Vertical and horizontal composition of fecal pollution indicator bacteria in lotic and lentic ecosystems at Turkish Thrace

Background and Purpose: Although freshwater ecosystems have natural bacterial populations, their distributions are negatively affected by agricultural activities, domestic and industrial discharges. Bacterial composition at different depths can limit the usage of the water column for drinking, irrigation or other intentions. This study was designed to give similar indications concerning the nature of distribution of indicator bacteria in two different freshwater ecosystem types (lotic and lentic biotopes), and also to identify the factors that might be responsible in shaping them. Materials and Methods: For this aim, stagnant and running water resources located in Meric-Ergene River Basin at Turkish Thrace were sampled at three water depths (surface, middle, bottom) and two sediment depths (shore and bottom) between the dates October 2014 and September 2015 at seasonal intervals. While the heterotrophic bacteria, total and fecal coliform bacteria, and Escherichia coli were recorded by the CFU and MPN techniques, some features (temperature, dissolved oxygen, pH, conductivity, salinity, nutrients, ions, and elements) were also measured by classical chemical, chromatographic or spectrometric methods. Results and Conslusions: According to the data, the bacterial distribution in each ecosystem was found as similar for the bottom and the surface water columns. Results were also supported statistically by Bray-Curtis similarity index and correspondence analyse. The relationships between the bacterial distribution and environmental features were evaluated by Spearman correlation index. Consequently, it was observed that the bacterial distribution can differ in both water column/ sediment depths and lotic/ lentic ecosystems. And, it was suggested that the middle water column in each ecosystem is the most proper column for human usage.