Search

Chara gymnophylla is one of the first charophyte species reported for Serbia during the late 19th and the early 20th centuries, and at that time it was the second in terms of the frequency of its occurrence in the country. General taxonomic misinterpretations in the past resulted in the concealment of another species, C. squamosa, within the findings attributed to C. gymnophylla. In Serbia, Chara gymnophylla was treated as C. vulgaris var. gymnophylla, and as such was not listed as a species inhabiting the country. Recent improvements in the taxonomic concept for C. squamosa prompted a revision of the rich material of C. gymnophylla, C. vulgaris var. gymnophylla, C. vulgaris var. nitelloides, and C. rohlenae, deposited in the BEOU collection. The revision process was conducted concurrently with fieldwork and the collection of new material. Our study confirmed the presence of C. squamosa in Serbia for the first time. Based on numerous revised samples from the BEOU collection, as well as recently collected specimens, the species’ continuous presence in Serbia since 1976 was confirmed. Chara squamosa and C. gymnophylla were thus added to the list of Characeae species inhabiting Serbia, and categorised as Critically Endangered according to the criteria outlined by IUCN. An overview of the biogeography, ecology and taxonomy of C. squamosa in Serbia is provided, particularly in relation to C. gymnophylla. The BEOU charophyte collection proved to represent a valuable and relevant resource for critical taxonomic revisions. The results presented in this study strongly encourage further studies on C. squamosa and C. gymnophylla distribution in the Balkan region and wider area in order to gain a deeper understanding of the species’ ecology and the further improvement of their taxonomic concepts., Chara gymnophylla jedna je od prvih vrsta pršljenčica zabeleženih u Srbiji krajem 19. i početkom 20. veka, i tada je na našim prostorima bila druga po učestalosti javljanja. Pogrešna taksonomska tumačenja u prošlosti dovela su do toga da je još jedna vrsta, C. squamosa, bila skrivena među nalazima vrste C. gymnophylla. Chara gymnophylla je pak kasnije u Srbiji taksonomski tretirana kao varijetet - C. vulgaris var. gymnophylla, i kao takva nije bila na listama vrsta koje naseljavaju teritoriju Srbije. U skorije vreme sugerisan je novi taksonomski koncept za vrstu C. squamosa, što je podstaklo reviziju bogatog materijala C. gymnophylla, C. vulgaris var. gymnophylla, C. vulgaris var. nitelloides i C. rohlenae, deponovanih u kolekciji BEOU. Proces revizije se odvijao paralelno sa terenskim istraživanjima i prikupljanjem novog materijala. Naša istraživanja su pokazala po prvi put prisustvo vrste C. squamosa u Srbiji. Zasnovano na brojnim revidiranim uzorcima iz kolekcije BEOU, kao i uzorcima prikupljenim u novije vreme, povrđeno je kontinuirano prisustvo ove vrste u Srbiji počev od 1976. godine. Chara squamosa i C. gymnophylla su dodate na listu vrsta pršljenčica koje naseljavaju teritoriju Srbije i klasifikovane su kao kritično ugrožene (CR) prema kriterijumima IUCN. U ovom radu dat je biogeografski, ekološki i taksonomski pregled vrste C. squamosa u Srbiji, u odnosu na vrstu C. gymnophylla. Kolekcija pršljenčica BEOU se pokazala kao dragoceni i relevantni resurs za kritičke taksonomske revizije. Rezultati prezentovani u ovoj studiji snažno podstiču dalja istraživanja distribucije vrsta C. squamosa i C. gymnophylla na Balkanu i na širem području, kao korak ka daljem rasvetljavanju njihove ekologije i utemeljenju taksonomskih koncepata.

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 and showed that Bovan Lake was of satisfactory ecological status and water quality at all localities, and meets the needs for all intended purposes.

Predmet istraživanja ove doktorske disertacije su fitoplanktonske cijanobakterije (Cyanobacteria) u malim akumulacijama i uticaji ekoloških faktora na prisustvo i dominaciju različitih vrsta, sa posebnim aspektom na potencijalno invazivne i toksične cijanobakterije. Trogodišnji monitoring je sproveden jednom mesečno na tri akumulacije (akumulacija Šumarice, akumulacija Bubanj i Aleksandrovačka akumulacija). Primenom metode samoorganizujućih mapa (SOM) omogućena je klasifikacija uzoraka na osnovu fizičkih i hemijskih parametara, kao i vizualizacija prostorne distribucije biotičkih parametara. Tri pomenuta vodna tela značajno se razlikuju po opštim karakteristikama, hemijskom sastavu vode i dinamici fitoplanktonskih cijanobakterija. Različitost ispitivanih akumulacija se ogleda u malom broju zajedničkih taksona i u taksonima koji su bili najfrekventniji i cvetajući: akumulacija Šumarice (Aphanizomenon flos-aquae), akumulacija Bubanj (Microcystis aeruginosa) i Aleksandrovačka akumulacija (Raphidiopsis raciborskii). Najznačajniji sredinski parametri koji utiču na zajednicu cijanobakterija su koncentracije ukupnog fosfora i azota. Naša studija pokazuje da ekstremne padavine mogu da dovedu do povećanja koncentracije hranljivih materija u rezervoarima, i uzrokuju značajan ekološki poremećaj zajednice (cvetanje potencijalno toksičnih cijanobakterija). Pojava i dominacija invazivne vrste R. raciborskii u Aleksandrovačkoj akumulaciji pokazuje da ova vrsta širi svoj areal rasprostranjenja. Prilikom sprovedenog istraživanja u okviru ove disertacije u Srbiji prvi put je detektovan toksin cilindrospermopsin (CYN). Ova studija je pokazala da je ekstrakt vrste R. raciborskii ispoljio genotoksičnost čak i u niskim koncentracijama i povećao oksidativni stres u jetri pacova nakon jednog izlaganja., The research subject of this doctoral dissertation includes phytoplankton cyanobacteria (Cyanobacteria) in the small reservoirs and the effects of ecological factors on the presence and dominance of different species, with particular aspects on invasive and potentially toxic cyanobacteria. Three-year monitoring was conducted (monthly) on three reservoirs (Šumarice reservoir, Bubanj reservoir, and Aleksandrovac reservoir). The method of self-organizing map (SOM) provided the efficient classification of samples, based on physical and chemical parameters, as well as the visualization of the spatial distribution of biotic parameters. These three water bodies are significantly different according to their general characteristics, chemical water composition, and cyanobacteria dynamics. The dissimilarity of the examined reservoirs is reflected in the small number of common taxa and in the taxa that were the most frequent and blooming: Šumarice reservoir (Aphanizomenon flos-aquae), Bubanj reservoir (Microcystis aeruginosa) and Aleksandrovac reservoir (Raphidiopsis raciborskii). Тhe most important environmental parameters affecting the cyanobacteria community are concentrations of total phosphorus and nitrogen. Our study shows that extreme precipitations can cause an increase in nutrient concentration in reservoirs and significant environmental disturbance to the community (blooming of potentially toxic cyanobacteria). The domination of invasive species R. raciborskii in Aleksandrovac reservoir indicates that this species is expanding its areal distribution. The research conducted in this dissertation has detected the toxin cilindrospermopsin (CYN) for the first time in Serbia. This study shows that the extract of R. raciborskii exhibited genotoxicity even at low concentrations and increased oxidative stress in rat liver after a single exposure.

Akumulacije predstavljaju važan vodni resurs namenjen dugoročnom snabdevanju vodom za piće, ali uprkos tome ne postoji adekvatan plan njihove zaštite. Predmet ove doktorske disertacije jeste praćenje prostorne i vremenske dinamike fitoplanktona akumulacije Vrutci, sa posebnim osvrtom na dinamiku potencijalno toksične cijanobakterije Planktothrix rubescens. Analiza je obuhvatala utvrđivanje sastava, brojnosti i biomase fitoplanktona na tri lokaliteta (Vodozahvat, Nikolići i Omar) i duž vodenog stuba tokom perioda od decembra 2013. do decembra 2015. godine. Pored toga praćeni su i osnovni fizički i (bio)hemijski parametri, takođe po mesecima i po dubini. Osnovni cilj studije je bio prikaz prostorne i vremenske dinamike vrste P. rubescens, otkrivanje najznačajnijih parametara odgvornih za njenu proliferaciju u akumulaciji, kao i procena uticaja „cvetanja“ ove cijanobakterije na dinamiku ostalih članova fitoplanktonske zajednice. Najveća brojnost i biomasa P. rubescens zabeležene su u julu 2015. godine na 6 m dubine (963855 ćel/ml odnosno 30,23 mm3/l) na lokalitetu Vodozahvat. Rezultati su pokazali da su temperatura vode i stabilnost vodene kolone faktori koji u najvećoj meri određuju rast P. rubescens, kao i da ova cijanobakterija ima uticaj na dinamiku drugih algi i cijanobakterija. P. rubescens je tokom perioda stratifikacije formirala metalimnionski maksimum hlorofila a praćen maksimumom koncentracije kiseonika (supersaturacija). Takođe, rezultati su pokazali da rast P. rubescens nije bio toliko uslovljen koncentracijom ispitivanih nutrijenata, iako je akumulacija u proseku bila eutrofna. Neophodno je sprovođenje organizovanog monitoringa osnovnih parametara kvaliteta vode, kao i redovno praćenje vertikalne distribucije biomase P. rubescens u akumulaciji Vrutci., Reservoirs represent an important water resource intended for long-term supply, but despite that, there is no adequate plan for their protection. The subject of this dissertation is the survey of spatial and temporal dynamics of phytoplankton of the Vrutci reservoir, with special reference to the dynamics of the cyanobacterium Planktothrix rubescens. The analysis included determining the composition, abundance and biomass of phytoplankton at three sites (Vodozahvat, Nikolići i Omar) and along the water column during the period from December 2013 to December 2015. In addition, the basic physical and (bio)chemical parameters were also monitored by months and by depth. The aim of the study was to review the spatial and temporal dynamics of P. rubescens, to discover the most important parameters of its blooming in the reservoir and to assess the impact of this cyanobacterium on other members of phytoplankton. The highest abundance and biomass of P. rubescens were recorded in July 2015 at a depth of 6 m (963,855 cells/ml and 30.23 mm3/l, respectively) at the Vodozahvat. The results showed that water temperature and water column stability are the factors that largely determine the growth of P. rubescens, and that this cyanobacterium has a great influence on the dynamics of other algae and cyanobacteria. P. rubescens formed a metalimnion maximum of chlorophyll a during the stratification period, followed by a maximum of oxygen concentration (supersaturation). Also, the results showed that the growth of P. rubescens was not so much conditioned by the concentration of the nutrients, although the reservoir was eutrophic on average. It is necessary to conduct organized monitoring of the basic parameters of water quality as well as regular monitoring of the vertical distribution of P. rubescens biomass in the Vrutci reservoir.

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 water quality classification and on diatom index choices. Artificial substrates in our study did show potential as an alternative for natural substrate, but further studies are required, particularly in various types of lentic ecosystems to confirm our findings and support artificial substrate employment in lake water quality assessment., Diverses études rapportent des résultats contrastés sur l'effet du type de substrat sur la composition de la communauté de diatomées, mais la question particulièrement importante est de savoir si cela affecte ou non les évaluations de la qualité de l'eau basées sur les diatomées. Nous avons cherché à savoir si le type de substrat est un prédicteur significatif de la composition de la communauté de diatomées et s'il affecte l'évaluation de la qualité de l'eau des lacs basée sur les indices de diatomées. Cette étude a eu lieu dans le lac Sava (Serbie). Nous avons utilisé des carreaux de verre, de céramique, de saule et d'if comme substrats artificiels pour le développement du périphyton, et des galets du littoral du lac comme substrat naturel. Les résultats ont révélé des différences dans la composition de la communauté de diatomées et dans les valeurs des indices de diatomées liées aux substrats. Une distinction a été reconnue entre les substrats naturels, artificiels en bois et artificiels inertes. Cependant, l'évaluation finale de la qualité du lac basée sur les indices de diatomées était plus ou moins similaire dans tous les types de substrats de notre étude, et dépendait des plages de valeurs associées à la classification de la qualité de l'eau et des choix d'indices de diatomées. Les substrats artificiels dans notre étude ont montré un potentiel comme alternative au substrat naturel, mais des études supplémentaires sont nécessaires, en particulier dans divers types d'écosystèmes lentiques pour confirmer nos résultats et soutenir l'utilisation de substrats artificiels dans l'évaluation de la qualité de l'eau des lacs.

Lampenflora communities of bacteria, cyanobacteria, algae, mosses and lichens colonize illuminated show-caves as a consequence of disturbances to the caves’ ecological equilibrium. These communities have unesthetic impacts and can cause the biodeterioration of limestone. A 15% hydrogen peroxide solution was proposed for use as an ecological agent for the safe removal of these microorganisms. This study tested the effects of three different biocides (hydrogen peroxide, a commercial solution containing salicylic acid and a product containing chlorine dioxide as the active component), on the growth of green algae (Chlorella sp.), which are frequently encountered in lampenflora communities. Chlorella sp. was treated with the biocides under laboratory condition, and chlorophyll a (Chl a) concentrations were measured 1 h, 3 days, 7 days and 10 days after treatment. The change in Chl a concentration was compared to the untreated control group at each time point. All three biocides prevented the growth of green algae and the product containing chlorine dioxide appeared to be the most effective growth inhibitor. Hydrogen peroxide is known to suppress lampenflora growth in caves, and further studies on other biocides remain necessary to identify a solution that is both ecologically safe and economically feasible.

Predmet ove doktorske disertacije jeste procena diverziteta cijanobakterija u vodama koje se se koriste za vodosnabdevanje i rekreaciju. U tu svrhu, napravljena je baza podataka rezultata mikroskopskih analiza, dopunjena podacima iz publikovane literature. U periodu 2012-2017.god., analizirano je ukupno 503 uzorka, uzetih sa 35 odabranih lokaliteta, pri čemu je identifikovano 148 taksona. Zajedno sa podacima iz 119 pregledanih naučnih publikacija, zabeleženo je ukupno 328 taksona cijanobakterija (iz 84 roda, 28 familija i 6 redova) za ispitivanu grupu voda. Među njima, preovlađuju predstavnici reda Synechococcales (~35%), dok dominira homocitna forma cijanobakterija (~47%). Osim toga, 77 taksona se može okarakterisati kao potencijalno toksično, dok se 9 vrsta smatra invazivnim. Posebna pažnja posvećena je vrstama koje su potencijalno toksične i/ili invazivne, pošto njihova intenzivna proliferacija može predstavljati rizik po zdravlje ljudi i životnu sredinu. U tu svrhu, kao deo istraživanja, analizirana je vremenska dinamika (nedeljna, mesečna i godišnja) cijanobakterija unutar zajednice fitoplanktona, kao i veza sredinskih faktora i cijanobakterija/fitoplanktona u Savskom jezeru, akumulaciji Pariguz i reci Dunav, ali i pojave mikrocistina u akumulaciji Pariguz. Tri ispitivana vodna tela se značajno razlikuju po opštim karakteristikama, hemijskom sastavu vode i dinamici zajednice fitoplanktona. Ipak, povećana mutnoća vode se izdvaja kao faktor koji bi mogao imati važnu ulogu u favorizovanju potencijalno štetnih taksona. Shodno tome, povećanje providnosti vode predstavlja neophodan preduslov za efikasnije upravljanje vodama i kontrolu razvoja vrsta štetnih po zdravlje ljudi i životnu sredinu, poput Limnothrix redekei, Planktothrix agardhii i Cylindrospermopsis raciborskii., supply and recreation. In this regard, a database obtained from the the results of microscopic analyzes was created, supplemented by data from the published literature. In the period between 2012-2017, a total of 503 samples were analyzed, taken from 35 selected localities, and 148 taxa was identified. Together with data from 119 scientific publications, a total of 328 cyanobacterial taxa (belonging to 84 genera, 28 families and 6 orders) were recorded for the investigated group of water bodies. Among them, representatives of the order Synechococcales (~ 35%) predominate, while the homocytic form of cyanobacteria (~ 47%) prevailes. In addition, 77 taxa could be characterized as potentially toxic, while 9 species are considered invasive. Special attention has been paid to species characterized as potentially toxic and/or invasive, as their excesive proliferation can pose a risk to human and environmental health. For this purpose, as part of the study, the temporal dynamics of cyanobacteria (weekly, monthly and annual) within the phytoplankton community has been analyzed, as well as their relationship with environmental factors in the Sava Lake, the Pariguz reservoir and the Danube River and, additionally, the occurrence of microcystins in the Pariguz reservoir. The three observed water bodies differ significantly regarding their general characteristics, water chemistry and dynamics of the phytoplankton community. Nevertheless, high water turbidity stands out as a factor that could play an important role in favoring potentially harmful taxa. Thus, increasing water transparency could be a necessary precondition for efficient water management in terms of controling the development of species harmful to human and environmental health, such as Limnothrix redekei, Planktothrix agardhii and Cylindrospermopsis raciborskii.

Aerophytic phototrophs, colonizers of different substrates exposed to air, among which are rock substrates in cave habitats, are in general not sufficiently investigated and studied. From the ecological point of view, seasonal/temporal variations and parameters that influence aerophytic phototrophic communities through seasons still remain largely unknown. Seasonal analysis of phototrophic microorganisms from biofilms developed at entrances of Samar and Jezava caves in Eastern Serbia was performed four times a year. All identified phototrophic representatives were assigned to a certain division or group. The relationship between documented groups and different measured, determined and observed ecological parameters was illustrated using principal component analysis (PCA). A high diversity of cyanobacteria and algae was observed as a result of seasonal sampling: 141 taxa in Samar and 61 taxa in Jezava Cave. Cyanobacteria were dominant in both caves (coccoid forms prevailing) and were followed by Bacillariophyta. Bacillariophyta were positively correlated with light intensity and sites where seeping water was present, and cyanobacteria with water content in biofilm, Chl a and relative air humidity. Higher diversity of phototrophs was documented in December and March, and lower in May and August in both caves with Chl a values having the same trend as the diversity of phototrophic microorganisms. This was especially the case with biofilms in which diversity was more prone to seasonal changes and where Cyanobacteria dominated. Only 24 taxa were documented during all four seasons in Samar Cave (Cyanobacteria, Bacillariophyta and Chlorophyta representatives) and three in Jezava Cave (Cyanobacteria only).

Phosphorus overenrichment of shallow ponds prevailing in wetlands leads to their eutrophication causing the collapse of those vulnerable habitats. The potential of phosphorus accumulation by periphyton developed on artificial substrata has been investigated in two shallow ponds (Baračka and Široki Rit) in northwest Serbia and compared to the same ability of plankton and metaphyton. The periphyton substrate carrier has been submerged from May to October. Both continuously (CS) and monthly developed (MS) periphyton were sampled. Autotrophic component of all investigated communities has been qualitatively assessed. Maximum accumulation of only 14.7 mg TP/m2 was recorded in three-month exposed periphyton CS. MS exposed from July to August reached maximal 12.7 mg TP/m2. Plankton community that was characterized by more diverse and abundantly developed algal component was more effective in phosphorus accumulation (0.7 mg/g dry weight) in comparison with dominantly inorganic and diatom-dominated periphyton in Baračka. Unstable conditions caused by recent revitalization (dredging organic matter and mud from pond basin—redigging) as well as rapid desiccation of Široki Rit disabled making an unambiguous conclusion about the efficiency of phosphorus accumulation among different communities, but suggested slight potential of phosphorus harvesting by metaphyton in this pond. Due to the shorter exposure time that brings the reduced risk of unpredictable changes in the ecosystem, as well as the considerable amount of accumulated phosphorus, large-scale application of one-month exposed periphyton developed on artificial substrates would be more advisable for phosphorus harvesting in nutrient affected shallow ponds.

Charophyte species delineation is regularly based on a set of thallus morphological character- istics, but considering pronounced phenotypic plasticity, difficulties and doubts commonly occur in Chara species determination. DNA barcoding may contribute to solving these chal- lenges. Here we characterize Chara contraria with an unusual set of morphological character- istics, and specimens morphologically resembling Chara connivens collected in Serbia, by describing their morphological traits and analysing matK barcoding results. Our results indi- cated that dioecious Chara specimens, tentatively determined as Chara “connivens” based on morphological traits, were genetically more closely related to C. globularis. These Chara “connivens” specimens formed a sister group to a monophyletic C. globularis cluster, suggesting that it may be neither C. connivens nor C. globularis. We strongly encourage further barcoding of C. “connivens” samples from freshwater, in order to find out if there are consistent genetic differences between the dioecious freshwater C. “connivens” and monoecious C. globularis. Barcoding of matK placed the monoecious Chara specimens, which based on morphological characteristics initially were determined as C. virgata, into the C. contraria group. This indicates that the microscopic traits which commonly are used for Chara species determination some- times are misleading. In general, our study challenges the commonly used phenetic species concept in Charophyte taxonomy and illustrates the importance of molecular approaches to evaluate the validity of morphological characteristics of the plant thallus in species delineation.

Phototrophic microorganisms can be found in biofilms at entrances to caves where they have access to sufficient sunlight, water and nutrients; however, they can also be found inside caves, where they are carried by animals and people, and can proliferate in the presence of artificial light. Although the genus Humidophila includes some well-known cosmopolitan species, further exploration of its rare, insufficiently investigated representatives in different geographical areas and unusual habitats is necessary. Caves remain unknown, little-explored habitats, and many species currently known to science were recorded for the first time. This study aimed to report species belonging to the genus Humidophila that were identified in 19 caves in Serbia. A total of ten species of this genus were recorded and some of them are documented for the first time in Serbia. The most abundant species were H. contenta (found in 16 caves), H. paracontenta, and H. aerophila (found in 13 caves), whereas H. pyrenaica was identified in only one cave. The rare species, H. brekkaensoides and H. vidalii, were also documented and described, but with different dimensions from those provided in current identification keys.

Phototrophic microorganisms from two caves in Serbia (Podpeć and Stopić) were examined. Samples were taken from the entrances where natural light was present, as well as from the inside caves near artificial light (lampenflora community). Cyanobacteria, Chlorophyta, Bacillariophyta and Xanthophyta were documented, with 51 taxa in total. The highest number of taxa recorded in the Cyanobacteria were coccoid cyanobacteria; Gleocapsa and Chroococcus were dominant. According to the redundancy analysis (RDA), Cyanobacteria were dominant at cave entrances while other groups (Chlorophyta, Bacillariophyta and Xanthophyta) were documented in lampenflora samples. Temperature, relative humidity, and light intensity were measured, as well as chlorophyll a concentrations and biofilm parameters (water, organic and inorganic matter content). Ecological parameters did not show significant variation, while light intensity de-pended on the position of sampling sites. RDA showed that the water content was higher in biofilm samples from cave entrances, while levels of inorganic matter were increased in lampenflora samples. The concentration of chlorophyll a did not show significant correlations with any of the measured ecological or biofilm parameters. Although the ecological parameters inside the cave did not show significant variation, they should be monitored because of the potential influence on the development of the lampenflora community that has a negative aesthetic impact on cave formations.