caa a22 4500 445892420 CHVBK 20180317145620.0 cr unu---uuuuu 170323e20110701xx s 000 0 eng 10.1007/s10750-011-0682-8 doi (NATIONALLICENCE)springer-10.1007/s10750-011-0682-8 Longitudinal and seasonal changes in the origin and quality of transported particulate organic matter along a gravel-bed river [Elektronische Daten] [Fumikazu Akamatsu, Sohei Kobayashi, Kunihiko Amano, Satoru Nakanishi, Yurika Oshima] Particulate organic matter (POM) plays an important role in nutrient dynamics in river ecosystems, but little is known about changes in the origin and quality of POM in relation to physical and seasonal changes along rivers. Using stable isotope and stoichiometric analyses, we investigated the changes in origin and quality of POM of three different size fractions (fine [FPOM], 1.2-100μm; medium [MPOM], 100-250μm; and coarse [CPOM], 250-1,000μm) at 14 sites along a gravel-bed river over four seasons. FPOM and MPOM accounted for 90% of all POM at all study sites. At each site, the δ13C level was lower for FPOM (range: −29.0 to −21.1‰) than for MPOM (−26.9 to −17.2‰) and CPOM (−27.5 to −16.3‰). The C:N ratio was lower for FPOM (6.9-15.6) than for MPOM (6.3-17.4) and CPOM (5.7-27.1). The contribution of periphyton to POM of all size fractions had a tendency to increase downstream, though the trend was less clear and varied seasonally for MPOM and CPOM between sites in middle and downstream reaches. Contrastively, the C:N ratio in all size fractions of POM consistently decreased downstream. The downstream decrease in the C:N ratio of POM can be partly explained by the increase in the contribution of periphyton, which seems to be associated with increased discharge and enhanced periphyton dislodgement, especially in winter. In addition, an increase in bacterial biomass associated with the greater nutrient availability in pool areas is another possible reason for the decrease in the C:N ratio of POM downstream. Springer Science+Business Media B.V., 2011 Carbon stable isotope ratio nationallicence Carbon-to-nitrogen ratio nationallicence Nutrient nationallicence Periphyton nationallicence Pool-riffle sequence nationallicence Akamatsu Fumikazu Water Environment Research Group, Public Works Research Institute, 1-6 Minamihara, 305-8516, Tsukuba, Japan aut Kobayashi Sohei Water Environment Research Group, Public Works Research Institute, 1-6 Minamihara, 305-8516, Tsukuba, Japan aut Amano Kunihiko Water Environment Research Group, Public Works Research Institute, 1-6 Minamihara, 305-8516, Tsukuba, Japan aut Nakanishi Satoru Water Environment Research Group, Public Works Research Institute, 1-6 Minamihara, 305-8516, Tsukuba, Japan aut Oshima Yurika Water Environment Research Group, Public Works Research Institute, 1-6 Minamihara, 305-8516, Tsukuba, Japan aut Hydrobiologia Springer Netherlands 669/1(2011-07-01), 183-197 0018-8158 669:1<183 2011 669 10750 https://doi.org/10.1007/s10750-011-0682-8 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10750-011-0682-8 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Akamatsu Fumikazu Water Environment Research Group, Public Works Research Institute, 1-6 Minamihara, 305-8516, Tsukuba, Japan aut NATIONALLICENCE 700 1- Kobayashi Sohei Water Environment Research Group, Public Works Research Institute, 1-6 Minamihara, 305-8516, Tsukuba, Japan aut NATIONALLICENCE 700 1- Amano Kunihiko Water Environment Research Group, Public Works Research Institute, 1-6 Minamihara, 305-8516, Tsukuba, Japan aut NATIONALLICENCE 700 1- Nakanishi Satoru Water Environment Research Group, Public Works Research Institute, 1-6 Minamihara, 305-8516, Tsukuba, Japan aut NATIONALLICENCE 700 1- Oshima Yurika Water Environment Research Group, Public Works Research Institute, 1-6 Minamihara, 305-8516, Tsukuba, Japan aut NATIONALLICENCE 773 0- Hydrobiologia Springer Netherlands 669/1(2011-07-01), 183-197 0018-8158 669:1<183 2011 669 10750 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer