Stable Carbon Isotopes’ Ratio in Frog Tissues and Organs During the Postlarval Period of Ontogenesis

Abstract

The paper presents the results of mass spectrometric measurements of the ratio of stable carbon isotopes in the organs of metamorphosing larvae, actively growing yearlings, and 2- and 3-year-old frogs. The profound restructuring of the digestive system and skin during the metamorphosis climax reduces carbon exchange between metamorphs and the environment. As metamorphosis progresses, the δ¹³C values of samples containing material from most metamorphic organs do not change significantly, while liver samples become enriched in the heavy carbon isotope. During 3 years of rapid growth of juvenile frogs, bone tissue, skin, lens, and brain are enriched, while the gonads are depleted in heavy carbon isotope. Isotopic signatures of muscle tissue and myocardium do not change significantly in growing frogs. It is assumed that differences in the levels of carbon isotope fractionation in organs are caused by partial conversion of absorbed nutrients, while the whole organism is characterized by almost complete conversion of absorbed substances.