ЗАСТОСУВАННЯ НОВІТНЬОГО ІНТЕГРАЛЬНОГО ІНДЕКСУ ОКИСНОГО СТРЕСУ В ОЦІНЦІ ВПЛИВУ ДОВКІЛЛЯ НА ПРІСНОВОДНИХ МОЛЮСКІВ

Abstract

The adverse environmental impacts cause the oxidative stress responsein the aquatic animals. However, depending on the severity and duration of impact, this response can be highly different. The aim of this study was the analysis of available results of the evaluation of antioxidant activities in the freshwater mollusks in the sense of the successfulness of the oxidative stress response. The recently proposed integrative index ‘Preparation to the oxidative stress’ (POS) was applied. Three populations of bivalve mollusks from the basin of the river Dniester were compared during three seasons, and in their ability to withstand heating (25o C and 30o C during 14 days) and exposure to ionizing radiation (14 days after the acute exposure to 2 mGy). The musselswere sampled in the low disturbed pristine site, highly polluted agricultural region and the cooling pond of the nuclear power plant with the constantly elevated temperature. The parameters for the calculation of POS included superoxide dismutase activity, catalase activity, glutathione S-transferase activity, glutathione concentration, and metallothionein (from its thiol groups) concentration. The values were calculated as the magnitude of change (as % change) in comparison to the corresponding control (less disturbed field group or non-exposed group). Three criteria for POS were applied. The number of the positive and negative changes and their limits were indicated. The analysis have shown that the POS responses were in the limits of adaptive ability in all studied cases. However, the results of POS calculation allowed the distinguishing of the responses that arerealized in the field and experimental exposures of mollusks.The most distinct responses were shown for the glutathione (mainly positive changes) whereas the metalothionein level was mainly oppressed, particularly under the heating. The depressive direction was estimated in the cases of extreme temperatures, irradiation and, mainly for the mollusks from the highly polluted sites. The key importance of POS as a survival strategy of the mussels exposed to adverse impact depending on the life historyis evident.