Temperature and salinity effects on magnesium, manganese, and barium incorporation in otoliths of larval and early juvenile spot Leiostomus xanthurus

Abstract

The use of otolith chemistry to delineate fish populations and trace migration pathways is premised on a significant correlation between the elemental composition of otoliths and physicochemical properties of the ambient environment. However, few experiments have been rigorously designed to address the effects of temperature and salinity on the elemental composition of otoliths. We examined the effects of temperature and salinity on the incorporation of magnesium (Mg), manganese (Mn), and barium (Ba) in the otoliths of larval and early juvenile spot Leiostomus xanthurus by rearing fish in the laboratory under controlled environmental conditions. L. xanthurus are an estuarine dependent species that traverse varying temperature and salinity regimes throughout their life histories. It is important, therefore, to understand the influence of physicochemical properties of different water masses before attempting to reconstruct important life history transitions based on variations in otolith chemistry. Both [Mg/Ca]otolith and the Mg partition coefficient, DMg, were not significantly affected by either temperature or salinity, but were correlated with otolith precipitation and somatic growth rates. Temperature and salinity had significant interaction effects on DMn, but not on [Mn/Ca]otolith. Finally, DBa was influenced by salinity but not temperature. These results highlight the complex nature of elemental deposition in otoliths, and suggest that both environmental and physiological effects likely influence elemental ratios in fish otoliths.