Instability of statolith elemental signatures revealed in newly metamorphosed sea lamprey (Petromyzon marinus)

Abstract

Techniques that use calcified structures to identify the natal origin of organisms assume that reworking of previously deposited material does not occur. While verified for otoliths, this assumption remains unverified for statoliths. Herein, we test the stability of sea lamprey (Petromyzon marinus) statolith microchemistry during metamorphosis. Using laser ablation inductively coupled plasma mass spectrometry, we quantified the concentrations of nine elements in statoliths from sea lamprey larvae (n = 118) and newly metamorphosed (n = 115) individuals that were collected across six tributaries of varying alkalinity in the Laurentian Great Lakes and Lake Champlain basins. In newly metamorphosed individuals from all streams, the portion of the statolith deposited during the larval stage was enriched in rubidium (Rb), strongly suggesting a chemical reworking of statoliths during metamorphosis. As the ability to discriminate among sea lamprey from different streams in the Great Lakes and Lake Champlain mostly relies on premetamorphic levels of Rb, strategies for the use of statoliths to identify the natal origin of sea lamprey parasitic juveniles and spawners (postmetamorphic stages) should take into account the chemical changes associated with metamorphosis.