Physical, Chemical and Biological Indicators of the Jablanica River Water Quality (Republic of Srpska, Bosnia and Herzegovina)

Dragojla Golub1, Svjetlana Lolić1, Dejan Dmitrović1, Radoslav Dekić1, Goran Šukalo1, Svjetlana Cvijić1

 

1 University of Banja Luka, Faculty of Natural Sciences and Mathematics,  Department of Biology and Department of Ecology and Environment Protection, Mladena Stojanovića 2, 78000 Banja Luka, Republic of Srpska, Bosnia and Herzegovina; E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

 

Abstract

During 2016 and 2018, research was carried out on physical, chemical, as well as certain biological elements of water quality (phytobenthos, macrozoobenthos and ichthyofauna) of the Jablanica River. The Jablanica River is the right tributary of the Sava River, about 35 km long, with its entire catchment area in the Republic of Srpska. The aim of this paper was to determine, based on the selected water quality parameters, the current state of the quality and ecological status of the water. The values of most of the analyzed physical-chemical water quality parameters of the Jablanica River are classified as class I and II. The results obtained on the basis of the qualitative and quantitative composition of the community of phytobenthos, macrozoobenthos and ichthyofauna, as well as the saprobic index, indicates that the water of the Jablanica River corresponds to beta-mesosaprobic waters. Such results show that the water of the Jablanica River is at a satisfactory level and that, given the importance this watercourse has in maintaining the diversity of the wider Sava River Basin, it should be preserved under constant monitoring.

Keywords: Jablanica River, water quality, saprobic index, ecological status.

Introduction

 

The Jablanica River is the right, westernmost tributary of the Sava River in Bosnia and Herzegovina with a surface area of 476.74 m2 and a main course of 35 km. The larger tributaries are Vrbaška (drainage area 85.5 km2), Lubina (drainage area 119.8 km2) and Jurkovica (drainage area 81.3 km2). The Jablanica River springs at about 300 m a.s.l. in the northwest part of the basin, and is formed from a branched spring on the southern slopes of the mountain of Prosare. It confluences the Sava River 4 km before the town of Gradiška about 86 m a.s.l. (Water Management Plan for the Sava River Basin in the Federation of Bosnia and Herzegovina for the period 2015 and 2016-2021). The catchment area of the Jablanica River has been recognized as a natural floodplain retention zone and a potential flood control measure for the Sava River and its tributaries, but also as a zone that, as such, plays an important role in preserving biodiversity. The preservation of the hydro-system of the catchment area of the Jablanica River represents an important task since this area is already under the influence of existing hydrotechnical operations, artificial fertilizer and pesticide wash-off from surrounding agricultural land and waste disposal (Dekić and Golub, 2016). Among the existing hydrotechnical flood defence operations on the Jablanica River, there is the Jablanica embankment, a regulated river bed 6.5 km long, as well as the peripheral and hydromelioration canals of Jurkovica-Jablanica and Topola-Jablanica (Spatial Plan of Gradiška Municipality 2005- 2020, 2007; Marković et al., 2016). It should be noted that a water supply project that would supply water to orchards and agricultural areas in Potkozarje in the municipality of Gradiška, construction of reservoirs on the rivers Jablanica, Vrbaška, Lubina and Jurkovica are being considered, which can certainly lead to a significant decrease in the amount of water in the mentioned watercourses (Integrated Water Management Strategy of the Republic of Srpska, 2015). Considering the significance and potential of the catchment area of the Jablanica River as part of the natural Sava River Basin area of the Sava River, the aim of this paper was to provide data on water quality, primarily from the point of view of aquatic biocenoses as a saprobiological indicator. These sorts of data are mostly non existant, and so far, only qualitative and quantitative research has been done on the composition of the ichthyofauna of the Jablanica River, as an indicator of water quality (Golub et al., 2018).

 

Materials and Methods

Field research in the area of the Jablanica River was carried out during 2016 and 2018. Sampling was carried out at two sites: Vrbaška (L1) and Lužani (L2) (Figure 1), in the wider area of the municipality of Gradiška. The first site (Vrbaška) is located at N 45.11872º and E 017.19074º and 94 meters above sea level, while the second locality (Lužani) is 45.09285º and E 017.16960 and 99 meters above sea level.

 

fig01
Figure 1: Jablanica River with sampling localities (Google Earth, modified).

 

Physical and Chemical Characteristics

An analysis of a part of the physico-chemical parameters of water was performed on the field (water temperature, pH, dissolved oxygen, turbidity and conductivity) by using a thermometer, pH-Meter HI 98127, Oxy Meter HI 9142, Conductometer Nahita and a EUTECH Turbidimeter TN100. Other parameteres (BOD5, phosphates, sulphates, ammonia, nitrites and nitrates) were determined in the laboratory by using DRELComplete Water LabDR2800 according to standard procedures. The obtained results were interpreted on the basis of the relevant legislation of the Republic of Srpska in the area of surface water quality (Off. Gazette of the Republic of Srpska, No. 42/01).

 

Phytobenthos

To determine the qualitative composition of phytobenthos, the material from the bottom was collected and then fixed in an acidic Lugol's iodine solution. Samples were observed using a Leica DM 1000 microscope with an accompanying Leica DSF245 camera. The algae identification was performed using the following keys: Bey and Ector (2013), Hindak (1978), Hofmann et al. (2011), Houk et al. (2010), Krammer and Lange-Bertalot, (1988), Lange-Bertalot et al. (2006). The saprobic index was determined on the basis of the relative number of indicator organisms according to the classical Pantle-Buck method (in Grginčević and Pujin, 1998), using the list of indicator taxa Wegl (1983). The concentration of chlorophyll "a" was determined by the standard spectrophotometric method (APHA-AWWA-WEF, 1998).

 

Macrozoobenthos

Macrozoobenthos samples were collected at two sites of about 50 m in length, using a mesh (frame dimensions: 25 x 25 cm with a mesh size of 500 μm) on the principle of 20 sampling replicates, in proportion to the composition and substrate coverage. The collected samples were fixed with 96% ethanol and labeled. After washing and homogenization of the samples in the laboratory, subsampling and analysis of ¼ of each sample was performed. Qualitative and quantitative analysis of macrozoobenthos was performed using a Leica EZ4D stereomicroscope, a Leica DM500 microscope and appropriate literature for determination (Friday, 1988; Timm, 1999; Kriska, 2013). The number of individuals is expressed per square meter (ind/m2). Water quality was assessed by applying the saprobic index by Pantle-Buck, based on data for the saprobic values of taxa given by Walley et al. (2001).

 

Ichthyofauna

Sampling of ichthyofauna in the area of the Jablanica River was conducted in accordance with the standard for sampling of fish with electricity for the purpose of water quality analysis (EN 14011: 2003, IDT). Sampling was performed by ELT62II GI HONDA GCV160, 3 kW. Fish were identified using keys (Kottelat and Freyhof, 2007; Sofradžija, 2009), counted and measured by individual mass, after which they were returned to the water unharmed. The saprobic index was determined by the Pantle-Buck (in Grginčević and Pujin, 1998).

 

Results and Disccusion

Physical and Chemical Characteristics

The parameters of the physical and chemical characteristics of the water tested are given in Table 1, while in accordance with the Regulation on the classification of waters and categorization of watercourses. (Off. Gazette of the Republic of Srpska, No. 42/01) the classification of the given watercourse was performed (Table 2).

 

tab01

 

tab02

 

The analysis of the water quality of the Jablanica River at both locations has shown that it is mildly alkaline. Most of the tested parameters indicate water of satisfactory quality, that is, class I and II water. A deviation was observed in BOD5 with a value of 4.3 g/m3 at Site I. The reason for these deviations can be explained by a higher organic load in that part of the watercourse, where Jablanica is categorized as having class III water quality. Since 2009, the Jablanica River has been included in the surface water quality monitoring program of the Republic of Srpska as one of the points of national supervisory monitoring (Monitoring of the Water Quality of the Watercourses in the Territory of the Republic of Srpska for 2009, 2010). The 2009 report only contains data results pertaining to microbiological parameters which reveal that, during the observed period, the organic and fecal load of the Jablanica River pointed to the class III category waters.

 

Phytobenthos

The presence of a total of 22 different types of algae was determined at the Lužani locality (Table 3). As expected for phytobenthos, algae from Bacillariophyta (Sigee, 2004), which are represented with a total of 20 taxa, are dominant. Cyanobacteria are present only with one taxon of Phormidium sp., and Chlorophyta with one species of Mougeotia viridis whose abundance is large and dominates in the sample. This is the algae of the filamentous thallus that normally inhabit the benthos of freshwater streams (Bey and Ector, 2013) of good ecological status. Gyrosigma attenuatum dominates among silicate algae, which is also an indicator of β-mesosaprobic waters, and there are many different species of the genus Cymbella.

 

tab03

 

A total of 35 different algae taxa were determined at the Vrbaška site, 31 of which belong to the division of Bacillariophyta. Almost all species found on the Lužani locality were also determined here, except for the species Fragilaria capucinus, Meridion aciculare and Stauroneis anceps. The number of algae in a qualitative and quantitative sense is far greater than at the Lužani location. The reason for this distribution of phytobenthos should be sought in the very nature of the bottom of the riverbed. Namely, the Vrbaška site is located downstream of the Jablanica River and the bottom contains more sludge. Gyrosigma attenuatum dominates in quantity and there are many different species from the genera Cymbella, Navicula and Nitzschia. Here, Cyanobacteria Phormidium sp., Chlorophyta Mougeotia viridis, and Xanthophyta Vaucheria sp., on which periphyton green algae from the genus Characium, can be found.

Cyanobacteria from the genus Gloeocapsa, Chamaesiphon, Phormidium and others, as well as Bacillariophyta, in particular the genus Cocconeis, Cymbella, Gomphonema, Gyrosigma and Melosira, are dominant in the phytobenthos composition of small watercourses (Skacelova et al., 2010). However, only one species of cyanobacterium from the genus Phormidium was identified in the samples from the Jablanica River, while other representatives of this division were not found.

Based on the frequency of the identified species, the Pantle-Buck saprobic index at the Lužani site was 1.76, and 1.81 at the Vrbaška site, indicating β-mesosaprobic water of good ecological status (Off. Gazette of the Republic of Srpska, No. 42/01). The measured concentration of chlorophyll "a" also indicated a good ecological status: at the Lužani site the value of this parameter was 4.33 mg/m3, and 6.15 mg/m3 at the Vrbaška site.

 

Macrozoobenthos

A qualitative and quantitative analysis of the macrozoobenthos of the Jablanica watercourse revealed higher-density assemblages of this community and the presence of a large number of taxa at the Lužani locality in relation to the Vrbaška site (Table 4). The highest numbers recorded are at the Vrbaška site for Trichoptera larvae from Hydropsyche, and at the location Lužani for representatives of Coleoptera from the genus Esolus. The aforementioned members of the macrozoobenthos community were found at both locations, as well as representatives of six additional taxa.

The Jablanica watercourse is the habitat of a rare species of Macronychus quadrituberculatus Müller, 1806, from the Elmidae family, also found at both sites. Representatives of this species are also registered on the longitudinal profile of the Sava River (Ćuk et al., 2014) into which the Jablanica watercourse flows into the Gradiška. In addition to the above findings, and based on the available literature, this species has been registered in several locations in Croatia (Kerovec et al., 2008; Mičetić Stanković et al., 2015) and Serbia (Novaković and Mesaroš, 2014). The composition of the macrozoobenthos in lowland watercourses of medium-sized streams of the Pannonian Ecoregia of Croatia (Kerovec et al., 2008) shows similarities with the composition of the macrozoobenthos of the medium and predominantly lowland watercourse of the Jablanica River, from the same ecoregion.

The qualitative and quantitative characteristics of the macrozoobenthos community of the Jablanica watercourse at both sites which were included in this study indicate β mesosaprobic water, i.e. of good ecological status. Based on the values of the saprobic index and the Trent biotic index, the quality of the water of the Jablanica River in 2009 ranged from a class II to III, depending on the locality (Monitoring the Water Quality of the Watercourses in the Territory of the Republic of Srpska for 2009, 2010).

 

tab04

 

Ichthyofauna

As a result of ichthyological studies conducted in September 2016 (Golub et al., 2018), one species of agnathans and 16 species of fish from eight families were found at two sites of the Jablanica River. The Cyprinidae family was dominant and presented with nine species, while the remaining families (Cobitidae, Esocidae, Percidae, Centrarchidae, Lotidae, Balitoridae and Gobiidae) were presented by one species. In the Vrbaška locality, where 15 species were found, the most numerous were chub (Squalius cephalus), barbel (Barbus barbus) and nase (Chondrostoma nasus). On the other side, at the Lužani locality, where nine fish species were found, the most frequent species were spirlin (Alburnoides bipunctatus) and chub (Squalius cephalus). The presence of three introduced / invasive species of fish, monkey goby (Neogobius fluviatilis), pumpkinseed (Lepomis gibbosus) and Prussian carp (Carassius gibelio), all found at the Vrbaška locatity, were observed. Given the presence and abundance of indicator fish species, the saprobic index according to Pantle-Buck was 1.90 for the Vrbaška locality and 1.76 for the Lužani locality that characterized the water of the explored sites as β mesosaprobic water, with good ecological status (Golub et al., 2018; Off. Gazette of the Republic of Srpska, No. 42/01).

Data on the ichthyofauna of the Jablanica River from the "Fisheries Management Plan for the Sava River" (1984) show that this watercourse is inhabited by eight species of fish, which to a considerable extent differ from the results of our research where 17 species were found. According to the Report on Ichthyofauna Research in 2009, 13 species of fish were identified in the Jablanica River (Monitoring the Water Quality of the Watercourses on the Territory of the Republic of Srpska for 2009, 2010) (Table 5).

At first glance, it is evident that there is a much larger number of identified species in our research in relation to previous surveys. A problem that was observed when comparing data on the number of occurring species is absence of data on sampling methodology. The research conducted in 1984 contains no data on exact location, number of sampling sites or sampling methodology. Research in 2009 was also conducted at two localities, namely at Jablanica and the Jablanica rivermouth. Data on sampling methodology were also missing. On the other hand, research purposes were also different. The ichthyological surveys carried out in 1984 were aimed at analyzing the numbers and masses of species attractive to sport fishing, while other species are only mentioned as being present, withount defining types of species and how many of them are present. The reasons for the obviously richer ichthyocenosis established in our research (particularly in relation to the 1984 results) should be sought in the sampling methods (probably less selective in our research), but also in the number of sampling sites. What is noticeable is that almost all the introduced invasive fish species were not identified in previous research.

 

tab05

 

Conclusions

Based on the results of the analyses of physical-chemical and biological parameters of water quality, it was determined that the water of the Jablanica River corresponds to beta-mesosaprobic waters (class II water quality), that is, water of good ecological status. Such water is treated as moderately burdened, but with favorable conditions for the life and survival of aquatic organisms, which is reflected in the number of aquatic organisms ascertained, especially having in mind the dynamics of sampling. In this sense, the Jablanica River is of vital importance in maintaining biodiversity within a wider catchment area of this river, as well as the Sava River.

 

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