caa a22 4500 605455244 CHVBK 20210128100211.0 cr unu---uuuuu 210128e20150201xx s 000 0 eng 10.1007/s10872-014-0262-4 doi (NATIONALLICENCE)springer-10.1007/s10872-014-0262-4 Characteristic of Si:P:N ratio in bottom water in central Suo-Nada, western Seto Inland Sea [Elektronische Daten] [Kazuo Abe, Mutsumi Tsujino, Norihisa Nakagawa, Katsuyuki Abo] The nutrient composition in seawater is considered to determine the regional phytoplankton species, its composition, and its productivity. In order to examine the nutrient composition ratio in Suo-Nada, western Seto Inland Sea, where the oligotrophication process is progressing, the relationship among silicic acid [Si(OH)4], phosphate (PO4),and total dissolved inorganic nitrogen (DIN; NO3+NO2+NH4) in bottom water was investigated. From April through July, as stratification progressed, a stagnant water mass appeared in the bottom layer of the central part of Suo-Nada. Nutrient and apparent oxygen utilization (AOU) concentrations in this bottom water increased in this period. A plot of nutrients against AOU concentrations showed good linearity for Si(OH)4, PO4, and DIN, which suggests that increase in nutrients was accompanied by dissolved oxygen consumption due to the degradation of organic matter. The Si:P:N ratio calculated based on the increased nutrient-AOU relationship in bottom water from April through October was determined to be 25:1:9. Meanwhile, the average Si:P:N ratio existing in bottom water during the same period was 28:1:8. The two ratios obtained showed good agreement in general, although the difference between them is probably attributed to the existence of preformed fractions of each nutrient. This finding suggests that the nutrient composition ratio in bottom water generally could be regulated by the biological uptake-regeneration process from April through October in this study area, and the obtained ratio (28:1:8) is a regional characteristic with large deviation from the Redfield-Brzezinski nutrient ratio of 15:1:16. The Oceanographic Society of Japan and Springer Japan, 2014 Nutrient nationallicence Regeneration nationallicence Bottom water nationallicence Si:P:N ratio nationallicence Suo-Nada nationallicence Seto Inland Sea nationallicence Abe Kazuo National Research Institute of Fisheries and Environment of Inland Sea, 2-17-5 Maruishi, 739-0452, Hatsukaichi, Japan aut Tsujino Mutsumi National Research Institute of Fisheries and Environment of Inland Sea, 2-17-5 Maruishi, 739-0452, Hatsukaichi, Japan aut Nakagawa Norihisa National Research Institute of Fisheries and Environment of Inland Sea, 2-17-5 Maruishi, 739-0452, Hatsukaichi, Japan aut Abo Katsuyuki National Research Institute of Fisheries and Environment of Inland Sea, 2-17-5 Maruishi, 739-0452, Hatsukaichi, Japan aut Journal of Oceanography Springer Japan 71/1(2015-02-01), 53-63 0916-8370 71:1<53 2015 71 10872 https://doi.org/10.1007/s10872-014-0262-4 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s10872-014-0262-4 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Abe Kazuo National Research Institute of Fisheries and Environment of Inland Sea, 2-17-5 Maruishi, 739-0452, Hatsukaichi, Japan aut NATIONALLICENCE 700 1- Tsujino Mutsumi National Research Institute of Fisheries and Environment of Inland Sea, 2-17-5 Maruishi, 739-0452, Hatsukaichi, Japan aut NATIONALLICENCE 700 1- Nakagawa Norihisa National Research Institute of Fisheries and Environment of Inland Sea, 2-17-5 Maruishi, 739-0452, Hatsukaichi, Japan aut NATIONALLICENCE 700 1- Abo Katsuyuki National Research Institute of Fisheries and Environment of Inland Sea, 2-17-5 Maruishi, 739-0452, Hatsukaichi, Japan aut NATIONALLICENCE 773 0- Journal of Oceanography Springer Japan 71/1(2015-02-01), 53-63 0916-8370 71:1<53 2015 71 10872