Dragana Vukov

Heavy metal accumulation of Danube river aquatic plants — indication of chemical contamination

In this paper, the ecological status of a section of the Danube River flowing through Serbia from Bezdan to Djerdap was evalutated. Using the chemical composition of water, sediment samples from the littoral zone and dominant aquatic macrophytes, the level of chemical pollution was ascertained. Chemical analyses of the water and sediment indicated that the tributaries flowing into the Danube significantly influenced the chemical load of the water and as a direct consequence, the sediment. The concentration of heavy metals including Cu, Mn and Cd found in plants of the Potamogeton genus, further indicated significant chemical pollution, establishing a clear link between the chemical composition of plant tissues and the chemical composition of water and sediment. This paper therefore describes how the chemical composition of aquatic plants can be used as a reliable indicator for heavy metal pollution of aquatic ecosystems.

Chemical Composition of Essential Oil and Leaf Anatomy of Salvia bertolonii Vis. and Salvia pratensis L. (Sect. Plethiosphace, Lamiaceae)

The taxonomical relationship between Salvia pratensis and S. bertolonii has been unclear for a long time. Salvia bertolonii has alternatively been considered a synonym, a subspecies, a problematic subspecies and a form of Salvia pratensis. However, both these two species are sometimes used in traditional medicine instead of sage (Salvia officinalis) or as an adulteration for the same drug. In order to confirm the status of S. bertolonii, together with the potential identification characteristics for differentiation from sage, both taxa were analyzed through the analysis of their essential oils, together with the micromorphological characteristics of the leaf surface and the anatomy and morphology of the leaves. The obtained results show that there are clear differences in the quantity of essential oil (0.073% for S. pratensis and 0.0016% for S. berolonii). The major compound in the essential oil of S. pratensis was E-caryophyllene (26.4%) while in S. berolonii essential oil caryophyllene oxide was the major component (35.1%). The micromorphological differences are also pronounced in the leaf indumentum (density and distribution of certain types of non-glandular and glandular trichomes). Clear distinction between the investigated Salvia species is also observed in the leaf anatomy (in S. pratensis leaves are thinner, palisade tissue is made of 1-2 layers of cells, and leaves of S. bertolonii are characterized by 2-3 layers of palisade tissue cells, and consequently thicker).

The distribution and the abundance of hydrophytes along the Danube River in Serbia

The Danube River runs through Serbia with flow 588 km long. Different hydrological, geological and ecological conditions occuring along the Danube in Serbia enables its division into four sections: The upper region, Đerdap I accumulation, Đerdap II accumulation, and the lower region. Each section is characterized by unique plant species diversity, frequency of occurrence and distribution pattern. The species diversity ranged from low in the upper reach, to high or very high in the impoundments and decreased in the lower reach. This paper provides a basis for a detailed study on the influence of large power plant impoundments over the aquatic vegetation of rivers.

Alien invasive neophytes of the Southeastern part of the Pannonian Plain

Floristic diversity in the Pannonian Plain is the result of mosaic habitat composition, characterized by steppes, saline meadows, and lowland forests along major rivers. In the last few centuries, the flora has become enriched by species introduced by human activities, such as colonization and industrialization. Presently it consists of nearly 1800 species. As a result of 30 years of field research as well as herbarium and literature searches, a list of invasive alien neophytes has been compiled and is presented here. The list includes 152 species, classified as either naturalized, casual, or unknown. One of the species is listed in Red Book of Serbian Flora. Eighty species are naturalized, and 61 are casual species. The majority of the introduced flora originates from North America (66) and the Old World (43). Most alien invasive species of the Southeastern part of the Pannonian Plain, were introduced accidentally by seed material or deliberately by nursery saplings. The annual and perennial herbaceous plants, which flower in the summer and summer-autumn periods, are represented in the greatest numbers. The alien flora was further analyzed with respect to taxonomy, life forms, pollination, and seed dispersal mode. The greatest number of alien species appears in anthropogenic and semi-natural habitats (59). In natural habitats, 45 invasive taxa were recorded, representing a conservation threat to biodiversity.

Combined effects of physical environmental conditions and anthropogenic alterations are associated with macrophyte habitat fragmentation in rivers - Study of the Danube in Serbia

We hypothesize that the physical features of river habitats and anthropogenic hydromorphological alterations influence macrophyte communities and lead to habitat fragmentation. Sampling included 1081 contiguous survey units positioned in the main channel and side arms along 588km of the Danube River, along its middle course. To identify habitat fragments, Multivariate Regression Tree analysis (MRT) was applied on macrophyte and environmental data. Indicator species analyses were combined with MRT. To identify habitat fragments on a scale larger than final MRT groups, we set thresholds for an MRT complexity parameter. We identified 20 fine, 7 medium, and 3 large scale habitat fragments. Damming was the main fragmentation agent. Macrophyte communities show continuous variation at all scales of habitat fragmentation. High species diversity indicates major anthropogenic alteration of the rivers hydrology and decline of the natural riparian zone. Future studies of the macrophyte communities, and their habitat fragmentation must include more factors (e.g. nutrient status, physicochemical quality of the water, etc.), as well as assessment of the importance of tributaries.

The relationship between habitat factors and aquatic macrophyte assemblages in the Danube river in Serbia

Our objectives were to offer insight into the characteristics of the physical environment in the River Danube in Serbia; and to show the relationship between selected environmental factors and the composition and abundance of macrophyte species. The macrophyte survey method followed the European Standard EN 14184, applying Kohler’s five-level descriptive scale. Principal component analysis was carried out to examine the variation in aquatic vegetation, and to analyze the effect of environmental variables on the aquatic vegetation, redundancy analysis was used. To build a simpler model with fewer explanatory variables, yet sufficiently explaining species variability, forward selection of environmental variables was done. Our results confirmed that physical environmental factors significantly influence the establishment and structure of macrophyte vegetation, with the level of hydrological connectivity to the main river channel being the most important, followed by the transparency of the water column, sediment texture and water-flow velocity. In order to inspect the individual relation between best-fitted plant species and each of selected environmental variables, Spearman’s rank correlation coefficients were calculated. We have distinguished plant species with preferences to specific combinations of analyzed factors. Our results provide a background for future, more specific studies on the macrophyte/habitat relationship. https://doi.org/10.2298/ABS160516116V Received: May 16, 2016; Accepted: June 21, 2016; Published online: October 31, 2016 How to cite: Vukov D, Ilic M, Cuk M, Igic R, Janauer GA. The relationship between habitat factors and aquatic macrophyte assemblages in the Danube river in Serbia. Arch Biol Sci. 2017;69(3):427-37.

Analysis of anatomical and micromorphological characteristics of Iva xanthifolia nutt.

Iva xanthifolia is a North American weed species, which was introduced and naturalized in Europe. Anatomical and micromorphological characteristics of this species were investigated, in order to get better knowledge of its biology, which could help in development of strategies for prevention of its spreading. Detailed descriptions of lamina, petiole, stem and inflorescence axis anatomical structures were given, together with micromorphological characteristics of epidermis and indumentum of lamina, petiole, stem, inflorescence axis, involucre and fruit. All vegetative organs had mesomorphic structure, with some xeromorphic adaptations. Mechanical tissue was well developed, which gave those plants additional strength and resistance. Trichomes were the most numerous on lamina and in the region of inflorescence, while rare on petiole and stem epidermis and their distribution varied according to plant organ.