engleski

Impact of invasive peracarid crustaceans on benthic macroinvertebrate assemblages in Croatian large rivers – preliminary assessment

In this study we investigated longitudinal distribution changes and density of native and alien Peracarida (Amphipoda and Isopoda) in Croatian large rivers and their proportion in total density of benthic macroinvertebrate assemblages. Qualitative and quantitative benthos samples collected using hand net (25x25 cm, ᴓ500 µm) in five major large rivers from 2004 to 2018 at 236 sites were used for distribution changes. Peracarid densities and proportions in macroinvertebrate assemblages were established using quantitative samples collected at 48 sites in 2015 and 2016. In a total 16 peracarid species were recorded, eleven alien and five native. Dikerogammarus haemobaphes was the most upstream distributed alien species in the Sava River and D. villosus in the Drava River. Upstream spread of D. haemobaphes in Sava (front at 648 rkm in 2018) was much faster during the last three years (2015-2018: 4.6 km year-1), than before (2012- 2015: 0.9 km year-1). Front of D. villosus in Drava River was at 289 rkm in 2018, while its upstream spread ranged 2-22 km year-1 in the study period. Proportions of alien species in the total abundance of benthic assemblages were very variable (range: 0.01-90.9%, avg: 29.7%) and species with the highest densities and proportions were Chelicorophium curvispinum in the Drava and C. sowinskyi in the Sava River (>70% at some sites). Upstream sections of Sava and Drava had lower densities and proportions of invaders in macrozoobenthos than downstream sections. Future studies should assess the spread and impact of alien peracarid crustaceans on macroinvertebrate assemblages in Croatian rivers.

distribution changes ; distribution front ; invasive ; peracarid crustaceans ; density

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