[Extraction of lithium ions from fresh water by Lampetra fluviatilis lampreys and Oncorhynchus nerka salmon in natural ecosystems].

Some theoretical criteria are discussed which allow, using the data on the dynamics of natural concentrations and the rate of excretion of elements (ions) in aquatic animals during prolonged starvation, to establish the presence or absence of direct uptake of these elements from water under natural conditions. During pre-spawning starvation of the lamprey Lampetra fluviatilis and salmon Oncorhynchus nerka, it was shown that they are capable to accumulate Li+, similarly to Na+, directly from the fresh water. Natural concentrations of Li+ in muscles, measured mass-spectrometrically using isotope dilution, vary in the lamprey within 0.3-0.6 muequiv./kg, and in spite of the rapid excretion of this ion by the kidneys, are not decreased within a 7-month starvation; in the salmon from the lake Dal'nee (Kamchatka) they vary within 0.1-0.2 muequiv./kg. The period of semi-exchange of Li+ in lampreys in fresh water is equal approximately to 1 day.