JOINT AND SINGLE TOXICITY OF CD AND FE RELATED TO METAL UPTAKE IN THEMAYFLY LEPTOPHLEBIA-MARGINATA (L) (INSECTA)

The toxic effects of Cd and Fe on the mayfly Leptophlebia marginata we re tested during single and joint exposure to the metals. Data on upta ke and localization of the metals were related to the following biolog ical parameters: survival, food consumption (% gut contents) and activ ity (escape from prodding). The uptake of Cd by L. marginata was signi ficantly reduced by the presence of Fe (p<0.0005). Fe2+- and Fe3+-crus ts on the gills, body surface and on the gut membrane precipitated whe n the mayflies were exposed to either Fe alone or to Fe and Cd. This c aused decreased food consumption by the mayflies. In the pigments of t he eyes and the cuticle Fe2+ was found. Exposure to Cd led to disturba nces in Cl- and K+ ion balance, which were ameliorated by additional F e-exposure due to co-precipitation processes. Exposure to Cd caused an increase in the concentrations of S and P in the mayflies. Whereas Fe caused sublethal effects (food consumption) without being taken up in to the organism. Cd caused lethal effects (inactivity, death) due to d isturbances of the ion balance at the membranes.