MICRODISTRIBUTION OF Gammarus bosniacus Schäferna, 1923 (Amphipoda: Gammaridae) IN THE RIVER BOSNA AT PROTECTED AREA OF VRELO BOSNA

Abstract

The microdistribution of crustaceans in the benthic communities of aquatic ecosystems is influenced by a number of factors such as the availability of resources, the population density of predators and symbionts, the variability and structure of the habitat, and the seasonal dynamics of the species itself. The most important ecological factors that determine the type of habitat for the macrozoobenthos species are the speed of the flow, the type of substrate and the temperature of the water. The species Gammarus bosniacus Schäferna, 1923 is an endemic species of crustacean with a narrow distribution in the upper reaches of the Bosna River in the Vrelo Bosna Protected Area and, according to recent data, in some watercourses on Mt. Bjelašnica. The aim of the study was to 
determine the density of the Bosnian crustacean population on different types of substrates (microhabitats) in the river Bosna. Sampling of macrozoobenthos was realized four times during each season in 2013 and 2014 at three sites. Population density was monitored in three different microhabitats: phytal, argillal and mesolithic. ANOVA testing revealed statistically significant differences in the number of individuals of the Bosnian crustacean in the investigated microhabitats. Using the t-test, statistically significant differences in the abundance of phytal compared to argillal and mesolital were determined. On the basis of the conducted analyses, it was determined that individuals of this narrowly distributed species aggregate on the plant substrate.