Abstract—Diatoms are an important group of aquatic ecosystems and diatom-based indices are increasingly becoming important tools for the assessment of ecological conditions in lotic systems. Although the studies are very limited about Turkish rivers, diatom indices were used for monitoring rivers in different basins. In the present study, we used OMNIDIA program for estimation of stream quality. Some indices have less sensitive (IDP, WAT, LOBO, GENRE, TID, CEE, PT), intermediate sensitivities (IDSE, DESCY, IPS, DI-CH, SLA, IDAP), the others higher sensitivities (SID, IBD, SHE, EPI-D). Among the investigated diatom communities, only a few taxa indicated alfa-mesosaprobity and polysaprobity. Most of the sites were characterized by a great relative contribution of eutraphent and tolerant ones as well as oligosaprobic and betamesosaprobic diatoms. In general, SID and IBD indices gave the best results. This study suggests that the structure of benthic diatom communities and diatom indices, especially SID, can be applied for monitoring rivers in Southern Turkey. Keywords—Diatom, Darı stream, OMNIDIA, Turkey, Water quality. I. INTRODUCTION LASSICALLY, physical and chemical monitoring reflects instantaneous measurements while biotic parameters provide better evaluation of environmental changes. Because community development integrates a period of time reflecting conditions that might not be any longer present at the time of sampling and analysis [1]. Diatoms have been used for the assessment of short- and long-term environmental change [2]. Diatoms are widely used in bioassessments, and a substantial number of diatom indices have been developed for estimation of water quality in various geographic areas. The first studies of diatoms and river pollution were carried out 60 years ago, and the suitability of these micro-algae as bioassessment indicators for monitoring river quality was quickly demonstrated. These studies demonstrated the potential and robustness of diatoms that could enable their use to monitor river quality. After these first approaches, benthic diatoms in rivers became an obligatory bioindicator for use in several European and American countries in the late 90s. The overall objective of this report is to describe the studies performed in the first ten years of the twenty-first century [3]. Assoc. Prof. Dr. Hasan Kalyoncu is with the Süleyman Demirel University, Isparta/Turkey (Phone: +905326776615, e-mail: hasankalyoncu@sdu.edu.tr). Burcu Serbetci is with the SGS Antalya Food Control Laboratory, Antalya/Turkey (e-mail: burcuserbetci@gmail.com). Numerous studies focusing on the application of standardized methods based on diatom assemblages for water quality assessment have been carried out, especially in the northern hemisphere and in particular in European countries [4]-[6]. Several diatom-based indices have been developed most of which are based on the weighted average equation of Zelinka & Marvan [7] and are general pollution indices. There are as many indices as the number of researchers working in the field [8]-[11]. In Turkey, the first studies on the use of epilithic diatom for monitoring of the pollution levels of lotic systems were carried out in Isparta stream [12], [13]. First used index was Saprobi index for Turkey and the index gave good results, but this topic is still new in Turkey [14], [15]; Isparta [16] and Aksu [17] streams were investigated by using Saprobity Index [7]. Gürbüz and Kıvrak [18] practised firstly three different indices [TDI, SI and IDG] on Karasu River [Erzurum] while, OMNIDIA software program was firstly used for Akçay stream [Muğla] in Turkey [19]. Kalyoncu et al. [20] used saprobi index in Darıören stream in Isparta and compared saprobi index with diversity and species richness. Also, Kalyoncu et al. [21] compared the performance of three types of benthic diatom indices: (Swiss Diatom Index (DI-CH), Trophic Index (TI) and Saprobic Index (SI)) in Isparta stream and they concluded that in these rivers, DI-CH and TI could be more useful than SI. On Aksu river catchment area was used several indices and compared macrozoobenthic index and diversity [17]. Also, the diversity and ecology of diatoms from Felent Creek was investigated by Omnidia software [22]. The aims of this study are to test the use of epilithic diatoms as indicators and the use of diatom indices as a tool for estimating the creek water quality. This study presents the relationship between measured water quality variables in the Darı stream and diatom index scores. Diatom index scores were calculated and correlated to concurrent physical and chemical water quality data. The results of these correlation analyses were compared to results obtained in similar studies. II. MATERIAL AND METHODS Six sites were monthly established between June 2009 and May 2010 along the Darı stream and its tributaries: four sites (1 st , 2 nd , 3 rd and 4 th ) in the relatively less impacted agricultural and forested headwaters to act as reference sites; site 5 in the relatively moderately polluted urban area; and site 6 in highly polluted downstream area after the urban area (Fig. 1). Applicability of Diatom-Based Water Quality Assessment Indices in Dari Stream, Isparta- Turkey Hasan Kalyoncu and Burcu Şerbetci C World Academy of Science, Engineering and Technology International Journal of Environmental and Ecological Engineering Vol:7, No:6, 2013 386 International Scholarly and Scientific Research & Innovation 7(6) 2013 scholar.waset.org/1307-6892/2247 International Science Index, Environmental and Ecological Engineering Vol:7, No:6, 2013 waset.org/Publication/2247