Abstract:

This dataset lists the compound-specific carbon stable isotope values (delta-13C) of five essential amino acids for tissue samples collected in 2016 for the food web project within the Coastal Waters Consortium III. The dataset includes tissue samples of multiple consumers (fish, invertebrates, terrestrial vertebrates) and primary producers from salt marshes in southern Louisiana. Samples were collected using seine/gill nets (e.g. fish), sweep nets (insects), hand (ribbed mussels and plants) and filtration onto pre-combusted Whatman GF/F filters (particulate organic matter). All samples were frozen at -80degC until further processing for stable isotope analysis. All samples were analyzed at Louisiana State University.

Suggested Citation:

Moyo, S., Olin, J., Johnson, J., Lopez-Duarte, P., Roberts, B.J., Hooper-Bui, L., Bennadji, H., Polito, M.J.. 2020. Southern Louisiana Marsh Food Webs: 2016 Amino Acid Compound-Specific Stable Isotope Data. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-fx66-gp35

Purpose:

The delta-13C-AA of essential amino acids were obtained to describe carbon source used in salt marsh animals collected along a salinity gradient in Barataria Bay, Louisiana. Essential amino acids are incorporated into consumer tissues from their diet with minimal modification, and thus are suitable tracers of basal carbon resource use in food webs.

Data Parameters and Units:

CWC_ID: code assigned by our group to every sample collected; Other_ID: 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: habitat description where samples were collected (creek, creek bank, edge, embayment, main creek, marsh surface, pond, tributary creek #4); Gear: type of gear used to collect the sample; Node Group: refers to the functional group the species belongs to according to existing literature; Node Code: short version of node group; Common Name: generally used name; Scientific Name: Genus and species, Genus only when species is unknown, Order or Family when species is unknown, or general description (Particulate Organic Matter, Filamentous Green Algae); n: number of individual animals that make up the sample; Total Length (mm): in millimeters (where applicable); Fork Length (mm): in millimeters (where applicable); Sex: male, female, or not available (unidentified or not applicable); Tissue or Material Type: type of tissue (ground plant, muscle, whole body) or inert substrate material (Filters were used for Epiphytic macroalgae, filamentous green algae, and particulate organic matter) analyzed; Collection Notes: any additional information regarding collection, storage, or processing; 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_Thr: stable carbon isotope ratio (delta-13C) of threonine in ‰; d13C_PHE: stable carbon isotope ratio (delta-13C) of phenylalanine in %.

Methods:

Fish were collected using a combination of seine nets and gill nets mist nets. Invertebrates and algae were collected by hand or sweep nets. Particulate organic matter (phytoplankton) was collected by filtering water through pre-combusted Whatman GF/F (0.7µm) filters. Amino acids were derivatized with methyl chloroformate and measured derivative δ13C were corrected for exogenous carbon and kinetic fractionation using the δ13C of derivatized amino acid standards of known isotopic composition, as detailed in Walsh et al. (2014) Rapid Commun. Mass Spectrom. 28: 96-108.

Instruments:

All samples destined for delta-13C of essential amino acids were analyzed at the Stable Isotope Ecology Laboratory at Louisiana State University (LSU), Baton Rouge, Louisiana using 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 ±0.2‰, Ile ±0.3‰, Leu ±0.2‰, Thr ±0.3,Phe ±0.2‰; fish standard: Val ±0.2‰, Ile ±0.1‰, Leu ±0.2‰,Thr±0.3, Phe ±0.3‰).

Provenance and Historical References:

Walsh, R. G., He, S., & Yarnes, C. T. (2014). Compound-specific δ13C and δ15N analysis of amino acids: a rapid, chloroformate-based method for ecological studies. Rapid Communications in Mass Spectrometry, 28(1), 96–108. doi:10.1002/rcm.6761

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