Indicative status assessment of the Danube River (Iron Gate sector 849 - 1,077 rkm) based on the aquatic macroinvertebrates

 Vanja Marković1, Ana Atanacković1, Bojana Tubić1, Božica Vasiljević1, Margareta Kračun1, Jelena Tomović1, Vera Nikolić2 and Momir Paunović1

 


1 University of Belgrade, Institute for Biological Research "Siniša Stanković", Despota Stefana 142, 11000 Belgrade, Serbia; e-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

2 University of Belgrade, Faculty of Biology, Department of Zoology, Studentski trg 16, 11000 Belgrade, Serbia

 

 

Abstract

The aim of this paper is to present the results of the ecological status assessment of the Danube River in the Iron Gate Region (rkm 849 to 1077), based on the analysis of the macrozoobenthos community. The investigation was performed in September 2011. The following metrics were used: Saprobic Index (Zelinka & Marvan), BMWP (Biological Monitoring Working Party) and ASPT (Average Score Per Taxon) indices, participation of Tubificidae (% Tubificidae), total number of taxa, number of gastropods and bivalves taxa and Shannon's Diversity Index. Based on the value of the selected metrics, the status of the Danube in the Iron Gate stretch was assessed as moderate (class III). A total of 61 macroinvertebrate taxa were recorded. With regard to the taxa richness, the dominant components of the community were found to be Insecta, Oligochaeta and Mollusca. With respect to the percentage participation/relative abundance, Molusca and Crustacea were found to be the principal components.

Keywords: Danube River, Iron Gate, macrozoobenthos community, water quality

 

 

Introduction


The Serbian part of the Danube is 588 km long and covers the middle stretch and a part of the lower stretch. The major part of the Serbian sector of the Danube (358 km) belongs to the Pannonian plain. In this section the Danube is a typical lowland river with a slope of 0.05–0.04 ‰ (Paunović et al., 2005). The Iron Gate sector is transitional (between the middle (Panonian) and the lower part of the Danube), and in many aspects (geomorphology, hydromorphology, etc.) is specific. Due to the dam construction at 943 rkm (Djerdap I; 1970), a large, 100 km long, reservoir was formed. After the damming of the Danube, the flow rate was slowed down upstream to Slankamen (1,215 rkm). In 1984, another dam (Iron Gate II, 863 rkm) was built.

Besides hydromorphological pressures, the Iron Gate sector is influenced by the urban waste waters from numerous settlements within the stretch, as well as by the Kostolac Power Plant. The Iron Gate Reservoir therefore acts as a depository of sediment and adsorbed pollutants. Through water-sediment interaction, water quality may also be affected, although its extent is yet to be studied (Paunović et al., 2005).

The Serbian reach of the Danube has been extensively examined since the early sixties (for details see Paunović et al., 2007). The results of studies referring primarily to water pollution problems (Jankovic & Jovicic, 1994) showed that water quality in the Serbian reach of the Danube had deteriorated in comparison to the 1960–1970 period. The long-term damaging impacts resulted mostly from the increase of untreated industrial and communal effluents, originating from rapidly growing cities along the river banks, from leaching and erosion of extensively fertilized agricultural soils, as well as from changes in the hydrological regime induced by the damming of the Danube and the creation of the hydropower reservoirs Djerdap (Iron Gate) I and II.

The aim of this work is to provide results on the ecological status assessment of the Iron Gate (Djerdap) stretch of the Danube, based on the national legislation (Službeni Glasnik RS, 74/2011). According to the national water body delineation, the Serbian stretch of the Danube River covers nine water bodies (Službeni Glasnik RS, 96/2010) and four of them are situated within the investigated stretch - D_1, D_2, D_3 and D_4.

 

Material and Methods

Samples were collected in September 2011 at seven sampling sites (Figure 1, Table 1). The semi-quantitative sampling was performed using a hand net (25x25 cm, 500 µm mesh size). The multi-habitat sampling procedure (Hering, 2004) was applied. The samples were preserved using 4% formaldehyde solution and further processed in the laboratory. The identification was carried out in accordance with the recommendation on the required taxonomic level (Schmidt-Kloiber & Nijboer, 2004).

 

Fig1

Figure 1: Map of the sampling sites

 

Table 1: Sampling sites

Tab1

 

The following metrics were used to evaluate the ecological status: Zelinka and Marvan Saprobic Index (SI, Zelinka & Marvan, 1961), BMWP and ASPT scores (Armitage, 1983), Shannon's Diversity Index (Shannon, 1948) and percentage participation of Tubificidae in the total macroinvertebrate community (% Tubificidae). The taxa richness parameters (total number of species, number of species of bivalves and number of species of gastropods) were also considered as the metrics for the ecological status assessment. The saprobiological analysis was performed using a list of bioindicator organisms according to Moog (Moog, 1995). The metrics calculation was done using AQEM software (AQEM, 2002).

The indicative status assessment was performed according to relevant national regulations (Službeni Glasnik RS, 74/2011).