Distributional patterns of fecal indicator bacteria in spring area of Plitvice lakes National park

Abstract

Background and purpose: Fecal indicator bacteria (FIB) have widespread use as indicators of water quality and health hazards. The purpose of this study was to determine distributional patterns of FIB and to assess their origin on several sites in spring area and in vertical profile of Prošćansko Lake in Plitvice Lakes National Park.

Materials and Methods: The study was conducted from March to January 2013 on 9 sampling sites. Standard microbiological methods were used to determine densities of total coliforms (TC), fecal coliforms (FC), fecal streptococcus (FS), Pseudomonas aeruginosa (PS) and Clostridium perfringens in water samples.

Results and Conclusions: Source area sustained higher densities of FIB compared to Prošćansko Lake, throughout the study period. Sampling site White River below the village had highest values of certain FIB, indicating Plitvički Ljeskovac as main fecal pollution source. There were seasonal differences in TC and FC with July and October displaying increased densities, the latter probably due to heavy rainfall. The ratio FC/FS in July indicated contamination of mainly animal origin. At the sampling site of Matica River estuary in Prošćansko Lake, an increased densities of TC and FC bacteria were observed compared to other sites and depths, possibly due to source streams influence and stratification conditions. This study showed that the indicator bacteria of fecal contamination in the spring area of the Plitvice Lakes National Park are present and their quantity and distribution patterns depend on season, weather conditions and different effects in water column of the lake.

Keywords: total coliforms, fecal coliforms, FC/FS ratio, Pseudomonas aeruginosa, source streams, lake, protected area