Bimodal vertical distribution and diel migration of the copepods Metridia pacifica, M. okhotensis and Pleuromamma scutullata in the western North Pacific Ocean
Bimodal vertical distribution and diel migration of the copepods Metridia pacifica, M. okhotensis and Pleuromamma scutullata in the western North Pacific Ocean
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北太平洋西部桡足类 Metridia pacifica、M. okhotensis 和 Pleuromamma scutullata 的双峰垂直分布和昼夜迁移
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发表时间：
1989
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影响因子：
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通讯作者：
H. Hattori
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文献类型：
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作者：
H. Hattori
本文研究了西北太平洋亚北极水域3种甲壳类桡足动物--太平洋甲虫(Metridia Pacillia)、短尾甲虫(M.okhotensis)和斯卡鲁拉特侧乳甲(Pleuromama Scuullata)在细微尺度上垂直分布的日变化。1983年6月和8月，使用朗赫斯特-哈迪浮游生物记录仪(LHPR)在俄亚西俄州水域的两个站点进行了采样。每隔几个小时重复采样四到五次，深度约为1000米。垂直分辨率为5~40m，两个站位的桡足类全天都集中在表层(0~60m)和中层(200~300m)。年轻的太平洋微藻(C III和C IV)在两个地层中都占主导地位。尽管大多数雌性CV和成年雌性在20~30mh-1表现出双向垂直迁移，但相当数量的雌性不会向上迁移，而是在夜间停留在深层。同样的趋势在黄曲霉和天牛中也很明显。前肠内容物观察表明，尽管深层个体的食物不同，但深层模式种群的取食活动与表层模式种群的取食活动一样高。这种双峰分布可能会增加桡足类种群的种内多样性，这可能是为什么在夏末到冬季相对简单的高纬度生态系统中，甲足类占主导地位的原因。
Diel changes in fine-scale vertical distributions of three calanoid copepods Metridia pacifica, M. okhotensis and Pleuromamma scutullata in the subarctic waters of the western North Pacific were examined. Sampling was carried out in June and August 1983, at two stations in Oyashio water using a Longhurst-Hardy Plankton Recorder (LHPR). Sampling, down to about 1 000 m, was repeated four to five times at intervals of several hours. Vertical resolution was 5 to 40 m. Copepods were concentrated in two strata, the surface (0 to 60 m) and the mesopelagic (200 to 300 m) layers, throughout the day at both stations. Younger M. pacifica (C III and C IV) were dominant in both strata. Although most female C V and adult females demonstrated diel vertical migration at 20 to 30 m h-1, a significant number of females did not migrate upward but remained in the deep stratum at night. The same trend was evident in M. ohkotensis and P. scutullata. Foregut content observations indicated that feeding activities of the deep mode populations were as high as those of the surface mode, though food of deep individuals was different. Such a bimodal distribution may increase intraspecific diversity of copepod populations and is possibly why metridiid copepods dominate during late summer to winter in the relatively simple ecosystems of high latitudes.