MOCNESS-CTD Data from Guaymas Basin vent region, AII-112-28, 1985 from R/V Atlantis II AII-112-28, July 1985

<p>MOCNESS-CTD Data from Guaymas Basin vent region, AII-112-28, 1985 from R/V Atlantis II AII-112-28, July 1985. The first three tows report conductivity in the cond_sal column and thereafter, salinity is reported.</p>

<p>From cruise report:&nbsp;<br />
The MOCNESS, Multiple Opening/Closing Net and Environmental Sensing System, was &nbsp;used to sample the zooplankton in the Guaymas Basin deep sea vents study area (Southern &nbsp;Trough) between 26 July and 1 August 1985. The purpose of the sampling was to characterize &nbsp;the zooplankton populations within 100 meters of the sea floor in the vicinity of the &nbsp;hydrothermal vent activity and to compare animals caught in this region with animals caught in &nbsp;adjacent areas outside the immediate influence of the vents and in the water column above the &nbsp;vents area.</p>

<p>A MOCNESS-1 was used to make these collections. This system was equipped with 9 1-m^2 nets of 333 µm nitex nylon mesh, which presented a 1-m^2 mouth opening when towed with &nbsp;the frame at 45 degrees from the vertical. The system carried Sea Bird temperature and salinity &nbsp;probes, a down welling light sensor, a bottom finding 12 kHz pinger, a pressure transducer, a &nbsp;modified TSK flowmeter, and an angle inclinometer. Data from the sensors were transmitted up &nbsp;to a deck unit via conducting cable where they were displayed and saved on 1/4\" cassette tape. &nbsp;Data were also passed from the deck unit to a CBM microcomputer for real time processing, &nbsp;storage on floppy disc, printing, and plotting.</p>

<p>A variety of towing strategies were used (Figures 1 and 2). Four long horizontal tows &nbsp;with the MOCNESS maintained approximately 100 m above the sea floor in approximately 2000 &nbsp;meters of water were taken both along the axis of the Southern trough above the benthic study &nbsp;area and perpendicular to the axis of the trought. On these tows, the system was traveling above &nbsp;the bottom at between 1 and 2 knots and eight nets were opened sequentially at about fifteen &nbsp;minute intervals. Water filtered by each net was at least 500 m^3.</p>

<p>Three oblique tows were made to 1000 m. While hauling the system back to the surface, &nbsp;nets were opened and closed to sample the following depth strata: 1000-850, 850-700, 700-550, &nbsp;550-400, 400-300, 300-200, 200-100, 100-0m. Volume of water filtered by each net was &nbsp;between 500 and 1000 m3 . Two additional oblique tows were made to sample from within 50 meters of the bottom in the Southern Trough area to 850 m. The depth strata sampled were: &nbsp;1950-1800, `800-1700, 1700-1600, 1600-1450, 1450-1300, 1300-1150, 1150-1000, 1000-850 m &nbsp;and approximately 1000 m3 was filtered by each net. On the second of these tows, batteries in &nbsp;the underwater unit failed, and only depth specific samples from 1950-1800 and 1800-1700 m &nbsp;were obtained. A single oblique tow sampling 25 m intervals from 200 m to the surface was &nbsp;obtained on the last night of the MOCNESS work.</p>

<p>As part of this investigation, F. Manrique made visual and photographic observations of &nbsp;the plankton throughout the water column and especially in the vicinity of the deep-sea floor &nbsp;during ALVIN dive #1609 (1August 1985).<br />
This combination of tows (a total of 85 samples) and ALVIN observations provides a &nbsp;rather complete characterization of the vertical distribution of zooplankton populations from the &nbsp;deep-sea floor to the sea surface in the Guaymas Basin region. In addition, the horizontal &nbsp;distribution of zooplankton in the bottom water zone above this hydrothermal vents area an, for &nbsp;the first time, be studied and the results placed in the larger context of the distribution of the &nbsp;zooplankton in the water column as a whole.</p>

1985年7月“亚特兰蒂斯二世号”（R/V Atlantis II）航次AII-112-28站位瓜伊马斯盆地热液喷口区的MOCNESS-CTD数据。前3次拖曳作业的cond_sal列记录电导率数据，后续拖曳则记录盐度数据。

本数据集源自航次报告：
多网开合环境传感系统（Multiple Opening/Closing Net and Environmental Sensing System，简称MOCNESS）于1985年7月26日至8月1日期间，在瓜伊马斯盆地深海喷口研究区（南部海槽）开展浮游动物采样。本次采样旨在刻画热液喷口活动周边100米海底范围内的浮游动物种群特征，并将该区域捕获的浮游动物与喷口直接影响范围外的邻近区域及喷口区上方水柱中采集的个体进行对比分析。

本次采样使用MOCNESS-1系统完成。该系统搭载9张孔径为1平方米的333微米尼泰克斯（nitex）尼龙网网具，当拖曳框架与垂直方向呈45°角时，网口有效面积为1平方米。系统配备Sea Bird温盐传感器、下行光传感器、12kHz测深声呐、压力传感器、改装型TSK流量计及倾角仪。传感器采集的数据通过传输电缆上传至甲板单元，经显示并存储于1/4英寸盒式磁带中；同时数据也会从甲板单元传输至CBM微型计算机，用于实时处理、软盘存储、打印及绘图。

本次研究采用多种拖曳策略（见图1、图2）。在水深约2000米的区域，系统维持在海底上方约100米处，共完成4次长距离水平拖曳，拖曳路径分别沿南部海槽底栖研究区轴线及垂直于海槽轴线方向。拖曳过程中，系统以1至2节的航速在海底上方航行，每隔约15分钟依次开启8张网具，每张网具过滤的水体体积至少为500立方米。

共完成3次斜向拖曳作业，最大作业深度达1000米。在将系统回收至海面的过程中，通过开合网具对以下深度层采样：1000-850米、850-700米、700-550米、550-400米、400-300米、300-200米、200-100米、100-0米。每张网具过滤的水体体积介于500至1000立方米之间。另有2次斜向拖曳，采样范围为南部海槽区域海底上方50米至850米水深区间，采样深度层包括：1950-1800米、1800-1700米、1700-1600米、1600-1450米、1450-1300米、1300-1150米、1150-1000米、1000-850米，每张网具过滤水体约1000立方米。其中第二次拖曳时，水下单元电池失效，仅获取1950-1800米及1800-1700米深度层的专属样品。在MOCNESS作业的最后一晚，还完成1次斜向拖曳，以25米为间隔对200米水深至海面的水体进行采样。

作为本次调查的一部分，F·曼里克（F. Manrique）在1985年8月1日的“阿尔文号”（ALVIN）深潜器第1609次下潜过程中，对全水柱尤其是深海海底周边的浮游生物开展了目视与摄影观测。本次拖采样作业（总计85份样品）与阿尔文号观测数据相结合，完整刻画了瓜伊马斯盆地区域从深海海底至海面的浮游动物种群垂直分布特征。此外，本次研究首次实现热液喷口区上方底层水带中浮游动物水平分布的探究，并将研究结果置于整个水柱浮游动物分布的宏观背景下分析。