WP5 Analysis of Biominerals to Understand and Manage Aquatic Ecosystems
Wednesday, 16 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(MEL-1117-743594) Nucleation and growth of teleost fish otoliths.

Melancon, S.¹, Fryer, B.¹, Gagnon, J.¹, ¹ GLIER (University of Windsor), Windsor, Ontario, Canada

ABSTRACT- Otoliths are the ear stones of fish and are mainly composed of calcium carbonate (CaCO₃). Their continual growth is recognizable as concentric rings of alternating opaque and translucent zones. Otoliths are considered not subject to resorption, and as such, only ontogenic and environmental factors will result in changes to their composition. It is believed that once an element has entered the otolith it remains chemically and isotopically inert. All these factors make otoliths unique recorders of the environment and fish migrations. Previous work has demonstrated that otoliths of some fish can be comprised of 3 different CaCO₃ crystalline structures, aragonite, calcite and vaterite which can greatly differ in their trace elemental composition. Teleost fish are found in a wide variety of warm and cool habitats over a vast range of territories (Canada and United States). This project investigates the nucleation of otolith biomineralization and the effects of age on metal inclusion in endolymph and otolith. The first goal is to determine how otoliths crystallize and if there is a catalyst that would help the crystallization. The central cores of larval yellow perch otoliths are optically distinct compared to the surrounding core otolith material. Other researchers found that the core concentrations of Mn and Fe are higher than in the edges (Brophy et al. 2004). The literature does not provide any spectroscopic data on the origin of that material. This study will provide the first high resolution spectroscopic evaluations of the nucleating material of otolith cores and first trace metal composition of the endolymph. The second part of this project will evaluate variations in metal composition of endolymph and otolith with fish age. Otoliths and their endolymph will be analyzed using a combination of Scanning Electron microscopy (SEM), X-ray Absorption Fine-Structure Spectroscopy (XAFS) and Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS).

Key words: otoliths, nucleation, la-icp-ms, growth