Influence of sewage from different water treatment plants in the Cracow Region (Poland) on early developmental stages of water snails

Abstract

AbstractThe cocoons of the great pond snail, Lymnaea stagnalis (L.), and the great ramshorn, Planorbarius corneus (L.) were exposed to mechanically and biologically treated sewage from different water treatment plants in the region of Cracow (southern Poland). The control group consisted of snails from the same cocoon as the experimental snails. Mineral water and pond water from Zabierzów Bochenski (near Cracow) were used for the control groups. We found that mechanically treated sewage from the Plaszów sewage treatment plant was highly toxic (100% embryo lethality). The toxicity was reduced after mixing sewage with the control water (25% solution). However, in this group, the development of embryos was slower than in the control. No toxicity was observed in the biologically treated sewage from the same plant. The sewage from the Myslenice plant (mechanical treatment) was also very toxic (100% lethality), but this toxicity disappeared after keeping the sample at room temperature for 1 year. Water from the Vistula River was not toxic.