Lowland floodplains are complex ecosystems comprised of standing and flowing waters interacting with terrestrial habitats, and the main force creating, shaping and influencing, both habitats and biotic communities, is a hydrological regime and water supply from the parent river. In areas not much altered by anthropogenic influence, the Danube creates such floodplain areas, and temporary shallow water bodies within represent biodiversity important habitats. In the Kopački Rit Nature Park floodplain in Croatia, diversity based on Chironomidae (Diptera) in both benthic and epiphytic communities was studied in eight ponds (temporary shallow water body) and at two channel locations (permanent shallow water body). At each location samples of sediment and macrophytes were taken at three sites. The benthic chironomid community was comprised of 29 taxa, most abundant being representatives of the Chironomus genus and Tanypus kraatzi in ponds, and Polypedilum nubeculosum and Cladotanytarsus sp. in channel samples. Cricotopus gr. sylvestris, Paratanytarsus sp. and Endochironomus tendens were dominant epiphytic chironomids (18 taxa). Non-metric multidimensional scaling and analysis of similarity analyses showed there was a clear grouping of sampling locations based on their position in the park and the distance from each other, more evident in the case of benthic chironomid communities. Furthermore, when the water bodies were compared based on the community structure from different locations and substrates, there was also a statistically significant separation. Community composition indicates high productivity and organic matter production of studied water bodies, but moreover, the differences in substrate preferences evident in 16 common out of 31 recorded chironomid taxa, indicate the importance of habitat complexity preservation in a floodplain.

Floodwater mosquitoes lay their eggs on dry ground where water will eventuallyflood the area. By flooding the area and submerging the eggs of floodwater mosquitoes, the development of larvae begins. For a gravid female mosquito, the mostimportant thing is choosing the place where to lay eggs. As part of this research,which was conducted in April and May 2022, soil and leaf samples were taken on anarea of 50 x 50 cm from different altitudes in the area of Dunavac near Ilok (Danube)and Halaševo near Osijek (Drava) in order to determine at which altitude, the largestnumber of eggs are laid. Collected soil was submerged in the laboratory for the purpose of further mosquito development. Part of the larvae was preserved in alcohol,and part of larvae was left to develop into adults, after which species determinationwas carried out. A large difference was found in the potential of breeding sites in thefloodplain of the Drava and Danube, and the number of collected eggs ranged from0 to 66 per sample. The number of individuals sampled in the Danube area was 53,and in the Drava area 133. The individuals sampled in the researched areas weredetermined as Aedes vexans and Aedes sticticus. A large difference in oviposition wasfound in the floodplain of the Danube, while in the floodplain of the Drava, this levelis significantly higher.