Abstract:

This dataset contains the compound-specific stable carbon isotope values for twelve fatty acids from the primary producer (n = 6 species) and consumer (n = 16) tissues collected from 2015-2017 from eight sites in southern Louisiana. The compound-specific stable carbon isotope samples were analyzed at the WasserCluster Lunz - Biologische Station Inter-University Center for Aquatic Ecosystems Research (Lunz, Austria). Sample collection information is also presented.

Suggested Citation:

Olin, J.A.. 2020. Compound-specific stable isotope analyses of fatty acids of salt marsh species from 2015-05-01 to 2017-06-30. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-jdgx-js58

Purpose:

This dataset summarizes the compound-specific stable carbon isotopes values of fatty acids of multiple primary producers, invertebrate and vertebrate consumers in southern Louisiana salt marshes. Compound-specific stable carbon isotopes of these select fatty acids profiles of consumers reflect the carbon source of their diet items. Therefore, these data can be used to understand carbon flow in species and across food webs.

Data Parameters and Units:

Worksheet “CSIA-FA”: CWC_ID: user-defined code assigned to every sample; Other_ID: code that may have been assigned by other groups who collected the samples; Date: Month-Year the samples were collected; Season: season in which samples were collected; Year: year samples were collected; Area: location description for the particular area where samples were collected; Site: user-defined codes assigned to each sampling site; Habitat_Location: habitat description where samples were collected (Marsh platform); Latitude: latitude of sampled sites in decimal degrees; Longitude: longitude of sampled sites in decimal degrees; Node_Group: refers to the functional group the species belongs to according to existing literature; Node_Code: short version of node group; Species: lowest taxonomic unit to which the specimen could be identified; Common Name: generally used name; Tissue_Type: tissue type or matrix that was analyzed; CSIA-FA_Laboratory: where the samples were analyzed; Fatty acid composition of each sample, measured as proportions for different fatty acids. Each fatty acid is identified by its nomenclature. Worksheet "FA_Information”: Molecular formula and types of the fatty acids reported in worksheet "CSIA-FA”. Please note MUFA = Monounsaturated Fatty Acids; PUFA = Polyunsaturated Fatty Acids; and SFA = Saturated fatty Acid.

Methods:

Tissues were freeze-dried for 24 to 48 hours, homogenized into a powder. Fatty acid profiles were quantified using a three-step procedure: (1) triplicate extractions of freeze-dried tissue in a 2:1 chloroform/methanol solution for gravimetric determination of the total lipid (Folch et al. 1957); (2) derivatization of FA methyl esters (FAME) using sulfuric acid in methanol (1:100 mixture; Morrison and Smith 1964, Christie 1989); and (3) identification and quantification of FAME. Compound-specific stable isotope analyses were used to assess the origin and isotopic composition of different FA molecules. Fatty acids were separated using a gas chromatograph (Trace 1310 Thermo™) with helium as the carrier gas. The GC was coupled to an Isolink 2 where the separated FA were combusted at 1,000°C. The generated CO2 was transported with the carrier gas (helium) to the Conflo IV where each sample was diluted with the carrier gas helium and connected with the reference CO2 gas. Finally, all CO2 molecules were analyzed in the IRMS (Delta V Advantage).

Error Analysis:

The delta13C values were calibrated using a standard mixture of eight n-alkanoic acid ethyl and methyl esters (supplied by Indiana University Stable Isotope Reference Materials), where the r2 of the measured versus expected relationship was >0.99. Analytical precision was tracked using a C16 FA laboratory standard, which was analyzed after every tenth sample, which was 0.8 % (representing the 1 SD of 14 analyses of the C16 FA standard interspersed during the sample run).

Provenance and Historical References:

Christie, W. W. (1989). Gas chromatography and lipids. PJ Barnes and Associates (The Oily Press), Bridgewater, UK Folch, J., Lees, M., & Stanley, G. S. (1957). A simple method for the isolation and purification of total lipids from animal tissues. Journal of biological chemistry, 226(1), 497-509. Morrison, W. R., & Smith, L. M. (1964). Preparation of fatty acid methyl esters and dimethylacetals from lipids with boron fluoride–methanol. Journal of lipid research, 5(4), 600-608.

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