engleski

Recent changes of longitudinal distribution of invasive amphipods in Croatian large rivers

Ponto-Caspian amphipods are one of the most successful groups of invaders in European freshwaters, but rates of their spread and especially their impacts are still understudied in Croatia. The aims of this study were to establish longitudinal distribution changes of invasive amphipods Dikerogammarus haemobaphes, D. villosus, Chelicorophium curvispinum and C. sowinskyi, in Drava, Sava and Kupa River using our results and comparing them to previous studies. Qualitative benthos samples were collected using hand net (25x25 cm, ᴓ500 µm) in shallow bank area at 63 sites of three large rivers in June, July and August 2018. Sampling started from sites where each species was found previously, moving upstream until new distribution front was found. Distribution front of D. haemobaphes in the Sava River, the most upstream distributed invasive amphipod, has progressed forward for 13.7 km (4.6 km year-1). Distribution of D. villosus, C. curvispinum and C. sowinskyi is now better known in Sava (16.6 km upstream from the last site in 2016) and could be connected to the location of the most upstream river port from where D. villosus, and probably also C. curvispinum, had spread downstream. In the Drava River, D. villosus was found 3.6 km more upstream then in 2017, while distribution of D. haemobaphes in the Kupa River did not change. Therefore, longitudinal range extension of invasive amphipods is still ongoing and future studies should examine whether this tendency will continue and how it will affect macroinvertebrate assemblages in Croatian large rivers.

Ponto-Caspian invaders ; range extension ; benthos ; distribution front

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