The Effect of Small River Fragmentation on the Biodiversity and Structure of Macroinvertebrate Communities - page 01

Study Area

The Grošnica River is formed at the confluence of the Bajčetinski Stream and the Crni Stream at the Gledićke Mountains in central Serbia. The river forms a gorge in the upper flow, and in the lower part of the flow it forms a river valley (Baračkov, 1972). It is a torrential small river with a drainage surface of 69,2 km2. The Grošnica River has 20 tributaries, and it is the watercourse with the most dense drainage network in the Kragujevac Basin (Milanović, 2006).

 

Material and Methods

Macrozoobenthos sampling was conducted seasonally during 2011, 2012 and 2013, on several locations on the river course. In 2011 and 2012.

The material was sampled at 9 locations (7 on the upper stream, and 2 on the lower), and in 2013 samples were taken at 6 locations (4 sample sites on the upper half of the river, and 2 on the lower part). Abiotic data was provided at 6 locations in March the same year.

Macrozoobenthos sampling was performed using a Surber bottom sampler. The sampler was posted downstream and parallel to the flow during 5 minutes, and the stones, sand and other materials accumulated at the riverbed, were moved aside so that all benthic organisms could get inside the sampler. The sample was rinsed, and then stored in plastic containers fixed with 95% alcohol.

Oxygen concentration and saturation, as well as water temperature, conductivity, pH, water hardness, were measured by a multifunctional field instrument HANNA HI 98130.

Nitrate, phosphate and ammonium concentration was measured with an Aqalityc AL400 portable digital ion selective colorimeter with a chemical set.

Species determination, qualitative and quantitative analysis were conducted using optical microscope, binoculars and several identification keys (Elliot et al. 1988; Hynes 1967; Makovinská et al. 2004; Nillson 1996, 1997; Olmi 1976; Pfleger 2004; Waringer & Graf 1997).

 

Results

The results of chemical and physical analyses are presented in Table 1. Qualitative analysis of the samples from 2011-2013 has shown the presence of 76 taxa, whereas in the study conducted in 1973 there were 4 additional taxa. Eleven groups are common for both studies: Turbellaria, Oligochaeta, Hirudinea, Crustacea, Ephemeroptera, Plecoptera, Odonata, Coleoptera, Trichoptera, Diptera and Mollusca. Common groups differ in species composition and quantity. Macrozoobenthos groups found in 1973 and absent from our research are Hydrozoa, Collembola i Hydracarina. Groups present in the research from 2011-2013 and absent in 1973 are Nematoda i Lepidoptera. Orders of insects and other groups of macroinvertebrates are represented with different numbers of genera and species (Table 2).

 

Tab01

 

Tab02