Field observations of the effects of protracted low levels of ionizing radiation on natural aquatic population by using a cytogenetic tool.

In the present study, an effort is attempted to record the impact of chronic radiation on natural aquatic populations exposed to protracted doses (lower if compared to intervention levels but higher if compared to typical background) and to chemical pollution. The methodology is based on the analyses of chromosome aberrations observed in cells. Therefore, some preliminary research results on the cytogenetic effects on aquatic organisms of various taxa, in coastal ecosystems are presented, considering some selective regions of elevated natural gamma radiation and conventional pollution.

Radiological effects on populations of Oligochaeta in the Chernobyl contaminated zone.

A detailed investigation of 3 populations of Oligochaete species (Dero obtusa, Nais pseudobtusa and Nais pardalis) has been carried out in a contaminated lake of the close-in Chernobyl zone and in a control lake. Hydrochemical indices and concentrations of heavy metals, chloro-organic compounds and (90)Sr in bottom sediments have been measured. Absorbed doses were calculated on the basis of the results of radiochemical analysis and assessed directly with thermoluminescent dosimeters (TLD).

[Cytogenetic and population effects in oligochaeta from the Chernobyl zone].

Research on intensity and character of reproduction of Oligochaeta (Dero obtusa, Nais pseudobtusa and Nais pardalis) was carried out in 1995-1996 in two water-bodies: a) in the Chernobyl NPP zone near Yanov Village, with a dose rate of 14 microGy h-1 on the surface of the bottom sediment; b) at the Uzh River area (the control water-body). The changes in both intensity and reproduction type were observed in worms at the radioactively polluted water-body. Stimulation of paratomic division in D.

[Patterns in the distribution of chromosome aberrations in the cells of hydrobionts under the action of ionizing radiation and environmental chemical mutagens].

In studying the pattern of chromosome aberration distribution among hydrobiont cells in experimental and natural populations, it has been found that the Poisson distribution of chromosomes among cells occurs under the effect of ionizing radiation and under the combined effect of radiation and a chemical mutagen with a higher efficiency of the former. With the comparable efficiencies of both factors and with the effect of a chemical mutagen alone distribution of chromosome aberrations among cells resembles the geometrical one to a greater extent.