Ontogenetic changes in the trophic position of a freshwater Unionidae mussel

Natsuru Yasuno, Kentaro Shindo, Yuya Takagi, Gen Kanaya, Shuichi Shikano, Yasufumi Fujimoto, Tetsuo Shimada, Eisuke Kikuchi

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


Freshwater mussels have often been used as indicators of a trophic baseline (i.e., primary consumers) in the food web. To assess the utility of a large filter-feeding mussel, Cristaria plicata, as an isotopic indicator, we compared the carbon (&delta;13C) and nitrogen (&delta;15N) stable isotope ratios of the mussel with those of its potential food sources, particulate organic matter (POM) and sediment organic matter (SOM). The &delta;13C values of large mussels (shell length &gt; 140 mm,-31 ‰ to-29.2 ‰) were similar to those of POM (-30.2 ‰) rather than those of SOM (-27.6 ‰), indicating that mussel carbon was derived mainly from POM (mainly phytoplankton). In contrast, the mussels exhibited 6.3 ‰ to 9.0 ‰ higher &delta;15N values than did POM. Assuming a previously reported trophic enrichment factor (+3.4 ‰), the trophic level estimate of the mussel ranged from 2.9 to 3.6, indicating that they functioned as secondary rather than primary consumers. Our results also revealed positive correlations between shell lengths and &delta;15N values, suggesting that the mussels changed their trophic position from primary consumer (shell length < 140 mm) to secondary consumer (shell length > 140 mm) with growth. A significant inter-annual difference was found in the y-intercepts of the regression lines between shell length and &delta;15N, indicating that mussels can reflect inter-annual changes in the isotopic baseline (i.e., primary producers).

Original languageEnglish
Pages (from-to)341-349
Number of pages9
JournalFundamental and Applied Limnology
Issue number4
Publication statusPublished - 2014 Jul


  • Cristaria plicata
  • Trophic level
  • Zooplankton

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science
  • Ecology


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