A BIOLOGICAL WATER QUALITY ASSESSMENT BASED ON PHYTOBENTHOS AND MACROINVERTEBRATES AT THREE STATIONS ON THE RIVER NERETVA

This paper presents the research results of benthos community (phytobenthos and macroinvertebrates) on three locations of the Neretva River: Glavatičevo, Žitomislići and Višići. According to typology of rivers, the site Glavatičevo belongs undertype 10a, while sites Žitomislići and Višići are undertype JIVT (heavily modified water bodies). Research of the benthos community has been done in December 2016 with the simultaneous monitoring chemical parameters of water. All research states showed a great number and a high diversity of benthic taxa, although sampling was spent in December. The saprobic values of benthos community at the site Glavatičevo indicates to oligosaprobic level, the water unloaded with organic substances. The site Žitomislići points to oligo/betamesosaprobic level, the water a bit loaded with organic substances. The site Višići according to phytobenthos demonstrates to oligo/betamesosaprobic level, while according to benthic macroinvertebrates point to betamesosaprobic level (the water loaded with organic substances). Based on saprobic values and chemical parameters of water in keeping with The decision on the characterization of the surface and underground water, reference conditions and parameters for the detection of water state and water monitoring (Official newspapers FBiH, No. 1/14), a maximum ecological potential has been registered on sites Žitomislići and Višići, while a high ecological status has been registered on the site Glavatičevo.

benthos community points to the specificity of the area as well as the high degree of endemism (KAĆANSKI, 1978;MARINKOVIĆ-GOSPODNETIĆ, 1978).
In recent times, more precisely since establishing a water agency for the Adriatic Sea, regular biomonitoring programs are being conveyed within the framework of monitoring the state of the Neretva River.
This thesis presents assessment of ecological status on three locations of Neretva river using phytobenthos and macroinvertebrates community and chemical elements of water.

MATHERIAL AND METHODS -Materijal i metode
Research of benthos was made in December 2016. Phytobenthos, macroinvertebrates were sampled and chemical parameters of water were measured. The assessment of the ecological status has been made according to the applicable legal regulations, respectively the decision on the characterization of the surface and underground water, reference conditions and parameters for the detection of water state and water monitoring (Official newspapers FBiH,No. 1/14). Chemical parameters were measured by an ecological probe type WTW Multi-Parameter Instruments. pH values were measured by the pH-meter, model HANNA HI 98127, conductivity was measured by WTW field meter, model Cond 3110, and dissolved oxygen was measured by WTW field meter, model Ox 3205. Of chemical analyses the content of total carbon (TOC) and the content of total organs of carbon (NPOC) were determined by TOC analyzer. Samples for analyses concentrations of ammonium, nitrate and phosphates also were sampled. They were measured in the laboratory using a UV-visible spectrophotometer. Chemical analysis was done in Institute of Public Health FB&H Mostar.
Phytobenthos samples were taken according to European Standard EN 13 946 (2016). Phytobenthos were sampled from the surface of the rocks by scraping with a scalpel and a toothbrush. The samples of phytobenthos (diatoms and the other algae) were fixed in 4% formaldehyde at the site. Diatoms were determined from the permanent preparations that were made after the chemical processing of materials by HUSTEDT, (1930). Algae were determined using ZEISS light microscope (Axio Imager A2). The diatoms were identified at a high magnification (100X) while using immersion oil, and the other algae were identified under different magnification (4x, 10x and 40x). Counting of taxa was made in arbitrary transcriptions counting 400 frustules on a light microscope with the contrast (DIC) on magnification 1000x. The indetification of the species was made using the keys: GOLERBACH et al. (1953), , HUSTEDT, (1927HUSTEDT, ( -1966HUSTEDT, ( , 1930, KOMAREK and ANAGNOSTIDIS (1999), LENZENWEGER, (1996), ZABELINA et al. (1951), WEST, (1905), LANGE-BERTALOT (1986 -1991), KRAMMER, (2000KRAMMER, ( -2003, . Based on the qualitative and quantitative composition of phytobenthos, the saprobiological state of the investigated stations was determined. The indicator values of taxa were defined by WEGL, (1983) and the saprobity index was estimated according to  and ZELINKA-MARVAN, (1961). The relative abundance was expressed by number 1, 3 and 5 (1-single, 3-usual, 5-dominant). Water quality category was given by LIEBMANN, (1962) ( Table 1).
The samples macrozoobenthos were sampled by AQEM method and multihabitat sampling sheme. It covers the collection of material from all microstation of the defined station, which is represented by at least 5% coverage (totally 20 subsamples). In this study Surber's net a surface area of 0.1m 2 was used and a grinder mill with a diameter of 150 µm. The samples of macrozoobenthos were fixed in 80% EtOH at the site. The qualitative and quantitative analysis and determination of materials were made in the scientific research laboratory "Ruđer Bošković" Faculty of Science and Education at the University of Mostar. The determination of species was made using the keys for certain groups of macroinvertebrates: ASKEW, (1988), BELIFORE, (1983), CARCHINI, (1983), CONSIGLIO, (1980), ELLIOTT et al. (1988), ENGBLOM, (1996), HICKIN, (1967), NILSSON, (1996), PELEGER, (1999), WARINGER and GRAF (2011), WATSON and DALLWITZ (2005) under the sterezoom microscope Olympus SZX10. The Pantle-Buck saprobic index was used for assessing the ecological status and burden of organic pollution of aquatic ecosystems. Saprobic value of the taxa was defined by MOOG, (2002) and data base (freshwaterecology.com). The relative abundance was defined by RUSSEV, (1993). The water quality category was given by LIEBMANN, (1962) ( Table 1). The study area: The Neretva River is the largest river of the Adriatic catchment area. It flows 203 km through Bosnia and Herzegovina, and the last 22 km through the Croatia. River water flows mainly through limestone in accordance with the hydrogeological characteristics of the karst flow. Climate characteristics in the river basin vary with the distance from the sea. The climate is Mediterranean in the lowland area close to the sea, while the middle part has a continental climate and higher areas have a mountainous climate. The average rainfall is 1.650 1/m 2 , and varies between 1.500 and 1800 1/m 2 . Temperatures range between -29 and +43 °C, and the annual evapo-transpiration is 500-900 mm.
Three investigated stations are presented in this paper (Photo 1). The first site: Glavatičevo (Photo 2) is on 358 m atitude. According to typology of rivers, it belongs undertype 10a (medium high mountain stream on the carbonate substrate). The second site: Žitomislići (Photo 3) is on 19 m atitude. According to typology of rivers, it belongs undertype JIVT (heavily modified water body). The third site: Višići (Photo 4) is on 8 m atitude. It belongs undertype JIVT (heavily modified water body

RESULTS AND DISCUSSION -Rezultati i rasprava
The results of selected chemical parameters of water at investigated stations are shown in Table 2. All the stations showed a high oxygen value (dissolved oxygen-11.59-13.20 mg L -1 and saturation -96.4-113%). Reason for that can be the less values of water temperature, porosity of aquifer rock and contact with groundwater with atmosphere (CANTONATI, 1998). Conductivity was ranged between 284 and 456 µS/cm (table 2). The measured value of electrical conductivity can assess the degree of mineralization of water and also to evaluate of the kind of water (WALTON, 1989). Our values are in agreement with values for limestone substrate (MOGNA et al., 2015). Also, our values are in agreement with values of factors for the Žitomislići and Višići sites who were presented in the paper by IVANKOVIĆ et al. (2017).
In accordance with The decision on the characterization of the surface and underground water, reference conditions and parameters for the detection of water state and water monitoring (Official newspapers FBiH, No. 1/14), all the obtained values of chemical parameters of water at the Žitomislići and Višići sites are within the limits of maximum ecological potential, and at the Glavatičevo site are within the limits of a high ecological state.
In terms of phytobenthic communities, it was recorded a great number and high diversity of taxa. A total of 67 taxa of phytobenthos were determineted at all stations (Glavatičevo 26, Žitomislići 46 and Višići 20 taxa). The most common and the most numerous were representative from the classes of Bacillariophyceae. Species Cocconeis placentula Ehrenberg, Diatoma vulgaris Bory, Encyonema silesiacum (Bleisch) D. G. Mann, Navicula tripunctata (O. F. Müller) Bory, Rhoicosphenia abbreviata (C. Agardh) Lange-Bertalot and Ulnaria ulna (Nitzsch) Compère were registered at all stations. All presented taxa are cosmopolitan with a wide amplitude of appearances. Saprobic index for the phytobenthos at the site Glavatičevo was 1.41, at the site Žitomislići 1.7 and at the site Višići 1.8. According to the saprobic index site Glavatičevo belongs to I category of water quality or oligosaprobic water level (the unloaded to very little loaded waters), while the Žitomislići and Višići sites belong to I-II category of water quality or oligo-betamesosaprobic water level (the litlle loaded waters). According to the research results conducted by TROŽIĆ-BOROVAC et al. (2013) in the period from 2005. to 2010. were determined 62 taxa at the Žitomislići site and 47 at the Višići site. The reason for their greater number of taxa is certainly the greater number of samples as well as the longer period of research. The most numerous genera in this paper: Cocconeis, Encyonema, Diatoma, Gomphonema and Navicula were recorded in the study of other authors of karst rivers (WOJTAL, 2009), NOGA et al. (2013), MOGNA et al. (2015, IVANOV et al. (2006)). According to the list of indicator types (VAM DAM et al., 1994), the most abundant taxa at the sites on the Neretva River are alkaliphilous and circumneutral species, which corresponds to the measured pH values.
In terms of macroinvertebrates 198 individuals of 16 taxa were dermineted at the site Glavatičevo, 346 individuals of 16 taxa at the site Žitomislići and 381 individuals of 13 taxa. The most diverse groups at all stations were insect class representatives Insecta, especially orders Trichoptera, Ephemeroptera and Plecoptera. The species Gammarus balcanicus Schäferna, 1922, was the most diverse species at the Žitomislići and Višići sites. Saprobic index at the site Glavatičevo was 1.48, at the site Žitomislići 1.58 and at the site Višići 1.89. According to the saprobic index the site Glavatičevo belongs to I category of water quality or oligosaprobic water level (the unloaded to very little loaded waters), the site Žitomislići belongs to I-II category of water quality or oligo-betamesosaprobic water level (the litlle loaded waters) and the site Višići belongs to betamesosaprobic water level (moderately loaded waters).
Comparison of the values of saprobic index for both biological parameters indicates the relative uniformity.

CONCLUSION -Zaključci
Based on the results obtained by researching the benthic communities at the three Neretva River stations we make the following conclusions: • Data of chemical variables show good aeration, pH typical for carbonate bed/origin and generally oligotrophic conditions. • According to the chemical parameters of water, the largest number of benthic taxa are alkaliphilous and circumneutral species, and they are mesosaprobic indicators. • In the Neretva river were recorded high number and high diversity of phytobenthos and macrozoobenthos taxa. • According to the research results, the site Glavatičevo points to the good water quality, while the Žitomislići and Višići sites evaluated to the presence of organic contamination. • The high ecological status was assessed for the site Glavatičevo, and for the Žitomislići and Višići sites were assessed maximum ecological potential.