Checklist of non-native benthic macroinvertebrates and fish in the Dnieper River basin

An annotated checklist of non-native benthic macroinvertebrates and fish in 6 sub-basins (assessment units) of the Dnieper River is presented (based on a literature survey and the author’s unpublished data). In total, the checklist includes 92 non-native aquatic species (invertebrates – 57, fish – 35), primarily of Ponto-Caspian origin. This background information provides support for possible future development of relevant management options towards control of invasive species in the studied area, which is an important part of the European network of inland waterways and the European inland water “central invasion corridor”.


Introduction
The Dnieper River basin is an important part of the European network of inland waterways and the European inland water "central invasion corridor", linking basins of the Black and Baltic seas (Black Sea-Dnieper River-Pripyat River-Bug/Pripyat Canal-Vistula River-Baltic Sea waterway). It facilitates the dispersal of invasive aquatic species, primarily those of Ponto-Caspian origin in Europe (Karatayev et al. 2007;Panov et al. 2009;Semenchenko et al. 2009).
Despite publications during the last 15 years of review papers concerning non-native fauna of the Dnieper River (Grigorovich et al. 2002;Alexandrov et al. 2007;Arbačiauskas et al. 2008;Pligin et al. 2013;Semenchenko et al. 2009Semenchenko et al. , 2015, a complete list of non-native aquatic species for the whole river basin is still not available. The main objective of this data paper is to provide a first comprehensive annotated check-list for non-native aquatic benthic macroinvertebrates and fish for the Dnieper River basin.

Methods
For the present study, published information (primarily literature in Russian, Appendix 1) and the author's unpublished data on first records of nonnative aquatic benthic invertebrates and fish for 10 study areas, comprising 6 assessment units within the Dnieper River basin were analysed ( Figure 1 Table S1).
The lower sections of the river, namely the Dnieper Liman and Kakhovka Reservoir, were considered in our analysis as native areas for Ponto-Caspian species. The Zaporizhia, Dniprodzierzhinsk and Kremenchug Reservoirs are also deemed native areas for some of the species according to Mordukhai-Boltovskoi (1960) (Table S1). For the majority of deliberately introduced species, exact dates of their first records or their first introduction events are not known, and in these cases the most likely periods of introduction are provided. Also, our estimates of most probable pathways of introductions for accidentally introduced species are based primarily on our own expert opinion and may involve some level of uncertainty.

Results and discussion
The present version of the checklist includes 92 nonnative species (57 aquatic invertebrates and 35 fish), primarily of Ponto-Caspian origin (Table S1 and Semenchenko et al. 2015).
Species of Atlantic origin are limited to the lower parts of the Dnieper River, which can be attributed to intense shipping and numerous river ports in the Dnieper Liman. In other parts of the river and its basin, the number of non-native species other than those of Ponto-Caspian origin is low. Among the fish species, gobiids (specifically Neogobius spp), Black Sea sprat Clupeonella cultriventris (Nordmann, 1840) and the Amur sleeper (Perccottus glenii Dybowski, 1877) are the most successful invaders. Potentially these fish species could spread to other parts of the basin. Semenchenko et al. (2015) reviewed pathways and temporal trends of introductions of non-native aquatic species in the studied area (based on the initial version of the checklist in Table S1), as well as potential impacts of invasive species. Research into the ecological and economic impacts of aquatic non-native species in the Dnieper River basin is lacking. However, a list of 21 potentially harmful invasive ("Black list") species, namely 16 species of invertebrates and 5 species of fish is given.
Most likely, the present version of the checklist of non-native aquatic species in the Dnieper River basin is not complete, and should be consistently updated. However, the current information is useful in the development of relevant management options towards the control of invasive species in the region, as well as the generation of a predictive risk assessment for the spread of invasive aquatic species in adjacent European inland waters. Future research should be focused on the evaluation of actual impacts of these species and the development of a predictive risk assessment for new introductions in the area.