Seasonal abundance and vertical distribution of siphonophores in western Norwegian fjords
Seasonal abundance and vertical distribution of siphonophores in western Norwegian fjords
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挪威西部峡湾管水母的季节性丰度和垂直分布
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
U. Båmstedt
中科院分区：
文献类型：
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作者：
A. Hosia;U. Båmstedt
采用网样法对科尔斯峡湾和法纳菲峡湾管水母的季节性丰度进行了研究。全年优势种为油虱、芋螺和北极星萤叶甲。N.卡拉羊在5月底和6月初达到高峰。在冬季观察到相对较大的菌落数量少，管形虫数量多。Dimophyes arctica和L.芋螺总科在3月份发生了一次世代转换，当时大型越冬群体和小型年轻多胃群体在前者消失之前短暂共存。丰度最低，在冬季，和eudoxids始终比多胃殖民地的两个物种。多胃D. arctica和L.芋螺的发生期分别为5月上旬和6月下旬。在科尔斯菲尤尔地区，锥状透镜虫可能有1年以上的世代。利用遥控潜水器在9个峡湾对管水母的垂直分布进行了研究。无鞭毛藻的分布可能主要是N. cara，峡湾之间差异很大，分布的加权平均深度从99米到412米不等。Sognefjord的结果表明昼夜垂直迁移。在每个峡湾的成年殖民地的大部分发生在窗台深度以下。管水母没有观察到的地方已知的主机持久的种群Periphylla periphylla。
Seasonal abundance of siphonophores in Korsfjord and Fanafjord was studied by net sampling. Nanomia cara, Lensia conoidea and Dimophyes arctica were dominant species present throughout the year. Abundance of N. cara colonies peaked in late May and early June. Low numbers of relatively large colonies and high numbers of siphonulae were observed during winter. Dimophyes arctica and L. conoidea had a generation shift in March, when large over-wintering and small young polygastric colonies co-existed briefly before the former disappeared. Abundances were lowest during winter, and eudoxids were consistently more numerous than polygastric colonies for both species. Maximum abundances of polygastric D. arctica and L. conoidea occurred in early May and late June, respectively. Lensia conoidea may have more than one annual generation in Korsfjord. Vertical distributions of siphonophores were studied with an remotely operated vehicle in nine fjords. The distributions of agalmatid physonects, probably mostly N. cara, differed significantly between the fjords, with the weighted mean depths of the distributions ranging from 99 to 412 m. Results from Sognefjord suggested diel vertical migration. The bulk of the adult colonies in each fjord occurred below sill depth. Siphonophores were not observed at localities known to host persistent populations of Periphylla periphylla.