Effects Of Water Elements And Temperature On Otolith Incorporation Of Strontium And Barium In Larval-juvenile Flounder Paralichthys Olivaceus

An understanding of the effects of aquatic environmental factors on elemental incorporation into otoliths is fundamental for reconstructing life and environmental histories of fish using microchemistry analysis.The present study set a series of experiments to explore the relationships between otolith elemental incorporation and ambient water elemental concentrations,growth or water temperature in larval-juvenile flounder Paralichthys olivaceus.This study aimed to explain the mechanism of otolith elemental incorporation and provided fundamental support to address issues of fish ecology,such as stock discrimination,reconstruction of life history and resource management of the flounder.In this study,the relative or interactive effects of water elements?strontium Sr and barium Ba?on otolith elemental incorporation in larval-juvenile flounder were investigated.The results revealed that the otolith incorporation of Sr and Ba were positively dependent on the concentrations of elements in water.Sr was incorporated into otoliths more efficiently than Ba,and the partition efficiency(D_Me)of both elements decreased with increasing water elemental concentrations.Increasing Sr concentrations in water appeared to negatively affect the incorporation of Ba into otoliths rather than facilitate it as previously reported in fish reared in freshwater.The Ba concentrations in water did not influence the otolith incorporation of Sr,which agreed with the findings in other fish species.The negative effects of Sr concentrations on the otolith incorporation of Ba may be caused by the difference between elemental concentrations in freshwater and seawater.Generally,Sr concentrations in freshwater are lower than in seawater,while Ba concentrations in freshwater are pretty higher than in seawater.It is essential to cautiously address the interactive effects of multiple elements in the environment on otolith elemental incorporation when applying otolith microchemistry to fish ecology studies.This study mainly investigated the potential effects of growth under the same environmental conditions,but did not detect a significant effect of growth on otolith incorporation of either Sr or Ba in larval-juvenile flounder.This study found that the increase of water temperature could effectively promote the incorporation as well as the incorporation efficiency of Sr.The otolith incorporation of Sr was positively dependent on ambient Sr concentrations at each water temperature.It appeared that the otolith elemental incorporation of Sr was closely related to the ambient elemental concentration that fish experienced,suggesting that Sr could be used as an elemental fingerprinter to reconstruct the life and environmental histories of the flounder during the early life stage in nature.Overall,the otolith elemental incorporation in the flounder at early life stage could effectively reflect the chemistry of the environment,which means the elemental fingerprinting could be used to construct early life history of the flounder.Additionally,the interactive elemental effects as well as the somatic growth on the otolith incorporation of a target element should be cautiously considered and addressed when these experimental results are applied in field work,such as stock identification and life history construction.