Biological Indicators of Environmental Conditions and Water Quality in "Međuvršje Reservoir (Serbia)

Gorica Đelić1, Snežana Branković1, Marija Marković2


1 University of Kragujevac, Faculty of Science, Radoja Domanovića 12, 34 000 Kragujevac, Serbia; E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it , This e-mail address is being protected from spambots. You need JavaScript enabled to view it ;

2 University of Niš, Faculty of Science and Mathematics, Višegradska 33, P.O. Box 224, 18000 Niš, Serbia; E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it



Botanical composition, quantity of hydrophytes and their ecological and indicator values are the basis for the evaluation of the condition and the direction of aquatic ecosystems. The results of the floristic research of the Međuvršje Reservoir highlights the belt hygro /helophyte compared to belts to floating and submerged species. Analysis of values of bioindicator species indicates that in this ecosystem favorable conditions exist for the development of marsh vegetation.

Keywords: Međuvršje Reservoir, hydro / helophyte, hydrophytes, bioindicators.



The presence, distribution and mass of aquatic macrophytes are a good indicator of the state of a man-made water reservoir. Monitoring hydrophytes allows for the assessment of environmental conditions in aquatic ecosystems and serve as the basis for an adequate response in terms of preserving the normal functioning of the same.

The Međuvršje Reservoir was created in 1953 by making a concrete dam (32 meters in height) on the West Morava River. The lake is permanently exposed to siltation and eroded material and significant anthropogenic pressure, which promotes its eutrophication.

The aim of the research was to analyze the floristic structure of the Međuvršje Reservoir as an indicator of its future direction and dynamism.


Materials and Methods

Explored area

The Ovcar-Kablar Gorge is protected by the decree of the Government of the Republic of Serbia as a natural area of ​​outstanding features of the first category (Sl. Glasnik, No. 66/91). The gorge is formed by the Western Morava River flow through the mountain massifs of Ovcar (985 meters above sea level) and Kablar (885 meters above sea level). In the West Morava area there are three man-made lakes: Ovcar-Kablar; the Međuvršje Reservoir (the largest reservoir in West Morava - up to 11 km long with maximum depth 23 m) and Lake Parmenac (Đorđević, 1998).


Figure 1: Studied area.


Floristic research

Field studies were carried out in the period from 2014 to 2016. Collected plant material have been deposited in the Herbarium of the Institute of Biology and Ecology, Faculty of Science in Kragujevac.

The keys used for identification of plants are from Tutin at al, (1964-8-1980), Javorka and Csapody (1979) and Josifović et al. (1974). Quantitation of species is shown in relative value of the scale from 1 to 5: 5-en masse absent, 4 = very frequent, 3- frequent, 2-rare, 1-very rare.

Belonging to floral elements was determined by principle of division which created Meusel (Meusel et al., 1965). Grouping of life forms was carried out according to the Raunkiaer system (Ellenberg, Muller-Dombois, 1976). According to the Raunkiaer-in classification (Ellenberg, Dombois Müller, 1976), there are five main types of living forms: Phanerophytes (P), Chamaephytic (Ch), Hemicryptophytes (H), the Therophytes (T) and Cryptomonad (Cry) which includes: Geophytes (G) and Hydrophytes (Hyd).

Environmental features of the found plants have been established using the ecological index for humidity, acidity, i.e., pH reaction, an amount of nitrogen, light, temperature, and life forms. Analysis of life forms and floral elements of the collected plant species were done with the use of literature (Oberdorfer, 1962; Kojic et al., 1994, 1997; Stevanovic, 1992).


Results and Discussions

Absorbent vegetation of reservoir Međuvršje belongs to Class: Potametea Tx. et Prsg 1942- sublittoral community to floating and submerged plants; Class Lemnetea - communities of plants and floating charges Class Phragmitetea - swamp and marsh vegetation.

By studying the vascular flora of the artificial reservoir Međuvršje (Table 1) we found 35 species. Floristic analysis of macrophytes (Table 2.) was performed with the quantitative distribution (using a scale of relative value) at the sites (Figure 1.): Start of Zagrađe (I), Zagrađe (II), below the Uspenje Monastery (II), Rapajlovača (IV), the river bend at the Pejicina (V) and Lanterne (VI).

Analysis of floral elements has shown that out of the recorded number of species (Figure 2) cosmopolitan distribution has 22% of the species (Lemna minor L, Ceratophyllum demersum L., Alisma plantago aquatica L, Glyceria fluitans (L.) R. Br, Phragmites communis Trin., Schoenoplectus lacustris (L.) Palla, Typha latifolia L., Typhoides arundinacea (L.) Moench), circumpolar (Circ) and subcentral (subse.) has 18%, subeurop (Subeur) 15% of the species (Figure 2). Eurasian (Eur) and subcircumpolar (Subcirk.) distribution have two species (6%). Other floral elements are represented by only one species.

In comparison with the humidity as an environmental factor of the tested sites, most cases were represented by hygro / helophytes (42.4%), and mesophytes (27.2%) submerged hydrophytes (15.2%) and floating hydrophytes (12.2%). The area under higrophytes was significantly increased compared to previous studies (Simovic, 2000).




In relation to the nitrogen content we have found that in most % are represented by mesotrophic plants - 54.5%, and a transition band between the meso and eutrophic plants (27.2%). It was noted that the presence of species that transition between the group of meso- and eutrophic plants significantly increased as compared to previous studies of this ecosystem (Simović, 2000). As compared to the brightness of the habitat are represented half sciophytes (57.6%), and a transition band between half sciophytes and heliophytes (42.4%). Mesoterm species make up 75.7% of the total species in Medjuvršje, while 24.3% of all species belong to transition group from mesotherm to thermophilic species.


Figure 2: Representation of floral elements in the reservoir Međuvršje.


Figure 3: Representation of life forms in reservoir Međuvršje.


The combined plant varieties were classified into six life forms (P ZC, H, G, T, A).

The largest percentage (Figure 3.) are present geophytes (Y: 34%), then hemicryptophytes (H: 27%) and aquatic helophytes / hydrophytes (A: 27%). Two types (Salix alba L., Alnus glutinosa L.) are represented phanerophytes (P: 6%). With only one kind of (Bidens tripartitus L.) present a life form hemitherophytes (T: 3%) and a type of Lysimachia nummularia L. herbaceous chamaephytic (ZC: 3%).

Since the construction of a dam in Međuvršje, the reservoir receives minerals and nutrients and floods the coast, which favors the development of vascular hydrophytes (Simovic, 2000). According to Simovic (2000) Potamogeton natans L. formed a monodominant community at location Zagrađe, Potamogeton crispus L. was present throughout the reservoir, while Myriophyllum verticillatum L. was present only near the Jovanje Monastery.




In Zagrađe, on a bend of the river, on the right bank, wetland vegetation Class Phragmitetea (R. Tx et Prsg 1942) was developed. In 2010 the absolute dominance in this band has a reed which is formed almost impenetrable association Phragmitetum australis Savič 1926 (Figure 4) in which they are in small number of present Typha latifolia, Lemna minor, Glyceria fluitans, Stachys palustris L., Carex spp., Lythrum salicornia L., Salix alba, Alnus glutinosa. Our research in 2016 showed that Phragmites australis (Cav.) Trin. ex Steud. appeared fragmentary until the Peicin curve. Since the Ph. australis (syn Ph. communis), optimally develop in conditions where the water depth varies between 0.2-0.4 m, where the bottom is muddy and rich in organics, and in eutrophic water, its spreading into the reservoir indicates an increasing trend in debris accumulation at the bottom and thus significantly contributes to an increasing littoral belt.


Figure 4: Ass  Phragmitetum australis Savič 1926.


Glyceria fluitans (L.) R.Br. develops in very shallow water basin areas, often around the perimeter so to build a narrow coastal strip of marsh vegetation, produces a large plant mass, and causes accelerated healing. In 2000 it was represented in a part at Zagrađe, and in 2016 it also appears in a section below the Uspenije Monastery on the Rapajlovača site.

Typha latifolia develops in water up to 0.5 m deep, and field investigations have shown that it is the most frequently observed macrophyte (Figure 6) in a full reservoir, which is an indicator of depth reduction and eutrophic lakes.

A significant wetland species that was identified in the Međuvršje Reservoir is T. natans L. It is a species on the list of protected plant species by the Convention on the Conservation of European Wildlife and Natural Habitats (1979). The Flora Europaea (Tutin et al., 1964) states that it is the only species of the genus Trapa. However on the basis of their research Vasilyev (1949) and Janković (1957, 1958, 1973) state that includes the name of Trapa complex East Asian and European types.


Figure 5: Trapa natans L.


Physico-chemical properties of the substrate and water have an essential impact on the growth, development and distribution of Trapa M.Jank. (Blaženčić, J., 1971). There are numerous literature data that indicate that this type is growing in condition of low CaCO3 content (Jankovic 1958, Čanak and Stojanovic 1963, Tutin et al. 1968).

During field research in 2010 a population of a mono dominant water chestnut (Trapa natans L. Water chestnut family (Trapaceae)) was observed in a section of the Western Morava from the Nikolje Monastery to Rapajlovača (right side of the lake). An area near the Nikolje Monastery revealed the presence of individual specimens of T. natans L. No specimens of T. natans.

Research in 2016 showed a drastic expansion of this type in the area along the entire length of the lake to the Lanterna sote. Below Uspenije Monastery, on the left bank of the reservoir, we observed the presence of Trapa natans (width from the coast 10 m) and to a middle part Potamogeton fluitans Roth. and Myriophyllum spicatum L. From the Jovanje Monastery to the Vidovski Tunnel (a distance of about 1000 meters in length) a population of water chestnut developed along a wide coastal strip with a width of 20-25 meters on the left bank of the Western Morava flow (Figure 5). Near the Jovanje Monastery on the left bank is a reed belt (Typha latifolia), and water chestnut belt with a width of 15-20 meters, while to a middle part of the belt there is Potamogeton fluitans (Figure 7), Ceratophyllum demersum L.


Figure 6: Typha latifolia L., Trapa natans L.


Figure 7: Typha latifolia, Potamogeton fluitans Roth.



On the basis of performed floristic research of macrophytes in reservoir Međuvršje, the following can be concluded:

  • that there is a relatively high species diversity,
  • that the belt of hygrophyte / helophyte is increasing,
  • wetland vegetation is dominant,
  • eutrophication processes are accelerating,
  • steps should be taken to eliminate the causes that lead to eutrophication of the lake.



The authors would like to thank Goran Nikolic from TOC Čačak for his assistance and cooperation in carrying out field research.



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