Actions of atmospheric ionization on spontaneous activity of an amphibian larva

In Pleurodeles waltlii (Urodela) larvae, spontaneous activity and the tendency to leave water are significantly influenced by artificial air ionization. Atmospheric ions of negative and positive polarities have opposite effects: the latter reduce spontaneous activity by 48% whereas negative ions increase it by 39%. This difference must be considered the result of a specific behavioral effect rather than attributable to the stage of development of the larvae. A comparison of our results with data in the literature indicates that the action of the air ions on amphibian activity may involve the modulation of serotonin and prolactin releases.