English

Abstract

Abstract Due to the increasing anthropogenic pressures and the introduction of invasive alien species, indigenous crayfish species are rarely found in the urban areas of big cities. The aim of this research was to study, for the first time, presence and distribution of freshwater crayfish in artificial lakes of the Maksimir Park, located in the centre of Zagreb, the capital of Croatia. Additionally, the goal was to estimate population size and structure, and analyse morphometric characteristics, the proportion of injuries and crayfish body condition. In 4 out of 5 lakes within the park, two crayfish species, Astacus astacus and Astacus leptodactylus, were recorded with no overlap in their distribution. Each species was established in two lakes in relatively abundant populations. Differences in body condition, sex ratio and proportion of injuries were recorded between species. Recorded differences are most likely the result of different trapping techniques applied, predation of alien invasive species of turtles and intraspecific competition. Obtained results will serve as a baseline for further research and monitoring of the crayfish fauna in the Maksimir lakes.