Experimental assessment of the effect of different types of salt and temperature on the survival of the larval stage of eurasian perch Perca fluviatilis Linnaeus, 1758

Abstract

Salinization of freshwaters is a serious problem leading to a decrease in biodiversity and degradation of aquatic ecosystems. In conditions of climate warming, the toxic effect of salinization can increase. The aim of this study was an experimental assessment of the survival of the pre-larvae of the Eurasian perch Perca fluviatilis under conditions of different concentration of two types of salt (salt mining wastes and sodium chloride), and also under two temperature regimes. We found that under temperature conditions of 8–15 ° C, the mortality of pre-larvae was significantly lower compared to the values obtained with an increase in temperature by 5 °C. The tolerance limit (LC50 ) under exposition to salts for 24 hours was a mineralization value equal to 9.8 g/l and 8.7 g/l under an exposition of 72 hours. There were no significant differences between the two types of salts — salt mining wastes and sodium chloride in terms of LC50. There were also no significant differences in the time of death of 100 and 50% of the tested prelarvae. At the same time, a higher mortality of pre-larvae was revealed in solution of salt-mining wastes at concentrations of 7 and 8 g/l. At concentrations above 9 g/l, the opposite trend was observed — a greater mortality rate was found in sodium chloride solution. For both types of salts, a greater survival rate of prelarvae was revealed at a salt concentration of 8 g/l compared to a concentration of 7 g/l, which requires more detailed studies. These results are important for understanding the limits of tolerance to salinity in the larval stage of development of one of the most widespread ecologically flexible freshwater fish species. The relevance of the study is determined by current trends in climate change and the increasing level of salinization of boreal freshwaters as a result of salt pollution.