Mesozooplankton Size-Fractionated Dry Weight, cruise PTS02, Spring 2016

Mesozooplankton samples were taken during the spring of 2016 between March 30 and April 9 aboard R/V Point Sur 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. 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 in two aliquots using a Folsom Splitter aboard the ship. The 1/2 aliquot separated from the original sample was then split further in two subsamples: one was used to measure mesozooplankton dry weight and the other was processed for gut fluorescence (data reported in GRIIDC UDI: R4.x260.000:0035). 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 classes 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. Next, each size fraction was filtered onto pre-weighted nitex circles (2.5 mm diameter) with a 0.202 mesh size. Nitex circles were individually put in labeled plastic petri dishes and stored stacked inside sealed plastic bags to avoid moisture from getting in touch with the nitex before using them. After fractionation, each sample was poured onto a nitex circle using a filtering system aboard the ship, rinsed with DI water, transferred to its pre-labeled petri dish and frozen immediately after filtering. At the lab, the samples were dried up in an oven at 60 degrees Celsius over a period of 48 hours and weighted immediately after taking each sample out of the oven. The difference between the weight of the filter minus the weight after drying the sample constituted the mesozooplankton dry weight. These data will be used in combination with other mesozooplankton net data to study zooplankton processes in the river-dominated northern Gulf of Mexico.

中型浮游动物样本于2016年春季（3月30日至4月9日）在Point Sur号考察船（R/V Point Sur）上使用微型生物网（BIONESS）拖曳系统采集。样本来自三个网具，分别对应三个深度区间（如底层、中层、表层）。网具网眼尺寸为202微米，但部分样本来自网眼尺寸为0.333微米的网具。样本回收后立即转移至桶中，并加入碳酸水以阻止或避免个体浮游动物进一步的“网食行为”或反刍。通常，每个网样在船上使用福尔松分样器（Folsom Splitter）分为两等份。从原始样本中分离出的1/2等份进一步分为两个子样本：一个用于测量中型浮游动物干重，另一个用于肠道荧光分析（数据报告于GRIIDC UDI：R4.x260.000:0035）。若样本浓度过高，则将初始样本分为更小的等份（数据集中标注明确）。随后，使用网眼尺寸为0.212、0.5、1、2和4.75毫米的筛网，将对应等份按大小分为五类。样本分割和大小分级过程中使用过滤海水。接下来，每个大小分级样本通过船上过滤系统倒入预先称重的尼龙网圈（直径2.5毫米，网眼尺寸0.202微米）上，用去离子水冲洗后转移至预先标记的培养皿，并在过滤后立即冷冻。实验室中，样本于60摄氏度烘箱干燥48小时，取出后立即称重。滤器重量与样本干燥后重量的差值即为中型浮游动物干重。这些数据将与其他中型浮游动物网采数据结合，用于研究河流主导的墨西哥湾北部浮游动物过程。