Influence of river water quality on homeostasis characteristics of cypriniform and perciform fish

Abstract

Within an integrated ecosystem approach, it is preferable to evaluate the effects of pollution of surface waters through research on the organisms of fish. The aim of this study was to analyse the impact of a set of water quality indicators on the homeostasis of fish, in order to determine the response of a hydro-ecosystem to the impact of human activity. Fish samples were obtained from control catches in 16 control sites located in the rivers of Rivne Oblast which differ in intensity of anthropogenic load. The researchers observed that increased concentrations of phosphates and suspended substances, heavy metals, iron, fluorides and nitrogen compounds have violated the environmental state of the examined hydro-ecosystems. Parameters of the morphological homeostasis were assessed by the levels of the fluctuating asymmetry of the meristic signs of fish.The scientists recorded significant impairments (within IV points of body stability) in case of roach and bleak in the majority of the control sites. We carried out the analysis of cytogenetic parameters of fish homeostasis using a micronuclear test of blood erythrocytes.The investigation revealed a significant excess of spontaneous mutagenesis (1.1–1.7 times) in such species as roach, bleak and perch, and this is certainly a clear indicator of unfavourable ecological conditions of the water environment in seven areas of hydro-ecosystems. Given the results of the analysis, the authors found that different ecological groups of fish have their own complex and multifactorial processes of morphological and cytogenetic homeostasis formation. Furthermore, the regression dependences set out in the paper indicated the decisive impact of the oxygen regime of the water environment (COD, BOD5, О2), pollutants (Cu2+, Zn2+, Mn2+), and substances of biogenic group (NH4+, NO2–, PO4‑) upon fish homeostasis. differences in scope of homeostasis characteristics of different fish species were complemented by the differences in the composition of the regression equations. In particular, in case of species that had signs of homeostasis violation, the equation consisted of a greater number of members. The dependences for morphological and cytogenetic homeostasis of bleak and roach appeared to multifactorial. This finding suggests that these species are sensitive local indicators of the water environment both at early and late stages of ontogeny . Finally, as an outcome of the research we obtained prognostic forms of the relationship between water quality indicators and fish homeostasis that may form the basis of an environmental assessment method in which fish characteristics are used to assess the health of hydro-ecosystems.