Abstract:

This dataset contains larval fish diet and stable isotope data collected on board the R/V F.G. Walton Smith during Natural Resource Damage Assessment (NRDA) Plankton Survey Walton Smith 4 (WS4) in the northern Gulf of Mexico from 2011-04-20 to 2011-05-27. This survey (WS4, chief scientist: Malinda Sutor) was part of a series of NRDA cruises conducted in 2010 and 2011 to evaluate the distribution and densities of ichthyoplankton and other zooplankton in Gulf of Mexico waters potentially affected by the Deepwater Horizon Oil Spill (DWHOS) and in surrounding areas. Archived fish samples collected from one deep-pelagic plankton cruise (Walton Smith 4) conducted during the Deepwater Horizon NRDA were used to identify trophic (diet and bulk-tissue stable isotope) analyses of larval and juvenile deep-pelagic fishes within four dominant mesopelagic fish families (Myctophidae, Gonostomatidae, Sternoptychidae, Phosichthyidae). Samples were analyzed for stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) using a Thermo Delta V stable isotope ratio mass spectrometer coupled to a Costech 4010 elemental analyzer by a Thermo Confo IV continuous flow interface. Isotopic values were calculated relative to conventional standards for each element of interest and expressed in standard delta (δ) notation. Corresponding data sets for the specimens in this dataset can be found under the GRIIDC Unique Dataset Identifiers (UDIs): R6.x815.000:0006 (doi: 10.7266/n7-9vcj-nf90; MOCNESS instrument data), R6.x815.000:0010 (doi: 10.7266/n7-dp76-tz89; Ichthyoplankton data), R6.x815.000:0021 (doi: 10.7266/n7-9kwb-eh85; Zooplankton abundance data), R6.x815.000:0022 (doi: 10.7266/n7-q8s5-b255; Zooplankton imagery), and R6.x815.000:0034 (doi: 10.7266/WTSDCS65; Zooplankton stable isotope data).

Suggested Citation:

Gipson, Emily, Carley Zapfe, Verena Wang, Kevin Dillon, and Frank Hernandez. 2021. Larval fish diet and stable isotope data collected during NRDA Plankton Survey Walton Smith 4 (WS4) in the northern Gulf of Mexico from 2011-04-20 to 2011-05-27 on board the R/V F.G. Walton Smith Cruise WS1107. Distributed by: Gulf of Mexico Research Initiative Information and Data Cooperative (GRIIDC), Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-fhn0-k550

Purpose:

The purpose of these data is to describe diets and trophic linkages for dominant, deep-pelagic larval and juvenile fishes using gut content analysis and bulk-tissue stable isotope analysis.

Data Parameters and Units:

Fish Sample ID [Full sample ID for each individual fish specimen]; SAMPLE_TAXON_ID [Unique identifier for the taxonomic sample within each depth-discrete net sample (Field Sample ID + Sort Category + unique identifier)]; Field Sample ID [Unique identifier for each depth discrete net sample within the MOCNESS tow]; DeploymentID [Unique identifier for each MOCNESS tow]; FishID [Identifier assigned to each specimen removed from the same sample vial for analysis (Taxon - n); not unique among vials]; Family [Family level taxonomic identification]; Taxon [Lowest taxonomic identification]; Sample Date [Date sample was collected, M/DD/YYYY]; StationID [Station name (B# stations are from the NOAA SEAMAP Grid)]; DayNightSample [Time of day associated with the sample. Day (D) is 1 hour after sunrise to 1 hour before sunset. Night (N) is 1 hr post-sunset to 1 hr pre sunrise]; StartLat [Start latitude of the tow, decimal degrees]; StartLon [Start longitude of the tow]; UpperDepth [Minimum depth sampled by depth-discrete net (m)]; LowerDepth [Maximum depth sampled by depth-discrete net (m)]; Life Stage [Developmental stage]; SL [Standard length (mm)]; SIA ID [Specimen identifier for stable isotope analysis (SIA). SIA ID is equivalent to Fish Sample ID if one individual fish was analyzed. If multiple fish were combined for SIA, SIA ID is the Fish Sample ID of one fish from the combined sample with 'c' appended. E.g., 3 fish (Fish Sample ID: S5548-I-L001 M. wei-6, S5548-I-L001 M. wei-7, S5548-I-L001 M. wei-8) were combined into one stable isotope sample (SIA ID: S5548-I-L008 M. wei-8c), with the same 13C and 15N values reported for all individual fish within the combined stable isotope sample]; 13C [Stable carbon isotopic ratio (δ13C)]; 15N [Stable nitrogen isotopic ratio (δ15N)]; Gut Intact [Whole gut tract intact at the time of removal (Y- Yes, N- No, YSL - Yolk Sack Larvae)]; Gut Fullness [Amount of contents found in gut; on a scale of 0-3 with 0 being empty and 3 being 90% full or greater]; Cladoceran [Gut Contents - number of cladocerans present]; Whole Copepod [Gut Contents - number of whole copepods present]; Invert Egg [Gut Contents - number of invert eggs present]; Polychaete Segments [Gut Contents - number of polychaete segments present]; Invert Egg Sack [Gut Contents - number of invert egg sacks present]; Crustacean Fragments [Gut Contents - number of crustacean fragments present]; Copepod Head [Gut Contents - number of copepod heads present]; Chaetognath Mouthparts [Gut Contents - number of chaetognath mouthparts present]; Ostracod [Gut Contents - number of ostracods present]; Unid [Gut Contents - presence (1) or absence (0) of unidentified amorphous contents]; Copepod Fragment [Gut Contents - number of copepod fragments present (unidentified copepod - order unknown)]; Nauplii [Gut Contents - number of nauplii present]; Amphipod [Gut Contents - number of amphipods present]; Whole Cyclopoid Copepod [Gut Contents - number of whole cyclopoid copepods present]; Euphausid [Gut Contents - number of euphausids present]; Copepod Metasome [Gut Contents - number of copepod metasomes present (unidentified copepod - order unknown)]; Foraminefera [Gut Contents - number of foraminefera present]; Calanoid Copepod [Gut Contents - number of calanoid copepods present]; Bivalve [Gut Contents - number of bivalves present]; Fish Scale [Gut Contents - number of fish scales present]; Barnacle Cyprid [Gut Contents - number of barnacle cyprids present]; Gastropod [Gut Contents - number of gastropods present]; Harpacticoid Copepod [Gut Contents - number of harpacticoid copepods present]; Cyclopoid Copepod Head [Gut Contents - number of cyclopoid copepod heads present]; Euphausid Fragment [Gut Contents - number of euphausid fragments present]; Pteropod Shell [Gut Contents - number of pteropod shells present]; Radiolarian Fragments [Gut Contents - number of radiolarian fragments present]. Please note that NA = specimen analyzed for gut contents only, no stable isotope analysis; and unidentified copepod = order unknown.

Methods:

Specimens were measured for standard length (SL) prior to gut removal. Guts were removed from specimens while minimizing damage to the fish and the gut. Diet analysis for larvae largely followed the methods of Llopiz and Cowen (2008). Stomach contents were identified to the lowest taxonomic resolution, and intact prey were measured. Fish were transferred from 85% EtOH to deionized water, with water changes conducted every 24 hours for 2 days to remove residual preservative. Fish were dried at 60 °C for 24 hours, weighed (0.3 - 0.5 mg target weight), and packed whole into 5 x 9 mm Costech tin capsules. When necessary, multiple small fish from the same field sample (identical taxa from the same depth-discrete net tow) were combined to reach the required amount of material (see SIA ID header description to identify combined individual specimens). Large fish specimens were ground prior to weighing and packing. Bulk tissue stable isotope analysis was conducted at the University of Southern Mississippi Marine Ecosystems Research Laboratory. Samples were analyzed for stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) using a Thermo Delta V stable isotope ratio mass spectrometer coupled to a Costech 4010 elemental analyzer by a Thermo Confo IV continuous flow interface. Isotopic values were calculated relative to conventional standards for each element of interest and expressed in standard delta (δ) notation. Bulk tissue stable isotope analysis was conducted at the University of Southern Mississippi Marine Ecosystems Research Laboratory. Samples were analyzed for stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) using a Thermo Delta V stable isotope ratio mass spectrometer coupled to a Costech 4010 elemental analyzer by a Thermo Confo IV continuous flow interface. Isotopic values were calculated relative to conventional standards for each element of interest and expressed in standard delta (δ) notation.

Instruments:

Microbalance Thermo Delta V stable isotope ratio mass spectrometer Costech 4010 elemental analyzer

Provenance and Historical References:

Llopiz Joel K., Robert K. Cowen. 2008. Precocious, selective, and successful feeding of larval billfishes in the oceanic Straits of Florida. Marine Ecological Progress Series 358:231-244. https://doi.org/10.3354/meps07320

Individual Files: