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ABSTRACT: Food composition, fork length and condition factor of juvenile crimson sea bream Evynnis japonica were examined for two behaviorally distinct types of fish inhabiting a nursery ground. Studies were carried out from March to September 1996 at Morode Cove, Ehime Prefecture, Japan. One type of fish is solitary and territorial and the other type is aggregative. The food compositions of the two types of fish were different. Solitary fish foraged mainly on Gammaridea and Caprellidea (benthic organisms), and Copepoda (planktonic organisms); while aggregative fish foraged mainly on Copepoda, Appendiculata and Cladocera (planktonic organisms). These findings suggest that when we study food composition of E. japonica , it is imperative to consider whether the samples used for the analyses are from solitary (territorial) fish. Solitary fish showed significantly greater fork length and condition factor than aggregative fish, suggesting that the former will have a greater fitness value than the latter. 相似文献
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北海道奶牛业从20世纪50年代开始快速发展,奶农户数减少的同时经营规模不断扩大。但是奶牛饲养头数增加与土地规模扩大之间没能保持相应的良好平衡关系。所产生的家畜粪尿量加重了环境负担。本文阐明北海道奶牛业经营规模扩大过程与土地利用方式之间持有什么样的相互依存关系来展开,并从土地利用角度进一步研究了奶牛生产粪尿产生与土地利用之间的关系。 相似文献
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