Research into the Epipelic Diatoms of the Meriç and Tunca Rivers and the Application of the Biological Diatom Index in Water Quality Assessment

Abstract

The Meriç River is one of the longest rivers of the Balkans and the Tunca River is the most significant tributary of the Meriç River. In the present study, the epipelic diatoms of the Meriç and Tunca Rivers were investigated and the water quality was evaluated from a physicochemical and biological perspective. Epipelic (EPP) diatoms were collected from the middlestream of the Meriç River (Edirne Province of Turkey) and from the downstream of the Tunca River (before emptying into the Meriç River) and certain physicochemical parameters including dissolved oxygen (DO), oxygen saturation (OS), pH, electrical conductivity (EC), total dissolved solids (TDS), salinity, turbidity, nitrate (NO 3 ), nitrite (NO 2 ), ammonium (NH 4 ), phosphate (PO 4 ), sulphate (SO 4 ), chemical oxygen demand (COD) and oxidation-reduction potential (ORP) were measured during the field studies. The Biological Diatom Index (IBD) was used to determine the trophic status of the Meriç and Tunca Rivers in terms of EPP diatoms, and Cluster Analysis (CA) was applied to the detected biological data in order to classify the identified diatom taxa in terms of their dominance in the system. According to the results of the physicochemical analysis, the Meriç and Tunca Rivers have I. -II. Class water quality in terms of dissolved oxygen, oxygen saturation, pH, EC, TDS, NO 3 , NH 4 , SO 4 and COD parameters; and have III. -IV. Class water quality in terms of NO 2 and PO 4 parameters. 24 diatom species were recorded in the Meriç River by counting a total of 403 valves and a total of 19 diatom species were identified by counting a total of 409 diatom valves in the Tunca River. Cyclotella atomus Hustedt, Navicula gregaria Donkin, Nitzschia palea (Kützing) W.Smith and Nitzschia subacicularis Hustedt, were determined as the most dominant species in the Meriç River and Navicula erifuga Lange-Bertalot, Navicula gregaria Donkin and Navicula rostellata Kützing were recorded as the most dominant taxa in the Tunca River. According to the result of the IBD, the investigated rivers were found to be in a meso-eutrophic state and according to the results of CA, three statistical clusters were formed for both rivers, and were named as "dominant taxa", "frequent taxa" and "rare taxa".

Impacts of a Garbage Disposal Facility on the Water Quality of Çavuşlu Stream in Giresun, Turkey: A Health Risk Assessment Study by a Validated ICP-MS Assay

“…Origin characterization of metals dissolved in river water, as well as computing the proportional participation, is required to ensure environmental safety of aquatic ecosystems (Tepe & Aydın 2017;Tokatlı et al, 2019;Tokatlı et al, 2020). It is therefore beneficial to employ principal component analysis (PCA), hierarchical cluster analysis (HCA), and Pearson's correlation coefficient (PCC) analysis to assess the source and spread of metals in river waters (Köse et al, 2014;Çiçek et al, 2019;Ustaoğlu, 2020).…”

Spatial–temporal distributions, probable health risks, and source identification of organic pollutants in surface waters of an extremely hypoxic river basin in Türkiye

“…In three different investigations performed in 2020, pesticide residues in water and sediment samples from fluvial and lacustrine freshwater habitats of the Meriç–Ergene River Basin were investigated (Tokatlı et al, 2020a ; Tokatlı, 2020a , b ; Köse et al, 2018 ). In two similar studies carried out by Tokatlı et al, ( 2020b , c ), organic pollution levels and trophic statuses of the Meriç, Tunca, and Ergene Rivers were evaluated using diatom indices. In two separate studies conducted in 2020 and 2021, ecotoxicological and health risk assessments of toxic metals were evaluated in surface and groundwaters of the Meriç–Ergene Basin and Meriç River Delta (Tokatlı & Ustaoğlu, 2020 ; Tokatlı, 2021 ).…”

Benthic diatom communities and a comparative seasonal-based ecological quality assessment of a transboundary river in Bangladesh

“…Benthic diatom is a good indicator for evaluating environmental conditions [ 14 , 15 ]. Diatom species are an alarming agent in the aquatic ecosystem for seasonal dynamics due to their different lifestyle, habitat variance and regeneration systems [ 16 ].…”