## 3 Results
### Macrozoobenthos
During all the years of investigation (2018-2020), _Viviparus_ ssp. (_V. ater, V. contectus_, and _V. viviparus_) have been the dominant taxa covering all the biotopes and their share of biomass varied from 50 up to 90% (600 \(\pm\) 205 g m\({}^{-2}\)). Other gastropods such as _Lithoglyphus naticoides_ and _Eseriana esperi_ comprised 30-40%, but their share in the abundance was rather low. On the other hand, Tubificidae worms together made about 55% of the total abundance (10,800 \(\pm\) 3050 ind. m\({}^{-2}\)) without a significant share in biomass. _Polypedilum_ spp. was common in both sites of investigation, but only in Palanca were significant values reached (4972 \(\pm\) 1670 ind. m\({}^{-2}\) and 5.0 \(\pm\) 2.7 g m\({}^{-2}\), with the maximum at 14,080 ind. m\({}^{-2}\) and 37 g m\({}^{-2}\)). The composition of other subdominants with the joint share of about 10% of biomass was different depending on site and time. The abundance and biomass of community varied significantly with the average of 14,500 \(\pm\) 3500 ind. m\({}^{-2}\) and 0.8 \(\pm\) 0.2 kg m\({}^{-2}\) and with the highest figures of 58.800 ind. m\({}^{-2}\) and 3.4 kg m\({}^{-2}\) (Table 3). Nearly 67% of taxa have full or partly autecological characteristics in the Asterics database. Among the species, littoral species dominated (about 40%), and close values indicated common taxa for the potamal (31%). Groups within current velocity had the next ranking species: limno-rheophilic (18.5%), indifferent to the current velocity species (18.5%), limnophilic (13.9%), and the share of other species did not exceed 10% (Figure 8). Rare occurrence of such sensitive taxa as Ephemeroptera, Plecoptera, and Trichoptera both in modern and historical data [9] did not allow to compute DSFI. In both periods, Gather/Collector was dominating both in taxa number (27%) and total abundance and biomass (up to 92%) in composition of FFG. Based on taxa composition, the Potamon Type Index characterised the environmental state as \"bad\". In 2018-2020, species indicating \(\beta\)-mesosaprobic (27 from 54 saprophy indicators) and \(\alpha\)-mesosaprobic (17 from 54) conditions were the most abundant in all the samples, resulting in saprobic index calculated both in classic Zelinka and Marvan and Romanian version which did not exceed 2.5, and characterised the status as moderate. According to the BMWP and BBI indices, the modern condition of the lower reaches on investigated two sampling points during 2018-2020 of the Dniester River can be described as \"poor\". The LIFE index in this section of the river also had an average of values (5-7), which is typical of weakly flowing streams, and its changes both with correlation with annual runoff were not statistically significant. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{2}{c}{**1949–1951**} & \multicolumn{2}{c}{**2018–2020**} \\ \cline{2-5}
**Biotic Characteristics** & **Average \(\pm\) SE** & **Range** & **Average \(\pm\) SE** & **Range** \\ \hline \% Predators & 0.64 \(\pm\) 0.58 & 0–3.5 & 2.71 \(\pm\) 1.26 & 0–20 \\ \% Parasites & & & 0.74 \(\pm\) 0.48 & 0–10.33 \\ \% Other Feeding types & & & 0.19 \(\pm\) 0.08 & 0–1.34 \\ LIFE Index & 6.83 \(\pm\) 0.2 & 6–7.5 & 5.17 \(\pm\) 0.25 & 3–7 \\ \hline \hline \end{tabular} Abbreviations: BMWP-Monitoring Working Party, BBI-Belgian Biotic Index, DSFI-Danish Stream Fauna Index, LIFE-Lotic-invertebrate Index for Flow Evaluation.  
\end{table} 
Table 3: _Cont._