Aleksandar M. Ostojić

Effect of eutrophication on changes in the composition of zooplankton in the Grošnica Reservoir (Serbia, Yugoslavia)

The present paper cites results of 2-year research on zooplankton in the Grošnica Reservoir near Kragujevac during the period 1996–98. Comparison of the obtained results with those of earlier investigations performed during the period 1950–52 showed that changes have occurred in the interval. A significant increase was recorded in the number of zooplankton species, and only a small number of previously registered species were not recorded again. Considerable changes in the faunistic composition of zooplankton are also indicated by the low value of the Sørenson similarity index (32.12%) and Jaccard index (19.13%). At the same time, the abundance of zooplankton increased markedly, which suggests to us intensification of eutrophicaton processes. On the basis of the composition and abundance of zooplankton, it can be assumed that the Grošnica Reservoir belongs to the category of meso-oligotrophic lakes.

Composite Web Information System for Management of Water Resources

Management of water resources such as lakes and reservoirs involves many stakeholders and a huge amount of data that comes from various information systems and in different formats. These systems are typically very difficult to integrate, analyze and customize. This requires a new breed of information systems capable to answer the challenges of modern water information management. In this paper, we introduce the new application model for designing such systems and accompanying i-SeLaR software system - composite, service-oriented and multilayered web information system for management of Serbian lakes and reservoirs. We describe architecture and services of the application model, together with structure and functionalities of the software solution. i-SeLaR integrates data, tools and applications for collaboration, data and knowledge management, process automation, and analytics. Architecture and features of i-SeLaR provide scalability and flexibility, so the system can be scaled, customized and implemented in organizations of different types and sizes. i-SeLaR web portal is the central component which serves as a unique gateway to different data sources and services, and provides a seamless and unified web interface for monitoring and management of water resources. Practical results showed several benefits in terms of better integration and flexibility, enhanced collaboration, higher data quality, knowledge-based analysis and more informed decision making.

Total coliforms and data mining as a tool in water quality monitoring

Total coliforms, as a microbiological indicator of water quality, have been tested on the basis of condition, dynamics, as well as on the dependence on other physicochemical and biological parameters, by methods and models of data mining. Using a combination of intelligent approaches, cluster analysis and classification, total coliforms have been analyzed and modeled on the examples of the

Management information system of lakes and reservoirs

Information technologies provide a significant support in the management of lakes and reservoirs. Existing information systems mostly did not comprise all the necessary data and enabled collecting only a limited set of reports. More complex data analyses such as statistical analyses and data research were conducted in separate environments and recquired additional preparation of the data. Information system of lakes and reservoirs in Serbia (SeLaR) was produced in order to provide all the neccessary information for lake and reservoir management. The information system integrates a large data set and provide users with necessary information in the form of reports and charts. The users of the system are scientists and experts who study these issues, as well as students with the objective of continuous education. Furthermore, an interface was produced to enable linking with data research software. In this way a unique working environment was created to provide users with an efficient model of acquiring all the information necessary for the management and to find out new facts in data interaction, and also to make a forecast. This study presents an overview of the information system, its production model, the information available and the possibilities of data research.

Anti-Aspergillus properties of different extracts from selected plants

In vitro antifungal activity of methanol, acetone and ethyl-acetate extracts from Equisetum telmateia Ehrh., Allium flavum L., Sedum acre L., Sideritis montana L., Marubium peregrinum L. and Xeranthemum anuum L. grown in Serbia, were investigated by microdilution method. Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) have been determined. Testing was conducted against four Aspergillus species - A. flavus, A. fumigatus, A. niger and A. restrictus . All statistical analyses were performed using SPSS package. The tested extracts showed significant antifungal activity against A. restrictus and moderate activity against other Aspergillus spp. The best results showed ethyl acetate extract of S. montana , X. anuum and S. acre .

Heavy metal tolerance and removal potential in mixed-species biofilm

The aim of the study was to examine heavy metal tolerance (Cd2+, Zn2+, Ni2+ and Cu2+) of single- and mixed-species biofilms (Rhodotorula mucilaginosa and Escherichia coli) and to determine metal removal efficiency (Cd2+, Zn2+, Ni2+, Cu2+, Pb2+ and Hg2+). Metal tolerance was quantified by crystal violet assay and results were confirmed by fluorescence microscopy. Metal removal efficiency was determined by batch biosorption assay. The tolerance of the mixed-species biofilm was higher than the single-species biofilms. Single- and mixed-species biofilms showed the highest sensitivity in the presence of Cu2+ (E. coli-MIC 4 mg/ml, R. mucilaginosa-MIC 8 mg/ml, R. mucilaginosa/E. coli-MIC 64 mg/ml), while the highest tolerance was observed in the presence of Zn2+ (E. coli-MIC 80 mg/ml, R. mucilaginosa-MIC 161 mg/ml, R. mucilaginosa-E. coli-MIC 322 mg/ml). The mixed-species biofilm exhibited better efficiency in removal of all tested metals than single-species biofilms. The highest efficiency in Cd2+ removal was shown by the E. coli biofilm (94.85%) and R. mucilaginosa biofilm (97.85%), individually. The highest efficiency in Cu2+ (99.88%), Zn2+ (99.26%) and Pb2+ (99.52%) removal was shown by the mixed-species biofilm. Metal removal efficiency was in the range of 81.56%-97.85% for the single- and 94.99%-99.88% for the mixed-species biofilm.

Zooplankton Community Along the Sava River

The aim of this study was to examine for the first time the composition of zooplankton community along the greatest part of the Sava River flow. Eighty two zooplankton taxa were collected at the Sava River in September of 2012, 7 Rhizopoda, 8 Ciliophora, 57 Rotifera, 7 Cladocera, 2 Copepoda, and 1 Bivalvia. The number of zooplankton species found at sampling sites varied between 2 and 30. The most diverse group was Rotifera, which comprised 69 % of the total number of recorded taxa. The abundance of zooplankton was low and the abundance of individual zooplankton communities varied between 1 and 36 ind/L, and these results are in accordance with the results of previous works. The similarity indices (Sorensen’s and Jaccard’s) between the localities studied were rather low, despite relatively close distances between them. The probable reason was that the sites were localized at the sections of the river characterized by different environmental factors.