貧酸素化海域における水質浄化機能回復のための浅場造成手法に関する研究  [in Japanese] Investigation of Conditions Required to Construct an Artificial Shallow Area to Recover the Water Purification Function of a Hypoxic Sea  [in Japanese]

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Abstract

東京湾、大阪湾、伊勢・三河湾、瀬戸内海など、我が国の多くの沿岸、内湾では富栄養化が進行し、閉鎖性が強い海域では貧酸素水塊の形成が顕著である。貧酸素水塊は、一般に底生動物群集の構造に大きな影響を及ぼす。特に三河湾における貧酸素水塊は、底生動物の構造の変化だけでなく、これらが有する水質を浄化する作用、すなわち水質浄化機能を喪失させることが示されており、この原因のひとつに、埋め立てによる干潟域の喪失が指摘されている。干潟や浅場(ここで浅場とは、ラムサール条約が規定する、低潮時に水深6mを超えない海域を指す)は、アサリなどの有用水産生物の成育場・漁場である。さらに、干潟・浅場は底生生物現存量が多いため、水中の有機懸濁物除去速度で示される水質の浄化速度、すなわち水質浄化能に優れ、湾全体の物質循環に大きな影響を与えている。

To create a new artificial shallow area in a hypoxic bay, we propose methods to determine the depth for thearea and how to evaluate its effectiveness. The study was conducted in Mikawa Bay, Japan, which is a semienclosedsea and is regularly nutrient enriched. As a result, in summer, serious hypoxia is observed in the bottomlayer, which becomes progressively lethal to the macrobenthos. Therefore the aim of developing a new shallowarea should be to avoid hypoxia.To determine the depth of the shallow area to be newly created, we analysed field data such as macrobenthos,water temperature and dissolved oxygen concentration. We then used those results to estimate the survival rateof the short-necked clam (Ruditapes philippinarum), which depends on water temperature, dissolved oxygenconcentration and glycogen content in the body. We proposed that the depth of the artificial area should be wherethe survival rate for the short-necked clam will be over 70%. The effect of constructing the shallow area wasassessed on the basis of the water purification function, which is defined by the removal of particulate organicnitrogen by macrobenthos.All field data and numerical results, which predicted the effects of constructing the new shallow area, weremanaged in a Geographic Information System (GIS). The new methods and evaluation criteria presented in thispaper have both environmental and economic merits.

Journal

  • Journal of Fisheries Engineering

    Journal of Fisheries Engineering 38(1), 25-34, 2001-06-30

    The Japanese Society of Fisheries Engineering

References:  23

Cited by:  5

Codes

  • NII Article ID (NAID)
    10008273992
  • NII NACSIS-CAT ID (NCID)
    AN10278554
  • Text Lang
    JPN
  • Article Type
    Journal Article
  • ISSN
    09167617
  • NDL Article ID
    5848250
  • NDL Source Classification
    ZR26(科学技術--農林水産--水産)
  • NDL Call No.
    Z18-1327
  • Data Source
    CJP  CJPref  NDL  J-STAGE  JASI 
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