δ13C and δ15N in Micropterus Salmoides largemouth bass and their scales: a freshwater environmental proxy

Toyama is located in central Japan and features a variety of distinct geographical environments, a result of the 3000-m elevation that changes over short distances, and abundant water systems. We determined δ13C and δ15N of the lipid-extracted muscles of largemouth bass, a top aquatic predator, from eight dam lakes and two ponds.The mean δ13C and δ15N values for the lipid-extracted muscle of largemouth bass from all sampling locations showed large variability, but there were only small standard deviations at each sampling location. The dam lakes could be divided into two groups by their isotopic compositions, as a function of mean altitude and flushing rate of the dam water. Thissuggests that the isotope ratios for largemouth bass express the characteristics of each investigated hydrosphere environment and food chain. Moreover a very high correlation of isotopic values （δ13C, R2= 0.98; δ15N, R2= 0.95) was found between largemouth bass scales and lipid-extracted muscles, suggesting the more easily analyzed scales can replace muscle samples for the monitoring and comparison of hydrosphere environments throughout the world.