Preliminary Studies On The Population Ecology Based On Fish Otolith Microstructure And Microchemistry

Otolith is a metabolically inert calcium carbonate that can record the environmental history throughout fish life. This study applied daily growth increments, elemental compositon and stable isotpe composition in otoliths to investigate stock identification, migration history reconstruction and food web and trophic levels. The main findings are as follow:1. Otolith microstructure was used to investigate the early life history of Larimichthys polyactis and μ-XRF was applied to analyze the otolith element microchemistry. Nine elements including Sr、Zn、Cu、Ba、Fe、Mn、Pb、Hg、Ca were measured and migration environmental history of small yellow croaker was reconstructed based on the Sr/Ca ratio in the otolith.2. Otolith stable isotopic and elemental compositions were analysised to identify the stock structure of L. polyactis. Fish collected from the Bohai Sea and the Yellow Sea could be divided into the Bohai Sea group, the southern Yellow Sea group and the central Yellow Sea group based on the two methods. Discriminant analysis of 518O and δ13C values demonstrated a high significant difference with 85.7% classification accuracy and classification accuracy rates from linear discriminate function analyses (LDFA) of whole otolith chemistry data were high for each region with a mean accuracy of 85%.3. We first confirm the feasibility of stable isotope δ15N in otolith in investigating marine food web and trophodynamics.There was a positive correlation between δ15N in otolith andδ15N in muscle. High trophic continuum of pelagic food web was established based on otolith istotopic composition.