Is the relationship between body size and trophic niche position time-invariant in a predatory fish? First stable isotope evidence

Takefumi Nakazawa, Yoichiro Sakai, Chih Hao Hsieh, Tadatoshi Koitabashi, Ichiro Tayasu, Norio Yamamura, Noboru Okuda

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

Characterizing relationships between individual body size and trophic niche position is essential for understanding how population and food-web dynamics are mediated by size-dependent trophic interactions. However, whether (and how) intraspecific size-trophic relationships (i.e., trophic ontogeny pattern at the population level) vary with time remains poorly understood. Using archival specimens of a freshwater predatory fish Gymnogobius isaza (Tanaka 1916) from Lake Biwa, Japan, we assembled a long-term (>40 years) time-series of the size-dependence of trophic niche position by examining nitrogen stable isotope ratios (δ15N) of the fish specimens. The size-dependence of trophic niche position was defined as the slope of the relationship between δ15N and log body size. Our analyses showed that the slope was significantly positive in about 60% of years and null in other years, changing through time. This is the first quantitative (i.e., stable isotope) evidence of long-term variability in the size-trophic relationship in a predatory fish. This finding had implications for the fish trophic dynamics, despite that about 60% of the yearly values were not statistically different from the long-term average. We proposed hypotheses for the underlying mechanism of the time-varying size-trophic relationship.

Original languageEnglish
Article numbere9120
JournalPloS one
Volume5
Issue number2
DOIs
Publication statusPublished - 2010 Feb 9

All Science Journal Classification (ASJC) codes

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)
  • General

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