Seasonal shifts in the contributions of the Changjiang River and the Kuroshio Current to nitrate dynamics in the continental shelf of the northern East China Sea based on a nitrate dual isotopic composition approach
The northern East China Sea (ECS) serves as a spawning and nursery ground for many species of fish and squid. To clarify the basis of the food web in the northern ECS, we examined the nitrate (NO<sub>3</sub>) dynamics along four latitudinal transects based on stable nitrogen and oxygen i...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2014-02-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/11/1297/2014/bg-11-1297-2014.pdf |
| _version_ | 1818678526198415360 |
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| author | Y. Umezawa A. Yamaguchi J. Ishizaka T. Hasegawa C. Yoshimizu I. Tayasu H. Yoshimura Y. Morii T. Aoshima N. Yamawaki |
| author_facet | Y. Umezawa A. Yamaguchi J. Ishizaka T. Hasegawa C. Yoshimizu I. Tayasu H. Yoshimura Y. Morii T. Aoshima N. Yamawaki |
| author_sort | Y. Umezawa |
| collection | DOAJ |
| description | The northern East China Sea (ECS) serves as a spawning and nursery ground
for many species of fish and squid. To clarify the basis of the food web in
the northern ECS, we examined the nitrate (NO<sub>3</sub>) dynamics along four
latitudinal transects based on stable nitrogen and oxygen isotopes of
NO<sub>3</sub> (</i>δ</i><sup>15</sup>N<sub>NO</sub><sub>3</sub> and </i>δ</i><sup>18</sup>O<sub>NO</sub><sub>3</sub>) and
temperature–salinity dynamics in both winter (February 2009) and summer
(July 2009 and July 2011). The </i>δ</i><sup>15</sup>N<sub>NO</sub><sub>3</sub> and </i>δ</i><sup>18</sup>O<sub>NO</sub><sub>3</sub>, which were distinctly different among the potential
NO<sub>3</sub> sources, were useful for clarifying NO<sub>3</sub> sources and its actual
usage by phytoplankton. In winter, Kuroshio Subsurface Water (KSSW) and the
Yellow Sea Mixed Water (YSMW) predominantly contributed to NO<sub>3</sub>
distributed in the shelf water. In the surface water of the Okinawa Trough,
NO<sub>3</sub> from the KSSW, along with a temperature increase caused by an
intrusion of Kuroshio Surface Water (KSW), seemed to stimulate phytoplankton
growth. In summer, Changjiang Diluted Water (CDW), Yellow Sea Cold Water
Mass (YSCWM), and KSSW affected the distribution and abundance of NO<sub>3</sub>
in the northern ECS, depending on precipitation in the Changjiang drainage
basin and the development of the YSCWM in the shelf bottom water. Although
isotopic fractionation during NO<sub>3</sub> uptake by phytoplankton seemed to
drastically increase </i>δ</i><sup>15</sup>N<sub>NO</sub><sub>3</sub> and δ<sup>18</sup>O<sub>NO</sub><sub>3</sub>
in summer, relatively light nitrate with </i>δ</i><sup>15</sup>N<sub>NO</sub><sub>3</sub> lower
than expected from this fractionation effect might be explained by
contribution of atmospheric nitrogen and/or nitrification to NO<sub>3</sub>
dynamics in the surface and subsurface layers. If the latter were a dominant
process, this would imply a tightly coupled nitrogen cycle in the shelf
water of the northern ECS. |
| first_indexed | 2024-12-17T09:16:40Z |
| format | Article |
| id | doaj.art-25ecc548eaf247fa85b51b2a2daa86d4 |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-12-17T09:16:40Z |
| publishDate | 2014-02-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-25ecc548eaf247fa85b51b2a2daa86d42022-12-21T21:54:57ZengCopernicus PublicationsBiogeosciences1726-41701726-41892014-02-011141297131710.5194/bg-11-1297-2014Seasonal shifts in the contributions of the Changjiang River and the Kuroshio Current to nitrate dynamics in the continental shelf of the northern East China Sea based on a nitrate dual isotopic composition approachY. Umezawa0A. Yamaguchi1J. Ishizaka2T. Hasegawa3C. Yoshimizu4I. Tayasu5H. Yoshimura6Y. Morii7T. Aoshima8N. Yamawaki9Graduate School of Fisheries Science and Environmental Studies, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki city, Nagasaki, 852-8521, JapanGraduate School of Fisheries Science and Environmental Studies, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki city, Nagasaki, 852-8521, JapanHydrospheric Atmospheric Research Center, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, JapanSeikai National Fisheries Research Institute, Fisheries Research Agency, 1551-8 Taira-machi, Nagasaki 851-2213, JapanCenter for Ecological Research, Kyoto University, Japan, Hirano 2-509-3, Otsu city, Shiga, 520-2113, JapanCenter for Ecological Research, Kyoto University, Japan, Hirano 2-509-3, Otsu city, Shiga, 520-2113, JapanFaculty of Fisheries, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki city, Nagasaki, 852-8521, JapanFaculty of Fisheries, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki city, Nagasaki, 852-8521, JapanFaculty of Fisheries, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki city, Nagasaki, 852-8521, JapanFaculty of Fisheries, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki city, Nagasaki, 852-8521, JapanThe northern East China Sea (ECS) serves as a spawning and nursery ground for many species of fish and squid. To clarify the basis of the food web in the northern ECS, we examined the nitrate (NO<sub>3</sub>) dynamics along four latitudinal transects based on stable nitrogen and oxygen isotopes of NO<sub>3</sub> (</i>δ</i><sup>15</sup>N<sub>NO</sub><sub>3</sub> and </i>δ</i><sup>18</sup>O<sub>NO</sub><sub>3</sub>) and temperature–salinity dynamics in both winter (February 2009) and summer (July 2009 and July 2011). The </i>δ</i><sup>15</sup>N<sub>NO</sub><sub>3</sub> and </i>δ</i><sup>18</sup>O<sub>NO</sub><sub>3</sub>, which were distinctly different among the potential NO<sub>3</sub> sources, were useful for clarifying NO<sub>3</sub> sources and its actual usage by phytoplankton. In winter, Kuroshio Subsurface Water (KSSW) and the Yellow Sea Mixed Water (YSMW) predominantly contributed to NO<sub>3</sub> distributed in the shelf water. In the surface water of the Okinawa Trough, NO<sub>3</sub> from the KSSW, along with a temperature increase caused by an intrusion of Kuroshio Surface Water (KSW), seemed to stimulate phytoplankton growth. In summer, Changjiang Diluted Water (CDW), Yellow Sea Cold Water Mass (YSCWM), and KSSW affected the distribution and abundance of NO<sub>3</sub> in the northern ECS, depending on precipitation in the Changjiang drainage basin and the development of the YSCWM in the shelf bottom water. Although isotopic fractionation during NO<sub>3</sub> uptake by phytoplankton seemed to drastically increase </i>δ</i><sup>15</sup>N<sub>NO</sub><sub>3</sub> and δ<sup>18</sup>O<sub>NO</sub><sub>3</sub> in summer, relatively light nitrate with </i>δ</i><sup>15</sup>N<sub>NO</sub><sub>3</sub> lower than expected from this fractionation effect might be explained by contribution of atmospheric nitrogen and/or nitrification to NO<sub>3</sub> dynamics in the surface and subsurface layers. If the latter were a dominant process, this would imply a tightly coupled nitrogen cycle in the shelf water of the northern ECS.http://www.biogeosciences.net/11/1297/2014/bg-11-1297-2014.pdf |
| spellingShingle | Y. Umezawa A. Yamaguchi J. Ishizaka T. Hasegawa C. Yoshimizu I. Tayasu H. Yoshimura Y. Morii T. Aoshima N. Yamawaki Seasonal shifts in the contributions of the Changjiang River and the Kuroshio Current to nitrate dynamics in the continental shelf of the northern East China Sea based on a nitrate dual isotopic composition approach Biogeosciences |
| title | Seasonal shifts in the contributions of the Changjiang River and the Kuroshio Current to nitrate dynamics in the continental shelf of the northern East China Sea based on a nitrate dual isotopic composition approach |
| title_full | Seasonal shifts in the contributions of the Changjiang River and the Kuroshio Current to nitrate dynamics in the continental shelf of the northern East China Sea based on a nitrate dual isotopic composition approach |
| title_fullStr | Seasonal shifts in the contributions of the Changjiang River and the Kuroshio Current to nitrate dynamics in the continental shelf of the northern East China Sea based on a nitrate dual isotopic composition approach |
| title_full_unstemmed | Seasonal shifts in the contributions of the Changjiang River and the Kuroshio Current to nitrate dynamics in the continental shelf of the northern East China Sea based on a nitrate dual isotopic composition approach |
| title_short | Seasonal shifts in the contributions of the Changjiang River and the Kuroshio Current to nitrate dynamics in the continental shelf of the northern East China Sea based on a nitrate dual isotopic composition approach |
| title_sort | seasonal shifts in the contributions of the changjiang river and the kuroshio current to nitrate dynamics in the continental shelf of the northern east china sea based on a nitrate dual isotopic composition approach |
| url | http://www.biogeosciences.net/11/1297/2014/bg-11-1297-2014.pdf |
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