Papers by Gordana Subakov Simić
Kragujevac Journal of Science
Endoliths are more frequently found in extremely harsh environments, but they can inhabit mesic c... more Endoliths are more frequently found in extremely harsh environments, but they can inhabit mesic climate and subterranean habitats as well. Whether they are adapted to life inside rocks or do they seek refuge in this way, remains largely unknown for caves and pits. Consequently, subterranean habitats in limestone areas, were explored: three caves in Serbia (Cerjanska, Petnička and Potpeć) and one pit in Croatia (Keranova Golubinka). Sampling of rock substratum containing endoliths was performed at various distances from the entrance, at sites characterized by a lower level of light intensity. Phototrophs were separated from the rock matrix using 10% hydrochloric acid and analyzed using light microscopy. In general, low diversity of endoliths was observed, but representatives from Cyanobacteria, Chlorophyta and Xanthophyta were found. Cyanobacteria, more precisely coccoid forms (genera Aphanocapsa, Chroococcidiopsis, Gloeocapsa, Gloeocapsopsis, Synechococcus), were dominant. The most ...
Phototrophic biofilms can be found in different habitats, including subterranean ones, such as ca... more Phototrophic biofilms can be found in different habitats, including subterranean ones, such as caves. In caves, they thrive in the presence of daylight at the entrances, or in the vicinity of artificial light inside, and are usually very heterogeneous. For the purpose of this study, biofilm sampling from stone substrata was performed in 15 caves (mostly entrances) to examine biofilm characteristic and features, as well as to record the main phototrophic groups. Cyanobacteria, Bacillariophyta and Chlorophyta were the main phototrophs recorded. Cyanobacteria were, according to morphological characteristics, additionally divided into coccoid, simple trichal and heterocytous forms. Biofilms were sorted according to the degree of development and moisture (taking into account free seeping water and water bound in extracellular polymeric substances (EPSs)). Other parameters, namely the water content and content of organic/inorganic matter were determined too. According to the principal com...
Inland saline ecosystems are characterized by very specific and unique biodiversity Still, biodiv... more Inland saline ecosystems are characterized by very specific and unique biodiversity Still, biodiversity studies of saline habitats are mostly focused on lakes and ponds of natural origin We investigated the biodiversity of submerged macrophytes, phytoplankton and phytobenthos in the saline pond near Kikinda city (in Vojvodina, the northern province of Serbia) that was artificially made by commercial clay digging and abandoned in the landscape of the city suburban over time Collecting samples and field measurements were conducted in July 2018 The dense cover of macrophytes in the litoral area consisted of a carpet of Chara canescens with sparse specimens of Zannichellia palustris This is the second currently known locality of C canescens in Serbia which was recently rediscovered Despite the relatively wide range of this typically brackish species, populations of C canescens are isolated, and it is worldwide considered threatened/endangered and rare A total number of 27 algal taxa wer...
Cyanobacteria and algae, ecological, and parameters of biofilm developed at rock substratum at th... more Cyanobacteria and algae, ecological, and parameters of biofilm developed at rock substratum at the entrance of Samar Cave (Serbia), were analysed seasonally. Of 141 taxa, Cyanobacteria were dominant (coccoid forms prevailed – the most diverse was Gloeocapsa), followed by Bacillariophyta, then Chlorophyta. Diversity was higher in December and March, lower in May and August. Chl a values and biofilm water content had the same trend and were correlated with Cyanobacteria according to PCA.The 13th EuroSpeleo Forum, National Education Centre of the Red Cross Dolni Lozen, Sofia, Bulgaria, from 26th to 29th September 2019, [https://esf2019.speleo-bg.org/
Actinocyclus normanii f. subsalsa is considered native marine or brackish water species (Baltic S... more Actinocyclus normanii f. subsalsa is considered native marine or brackish water species (Baltic Sea, Caspian Sea). The species has spread into common freshwaters, throughout the world, and was considered as invasive or potentially invasive species (Kaštovský et al. 2010, Kipp et al. 2012). Phytoplankton, phytobenthos and epilithic samples were used for this study. In laboratory the field samples were treated with standard method with cold acid by Krammer and Lange-Bertalot (1986). Permanent slides were mounted in Naphrax. In Serbia, Actinocyclus normanii f. subsalsa, was registered in several rivers and canals. In 1997 was found as planktonic species in the Tisza River and in benthic samples (in mud) in the Veliki Bački Canal. In 2002 was found as planktonic species in the Danube–Tisza–Danube Canal (Kajtasovo) and the Ponjavica River (Brestovac and Omoljica). Four years later, in 2006, the species was found in plankton, benthos and epiphytic samples in the Ponjavica River (Omoljica)...
Water, 2022
The study aimed to investigate the physico-chemical properties as well as phytoplankton and bacte... more The study aimed to investigate the physico-chemical properties as well as phytoplankton and bacterial community diversity of Bovan Lake reservoir in Serbia to gain insight into the seasonal dynamic of water quality. All analyses were performed at three localities and water depths in spring, summer, autumn, and winter 2019. Seven phytoplankton phyla comprising 139 taxa were detected at all three localities (Chlorophyta 58%, Bacillariophyta 14%, Cyanobacteria 9%, Chrysophyta 5%, Dinophyta 5%, Euglenophyta 5%, and Cryptophyta 4%). Winter 2019 was characterized by the presence of 36 unique species in all phyla except Euglenophyta. Bacterial diversity analyses showed that Proteobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, and Verrucomicrobia dominated the water intake locality at all three water depths (0.5, 10, and 20 m below the surface). In general, the physico-chemical parameters, phytoplankton, and bacterial community composition depended on the season and the water depth...
Knowledge & Management of Aquatic Ecosystems, 2021
Various studies report contrasting results on the substrate-type effect on diatom community compo... more Various studies report contrasting results on the substrate-type effect on diatom community composition, but the particularly important question is whether or not it affects diatom-based assessments of water quality. We investigated whether the substrate type is a significant predictor of the diatom community composition and if it affects lake water quality assessment based on diatom indices. This study took place in Sava Lake (Serbia). We used glass, ceramic, willow and yew tree tiles as artificial substrates for periphyton development, and pebbles from the lake littoral as natural substrate. Results revealed differences in both the diatom community composition and diatom indices values related to the substrates. A distinction was recognized between natural, artificial wooden, and artificial inert substrates. However, the final lake quality assessment based on diatom indices was more or less similar in all substrate types in our study, and depended on value ranges associated with w...
International Journal of Environmental Research, 2013
The presence of cyanobacteria (blue-green algae) is a significant indicator of water quality,havi... more The presence of cyanobacteria (blue-green algae) is a significant indicator of water quality,having in mind that several genera have the quality of producing cyanotoxins, which are harmful to animals,plants and humans. Seven lakes in Vojvodina (Republic of Serbia) were examined in May and September 2007 for cyanobacterial presence and cyanotoxins content, Chl a concentration and index of phosphatase activity as the indicators of water quality. In the spring period, cyanobacteria species were not dominant in only 2 of 14 water samples. Microcystins were detected in all of the lakes examined. The concentrations of microcystins ranged from 6.66 μg/L (Provala Lake) to 199.9 and 238 μg/L (Palic and Ludas Lake respectively).The investigations conducted on 7 water ecosystems in Vojvodina, regarding the basic parameters of eutrophication, Chl a concentration and phosphatase activity index, have rendered the examined ecosystems immensely endangered due to significant water quality deteriorat...
Oceanological and Hydrobiological Studies, 2019
Planktothrix rubescens is a filamentous cyanobacterium with a worldwide distribution in lakes and... more Planktothrix rubescens is a filamentous cyanobacterium with a worldwide distribution in lakes and reservoirs of varying size and morphology. The objective of this study was to identify the population dynamics and the major drivers of P. rubescens blooms. Samples for qualitative and quantitative analysis of phytoplankton were collected every month in 2014 and 2015 from stationary depths, while the main physical parameters were measured in situ along the water column. Samples for chemical analysis were collected below the surface, at mid-depth (metalimnion) and near the bottom. In the periods of thermal stratification, P. rubescens formed the maximum biomass in the metalimnion, however, its volume-weighted biomass reached the maximum value in the winter mixing period (4.40 mm3 l−1). Changes in the P. rubescens population in the reservoir were related to changes in the measured environmental parameters. Significant physical, hydrological, meteorological and chemical parameters were dis...
Zbornik Matice srpske za prirodne nauke, 2019
Unique marshland area in the Danube floodplain - Special Nature Re?serve Gornje Podunavlje is con... more Unique marshland area in the Danube floodplain - Special Nature Re?serve Gornje Podunavlje is considered to be one of the last aquatic flora and fauna refuges in the region. The revitalization projects in SNP Gornje Podunavlje started in 2011. They were conducted in order to protect biodiversity and to provide the natural ecosystem. The aim of this study was to investigate and compare the present diversity and distribution of the charophytes in five ponds of SNR Gornje Podunavlje, depending on phases of the revitalization process within the ponds. The researched area includes the following ponds: Semenjaca, Sarkanj, Siroki rit, Sakajtas and Ribolov. The Siroki rit pond was under the process of revitalization during the field surveys, Semenjaca and Sarkanj have already been revitalized, and Ribolov and Sakajtas were not exposed to the revitalization processes at all. The field surveys were conducted monthly, from May to September 2016. Water quality parameters were measured in situ a...
Zbornik Matice srpske za prirodne nauke, 2017
Diversity of subaerial biofilm forming cyanobacteria, algae and fungi was investigated on 10 diff... more Diversity of subaerial biofilm forming cyanobacteria, algae and fungi was investigated on 10 different substrata from greenhouse of Botanical Garden ?Jevremovac?. Out of 37 documented taxa, 16 cyanobacterial and 10 algal taxa were identified. Remaining 11 taxa belong to the Kingdom of Fungi. The highest diversity of biofilm forming microorganisms, a total of 24 taxa, was detected on the corroded metal surface, while significantly lower number of taxa was recorded on other examined substrata. Cyanobacterium Porphyrosiphon sp., diatom Achnanthes sp. and green algae Chlorella sp. and Chlorococcum minutum were the most frequently encountered photosynthetic components of biofilms. In all analyzed samples, Trichoderma sp., followed by Cladosporium sp. and Rhizopus stolonifer, were the most frequently identified fungi.
International Journal of Speleology, 2019
Due to life in extreme environments, cyanobacteria and algae from cave biofilms that form at the ... more Due to life in extreme environments, cyanobacteria and algae from cave biofilms that form at the entrances or deep inside the cave around artificial lights are of increasing interest to many scientists. It is well-known that many phototrophic microorganisms are first to colonize exposed substrata and produce the organic matter on which other biofilm constituents relly. Many studies dealing with phototrophic microorganisms from biofilms focus on the diversity and community composition of cyanobacteria and algae, while quantitative assessments are rarely implemented. Biofilm sampling was conducted in Degurić and Vernjikica Cave located in Western and Eastern Serbia, respectively. Ecological parameters (temperature, relative humidity, light intensity) and distance from the entrance were measured. Additionally, chlorophyll content, as well as biofilm parameters (water content, organic and inorganic matter) were determined. The abundance of phototrophic microorganisms was assessed on microscope slides which contained 1 mg of biofilm that was dehydrated for a short period of time and homogenized prior to slide preparation, and then rehydratated. The biomass of recorded cyanobacterial and algal taxa was calculated by applying geometric approximations and standard mathematical formulas. In Degurić Cave, at the sampling site where the highest biomass was documented, the higher diversity, water content and chlorophyll values were also recorded, while in Vernjikica Cave a high content of organic matter was documented. According to the multivariate analyses performed, the biomass of simple trichal Cyanobacteria, Bacillariophyta, and Xanthophyta was positively correlated with the content of organic matter in biofilm and light intensity, while coccoid and heterocytous Cyanobacteria and Chlorophyta
Knowledge & Management of Aquatic Ecosystems, 2017
The summer phytoplankton community was studied across both vertical and temporal scales in relati... more The summer phytoplankton community was studied across both vertical and temporal scales in relation to environmental factors in the shallow recreational Sava Lake. The sampling was conducted weekly at four depths from mid-July until mid-September 2014, in order to detect short-term changes within the assemblages. Besides physical and chemical parameters, meteorological data was also included in the investigation, as that year was characterized with extreme rainfall, which caused serious flooding in the region. The community succession was characterized by a reverse in the cyanobacteria (Codon M) and chlorococcal green algae (Coda F and J). Statistical analyses (RDA) indicated that changes in the community composition and successional pattern could have been due to the mixing regime variations in the reservoir, most likely induced by weather disturbances, especially high precipitation and wind events. These events did not permit massive cyanobacterial development, although they most likely caused resuspension of dissolved phosphorus from the sediment. When observing functional groups, three groups could be distinguished by their response to the above-mentioned parameters: the first prefers high temperature and insolation (Lm, Y, Lo, Xph, W2 and M), the second is correlated with precipitation and wind (Td, C, K, MP and X2), while the third group tolerates cloudiness (H1, F, N, X1, D, J and P).
Oceanological and Hydrobiological Studies, 2017
Substrate specificity of the periphyton community is usually underestimated in both periphyton ec... more Substrate specificity of the periphyton community is usually underestimated in both periphyton ecology and biomonitoring studies, thus different kinds of both natural and artificial substrates (of organic and inorganic origin) are employed. Periphyton colonization and successional trajectories are particularly debatable processes when different kinds of substrates are considered. In our field experiment, we deployed four kinds of artificial substrates (two inorganic ones – glass and ceramic, and two organic ones – willow and yew wooden tiles) for the development of periphyton in an urban reservoir referred to as Lake Savsko (Belgrade, Serbia). We comparatively investigated the structure, colonization process, diversity and successional trajectories of periphyton. We also assessed the relationship between the dynamics of algae growth forms (ecological groups) on different substrates and selected abiotic limnological factors. Our objective was to determine whether the type of substrat...
Archives of Biological Sciences, 2019
Despite their unique ecology and implications for ecological assessment, diatoms in lentic ecosys... more Despite their unique ecology and implications for ecological assessment, diatoms in lentic ecosystems are still insufficiently studied in both scientific research and operational monitoring. In particular, the ecology of periphytic diatoms relative to the global expansion of cyanobacterial blooms in lakes has not been described at all. This study aims to describe the diversity and dynamics of a periphytic diatom community in the Vrutci Reservoir during Planktothrix rubescens bloom, and to evaluate the adequacy of standard diatom index implementation in lentic ecosystems relative to the diatom index adapted for lakes ? the Trophic Diatom Index for Lakes (TDIL). The study was conducted in the Vrutci Reservoir in western Serbia. Periphyton was developed on an artificial glass substrate during the summer of 2015, following a depth gradient of a stratified water column. Diatom diversity and abundance, as well as diatom indices were estimated. Discounting the cyanobacterial bloom, 79 taxa...
Studia botanica hungarica, 2016
In Serbia Actinocyclus normanii was registered in several rivers and canals. In 1997, it was foun... more In Serbia Actinocyclus normanii was registered in several rivers and canals. In 1997, it was found as planktonic species in the Tisza River and in benthic samples (in mud) in the Veliki Bački Canal. In 2002, it was found as planktonic species in the Danube-Tisza-Danube Canal (Kajtasovo) and the Ponjavica River (Brestovac and Omoljica). Four years later, in 2006, the species was found in plankton, benthos and epiphytic samples in the Ponjavica River (Omoljica). A. normanii is a cosmopolite, alkalibiontic and halophytic species. It occurs in waters with moderate to high conductivity and it is indicator of eutrophied, polluted waters. Its spread could be explained by eutrophication of surface waters.
Geographica Pannonica, 2007
650 µgL-1 in the reservoir, while the tap water contained 2.5µgL-1.
Oceanological and Hydrobiological Studies, 2015
During the twenty-five years of existence, water quality has declined and severe blooms of cyanob... more During the twenty-five years of existence, water quality has declined and severe blooms of cyanobacteria have occurred in the Grlište Reservoir. Changes in phytoplankton functional groups over time and along horizontal and vertical gradients were investigated in the course of a one-year study in this water-supply reservoir. We identified 19 dominant taxa, classified into 12 phytoplankton associations. The presence of the codons C, P, D and S1 differentiated the transitional from the lacustrine part of the reservoir. The nitrogen-fixing cyanobacteria Dolichospermum viguieri dominated the phytoplankton community in the epilimnion during August and September, when the reservoir showed P-limitation, but the bloom was not observed. The driving factors that accounted for the main variability in phytoplankton functional groups along the seasonal and vertical profile were identified using the direct gradient analysis (RDA). Our results revealed the importance of two bipolar factors. The fir...
Bulgarian Journal of Agricultural Science
DULIC, quality in semi-intensive carp production system using three different feeds. Bulg. J. Agr... more DULIC, quality in semi-intensive carp production system using three different feeds. Bulg. J. Agric. Sci., 16: 266-274 In the era of growing demand for sustainable usage of water, all types of aquaculture systems are under reconsideration. Until recently semi-intensive production was concerned to be one of the least polluting. Nowa-days, this fact has been reassessed especially in many countries culturing carp in this way. One of the most significant influences on a fish pond ecosystem in semi-intensive carp production is changing its characteristics by adding low quality supplemental feeding. Therefore, the type of fish feed, its physical and chemical characteris-tics can considerably change the water quality of a fish pond. Aiming to analyze the effect of commonly used feeds (cereals, pelleted and extruded feed) in semi-intensive production on the water quality, an experiment was carried out at three fish ponds during one production season. Even though the results of physical, che...
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Papers by Gordana Subakov Simić