Gordana Subakov Simić

Changes in the phytoplankton community and dominance of Cylindrospermopsis raciborskii (Wolosz.) Subba Raju in a temperate lowland river (Ponjavica, Serbia)

Species composition and seasonal succession of phytoplankton were analyzed in a lowland river located in South Banat (Ponjavica, Serbia). As a result of human activity, a network of irrigation channels was built on the Ponjavica River’s upper and lower courses. These channels reduce the water level in the river and help to create favorable conditions for accelerated eutrophication processes. Eight phytoplankton divisions with 444 taxa were present. Physical and chemical testing of water, phytoplankton abundance and biomass, as well as chlorophyll a concentration showed a high level of eutrophication. Cyanobacterial biomass developed in 2002 with dominance of Microcystis aeruginosa and Aphanizomenon flos-aquae. Changes in phytoplankton composition were observed during 2008, characterized by the appearance and dominance of Cylindrospermopsis raciborskii when this species accounted for more than 85% of the total phytoplankton biovolume. The change in dominant phytoplankton functional groups was observed: codons H1 and M characterizing summer in 2002 were replaced by codons SN and S1 in 2008. This study compares the presence of C. raciborskii with other phytoplankton species in relation to water quality parameters. High abundance of this species correlated positively with biochemical oxygen demand and turbidity, and negatively with NO3-N concentrations during the study period.

Cyanobacteria, algae and microfungi present in biofilm from Božana Cave (Serbia)

Caves represent very specific worldwide environments (Lamprinou et al., 2012) and many of them are included in the UNESCO World Heritage List (Czerwik-Marcinkowska, 2013). Cave habitats are characterized by almost constant temperature (T) and relative humidity (RH) all year round. A typical cave can be divided into three primary zones: the entrance-, transition-, and a deep cave zone (Tobin et al., 2013). Light intensity is the major factor which determines whether the microbial communities of cave stone substratum will be autotrophic (cyanobacteria and algae) or heterotrophic (bacteria and fungi) (Albertano, 2012). The above mentioned factors (T, RH, LI) determine which microbial communities can grow in a given location, but many other characteristics of caves, such as location, entrance dimensions, morphology, orientation, intrinsic substratum properties, and other microclimate parameters (air circulation, hydrological conditions, etc.) are also important (Martinez & Citation:

A sub-aerial biofilms investigation and new approach in biocide application in cultural heritage conservation: Holy Virgin Church (Gradac Monastery, Serbia).

Sub-aerial biofilms (SAB) on frescoes and façade of the Holy Virgin Church (Gradac Monastery, Serbia) were investigated to study the effectiveness of benzalkonium chloride (BAC) as a biocide. Antifungal activity of Origanum vulgare essential oil as a natural product with confirmed high fungicidal potential was also tested against fungi causing alterations on the frescoes. Chemical and mineralogical composition of the church historical mortar showed the dominance of calcareous minerals. In large areas on the church façade, coloured biopatinas formed by different groups of coccoid and filamentous cyanobacteria, green algae and filamentous fungi were found. Epilithic lichens and bryophytes were also present on the church exterior suggesting long-term ecological succession. The presence on the frescoes, of human pathogenic fungus Aspergillus fumigatus were found in the internal environment. Aspergillus and Penicillium species isolated from painted walls were subject to an in vitro biocidal assay with the biocide BAC. An aqueous solution of 0.25% and 0.15% BAC was able to reduce the viability of all the tested fungal isolates after exposure to the solution for 5 min, while exposure to an aqueous solution of 0.05% for 30 min reduced conidial viability. Origanum vulgare essential oil also showed strong antifungal potential against selected fungal isolates.

Diversity of Terrestrial Cyanobacteria Colonizing Selected Stone Monuments in Serbia

ABSTRACT The presence of biofilms on stone monuments can lead to biodeterioration processes that significantly lower not only the aesthetic value of cultural heritage sites but also cause considerable physical and chemical damage to stone surfaces. In terrestrial environments, cyanobacteria have a significant role in biofilm formation on a variety of natural and artificial stone substrata, including granite, sandstone, limestone, lime mortar, etc. Studies on cyanobacterial diversity and estimation of biodeteriorative activity on stone cultural heritage objects can be very important for conservators and restorers, and cyanobacteria removal from stone monuments is currently a great challenge for conservation science. In that sense, the diversity of terrestrial cyanobacteria was investigated at six localities in Serbia. Samples for cyanobacterial analyses were taken from surface biofilms covering different substrata: granite and lime mortar (The Monument to the Unknown Hero), sandstone (Brankos Bridge, Eiffel’s Lock) and carbonate rock (Medieval tombstones from Mramorje and Rastište, Gradac Monastery). A total of 18 cyanobacterial taxa were identified. The highest diversity was found on carbonate rock, followed by sandstone. Cyanobacteria were also recorded on an artificial substratum – lime mortar, while cyanobacteria were not found on granite. All detected cyanobacteria seriously impaired the structural and aesthetic integrity of the studied monuments via mechanical and chemical actions, so their presence must not be overlooked.

Periphyton Developed on Artificial Substrates: Effect of Substrate Type and Incubation Depth

The aim of this study was to assess the effect of substrate type and incubation depth on periphyton that had developed on artificial substrates. Uniform rectangular tiles made out of artificial substrates: glass, ceramic, willow tree and yew tree, were fixed on a floating buoy and deployed at three different depths in a photic zone of the Sava Lake (Belgrade, Serbia). Non-taxonomic attributes in the developed biofilm were estimated week-by-week from the start of the experiment in July, until its end in September 2014. Through assessment of substrate type and depth of incubation effect we concluded that these parameters for the fact influence periphyton development and composition. Glass was preferred by autotrophic component over ceramic and wooden substrates. In general, substrate type effect was diminished by increasing incubation depth. When non-taxonomic parameters are to be used in biomonitoring studies, our results suggest that glass substrate and shallow layer of water column (up to 50 cm) for incubation should be preferred.

Structure and succession of periphyton in an urban reservoir: artificial substrate specificity

Abstract 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 substrate affects periphyton characteristics at various levels and whether an artificial substrate potentially affects the bioindication capacity of ecological groups. We concluded that all substrates behave similarly at the level of structure and colonization phases, but when considering diversity and successional trajectories, the substrate specificity was demonstrated. Our results suggest that communities developed on inert substrates (glass and ceramic) could provide more realistic insight into complex environmental changes.

Cave biofilms: characterization of phototrophic cyanobacteria and algae and chemotrophic fungi from three caves in Serbia

Cyanobacteria, algae (Chlorophyta and Bacillariophyta), and fungi were identified from biofilm samples from three caves in western Serbia: Ribnička, Hadži Prodanova, and Rćanska. Temperature, light intensity, and relative humidity varied from 16.9 8C to 24.9 8C, 61% to 87%, and 215 Lux to 4400 Lux, respectively. In general, the highest number of documented taxa belonged to Cyanobacteria, with chroococcalean taxa prevailing and Gloeocapsa species as the most diverse. A large percentage of observed fungi were Ascomycetes or Zygomycetes, while the only representative of Basidiomycetes was Rhizoctonia s. lat. However, a redundancy analysis revealed that different taxonomic groups were dominant at different localities: cyanobacteria and fungi in Ribnička and Hadži Prodanova, and Chlorophyta and Bacillariophyta in Rćanska. The statistical analysis showed that relative humidity is an important physical parameter influencing the development of various microbial communities in different caves. Cyanobacteria were mostly found in places with lower relative humidity, while Chlorophyta and Bacillariophyta were found in places with higher humidity. The documented physical parameters did not have a significant impact on the distribution of fungi. Measured chlorophyll-a content was highest on horizontal surfaces, where the highest content of organic/inorganic matter were also recorded. The highest water content was observed in biofilm samples from which many cyanobacteria taxa were identified.