Trophic relationships in early spring along the Okhotsk coast of Hokkaido, Japan, as traced by stable carbon and nitrogen isotopes

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Abstract

We measured stable carbon and nitrogen isotope ratios (<sup>13</sup>C/<sup>12</sup>C and <sup>15</sup>N/<sup>14</sup>N) of organic matter sources and consumers, including fishery resources, along the Okhotsk coast of northern Hokkaido, Japan, in early spring to characterize the food web. Phytoplankton and benthic detritus, including ice algae, fecal pellets, and benthic microalgae, constituted the main food sources for primary consumers (zooplankton and small benthic invertebrates, respectively); seagrass and terrestrial plant debris served no trophic function for consumers. Planktivorous and benthivorous fish species could be differentiated using stable carbon isotope ratios. Differences in stable nitrogen isotope ratios revealed species-specific feeding habits of crustacean groups: copepods were separated into three groups as herbivorous, omnivorous, or omnivorous-carnivorous, and benthic amphipods were divided into two groups as either omnivorous or omnivorous-carnivorous. We distinguished four levels of both pelagic and benthic trophic linkages. The δ<sup>13</sup>C values were enriched by 0.9–1.3‰ at the linkage between each pelagic trophic level except between the 1st and 2nd levels; δ<sup>15</sup>N values were enriched by 2.2–2.9‰ at each level. For benthic trophic linkages, the enrichment for δ<sup>13</sup>C and δ<sup>15</sup>N values between each level ranged from 0.6‰ to 1.0‰ and from 1.6‰ to 2.6‰, respectively. Trophic positions of copepod, mysids, and sand lance appeared between pelagic and benthic linkages. This suggests that those species have fed on both pelagic and benthic diets.

Journal

  • Plankton and Benthos Research

    Plankton and Benthos Research 6(1), 56-67, 2011-02-01

    The Plankton Society of Japan, The Japanese Association of Benthology

References:  57

Codes

  • NII Article ID (NAID)
    10027958121
  • NII NACSIS-CAT ID (NCID)
    AA12130745
  • Text Lang
    ENG
  • Article Type
    ART
  • ISSN
    18808247
  • NDL Article ID
    10992459
  • NDL Source Classification
    ZR1(科学技術--生物学)
  • NDL Call No.
    Z54-J424
  • Data Source
    CJP  NDL  J-STAGE 
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