Determination of water quality of göksu stream (iIstanbul, Turkey) by using benthic macroinvertebrates and biotic indices

In order to determine the water quality of Göksu Stream using benthic macroinvertebrate and biotic index and to contribute to the biological inventory of our country, seasonal sampling was carried out by selecting five stations between December 2017 and September 2018. Physicochemical parameters were examined by taking water samples from five selected sampling points, benthic macroinvertebrate samples were collected and biotic indices were applied. As a result of the study, 33 taxa and 50.381 individuals per m2 were determined. 3 taxa belonging to the Gastropoda class [(Physella acuta (Draparnaud, 1805), Planorbis planorbis (Linnaeus, 1758), Planorbarius corneus (Linnaeus, 1758)]; 10 taxa belonging to the subclass of Oligochaeta [(Limnodrilus sp., Limnodrilus udekemianus (Claparède, 1862), Limnodrilus hoffmeisteri (Claparède, 1862), Nais pardalis (Piguet, 1906), Tubifex tubifex (Müller, 1774), Limnodrilus claparedeianus (Ratzel, 1868), Potamothrix hammoniensis (Michaelsen, 1901), Tubificinae, Enchytraeus buchholzi (Vejdovský, 1879), Lumbricidae)]; 1 taxa belonging to the Bivalvia class [(Mytilus galloprovincialis (Lamarck, 1819)]; 2 taxa belonging to the subphylum of Crustacea [(Asellus aquaticus (Linnaeus, 1758), Gammarus sp.)]; 1 taxa belonging to the order Ephemeroptera [(Baetis sp.)]; 1 taxa belonging to the order Odonata [(Orthetrum sp.)]; 14 taxa belonging to the order Diptera [(Chironomidae, Chironomus (Chironomus) riparius (Meigen, 1804), Endochironomus tendens (Fabricius, 1775), Cricotopus (Cricotopus) bicinctus (Meigen, 1818), Cricotopus (Cricotopus) cylindraceus, (Kieffer, 1908), Tanypus punctipennis (Meigen, 1818), Procladius (Holotanypus) sp., Zavrelimyia melanura (Meigen, 1804), Endochironomus albipennis (Meigen, 1830), Tipula sp., Simulium sp., Sciomyzidae, Dolichopodidae, Ephydridae)] and 1 taxa [(Hediste diversicolor (Müller, 1776)] belonging to the class Polychaeta has been identified. In addition to the determination of macroinvertebrates, water temperature (0C), pH, dissolved oxygen (mg/L), electrical conductivity (µS/cm), salinity (ppm), depth (cm), flow rate (m/s), ammonium nitrogen (NH4-N mg/L), nitrite nitrogen (NO₂-N µg/L), nitrate nitrogen (NO₃-N mg/L), orthophosphate (o-PO4 µg/L), total phosphorus (TP µg/L), biological oxygen demand (BOD5 mg/L) and suspended solid material (SSM g/L) measurements were also made. According to the Surface Water Quality Regulation (2021), the water quality classes of parameters measured in Göksu Stream were determined. In order to determine the water quality, BMWP (Biological Monitoring Working Group Biotic Index), ASPT (Mean Value of Each Taxon) and BBI (Belgium Biotic Index) indexes were calculated. Margalef and Simpson diversity indices were applied in the study. Sorensen and Jaccard similarity indices were calculated to determine the similarity ratio between stations. Descriptive statistics on data analysis; It is presented with mean and standard deviation values. Principal component analysis (PCA) was performed to examine the factor structures of physicochemical parameters. Kruskal Wallis test was applied to examine the differences of physicochemical parameters according to the station and seasons. All-pairwise method was applied to determine the different groups. Spearman correlation analysis was performed in order to determine the existence of relationship between physicochemical parameters