Background: One of the most abundant freshwater invaders is Dreissena polymorpha which provide wide-ranging direct and indirect impacts on the invaded ecosystems. A particularly notable impact on benthic communities is the extinction of native mollusks of the order Unionida. However, the settlement of D. polymorpha on unionid's shells in Kanevskoe Reservoir did not increase native unionid mortality. Since the reason for the successful coexistence of native unionids and invading dreissenids in Kanevskoe Reservoir is unknown, we hypothesized that these mollusks have different feeding spectra. To evaluate this hypothesis, we compared feeding spectra of the mollusks using a fatty acid (FA) marker analysis.

A new polymeric biocide polyhexamethylene guanidine (PHMG) molybdate has been synthesized. The obtained cationic polymer has limited water solubility of 0.015 g/100 mL and is insoluble in paint solvents. The results of acute toxicity studies indicate moderate toxicity of PHMG molybdate, which has a median lethal dose at 48 h of 0.7 mg/L for Daphnia magna and at 96 h of 17 mg/L for Danio rerio (zebrafish) freshwater model organisms. Commercial ship paint was then modified by the addition of a low concentration of polymeric biocide 5% (w/w). The painted steel panels were kept in Dnipro River water for the evaluation of the dynamics of fouling biomass. After 129-d exposure, Bryozoa dominated in biofouling of tested substrates, forming 86% (649 g/m ) of the total biomass on control panel surfaces. However, considerably lower Bryozoa fouling biomass (15 g/m ) was detected for coatings containing PHMG molybdate. Dreissenidae mollusks were found to form 88% (2182 g/m ) of the fouling biomass on the control substrates after 228 d of exposure, whereas coatings containing PHMG molybdate showed a much lower biomass value of 23.6 g/m . The leaching rate of PHMG molybdate in water was found to be similar to rates for conventional booster biocides ranging from 5.7 μg/cm /d at the initial stage to 2.2 μg/cm /d at steady state. Environ Toxicol Chem 2017;36:2543-2551. © 2017 SETAC.

The results of long-term complex hydrobiological studies of the cooling pond of the South Ukrainian Nuclear Power Plant (SU NPP) are presented. The abundance of zoo-and phytoplankton increased until 1984-1985, and then in the summer of 1986, against a background of extremely high temperatures in the reservoir, there was a significant (32-fold) drop in the mean biomass of phytoplankton, coinciding with the minimum abundance of zooplankton. In subsequent years, the abundance of these groups recovered, but has not reached previous levels. At present, the zooplankton contains a considerable amount of thermophilic species. Research in recent years indicates that the zooperiphyton is dominated by the invasive gastropods Melanoides tuberculata (Müller, 1774) and Terebia granifera (Lamarck, 1822). In the epiliton, the number of LDT (lowest determined taxa) and groups of invertebrate was more than double that in the epiphyton (17 and 7, respectively). At the first stages of the development of the pond ecosystem, the periphyton communities were dominated by zebra mussel Dreissena polymorpha Pall. These communities were eliminated as temperature increased, and after the commissioning of the NPP, the second and third power units were not completely restored in the environment of a constantly high thermal load. Over years, with the formation of bottom biotopes, the abundance of zoobenthos increased, and with an increase in the technogenic load, it decreased. At the present stage, the zoobenthos is impoverished (9 taxa) and is dominated by mainly juvenile tubificids.