Environmental sensitivity of fish Otolith Microchemistry

Abstract

A considerable aggregate of life-history, environmental and physiological information is incorporated within fish otoliths. This information may be discerned when appropriate analytical methods, based on an understanding of the mechanisms underlying changes in the structure and chemistry of otoliths, are utilized. Deposition of otolith carbonate may be regulated by many interacting factors, including age, physiology, environmental stress, availability of nourishment, ambient temperature, diurnal and seasonal cycles, and activity levels of individual fish. Complex interactions between genomic control and environmental conditions will ultimately govern depositional patterns. The chemical composition of otoliths is regulated by the physiological activity of fish, which in turn is influenced by environmental conditions. Interpretation of the chemical patterns in wild fishes must be validated by analysing the depositional patterns in fishes maintained under experimental conditions. Microchemistry analyses can provide life-history profiles and data on the environmental history of individual fish to clarify interpretation of age and growth trajectories. Several factors may contribute to the reported disparity in elemental studies, including suboptimal rearing environments, thermal effects on growth rate, and nutritional effects on otolith chemistry. Metabolic data describing growth and otolith crystallization obtained under artificial conditions that only grossly resemble the subtleties of the modelled environment may have a limited value and caution should be used when extrapolating results to natural systems.