SEASONAL CHANGES IN STREAM WATER QUALITY AND ITS EFFECTS ON MACROINVERTEBRATE ASSEMBLAGES IN A FORESTED WATERSHED

Abstract

In this study, indicator macroinvertebrate individuals was used in water quality assessments due to their broad spectrum of responses of macroinvertebrates individuals with specific tolerance limit values and preferences to changes in environmental factors. Because of their indicator properties, the interactions of macroinvertebrates individuals collected from an experimental watershed in Belgrad Forest of Istanbul and sixteen environmental variables were evaluated by using principle component analysis (PCA). We concluded that stream water quality parameters should be coupled with number of macroinvertebrate individuals in order to establish the linkage between hydrochemistry with biota. Axes to be evaluated in PCA analysis were determined to defined that both of F1 (53%) and F2 (29%) axes explain 82% of total variance together. All macroinvertebrate individuals and dissolved oxygen were found to be loaded positively loaded to Factor 1 but electrical conductivity, total hardness, alkalinity, HCO3, organic matter and potassium, loaded negatively to Factor 1. Water temperature, runoff, pH, turbidity, magnesium (Mg), sodium (Na), nitrate nitrogen (N-NO3) and ammonium nitrogen (NH4-N) and some individuals (Gerris lacustris and Perlodes microcephala) highly loaded to F2. UPGMA analysis was determined to similarity on numbers of macro invertebrate individuals in order to perform a seasonal evaluation. According to Output UPGMA dendrogram, the different number of macroinvertebrate individuals can be seen as the reflect of variable seasonal effect