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Title Transcription
ナカウミ コシンブ ニ オケル コテイ ノ スイチュウ エイゾウ ソノ5 : トウキ カラ シュンキ ノ キセツ ヘンカジ ニ オケル コテイ ノ ドウタイ
Title Alternative
Pictures of bottom surface in the central part of Lake Nakaumi (part 5) : dynamics of bottom water in the time of seasonal change from winter to spring
File
language
jpn
Author
Nomura, Ritsuo
Takata, Hiroyuki
Description
A characteristic change of bottom sediment and benthic organisms occurs in early
spring, when the thermal structure of lake water changes from warm bottom to cold one and from cold surface to warm one (so-called spring turnover). Oxygen contents much decrease in the bottom water from this time on and winter-thriving cionids disappear in this season. We succeeded to take a picture of these changes in every two hours during April 5 to May 2, 2007.
The followings are our major results:
(1) Unclear water, consisting of suspended fine-grained particles, is normal in Lake Nakaumi, but it became more unclear when plankton productivity (as chlorophyll production) has much increased. Our pictures showed that the suspended particles were not only produced by the winnowing of bottom sediments, but also transported from other places. Clear bottom water was developed while the water level is high in Sakai-minato, Sea of Japan coast, which suggests the upward inflow of marine bottom water. Clear bottom water was not formed while the water level in Lake Nakaumi is higher in comparison with that of Sakai-minato.
(2) We confirmed again the bottom turbulence occurred over the wind speed of 10 m/s, when winter-thriving organisms, as cionids, become weak in activity, and then easily blew away with less than this wind speed. The bottom surface has much changed to a desolate surface with a new grown bacterial mat.
Subject
spring turnover
unclear water
bottom turbulence
water dynamics
Journal Title
Laguna : 汽水域研究
Volume
16
Start Page
19
End Page
45
ISSN
21852995
Published Date
2009-06
NCID
AN10439529
Publisher
島根大学汽水域研究センター
NII Type
Departmental Bulletin Paper
Format
PDF
Text Version
出版社版
OAI-PMH Set
Estuary Research Center
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