Diversity of Aquatic Macroinvertebrates in Streams in the Belgrade Region (Does Different Stream Types Matter?) - page 01

Material and Methods

In September 2012, during the low water period, as a part of regular surface water quality monitoring in the Belgrade region, conducted by the Belgrade Institute of Public Health and the Institute for Biological Research "Siniša Stanković", benthic macroinvertebrate samples were taken. Semi-quantitative sampling was done by using a hand net (25x25 cm, 500 µm mesh size) and a Van Veen grab (270 cm²). Where possible, a multi-habitat sampling procedure (AQEM, 2002; Hering et al., 2004) was applied. The samples were preserved by using 4% formaldehyde solution and further processed in the laboratory. Identification was done to species-level for the majority of taxa using appropriate taxonomic keys.

The Belgrade region, with 1.7 million residents living in a 3223 km² metropolitan area (530 inhabitants per km²), is the largest and the most populated urban area in Serbia. Besides the Danube and the Sava Rivers, many smaller rivers, streams and canals and the left and right tributaries of these large rivers contribute to a very unevenly developed hydrographic network. Furthermore, geomorphology with its two main regions – the southern hilly Šumadija/Balkan region and the northern flat Pannonian Plain region, contributes to the unique hydrographic network of this urban area.

Five different water types according to current regulations/legislative (Official Gazette, 74/2011) were investigated. A list of sampling sites and watercourses with corresponding water types is provided in Table 1. Type 1 watercourses are large lowland rivers with a domination of fine substrate; Type 2 are large rivers with a medium-sized substrate, apart from the Pannonian rivers;

Type 3 are small to medium watercourses with a domination of larger substrate fraction, in altitudes below 500 m.a.s.l.; Type 6 are either watercourses which are not covered by current legislative (Official Gazette, 96/2010), or small watercourses outside the Pannonian Plain, apart from Type 3 and Type 4; Type 8 includes artificial water bodies – canals.

Generally, all watercourses in this region are under intense anthropogenic pressures. The canals in the northern, Pannonian region are exposed to heavy organic\nutrient pollution, mainly from agricultural land drainage, but also from households and slaughterhouses in this part of the region. Streams in the southern, Šumadija region, particularly those in the metropolitan area are under more intense urban pressure, with a higher proportion of impervious surfaces (due to "urban wash-off" which commonly occurs; Duda et al., 1982), in addition to communal, industrial and toxic pollution. Large rivers such as the Sava and the Danube, into which all the other smaller streams in the region flow, act as the main overall collectors in addition to being exposed to all the above mentioned pollutants.

It should be noted that, excluding the Danube and the Sava, the majority of the investigated watercourses are situated in the southern, Šumadija region. In the northern, Pannonian region, except for the Obrenovac Canal, all the investigated watercourses belong to Type 8 (canals).

Detrended correspondence Analysis (DCA; Hill and Gauch, 1980) was performed on a 21-by-65 samples-by-taxa (presence/absence) data matrix. The obtained ordination biplot, consisting of points representing taxa and squares representing samples, has exhibited their multivariate relations. The calculation was done using FLORA software (Karadžić et al., 1998; Karadžić, 2013).


Results and Discussion

A total of 65 taxa were identified in this investigation (Table 2). Oligochaeta were found to be the most diverse group with 17 taxa, followed by Crustacea and Gastropoda with 10 and 9 taxa, respectively. The diversity of other main macroinvertebrate groups was significantly lower (Table 3) These were found to be Oligochaeta and Crustacea, with 7 taxa each (Table 3). The Oligochaeta were the most diverse group in all analyzed watercourse types. In the large lowland rivers with a domination of fine substrate (Type 1) the most diverse group, besides worms, was Crustacea, while in all other types it was Gastropoda (Table 3). Regarding localities, the greatest diversity (and the only one with >15 taxa) was present at Stepojevac (Beljanica) with 21 taxa. On the other hand at the Dobanovci hunting area locality (Galovica) only one taxon was found. Low diversities (<5 taxa) were recorded in samples from Sopot Stream and the Obrenovac Canal (2 taxa, each), as well as the PKB Canal and the Barička Stream (3 taxa each).

Regarding the different stream types, overall diversity ranged from 9 taxa (Type 6) to 34 taxa (Type 8) (Figure 1).






Figure 1: Total number of taxa found in different stream types.