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ID 24670
file
Thumnail 50-1002.pdf 1.15 MB
title alternative
Oceanographic Characteristics of Hiroshima Bay Seasonal and Spatial Variations from 1989 to 1993
creator
Matsuda, Osamu
Yonei, Yoshimi
subject
海水交換
環境傾斜
富栄養化
広島湾
enviromental gradients
eutrophication
Hiroshima Bay
water exchange
NDC
Fishing industry. Fisheries
abstract
広島湾の海況の時空間変動と平均像に関する解析を、1989年から1993年の5年間の観測結果を用いて行った。広島湾は湾奥から湾口にかけての南北の環境傾斜が大きく、広島湾の海況特性は厳島と西能美島の間の那沙美瀬戸を境に北部海域と南部海域に二分されていた。北部海域は海況の季節変動が大きく、夏季には密度成層が発達していた。また、北部海域は太田川河口から那沙美瀬戸にかけて南北方向の環境傾斜が顕著であり、閉鎖性の強い典型的な富栄養海域であることが明らかになった。一方、南部海域は海況の季節変動が小さく、一年を通して鉛直混合が卓越していた。また、この海域のクロロフィルa温度分布には密度分布にみられた東西方向の勾配がみられなかったことは、湾奥部からの直接の栄養塩供給の影響が小さく、西部の河川水による栄養塩負荷量がそれほど大きくないのに対して、柱島水道を通しての海水交換により、湾外水、特に安芸灘の水塊の影響を強く受けているためと考えられる。
abstract
Seasonal and spatial variations of the oceanographic conditions in Hirosima Bay were characterized using the results of the field observations from 1989 to 1993. In Hiroshima Bay, the north-south enviromental gradients from the head to the entrance of the bay were observed. From the gradients, the bay is classified into two major regions, the northern and southern regions, by Nasami Strait where is located between Itsuku Is. and Nishi-Noumi Is. In the northern region, the seasonal variations in the oceanographic factors were remarkable and the density stratification developed in summer. In this region, the north-south enviromental gradients from the estuary of the Ohta River to Nasami-Strait were especially remarkable. This result indicated that this region is very stagnant and highly eutrophic. While, in the southern region, there was the west-east density gradient of surface sea water in the horizontal distribution. On the other hand, the horizontal distribution of chlorophyll a was roughly homogeneous, which shows relatively small influence of the nutrient loads from both the west and the north. Therefore, it is suggested that the southern region would be strongly influenced by the outside waters, in particular, the water of Aki-Nada adjacent to Hiroshima Bay.
journal title
Journal of the Faculty of Applied Biological Science, Hiroshima University
volume
Volume 33
issue
Issue 1
start page
9
end page
19
date of issued
1994-06
publisher
広島大学生物生産学部
農林水産研究情報センター
issn
1341-691X
ncid
SelfDOI
language
jpn
nii type
Departmental Bulletin Paper
HU type
Departmental Bulletin Papers
DCMI type
text
format
application/pdf
text version
publisher
department
Graduate School of Biosphere Science
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