Assessing the Trophic Level of a Mediterranean Stream (Nif Stream, ?zmir) Using Benthic Macro-Invertebrates and Environmental Variables

摘要

The study was conducted in Nif Stream (?zmir) and the aims of the study are (a) to determine the benthic macro-invertebrate composition of the stream, (b) to determine environmental features of the stream, (c) to investigate the relations between the determined species and the environmental variables and (d) to assess the trophic level of the stream which was under the pressure of industry, agriculture and settlement. Samplings of macrobenthic invertebrates were performed seasonally at eight stations between October 2013 and September 2014 in addition to measuring environmental variables of the localities. 11571 specimens were investigated and totally 77 taxa were determined. Chironomidae and Oligochaeta were the higher groups in terms of species richness with 25 and 17 species, respectively. Multivariate analyses indicate that pH, CaSUP2+/SUP and NOSUB3-/SUBN were the most effective variables and explained 48.6% of the variance in the distribution and abundance of benthic macroinvertebrates in Nif Stream. Along the measured physicochemical characteristics and scores of biological indices, the upper branches of the stream have good quality water while the middle and lower parts are heavily polluted.