Distribution and habitat preferences of the endangered mudminnow Umbra krameri Walbaum, 1792 in the Croatian parts of the Drava and Sava drainages

The European mudminnow ( Umbra krameri Walbaum, 1792) is a freshwater fish species with scattered distribution in the Danube and Dniester drainages, being the only native member of the Umbridae family in Europe. It inhabits irrigation canals, slow flowing and stagnant waters with dense vegetation, such as small ditches, oxbows and backwaters. In Croatia, it was first mentioned in 1897 in the Drava River drainage, and later on was recorded in the Mura River and in several localities of the Sava watershed. We studied 212 localities and recorded the presence of the species in 26 of them in the Drava, Sava and Mura river systems in Croatia. We present the first comprehensive data on the distribution and habitat preferences of Umbra krameri in Croatia, including historical data and recent data collected in the last six years. Our results show that U. krameri is an abundant and prevalent species in several localities in the Drava River system. Field data shows the suitability of secondary habitats for U. krameri , such as artificial canals with intensive organic load and pollution from anthropogenic sources, as well as the Sava River system being the southern border of the distribution of this species.