Alkaline earth metal and Mn distribution in otoliths of Anguilla spp. glass eels and elvers /
Takaomi Arai and three others.
Includes bibliographical references
Recent progress in otolith microchemistry techniques has revealed considerable information about early life history, including the timing and duration of the metamorphosis of the freshwater eel, genus Anguilla. In an attempt to reconstruct the life history, many reports have used otolith Sr: Ca ratios coupled with techniques to determine the age of otoliths. We validated the timing of metamorphosis in Anguilla japonica by examining both the otolith microstructure and microchemistry of fully grown leptocephalus (just before metamorphosis) and glass eel. It was revealed that a marked increase in otolith increment width, coin- cident with a drop in Sr: Ca ratios, heralded the onset of metamorphosis. However, this information was obtained mainly in Sr and Ca contents analysis and little is known about the distribution of other elements in the eel otolith, even alkaline earth metals, which have similar properties to Ca in chemical reactions due to the same 2+ valence. These elemental distributions in the otolith may constitute a valuable tool to study larva and juvenile eel ecology, and provide some understanding of the process of the elemental deposition in otoliths.