Effects of pesticides to benthic invertebrate community in the Serbian Danube stretch using the SPEAR index

Most pesticides in water are originated by surface runoff, or leaching through soil affecting different biological communities in aquatic ecosystems. The Serbian Environmental Protection Agency (SEPA) conducts regular surface water monitoring in the entire territory of Serbia. The present study aimed to provide data on effects of pesticides to non-target freshwater organisms (benthic invertebrates) using the SPEAR index at 9 sampling stations of the Serbian Danube stretch: Bezdan, Bogojevo, Novi Sad, Zemun, Smederevo, Banatska Palanka, Tekija, Brza Palanka, and Radujevac, over a six-year period (2014-2019). During 2014 extreme rainfall and floods were registered in Serbia, and in 2017/2018 extreme drought, respectively. Since the SPEAR index has been primarily developed for small to medium streams, the main goal of the study is to test the use of the SPEAR index in large rivers, such as the Danube River. Most commonly detected pesticides in higher concentration in the water of the Serbian part of the Danube River are: metolachlor, atrazine, terbuthylazine, desethylterbuthylazine, terbutryn and isoproturon. Benthic invertebrate community composition and structure varied from the Danube River entering to Serbia (Bezdan) to its leaving (Radujevac). As conclusion, lower SPEAR index values were calculated at sampling stations situated in the Danube River backwater zone, whilst the SPEAR index values were higher along the main course of the Danube River in Serbia. Also, the Danube River backwaters could act as refugia for more tolerant benthic invertebrate taxa to pesticide pollution.