EFFECTS OF PH ON THE WINTERING OF THE COMMON FROG (RANA-TEMPORARIA L.)

The aim of the present study was to establish whether acid water affec ts the behaviour and physiology of the wintering common frog. Frogs we re caught from two biotopes (''neutral'' and ''low-pH'' populations). Initially frogs were kept in containers in water with different pH whe re they could chose whether to be in or out of water. Then altogether 210 frogs were over-wintered at different pH and after winter the live r and muscle glycogen contents were determined from 106 frogs. In the biomonitoring experiments we tested If changes in water pH had had an effect on the total activity of wintering frogs. The same monitoring a pparatus was also used to measure the heart rates of the frogs at pH 4 and pH 6.5. Following metamorphosis the common frog is very well adap ted to cope with environmental acidity. It does not avoid water at pH 4 and wintering success occurs also in acid environment. In fact it is a matter of concern that mature frogs react so slightly to water acid ity and therefore they obviously do not avoid acid habitats.