Abstract:

This dataset lists the compound-specific carbon stable isotope ratio (delta-13C) of four essential amino acids for tissue samples collected in 2015 for the food web project within the Coastal Waters Consortium II. It includes tissue samples of multiple consumers (fish, invertebrates, terrestrial vertebrates) as well as primary producers from salt marshes in southern Louisiana. These samples were analyzed at Louisiana State University. Information gathered at the time of collection for each sample in this dataset can be found in the subset file of GRIIDC dataset R4.x264.218:0001 (2015 Food Web Sample Key) by referencing the CWC ID Number.

Suggested Citation:

Johnson, Jessica, Polito, Michael J.. 2019. Southern Louisiana Marsh Food Webs: 2015 Amino Acid Compound-Specific Stable Isotope Data. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-4mhn-2q24

Purpose:

The delta-13C-AA of essential amino acids were used to characterize carbon source usage in salt marsh animals collected in Barataria Bay, Louisiana. Essential amino acids incorporate into consumer tissues from the diet with minimal modification, and they act as tracers of basal carbon energy in a food web.

Data Parameters and Units:

File: 2015_CSIA_Food_Web_sub1.xlsx CWC ID Number: code assigned to every sample collected TISSUE: part of organism analyzed for SIA-AA d13C_VAL: stable carbon isotope ratio (delta-13C) of valine in ‰ d13C_ILE: stable carbon isotope ratio (delta-13C) of isoleucine in ‰ d13C_LEU: stable carbon isotope ratio (delta-13C) of leucine in ‰ d13C_PHE: stable carbon isotope ratio (delta-13C) of phenylalanine in %. File: subset_R4.x264.218-0001_For_2015_CSIA_sub1.xlsx A subset of the complete 2015 Food Web Sample Key file (GRIIDC dataset R4.x264.218:0001), containing only the samples in this bulk stable isotope dataset. CWC ID Number: code assigned by our group to every sample collected Other ID Number: code that may have been assigned by other groups who collected the sample Collection Date: month and year of collection Site: names assigned by our group to different marsh sites Latitude: in decimal degrees Longitude: in decimal degrees Habitat/Location (measurements in meters indicate distance from marsh edge): we use this parameter to identify where in the marsh (or relative to the marsh) the sample was collected. Gear: type of gear used to collect the sample Node Group: refers to the functional group the species belongs to according to a diet literature review performed as part of a food web study (GRIIDC R4.x264.221:0002) Node Code: short version of node group Common Name: generally used name Scientific Name: genus and species, or only genus when species is unknown n: number of individual animals that make up the sample Total Length (mm): in millimeters Fork Length (mm): in millimeters Carapace width (mm): in millimeters Weight (grams): in grams Sex: male, female, or not available (unidentified) Tissue Collected: type of tissue (whole body, muscle, stomach, liver, hepatopancreas, plant) collected Collection Notes: any additional information regarding collection, storage, or processing.

Methods:

Amino acids were derivatized with methyl chloroformate and measured derivative δ13C was corrected for exogenous carbon and kinetic fractionation using the δ13C of derivatized amino acid standards of known isotopic composition, as in Walsh et al. (2014) Rapid Commun. Mass Spectrom. 28: 96-108.

Instruments:

Derivatized amino acids were separated on a Trace 1310 Gas Chromatograph (Thermo Scientific) interfaced with a GC Isolink II (Thermo Scientific). The carbon stable isotope ratios were measured on a Delta V Advantage Isotope Ratio Mass Spectrometer (Thermo Scientific).

Error Analysis:

The delta-13C-AA values are means of triplicate injections from each sample. All samples were analyzed in runs with six injections each of AA and fish muscle standards (mean precision AA standard: Val ±0.3‰, Ile ±0.6‰, Leu ±0.4‰, Phe ±0.6‰; fish standard: Val ±0.3‰, Ile ±0.4‰, Leu ±0.3‰, Phe ±0.6‰).

Individual Files: