Spatial variation in organic matter utilization by benthic communities from Yura River–Estuary to offshore of Tango Sea,Japan |
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Authors: | Emily S Antonio Akihide Kasai Masahiro Ueno Nam-il Won Yuka Ishihi Hisashi Yokoyama Yoh Yamashita |
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Institution: | 1. Maizuru Fisheries Research Station, Kyoto University, Kyoto 625-0086 Japan;2. Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan;3. National Research Institute of Aquaculture, Fisheries Research Agency, Mie 516-0193, Japan;4. Ocean Research Institute, University of Tokyo, Tokyo 164-8639, Japan |
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Abstract: | We investigated the distribution of δ13C and δ15N of organic matter among benthic communities from the upper estuary of Yura River to offshore of Tango Sea, Japan, to determine spatial variation in utilization of organic matter by benthic communities. The δ13C values of benthic animals ranged from −27 to −15‰ in the upper estuary, −21 to −15‰ in the lower estuary, −20 to −16‰ in the shallow coast (5–10 m depths), −18 to −16‰ in the deep coast (30–60 m depths) and −19 to −15‰ in offshore (100–150 m depths) stations. Adapting the dual isotope values to mixing models, we estimated the relative contributions of potential food sources to the benthos diet. Phytoplankton and macroalgae that intruded the estuary in summer were utilized as alternative food aside from the terrestrial-origin organic matter assimilated by the estuarine benthic consumers. Resuspended benthic microalgae were important source of energy in the shallow coastal stations, while abundant supply of phytodetritus fueled the deep coastal and offshore benthic food webs. Spatial difference in the diet of benthic communities depends largely on the shifts in the primary carbon source. Thus, benthic communities are important link of autochthonous/allochthonous production and secondary production in the continuous river–estuary–marine system. |
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Keywords: | organic matter benthic community stable isotope spatial variation |
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