沿岸親潮における動物プランクトン群集の特徴〔含 質疑応答〕 (シンポジウム:沿岸親潮)  [in Japanese] Characteristics of Zooplankton Community in the Coastal Oyashio Water(Symposium: "Coastal Oyashio")  [in Japanese]

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Abstract

北海道南東岸における沿岸親潮の動物プランクトン群集の特徴を明らかにするために,季節的,鉛直的および水平的なネット採集試料の解析を行った.沿岸親潮の流入は2月~4月に見られ,これは当海域のバイオマスピーク(6月)の前であった.沿岸親潮と親潮接岸分枝ともに最優占分類群はかいあし類で,沿岸親潮中では小型冷水性かいあし類のPseudocalanus newmaniやAcartia longiremisが優占していた.水平的に動物プランクトン個体数とバイオマスはともに水温と正の相関があり,低水温の沿岸親潮中では低かった.これはバイオマスを左右する大型かいあし類の発育段階組成が沿岸親潮では休眠中の後期発育段階のみであったためであった.沿岸親潮の動物プランクトン群集のバイオマスが親潮接岸分枝よりも低い要因として,小型かいあし類が優占することや低温な環境下で成長が遅いこと,および珪藻類ブルームによるかいあし類の再生産効率の低下が影響していると考えられる.

Characteristics of mesozooplankton community in the Coastal Oyashio Water (COW) were analyzed based on zooplankton samples collected using 0.33mm mesh nets off the southeastern coast of Hokkaido. Intrusion of the COW was observed in February-April and that was earlier than the peak period of zooplankton biomass (419mg WM M^<-3>: 0-150m) in June (annual mean: 176mg WM M^<-3>). Copepods were the most dominant taxa (89±4% in abundance and 71±11% in biomass) throughout the study region. Numerically, small copepods (Pseudocalanus newmani and Acartia longiremis) predominated in the COW, whereas large copepods (Neocalanus spp. and Eucalanus bungii) did in the oceanic Oyashio water. Zooplankton abundance and biomass in the COW were lower than the adjacent oceanic Oyashio water. Low biomass in the COW was caused by the dominance of small-sized copepods and also by the predominance of only late copepodid stage in the COW in the stage composition of large-sized oceanic copepod E. bungii, that was distinct from that in the oceanic Oyashio water, i.e. more late copepodid stage, and predominance of early and middle copepodid stages. Slower growth rate of zooplankton in the COW due to low water temperature and negative effects of diatoms on reproductive success of copepods was considered as a possible cause for the low zooplankton biomass in the COW.

Journal

  • Bulletin on coastal oceanography

    Bulletin on coastal oceanography 41(1), 23-31, 2003-08

    日本海洋学会沿岸海洋研究会

Codes

  • NII Article ID (NAID)
    110007999294
  • NII NACSIS-CAT ID (NCID)
    AN10492259
  • Text Lang
    JPN
  • Article Type
    特集 // 会議録・学会報告
  • ISSN
    13422758
  • NDL Article ID
    6696502
  • NDL Source Classification
    ZM44(科学技術--地球科学--海洋・陸水・火山)
  • NDL Call No.
    Z15-533
  • Data Source
    NDL  NII-ELS  IR  NDL-Digital 
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