Mesozooplankton size-fractionated gut fluorescence data collected during R/V Point Sur cruise PTS03 from 2016-07-24 to 2016-07-30

This dataset contains measurements of mesozooplankton gut phaeopigments and associated metadata collected from 13 sampling locations during R/V Point Sur cruise PTS03 from 2016-07-24 to 2016-07-30 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.x260.000:0028 and R4.x260.000:0003 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.