Diversity of water beetles (Hydradephaga, Coleoptera) in temporary ponds of Lonjsko polje Nature park, Croatia

Main purpose of this research was to determined fauna of Hydradephaga and to relate their assemblages in temporary ponds of Lonjsko polje with respect to water permanence (hydroperiod) and shading of ponds by surrounding vegetation. Field survey was conducted in six different ponds in Lonjsko polje Nature Park from May to December 2004. Aquatic coleoptera were collected using semiquantitative method of sweeping D-frame pond net. During research period thirty species of Hydradephaga were identified, two of which are new records for Croatia (Hydroporus striola and Haliplus (Haliplinus) heydeni). The highest species richness was recorded for pond Trebež, with 16 species of Hydradephaga recorded exclusively in this pond. None species were in common for all investigated ponds. It is observed that water beetles prefer more permanent ponds with longer hydroperiod and open, less shaded habitats.