Ura Keisuke
Ocean Investigation for Fisheries Resources Development and Uutilization of Ocean Energy in the Sea Region Surrounding OKINOTORISHIMA
Journal of National Fisheries University Volume 62 Issue 2
Page 75-83
published_at 2014-03
Title
沖ノ鳥島海域における水産資源開発と海洋エネルギー利用のための海洋調査
Ocean Investigation for Fisheries Resources Development and Uutilization of Ocean Energy in the Sea Region Surrounding OKINOTORISHIMA
Creators
Urata Kazuya
Creators
Ikegami Yasuyuki
Source Identifiers
[PISSN] 0370-9361
Creator Keywords
Ocean Investigation
Okinotorishima
OTEC
CTD
An assessment of the nutrients, ocean resources, and ocean environment, which are vital to fisheries resources, is essential to preserve the fisheries resources in the vicinity of Okinotorishima. However, not many continuous investigations have been conducted. For the development of fisheries resources and utilization of ocean energy, an oceanographic investigation was conducted by the training ship Koyo Maru of the National Fisheries University. The investigations were carried out on the 9th and 10th of January, 2006 and the survey parameters consisted of, water depth, seawater temperatures at various depths, salinity, dissolved oxygen level, and water nutrients at various depths. The results were as follows: 1) The seawater temperature was approximately 24 ℃ at each observation point and decreased sharply to approximately 18 ℃ at a depth of approximately 200 m. At depths greater than 200 m, seawater temperature decreased gradually and 5 ℃ was recorded at 1000 m. The temperature difference between the surface and a depth of 1000 m was approximately 19 ℃ at each observation point. 2) High salinity levels from 34.7 to 34.9 PSU were observed from the surface to depths near 400 m. The salinity levels decreased to about 34.2 PSU near depths of 700 m. The salinity from depths greater than 700 m showed a tendency to increase. 3) The observation result showed that the amount of silicate around the surface was small. Therefore, it is possible to increase the number of diatoms (phytoplankton) by upwelling deep seawater and releasing silicate-rich water at the surface. 4) The phosphate levels at the surface ranged from 0 to 0.07 μmol/l. The level increased sharply until a depth of 500 m and was about 1.7 μmol/l at a depth of approximately 1200 m. The phosphate at depths greater than 1200 m exhibited a tendency to decrease. This tendency was similar to that observed in the case of silicate.
Languages
jpn
Resource Type
departmental bulletin paper
Publishers
National Fisheries University
Date Issued
2014-03
File Version
Version of Record
Access Rights
open access
Relations
[ISSN]0370-9361