|| 要旨トップ | 本企画の概要 |||日本生態学会第61回全国大会 (2014年3月、広島) 講演要旨
シンポジウム S10-5 (Lecture in Symposium/Workshop)
Despite archival biological specimens record ecological information in their tissues in the form of stable isotope ratios, there was a difficulty with estimating past food web properties because of lack of isotopic information on trophic baseline. Recently, δ15N of amino acid (δ15N AA) is regarded as a useful tool to estimate the precise trophic levels (TLs) of consumers. To reconstruct the long-term tropho-dynamics of a predatory fish (Opsariichtys uncirostris) in Lake Biwa, we analyzed δ15N of glutamic acid and phenylalanine (δ15N Glu and δ15N Phe) of its archival specimens collected from 1914 to the present. To chronologically calibrate the past aquatic food base on which δ15N Phe was more enriched with eutrophication, we also measured δ15N Phe for archival specimens of a pelagic fish Gymnogobius isaza which relies on aquatic food sources exclusively. The source mixing models of aquatic and terrestrial food sources revealed that the predator TLs increased in 1970s and then decreased in 1990s.Their TLs were strongly correlated with those estimated from their bulk δ15N, suggesting that the δ15N AA analysis of archival specimens is a promising approach to reconstruct the long-term changes in food web properties in lake ecosystem.