount...
Biotechnology & Biotechnological Equipment, 2015
Ecotoxicology and Environmental Safety, 2014
Plants, 2021
Upland rivers across Europe still exhibit undisturbed conditions and represent a treasure that we... more Upland rivers across Europe still exhibit undisturbed conditions and represent a treasure that we cannot afford to lose. We hypothesize that the combination of pristine and modified conditions could demonstrate biological responses along the stressor gradients. Thus, the response of aquatic macrophyte communities to anthropogenic stressors along upland rivers in Bulgaria was studied. Six stressors were selected out of 36 parameters grouped into hydromorphological, chemical variables and combined drivers (catchment land use). The stressors strongly affected species richness on the basis of biological type (bryophytes vs. vascular plants) and ecomorphological type (hydrophytes vs. helophytes). Hydrological alteration expressed by the change of the river’s base flow and altered riparian habitats has led to a suppression of bryophytes and a dominance of riverbank plant communities. Seventy-five percent of mountain sites were lacking bryophytes, and the vegetation at semi-mountainous sit...
All in-text references underlined in blue are linked to publications on ResearchGate, letting you... more All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
Biotechnology & Biotechnological Equipment, 2010
Environmental Science and Pollution Research, 2015
Ore mining and processing have greatly altered ecosystems, often limiting their capacity to provi... more Ore mining and processing have greatly altered ecosystems, often limiting their capacity to provide ecosystem services critical to our survival. The soil environments of two abandoned uranium mines were chosen to analyze the effects of long-term uranium and heavy metal contamination on soil microbial communities using dehydrogenase and phosphatase activities as indicators of metal stress. The levels of soil contamination were low, ranging from 'precaution' to 'moderate', calculated as Nemerow index. Multivariate analyses of enzyme activities revealed the following: (i) spatial pattern of microbial endpoints where the more contaminated soils had higher dehydrogenase and phosphatase activities, (ii) biological grouping of soils depended on both the level of soil contamination and management practice, (iii) significant correlations between both dehydrogenase and alkaline phosphatase activities and soil organic matter and metals (Cd, Co, Cr, and Zn, but not U), and (iv) multiple relationships between the alkaline than the acid phosphatase and the environmental factors. The results showed an evidence of microbial tolerance and adaptation to the soil contamination established during the long-term metal exposure and the key role of soil organic matter in maintaining high microbial enzyme activities and mitigating the metal toxicity. Additionally, the results suggested that the soil microbial communities are able to reduce the metal stress by intensive phosphatase synthesis, benefiting a passive environmental remediation and provision of vital ecosystem services.
This is the final report of a small project, part of the bigger one: CONTROL OF EUTROPHICATION, H... more This is the final report of a small project, part of the bigger one: CONTROL OF EUTROPHICATION, HAZARDOUS SUBSTANCES AND RELATED MEASURES FOR REHABILITATING THE BLACK SEA ECOSYSTEM: PHASE I. The report has been rusting for quite a long time in my PC, so I decided to upload it, although it is outdated, as it provides background information and can be used by other colleagues. The following is part of the introduction to the project: The aims of the project for the Kamchiya River are part of the aims of the BSERP. The tasks of the project derive from the Water Framework Directive (WFD) of the EU whose implementation is a key task of leading water specialists in most of the countries in the Western Black Sea and are also important for the other Black Sea countries. The WFD, focusing on the principles of integrated water management introduces the concept of the River Basin Management Plans. Watershed Directorates are being created in Bulgaria and development of Water Management Plans ar...
Acta Zoologica Bulgarica
The development in the middle section of the Vacha cascade and adequate utilization of the availa... more The development in the middle section of the Vacha cascade and adequate utilization of the available hydro power potential along the river valley Vacha includes the rehabilitation of the existing reservoirs and the construction of a new one – the Tsankov Kamak Reservoir. Longitudinal differences in physical and chemical parameters lead to a trophic gradient in reservoirs. Those gradients are further increased by the close proximity of the reservoirs in the Vacha cascade. The lower reservoirs in the cascade will be strongly infl uenced by the construction of the Tsankov Kamak Reservoir. Marked spatial heterogeneity in abiotic parameters and trophic response in the reservoirs were related to loading and water level fl uctuations due to dam operations. A gradient from eutrophic to mesotrophic state was observed between the stations in the Vacha Reservoir and a subsequent increase in the trophic state in the Krichim Reservoir, due to increased hydraulic loading. Assessment of deviations...
TRAYKOV, I. and A. TOSHEVA, 2015. Trophic state and macrophyte based assessment of the ecological... more TRAYKOV, I. and A. TOSHEVA, 2015. Trophic state and macrophyte based assessment of the ecological status of selected reservoirs in Bulgaria. Bulg. J. Agric. Sci., Supplement 1, 21: 121–125 The objectives of the study were to assess the trophic state and to compare it to the ecological potential of the water bodies according to the macrophyte assemblages within selected reservoirs. The studied reservoirs varied greatly in their trophic status, as well as in species composition and abundance. Sampling was conducted between 2009 and 2014. The concentrations of nutrients and the Carlson’s trophic state indices were used to assess the trophic state of the reservoirs. The trophic state varied between oligo-mesotrophic to hyper-eutrophic, with the majority being eutrophic. A discrepancy between the expected trophic state and the measured one was observed for each water body type. No correlation was observed between the trophic state and the ecological status of the water bodies. Trophic st...
TRAYKOV, I. and M. VLADIMIROVA, 2015. Relationships between trophic state and physicochemical var... more TRAYKOV, I. and M. VLADIMIROVA, 2015. Relationships between trophic state and physicochemical variables of some standing waterbodies on the territory of East-Aegean river Basin directorate, Bulgaria. Bulg. J. Agric. Sci., Supplement 1, 21: 126–136 The objectives of the study were to describe the physicochemical variables and to assess the trophic state of the reservoirs Ovcharitsa, Byal Kladenets, Skalitsa, Zhrebchevo and the fi shponds of Nikolaevo. Sampling was conducted at four occasions between April and August 2013. The concentrations of nutrients and the Carlson’s trophic state indices were used to assess the trophic state of the water bodies. The trophic state spans over several trophic categories – from oligo-mesotrophic to hypertrophic, with majority of the water bodies being eutrophic. Very strong positive correlation was observed between the transparency and the chlorophyl trophic state indices. Weaker, but still strong correlation was observed between the transparency an...
Plants
Upland rivers across Europe still exhibit undisturbed conditions and represent a treasure that we... more Upland rivers across Europe still exhibit undisturbed conditions and represent a treasure that we cannot afford to lose. We hypothesize that the combination of pristine and modified conditions could demonstrate biological responses along the stressor gradients. Thus, the response of aquatic macrophyte communities to anthropogenic stressors along upland rivers in Bulgaria was studied. Six stressors were selected out of 36 parameters grouped into hydromorphological, chemical variables and combined drivers (catchment land use). The stressors strongly affected species richness on the basis of biological type (bryophytes vs. vascular plants) and ecomorphological type (hydrophytes vs. helophytes). Hydrological alteration expressed by the change of the river’s base flow and altered riparian habitats has led to a suppression of bryophytes and a dominance of riverbank plant communities. Seventy-five percent of mountain sites were lacking bryophytes, and the vegetation at semi-mountainous sit...
Acta Zoologica Bulgarica
Three reservoirs are planned to be built in the upper section of the Arda River, Central Rhodope ... more Three reservoirs are planned to be built in the upper section of the Arda River, Central Rhodope Moun-tains, Bulgaria. Pursuant to a decision of the Environment and Waters Ministry relating to the Environ-mental Impact Assessment of the Madan Reservoir, a feasibility study was conducted on the loading and the eutrophication mitigation measures. Nutrient source apportionment modelling, and estimation of instream loads on which such modelling is validated, is made. The level of uncertainty increases when monitoring frequencies are low. In order to illustrate the level of variability that such uncertainty can gen-erate in modelling results, the most likely nutrient load with probable upper and lower boundary levels are calculated to demonstrate the likely possible range of nutrient loads from individual pressures (sources). The results are used to forecast the trophic state of the Madan Reservoir. Source apportionment model-ling should only be used as an indicator of the likely contrib...
The reservoirs are artificial water bodies with strong anthropogenic impact on the dynamics of th... more The reservoirs are artificial water bodies with strong anthropogenic impact on the dynamics of the environmental factors and the biotic interactions. The changes in the exploitation regime of the reservoir determine both the spatial and temporal changes of the environmental factors and the characteristics of the biotic community. The influence of the exploitation regime is illustrated by the changes in the basic environmental factors along the Kardjaly reservoir between 2000 and 2002. The hypolimnetic withdraw of waters and the changes in the water levels had a significant impact on the temperature and the oxygen regimes of the reservoir, the longitudinal gradients of the chemical parameters and as a consequence – on the biological response of the system. The sustaining of the water level above the mean annual level and the lower through-flow of the reservoir in 2002 led to strengthening in the spatial heterogeneity of the numbers and relative abundance of the zooplankton and a simu...
Bulgarian Journal of Agricultural Science
Longitudinal differences in physical and chemical parameters lead to a trophic gradient in the re... more Longitudinal differences in physical and chemical parameters lead to a trophic gradient in the reservoirs. Marked differences in abiotic parameters and trophic response were observed between the riverine and the lacustrine part of Ognyanovo reservoir in relation to nutrients loading. Abundance and species composition of aquatic macrophytes were studied between 2009 and 2012. The observations at each sampling station are based on transect monitoring data. Strong infl uence of water level fl uctuations and seasonal dynamics were observed, which emphasizes the problem of what the proper time is for macrophytes sampling in reservoirs to provide an adequate defi nition of the ecological state in the future. The gathered data are used to produce a map of the macrophytes distribution in the reservoir. Rapid spread of the invasive species Elodea nuttallii is described after it appeared in the reservoir. A multiple point of spreading of E. nuttallii is observed in relation to fi shermen and ...
Bulgarian Journal of Agricultural Science
New information on the distribution of some macrophytes from different types of limnetic water bo... more New information on the distribution of some macrophytes from different types of limnetic water bodies in Bulgaria was presented. The chorological data are related to 9 species: Ceratophyllum demersum, Lemna gibba, Myriophyllum spicatum, Myriophyllum verticilatum, Najas marina, Potamogeton gramineus, Potamogeton pectinatus, Potamogeton perfoliatus, Typha laxmanii.
Bulgarian Journal of Agricultural Science
The impact of single small hydropower plants on the environment is thought to be negligible. Thei... more The impact of single small hydropower plants on the environment is thought to be negligible. Their effect progressively increases with the cascade development of the river basins, thus the cumulative environmental effects of small hydropower reservoirs can have a signifi cant impact on the ecological state of the rivers. We have studied the effect of two small hydropower reservoirs on some parameters of river water quality. The Lakatnik Reservoir and the Svrazhen Reservoir are situated in the middle reaches of the Iskar River, directly one after another. The river water is rich in nutrients and organic substances and carries high amounts of suspended sediments. As it fl ows through the cascade, the river temperature increases, while oxygen concentration, electrical conductivity and suspended sediments decrease, mostly due to the enhanced degradation and transformation of the organic substances in the water. The amount of the phytoplankton depends on the residence time and the amount...
Biotechnology & Biotechnological Equipment, 2015
Ecotoxicology and Environmental Safety, 2014
Plants, 2021
Upland rivers across Europe still exhibit undisturbed conditions and represent a treasure that we... more Upland rivers across Europe still exhibit undisturbed conditions and represent a treasure that we cannot afford to lose. We hypothesize that the combination of pristine and modified conditions could demonstrate biological responses along the stressor gradients. Thus, the response of aquatic macrophyte communities to anthropogenic stressors along upland rivers in Bulgaria was studied. Six stressors were selected out of 36 parameters grouped into hydromorphological, chemical variables and combined drivers (catchment land use). The stressors strongly affected species richness on the basis of biological type (bryophytes vs. vascular plants) and ecomorphological type (hydrophytes vs. helophytes). Hydrological alteration expressed by the change of the river’s base flow and altered riparian habitats has led to a suppression of bryophytes and a dominance of riverbank plant communities. Seventy-five percent of mountain sites were lacking bryophytes, and the vegetation at semi-mountainous sit...
All in-text references underlined in blue are linked to publications on ResearchGate, letting you... more All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
Biotechnology & Biotechnological Equipment, 2010
Environmental Science and Pollution Research, 2015
Ore mining and processing have greatly altered ecosystems, often limiting their capacity to provi... more Ore mining and processing have greatly altered ecosystems, often limiting their capacity to provide ecosystem services critical to our survival. The soil environments of two abandoned uranium mines were chosen to analyze the effects of long-term uranium and heavy metal contamination on soil microbial communities using dehydrogenase and phosphatase activities as indicators of metal stress. The levels of soil contamination were low, ranging from 'precaution' to 'moderate', calculated as Nemerow index. Multivariate analyses of enzyme activities revealed the following: (i) spatial pattern of microbial endpoints where the more contaminated soils had higher dehydrogenase and phosphatase activities, (ii) biological grouping of soils depended on both the level of soil contamination and management practice, (iii) significant correlations between both dehydrogenase and alkaline phosphatase activities and soil organic matter and metals (Cd, Co, Cr, and Zn, but not U), and (iv) multiple relationships between the alkaline than the acid phosphatase and the environmental factors. The results showed an evidence of microbial tolerance and adaptation to the soil contamination established during the long-term metal exposure and the key role of soil organic matter in maintaining high microbial enzyme activities and mitigating the metal toxicity. Additionally, the results suggested that the soil microbial communities are able to reduce the metal stress by intensive phosphatase synthesis, benefiting a passive environmental remediation and provision of vital ecosystem services.
This is the final report of a small project, part of the bigger one: CONTROL OF EUTROPHICATION, H... more This is the final report of a small project, part of the bigger one: CONTROL OF EUTROPHICATION, HAZARDOUS SUBSTANCES AND RELATED MEASURES FOR REHABILITATING THE BLACK SEA ECOSYSTEM: PHASE I. The report has been rusting for quite a long time in my PC, so I decided to upload it, although it is outdated, as it provides background information and can be used by other colleagues. The following is part of the introduction to the project: The aims of the project for the Kamchiya River are part of the aims of the BSERP. The tasks of the project derive from the Water Framework Directive (WFD) of the EU whose implementation is a key task of leading water specialists in most of the countries in the Western Black Sea and are also important for the other Black Sea countries. The WFD, focusing on the principles of integrated water management introduces the concept of the River Basin Management Plans. Watershed Directorates are being created in Bulgaria and development of Water Management Plans ar...
Acta Zoologica Bulgarica
The development in the middle section of the Vacha cascade and adequate utilization of the availa... more The development in the middle section of the Vacha cascade and adequate utilization of the available hydro power potential along the river valley Vacha includes the rehabilitation of the existing reservoirs and the construction of a new one – the Tsankov Kamak Reservoir. Longitudinal differences in physical and chemical parameters lead to a trophic gradient in reservoirs. Those gradients are further increased by the close proximity of the reservoirs in the Vacha cascade. The lower reservoirs in the cascade will be strongly infl uenced by the construction of the Tsankov Kamak Reservoir. Marked spatial heterogeneity in abiotic parameters and trophic response in the reservoirs were related to loading and water level fl uctuations due to dam operations. A gradient from eutrophic to mesotrophic state was observed between the stations in the Vacha Reservoir and a subsequent increase in the trophic state in the Krichim Reservoir, due to increased hydraulic loading. Assessment of deviations...