Alien macroinvertebrates in Croatian freshwaters

Abstract

Alien aquatic macroinvertebrates, especially invasive crustaceans and molluscs, have heavily impacted native species and ecosystem processes in freshwaters worldwide. Knowledge on alien species distribution is necessary to understand their dispersal dynamics and prevent future invasions, and to predict and reduce undesirable impacts. Literature data on alien macroinvertebrate species (AMS) in Croatia are sparse and a complete inventory of alien macroinvertebrates in Croatian freshwaters has never been conducted. The aim of this study was to present a database of AMS in Croatian freshwaters and to analyse their origin, pathways of introduction and distribution. The AMS database was built based on literature data and the authors' unpublished data, and included a total of 1,411 records from 689 sites across Croatia. In total, 29 AMS were recorded until 2019, belonging to five major taxonomic groups: subphylum Crustacea (16 species) and phyla Mollusca (7 spp.), Annelida (4 spp.), Cnidaria (1 sp.), and Platyhelminthes (1 sp.). The area of origin of most species is the European Ponto-Caspian region (19 spp., 66%), and the rest originate from North America (5 spp.), Asia (4 spp.) and New Zealand (1 sp.). The most important pathways of unintentional primary introductions were stowaway-shipping (20 spp., 69%) and contaminant-fish stocking (6 spp., 21%). All 29 AMS species were found in the Black Sea Basin (Danube Basin) and five of those were also recorded in the river catchments of the Adriatic Sea Basin. For most AMS, the Sava and Drava Rivers are the main river corridors for their westward spread from the Danube. Since studies of AMS dispersal mechanisms are lacking and only a few studies report the impacts of invasive AMS in Croatia, future studies should be focused on the dispersal dynamics and ecological impact of invasive macroinvertebrates in Croatian freshwaters. Citation: Žganec K, Lajtner J, Ćuk R, Crnčan P, Pušić I, Atanacković A, Kralj T, Valić D, Jelić M, Maguire I (2020) Alien macroinvertebrates in Croatian freshwaters. Aquatic Invasions 15(4): 593-615, https://doi.