Mesozooplankton size-fractionated gut fluorescence data collected during R/V Point Sur cruise PTS02 from 2016-03-30 to 2016-04-09

This dataset contains measurements of mesozooplankton gut phaeopigments and associated metadata collected from 20 sampling locations during R/V Point Sur cruise PTS02 from 2016-03-30 to 2016-04-09 in the Mississippi Bight, Gulf of Mexico. Mesozooplankton samples were taken during the spring of 2015 using a mininess (BIONESS) tow system. Samples were taken from three nets, corresponding to three depth intervals (e.g., bottom, midwater, surface). Nets had 202-micrometer mesh size, but in some cases, samples were taken from nets with 0.333-micrometer mesh due to system issues. Samples were transferred into a bucket immediately after retrieval and carbonated water was added to the sample to stop or avoid further 'net feeding' or regurgitation from individual zooplankton. Typically, each net sample was split into two aliquots using a Folsom Splitter aboard the ship. The 1/2 aliquot separated from the original sample was then split further into two subsamples: one was used to measure mesozooplankton gut fluorescence and the other was processed for dry weight (reported separately). When samples were too thick, the initial sample was split into smaller aliquots (clearly indicated in the dataset). The corresponding aliquot was then size fractionated into five size bins using sieves with meshes measuring: 0.212, 0.5, 1, 2, and 4.75 mm. Filtered seawater was used during sample split and size fractionation. After fractionation, each sample was poured onto a GF filter (2.5 mm diameter) using a filtering system aboard the ship, rinsed with DI water, wrapped in aluminum foil and quick-frozen immediately after filtering by depositing the sample into liquid nitrogen. Before filtering, each sample was kept in the dark in an ice bath. Samples were processed following Strickland and Parsons (1968) spectrophotometric determination of phaeopigments protocol. These data will be used in combination with other mesozooplankton net data to study zooplankton processes in the river-dominated northern Gulf of Mexico. Data is reported in units of micrograms of phaeopigments per liter. Related mesozooplankton size-fractionated dry weight data and BIONESS profile data are available under GRIIDC UDIs R4.x260.000:0027 and R4.x260.000:0002 respectively. The gut fluorescence data come from the same net analyzed for dry weight, and both gut fluorescence and dry weight data come from the net tows, BIONESS profile datasets, which contains all the detailed information about the station, net start/end coordinates, and sampling information.

本数据集收录了2016年3月30日至2016年4月9日期间，在墨西哥湾密西西比湾（Mississippi Bight）执行的R/V Point Sur航次PTS02中，于20个采样站位获取的中型浮游动物（mesozooplankton）肠道褐色素（phaeopigments）测量数据及相关元数据。
中型浮游动物样品采集于2015年春季，采用mininess（BIONESS）型拖网系统完成采样。样品分别从三张网具中获取，对应三个水深分层（例如底层、中层、表层）。所用网具的网目尺寸为202微米，但部分情况下因系统故障，采用了网目尺寸为0.333微米的网具采集样品。
样品被打捞上船后立即转移至桶中，并加入碳酸水以终止或避免浮游动物个体出现“网食”或反吐现象。通常情况下，每份网采样品会通过船上的福尔萨姆分样器（Folsom Splitter）均分为两份子样。从原始样品中分离出的1/2子样会进一步被拆分为两份次级子样：一份用于测量中型浮游动物肠道荧光值，另一份用于干重测定（相关数据将单独发布）。
当原始样品量过大时，会先将其拆分为更小的子样（数据集内已明确标注）。随后通过孔径分别为0.212、0.5、1、2及4.75毫米的筛网，将对应子样按尺寸分为5个分级区间。样品分样及尺寸分级过程中均使用过滤海水。
分级完成后，使用船上的过滤装置将每份样品转移至直径2.5毫米的GF滤膜（GF filter）上，随后用去离子水冲洗，并用铝箔包裹，过滤完成后立即将样品浸入液氮中快速冷冻。过滤前，所有样品均避光置于冰浴中保存。
样品的处理流程遵循斯特里克兰德和帕森斯（1968）提出的分光光度法测定褐色素的标准规程。本数据集将与其他中型浮游动物网采数据结合，用于研究以河流输入为主的墨西哥湾北部海域的浮游动物生态过程。
数据集以每升微克褐色素为单位进行记录。相关的中型浮游动物尺寸分级干重数据及BIONESS剖面数据可分别通过GRIIDC唯一数据标识符（UDIs）R4.x260.000:0027与R4.x260.000:0002获取。
肠道荧光值数据与干重测定数据取自同一网具采集的样品，且两类数据均来自BIONESS剖面数据集，该数据集包含了站位、网具起止坐标及采样信息的全部详细内容。