Content uploaded by Vesela Evtimova
Author content
All content in this area was uploaded by Vesela Evtimova on Sep 16, 2015
Content may be subject to copyright.
A preview of the PDF is not available
Long-term changes of zooplankton and dynamics of eutrophication in the polluted system of Strouma River - Pchelina Reservoir (South-West Bulgaria)
Abstract and Figures
The qualitative and quantitative parameters of zooplankton in the Struma River – Pchelina Reservoir system and the ecotone zone between them are compared for the periods 1990-1992 and 2001-2003. The effects of transition from lotic to lentic conditions and the anthropogenic impact on the formation of zoo-plankton communities were investigated. During the first period the reservoir was a typical mesotrophic water body. More than 15 zooplankton species, that were present during 1990-1992, could not be found in 2001-2003. They are all pelagic elements. The number of species found only during the second period was 36. All of them are characteristic of eutrophic water bodies. Significant changes in the quantitative parameters of zooplankton were established in all parts of the system. The values of species diversity indices also have changed significantly in a way which suggests that the process of eutrophication has advanced.
Figures - uploaded by Vesela Evtimova
Author content
All figure content in this area was uploaded by Vesela Evtimova
Content may be subject to copyright.
... In such systems, the relationships between biological communities and their physical-chemical environment are in permanent process of responding to climate changes and the effects produced by the operational management of the dam [ 7 ]. There are several investigations on ecotone river-reservoir zones in Bulgaria, that concern different types of dams and communities [ 1,[8][9][10][11][12][13] ]. ...
... The drifted zoobenthic components were found in the ecotone zone. As a natural process in the river stream a part of the benthic organisms are involved in the biological drift [ 12 ]. ...
... All species from the family were present at the ecotone sampling points. Species like Pleuroxus aduncus, Alona costata and A. rectangula usually inhabit swamps and bogs [ 12 ]. Leydigia leydigi was found in the ecotone and is newly reported for Iskar reservoir. ...
The zooplankton parameters in Iskar River–Iskar Reservoir system and the ecotone zone between them were studied within the period 2009–2015. Samples were collected during different seasons at four fixed sampling points in order to determine the zooplankton species composition, abundance, species diversity and the ecotone effects. Eighty-five zooplankton taxa were identified. Most of the established taxa were euribiont and typical for Bulgarian stagnant waters. The order Copepoda was the most abundant for both ecotone and lacustrine zone of the system. A drastic change in the dominant complexes was registered, compared to the existing published data. The RCC index has been applied in order to assess the trophic state of the investigated system river-reservoir.
... The nauplii and copepodid development stages of Cladocera and Copepoda were encountered during almost the whole period of study (Tables 1 and 2). The zooplankton community was distinguished by considerable species diversity and included characteristic for Bulgarian freshwaters taxonomic groups Kozuharov et al., 2007;Tisheva and Kozuharov, 2013;Naydenov, 1993). ...
... The obtained results confi rmed the low species diversity of "Kardzhali" Dam found by Traykov et al. (2003Traykov et al. ( , 2005 in comparison to other reservoirs in Bulgaria, where the species number amounted to 115 (Kozuharov et al., 2007;Kozuharov et al., 2013;Tisheva and Kozuharov, 2013). Despite that it is the highest in comparison to other reservoirs of the cascade due to the short hydraulic residence time (Naydenov, 1984). ...
... In our study there were no differences in the community structure between years 2009 and 2011 and Cladocera took 68% from total abundance during the fi rst year at the expense of lower numbers of Copepoda order. (Traykov, 2003), characteristic for big part of Bulgarian reservoirs (Naid-enov, 1984b, Kozuharov et al., 2007. The reare several times high erabundance values on all stations during 2011 than in 2009, varying from 28 200 at station 2 till 647 800 individuals.m ...
TERZIYSKI, D., V. TZAVKOVA, R. KALCHEV and I. ILIEV, 2015. Impact of the fi sh cage aquaculture on the zooplankton community in " Kardzhali " Dam Lake, Bulgaria. Bulg. J. Agric. Sci., Supplement 1, 21: 45–55 Based on complex water body investigations including also studies of zooplankton community the effect of cage fi sh breeding on zooplankton cenotic indicies of Shanon, Pielu and Simpson in " Kardzhali " Dam Lake was analyzed. The spatial horizontal distribution of zooplankton biomass and the indicies of species diversity distinguished the zone in proximity of cage facilities as most antropogenically loaded, while the remote aquatic regions showed relatively high species diversity and stability values. Additionally the ratio Cladocera/Copepoda by biomass was calculated and the vertical zooplankton gradient distribution presented.
... In Bulgaria, the studies on the ecotone river-reservoir zones are several and their results concern different types of dams which makes difficult to draw general conclusions (Kovachev, Uzunov 1979, Naidenow W. 1981a, b, Naidenow, Baev 1987. Data concerning the changes of zooplankton in the ecotone between river and reservoir in Bulgaria were discussed by Kozuharov (1995Kozuharov ( , 1996, Kozuharov et al. (2007), Traykov et al. (2011). No data that fundamentally concern the zooplankton of Iskar reservoir can be found in the available literature for the last 30 years. ...
... The ecotone is a place with dynamic conditions of accumulation, decomposition and transfer of the pollutants within the river flow and later in the reservoir. Zooplankton communities are highly sensitive to environmental variations, especially in the ecotone zones (Naidenow, Baev 1987;Kovachev, Kozuharov 1994, Kozuharov 1995Kozuharov 1996;Kozuharov et al. 2007). As a result, the changes in their abundance and composition can provide important indications of environmental change. ...
... Most of them were found in the upper part of the ecotone (Station 1), where the stream of the river is significant. As a natural process in the river stream, some benthic organisms are part of the biological drift (Kozuharov et al. 2007). The zooplankton in Iskar reservoir was presented mainly by eurybiont species and components. ...
Iskar Reservoir is the largest reservoir in Bulgaria and provides more than 2/3 of the water for the capital Sofia. There are no data about the zooplankton of the reservoir for the last 30 years. The qualitative and quantitative zooplankton parameters in the ecotone zone Iskar river – Iskar reservoir were studied from July 2009 to March 2014. The zooplankton community was composed of 29 species of Rotifera, 17 species of Cladocera, 4 species of Copepoda and 3 species of Protozoa. Some not typical plankton elements were also found. The broad characteristics of the zooplankton in Iskar reservoir were compared with the available previous data and publications. There is a significant difference in the species composition. Daphnia hyalina and Syda crystalina are among the dominants in earlier periods. Recently these two species weren't found in the zooplankton composition of Iskar reservoir. Among the copepods Thermocyclops crassus is a species, that a few years ago occurs sporadically in Bulgarian waters. At present, it is common for Iskar reservoir. The cladocera Leptodora kindti was registered for the first time in the reservoir. Some relations were found between the trophic state of the reservoir and the zooplankton community. The obtained preliminary results from this study indicate an advanced process of eutrophication.
... During the two samplings, 12 quantitative samples were collected at 6 sites by using an Apstein plankton net 55 µm mesh size and via filtering of 100 dm 3 of water through the net. This method of direct filtering a certain amount of water through Apstein plankton net is widely used in the study of shallow holo-polymictic standing water bodies and ecotone river-reservoir zones (Kozuharov et al., 2007;Yakimov et al., 2016). The samples were fixed in 4% formalin. ...
... The big differences in the RCC index of the different stations showed the influence of the flowing rivers and the nutrients they carry (Kozuharov et al., 2007). There are specific conditions in the ecotone zones, which lead to mass development of one zooplankton group or the complete absence of another, which is clearly visible at site 1 in the spring and at site 4 during the two studied seasons. ...
The zooplankton community in Mandra Lake has been almost unstudied since it was turned into reservoir in 1963. Human intervention in the natural water regime of the lake has affected the species diversity of the aquatic system. This study was conducted in March 2017 and December 2018 in the reservoir. A total of 64 zooplankton taxa from the groups Protozoa, Rotifera, Cladocera and Copepoda were identified in the studied samples. The majority of these organisms (37%) belonged to the Rotifera group, with most common species in spring-Keratella hiemalis Carlin, 1943 and Polyarthra major Burckhardt, 1900. During the investigation period, the most frequent zooplankton components were Chydorus sphaericus (O.F. Müller, 1776) and Nauplii and Copepodites of Copepoda. 22 species from class Branchiopoda were established. Considerable changes in the quantitative composition of Rotifera at different sampling points and years are indicated by the low values of the Jaccard similarity index. When comparing the two spring seasons (1955 and 2017), the index has a value of less than 9 %. At the same time, the number of species increased 2.5 times.
... The zooplankton in most of the studied reservoirs has been poorly studied with the exception of Pchelina Reservoir (Kozuharov 1994, 1996, Kozuharov et al. 2007, Kozuharov et al. 2013. Moreover, to the best of our knowledge, this is the first study to test the applicability of zooplankton in the assessment of reservoirs in Bulgaria and to compare indices based on zooplankton abundance S PB , Sr% and RCC%. ...
The assessment of the current state of lakes and reservoirs is a prerequisite for the conservation and management of these ecosystems as well as for their restoration and mitigation of the damages triggered by various pressures. The aim of the present study was to explore associations of the zooplankton communities with the trophic state and (or) ecological potential (EP) of reservoirs, incorporating also standard physical and chemical factors and primary production. We recorded 48 zooplankton taxa: 32 rotifer, nine cladoceran and seven copepod taxa. Our results suggested a significant relationship of both zooplankton community and univariate metrics with trophic state index (TSI) and conductivity. Reservoirs with the highest correlation with TSI and chlorophyll a were with the highest trophic state. Most of the rotifers identified as indicator taxa evidenced eu-mesotrophic conditions or moderate-poor EP. The indicator cladocerans were significantly associated with moderate EP. The indicator copepods were associated with higher EP and oligo-mesotrophic conditions. Policy-driven approaches identified littoral macrozoobenthos as the key invertebrate group for the assessment of lentic water bodies, while science-driven studies focus more on the pelagial zooplankton communities in assessments of ecosystem health. The pelagial and the littoral of a lake (or a reservoir) are very different in the conditions, which they provide; they could be affected by distinct stressors, thus triggering a specific response of their communities. Studying lentic ecosystems in a more holistic way, across various water body types and for longer periods, would result in rigorous assessment schemes and improved management of the ecosystem health.
... The major part of the inland waters in Bulgaria are small and shallow artificial lakes (MICHEV & STOYNEVA, 2007), however, the investigations of lentic water bodies is dominated by researches in big, multipurpose reservoirs (NAIDENOW, 1970;NAIDENOV & BAEV, 1987;BESHKOVA, 1996;BESHKOVA & BOTEV, 1994;KALCHEV, 1994;KALCHEV et al., 1996;2003;2004;KALCHEV & BOUMBAROVA, 1996;KOZUHAROV, 1994;1996;KOZUHAROV et al., 2007;. ...
The current status of a lake can be evaluated via monitoring based on biological quality elements. Reference aquatic flora communities reflect pristine situations that exist or would exist with no or very minor disturbances from anthropogenic pressure. Phytoplankton and macrophytes were studied in 10 national lake types (L1, L3, L4, L5, L7, L8, L11, L12, L13, L17). Type-specific taxa and groups character in reference and near reference conditions were described. Abiotic parameters (water chemistry) were also discussed. Descriptor species from 25 FGs were registered in phytoplankton communities in lakes in reference and near reference conditions. Dinoflagellates (L0) cryptomonads (Y) and various benthic/periphytic taxa (MP) were distributed in almost all lake types. Character descriptor species and FGs were reported for lake types L1 and L5. Motile mixotrophic dinoflagellates (L0) and cryptomonads (Y) had highest relative biovolume in ultra-oligotrophic alpine lakes (L1) due to their ability to utilize effectively scarce trophic resources. Motile euglenoids (W1, W2), small-celled colonial Cyanobacteria (K), green algae and small cryptomonads (X1, X2), coccal green algae (J) and meroplanctonic diatoms (MP) dominated phytoplankton community in riverine marshes (L5). Recorded FGs from natural lakes were also common in and their analog among heavy modified water bodies: shallow lowland reservoirs L17. Phytoplankton communities of L13 (small and medium-size semi-mountain reservoirs in the Eastern Balkans) were more similar with those of L11 (large deep reservoirs) and mountain L1, L3. Further surveys are needed in order to classify specific features of phytoplankton communities in L3, L4, L7, L11 and L12.
... At the beginning of the 21st century, interest in the ecotones of freshwater ecosystems was reflected in a number of works by Russian researchers [7][8][9][10]. The river ecotones represent regions of significant plankton species diversity and numerical variability [11][12][13][14] due to the variance in environmental gradients (mineralization, nutrient content, temperature, etc.), which leads to a high level of ecological heterogeneity in the Diversity 2023, 15,199 2 of 16 river landscape [15]. However, the question of the presence of an ecotone in various types of aquatic ecosystems remains relevant. ...
The gradients of hydrological, hydrophysical, and hydrochemical conditions form the transition zones in river mouth areas. These areas are considered ecotones in the presence of the edge effect. Our research aimed to identify the main patterns in the structural organization of zooplankton communities in different types of river mouth areas in lowland reservoir tributaries within the Middle Volga basin. A cluster analysis was performed to structure and determine the zooplankton communities. The identified zooplankton communities were characterized by the noticeable heterogeneity in the species structure. We analyzed the spatial distribution of the structural indicators of zooplankton communities and, on the basis of RDA, determined the factors that significantly affect the organization of the ecotone community. An ecotone was found in all types of river mouth areas where the highest density, biomass, diversity, species, and functional richness of zooplankton were noted, as compared to bordering zooplankton communities. As the morphological structure of the mouth areas became more complex, the values of the main structural parameters of zooplankton communities increased. It was demonstrated that conditions in the ecotones are favorable to the development of zooplankton alien species. The major factors determining the species structure of the ecotone zooplankton community were water electrical conductivity (R² = 21.07%, p-value = 0.001), dissolved oxygen content (R² = 10.33%, p-value = 0.003), and water transparency (R² = 9.77 %, p-value = 0.001).
... Because of this reason, zooplankton samples, each of 100 dm3 of water, were collected from various spots around each station by means of a bucket and filtered through an Apstein plankton net. This method of directly filtering a certain amount of water through Apstein plankton net is widely used in the study of shallow holo-polymictic standing water bodies such as the studied reservoir and in ecotone river-reservoir zones (EN-15110: 2006;Kozuharov et al. 2007;Yakimov et al. 2016;Protasov et al. 2019). Samples, fixed in 4% formalin, were counted by using the method of V. Hensen modified by Dimoff (1959) and Naidenow (1981). ...
The aim of the present study was to trace the influence of some environmental factors (w.temperature, wind, transparency, depth) on the distribution of zooplankton communities in the system Reservoir Mandra and the ecotone zones formed at the confluence of rivers Fakiyska, Sredetska, Izvorska and Rusokastrenska. Four samplings were performed at seven sites between February 2020 and January 2021. After determining the species composition and abundance, the results were subjected to structural analysis and Canonical Correspondence Analysis (CCA). A total of 67 taxa were identified, constituting about 48% of the Rotifera group, 27% of Cladocera and 19% of the Copepoda and only 6% from Protozoa. The Shannon-Weaver index for individual species diversity was between 2.37 and 0.62. The positive and negative correlation of zooplankton distribution in CCA shows that the relative abundance of any species depends on specific environmental variables. Analysis showed that temperature and wind had the strongest impact on the distribution of zooplankton.
... The major part of the inland waters in Bulgaria are small and shallow artifi cial lakes (Michev and Stoyneva (eds.), 2007), however, the investigations of lentic water bodies is dominated by researches in the big, multipurpose reservoirs (Naidenow (1970); Saiz (1981;Naidenov (1984); Naidenov and Baev (1987); Beshkova (1996); Beshkova and Botev (1994); Kalchev (1994;; 2003;2004); ;Kozuharov (1994;; Traykov (2005); Kozuharov et al. (2007;2009). These studies revealed that different aspects such as geographical position and morphometry play an important role in determining the lake trophic state and corresponding biological communities. ...
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 fishponds 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 and the phosphorus trophic state indices. The relationships between the trophic state indices depended on the depth of the water body and the influence of the heated waters from the thermal power station “Maritsa Iztok-2”. The trophic state of the water bodies depends not only on the amount of the available nutrients, but also on the circulation pattern and the length of the vegetation period. The thermal pollution from large steam electric power plants not only changes the environmental factors, but also the relationships between the physicochemical variables and the biological communities in the water bodies. Our results show the different response of the studied variables in thermally influenced water bodies, compared to different unaffected by heated waters systems. © 2015, National Centre for Agrarian Sciences. All rights reserved.
Eutrophication as one of the importunate environmental hazards in the aquatic ecosystems causes pronounced deterioration of the water quality and represents serious threat to the biotic components of this ecosystem. The main environmental effects of eutrophication are increase of suspended particles owing to extensive macroalgal blooms, decrease of water clarity, and increase in the rate of precipitation that led to the destruction of benthic habitat by shading of submerged vegetation. In addition, other important effects are also known such as the bottom-water hypoxia, production of CO2 associating the decomposition of intensive produced organic matter which enhances water acidification, and altering biogeochemical processes, including sediment anoxia, accumulation of deleterious hydrogen sulfide, and nutrient cycling. Shift in the phytoplankton community was frequently reported in numerous eutrophic coastal waters owing to the variable nutrient requirement of different phytoplankton groups and the ratios between the different nutrients in these waters. Eutrophication is often accompanied by algal blooms which are frequently harmful and cause various injuries to the aquatic animals, such as clogging of fish gills, poisoning by toxins secretion, and localized anoxia, which consequently lead to detrimental effect on the fishing resources and the national economy through mass mortality of variable aquatic animals. The hypoxia conditions in bottom waters cause escape of sensitive demersal and other benthic fishes, mortality of bivalves, echinoderms and crustaceans, and extreme loss of benthic diversity, which led to changes in the diet of bottom-feeding fishes as well as shift in dominance among demersal fish species. Increase of algal growth/organic production rates led to changes in the benthic community structure, such as replacement of hermatypic corals with coralline algae, filamentous algae, macroalgae, and/or a variety of filter feeders and increase of bioerosion in some forms. Trophic linkages between pelagic and benthic communities are affected by eutrophication in the coastal waters, where the feeding habit of higher consumers such as benthic fish changes to derive high percentage of their energy from pelagic primary production sources. Shellfishes as an intermediate link between the water column and demersal fish could also be affected by eutrophication and will impact (as prey) on the demersal fish production. Meanwhile, increasing turbidity with eutrophication led to a shift in fish species owing to change of feeding on zooplankton to benthic organisms. Severe shading and light attenuation caused by blooms of both macroalgae and phytoplankton in eutrophic conditions hinder the photosynthetic processes in benthic plants and has led to the decline of seagrass habitats. High nutrient levels may lead to disturbance in nitrogen and phosphorus metabolism in seagrass and consequently cause a change in plant communities. Coral reefs are affected by eutrophication in different aspects. The organic compounds released from algal blooms promote microbial activity on coral surfaces and cause coral mortality, while synergistic effect of both the dissolved organic matter and rates of bioerosion has a pronounced role in reef degradation. Harmful algal blooms caused a complete loss of the branching corals, and substantial reductions in the abundance, richness, and trophic diversity of the associated coral reef fish communities. Eutrophication and siltation have severely stressed many fringing and offshore reefs that prefer to grow in nutrient-poor waters, and cause physiological changes in growth and skeletal strength, decrease of reproductive effort, and a reduced ability to withstand disease. In many marine eutrophic habitats, zooplankton community experienced a decline in species richness and abundance, change in structure, size, reproduction rate, and feeding habits. Size change in zooplankton occurs owing to the replacement of small species by another relatively large species of the same group, while the structure may change because of the trophic relationship of zooplankton with their prey (primary producers) and predators (fishes). Although benthic foraminiferans have been widely used as indicators of eutrophication in coastal marine ecosystems, low species diversity and high population densities of several benthic foraminiferans were reported in eutrophic area. On the other hand, smaller opportunistic benthic foraminiferal species dominate in the coral reef ecosystems and lead to a decline of larger endosymbiont-bearing taxa, while the hypoxia-tolerant foraminiferan species increased in abundance against the disappearance of the more sensitive species.
Seasonal and annual changes of the phytoplankton composition in the Pchelina reservoir
- I Botev
beshKOva M., I. bOtev 1994. Seasonal and annual changes of the
phytoplankton composition in the Pchelina reservoir. -Hydrobiology, 39: 27-33. (In Bulgarian, English summary).
Methods used in plant sociology and agricultural botanical grassland research. – Herbage review
- M De Vries
De vries M. 1937. Methods used in plant sociology and agricultural botanical grassland research. – Herbage review,
5: 38-61.
Mutual effects of the Tundja River and Zrebchevo Dam Lake on the development of the macrozoobenthic communities
- S Kovachev
- Y Uzunov
KOvachev S., Y. UzUnOv 1979. Mutual effects of the Tundja
River and Zrebchevo Dam Lake on the development of
the macrozoobenthic communities. -Hydrobiology, 15:
43-48. (In Bulgarian, English summary).
Water quality and formation of macrozoobenthos in the system Rositsa River -Aleksander Stamboliiski Reservoir and assessment of the ecotone effects
- S Kovachev
- Y Uzunov
KOvachev S., Y. UzUnOv 1987. Water quality and formation of
macrozoobenthos in the system Rositsa River -Aleksander
Stamboliiski Reservoir and assessment of the ecotone effects. -Hydrobiology, 31: 28-35.
Analysis of the qualitative composition of zooplankton of the system River Struma -Reservoir Pchelina for the period 1990-1992. -Hydrobiology
- D Kozuharov
KOzUharOv D. 1995a. Analysis of the qualitative composition
of zooplankton of the system River Struma -Reservoir
Pchelina for the period 1990-1992. -Hydrobiology, 39:
33-46. (In Bulgarian, English summary).
Changes of zooplankton parameters in the ecotone zone river -reservoir under the anthropogenic impact
- N Baev
naidenOw W., N. baev 1987. Changes of zooplankton parameters
in the ecotone zone river -reservoir under the anthropogenic
impact. -Hydrobiology, 31: 3-14. (In Bulgarian, English
summary).
Die hydrobiologishe Erforschung der Fauna im Einzugsgebeit der Orava und deren Entwicklung in Hinblick auf Wassergutte und Ausswirckungen des neuen Stausees
- S Obr
Obr S. 1972. Die hydrobiologishe Erforschung der Fauna im Einzugsgebeit der Orava und deren Entwicklung in Hinblick
auf Wassergutte und Ausswirckungen des neuen Stausees.
Folia FSN UPB XIII, 3. 101 p.
Changes of zooplankton structure in the Zrebchevo Reservoir as a result of pollution and hydrotechnical devices
naidenOw W. 1981. Changes of zooplankton structure in the
Zrebchevo Reservoir as a result of pollution and hydrotechnical devices. – Hydrobiology, 15: 22-43. (In Bulgarian,
German summary).
Improved quantitative method for the counting of plankton
dimOff I. 1959. Improved quantitative method for the counting
of plankton. -Comptes rendus De l' Academie Bulgare des
Sciences, 12 (5): 2-3. (In Russian, French summary).