Five spatially separated Kamchatka populations of the Marsh frog were studied, the water bodies of whose habitats differed in pH (7.40–10.34) and mineralization (239–1597 mg/dm). The maximum values of the average age and average body length of marsh frogs were achieved by the maximum duration of the activity season of the population habitats and intermediate pH values. At the highest pH values (10.0 and 10.34), a decrease in the average population body length and the rate of annual growth increments in frogs was observed, compared to individuals living in water bodies with lower pH values. This gives reason to assume a negative effect of highly alkaline water on postmetamorphic growth. As the mineralization of water bodies in population habitats increased, the average body length values for the populations grew, while annual growth increments rates decreased. However, this may be due not to the influence of mineralization, but to the strong positive correlation between mineralization and the water temperature, and hence the duration of the activity season of the frogs. The impact of the duration of the activity season on age and growth characteristics was stronger than the influence of both pH and mineralization.
Bryakova et al. (Wed,) studied this question.