Study on interaction of marine snow dynamics and biological processes within the vicinity of the pycnocline of upper ocean.

上层海洋密斜层附近海洋雪动力学与生物过程相互作用的研究。

基本信息

批准号：
16370010
负责人：
KOIKE Isao
金额：
$ 6.91万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

项目摘要

Although marine snow plays important role on the transport of organic carbon produced at the upper ocean into the ocean interior, its biogeochemical studies have been restricted to the coastal area, because of the access problems. In this study, we focused on the interaction of biological processes and physical environments in the vicinity of upper layer, to understand the production and vertical transfer of marine snow by using newly developed marine-snow camera. In FY2004, improvements of the camera systems and their performance test have been conducted, i.e., use of new LED light source and addition of clear sight and others. Main field campaign was performed during the Hakuho-Maru Cruise (July-September, 2005) to the central Pacific transect (10°S - 53°N, 160°W), which includes from oligotrophic region to rather nutrients rich sub-arctic region. In this long transect, no survey has been done before using marine snow camera. Followings are major results obtained from the field studies. (1) Presence of peak of marine snow abundance was confirmed at the pycnocline of the nutrients rich sub-arctic area. (2) Integrated amounts of chlorophyll a at the 0-200m depth along the transect showed about 2.5 fold difference, while the same treatments of marine snow volume gave about 50 times difference. This comparison suggests that several factors including physical environments, size of phytoplankton, and food web structures in this transect control abundance of marine snow in the upper layers. (3) The depth of pycnocline located between 30-110m depths in the study areas. The ratio of integrated chlorophyll a amounts between 0-100m and 100-200m depths along the transect showed a good correlation with the ratio of marine snow volume obtained by the same treatment. Since primary source of marine snow (>0.5mm size) is phytoplankton of 0.8-100 micron size, aggregation processes to produce marine snow may occur without any large vertical movement of these source materials.

尽管海洋雪在上层海洋产生的有机碳向海洋内部的运输中发挥着重要作用，但由于访问问题，其生物地球化学研究仅限于沿海地区。在本研究中，我们重点关注生物之间的相互作用。 2004 财年，我们对相机系统及其性能进行了改进，即使用新型LED光源和在白凤丸巡航（2005 年 7 月至 9 月）期间，在太平洋中部断面（南纬 10° - 北纬 53°，西经 160°）期间进行了主要的野外活动，其中包括从贫营养区到在这片营养丰富的亚北极地区，在使用海洋雪相机之前没有进行过调查，以下是现场研究获得的主要结果（1）海洋峰值的存在。在营养丰富的亚北极地区的重斜层证实了积雪丰度。（2）沿样线0-200m深度的叶绿素a的积分量显示出约2.5倍的差异，而海洋积雪量的相同处理给出了约50倍。这一比较表明，包括物理环境、浮游植物大小和食物网结构在内的几个因素控制着上层海洋积雪的丰度。研究区 30-110m 深度之间的比重斜层沿样线 0-100m 和 100-200m 深度之间的综合叶绿素 a 量的比率与通过相同处理获得的海洋积雪量的比率具有良好的相关性。海雪（>0.5毫米尺寸）的来源是0.8-100微米尺寸的浮游植物，产生海雪的聚集过程可能这些源材料没有任何大的垂直移动即可发生。