Stable isotope values from coastal Louisiana mangrove and salt marsh communities in May 2016

The salt marshes along the Gulf of Mexico provide a critical habitat for many species, but their spatial distribution is changing, because black mangroves (Avicennia germinans) are expanding due to warmer winters.  This dataset provides bulk carbon, nitrogen and sulfur stable isotope values of primary producers, soil organic matter, and common aquatic consumers collected in Spartina alterniflora-dominated (salt marsh), Avicennia dominated (mangrove), and mixed (transitional) habitats at two locations in coastal Louisiana. These data can be used to assess the relative importance of specific basal carbon sources to soil organic matter and aquatic consumers across habitat types.

Methods
These data were collected in May 2016 in southeastern Louisiana along the northern coast of the Gulf of Mexico.  Samples were collected at two locations: Grand Isle (29.223626°, -90.043768°) and Bay Champagne (29.138952°, -90.178298°). Three habitat types were sampled at each location: a salt marsh area dominated by Spartina alterniflora, a mangrove area dominated by Avicennia germinans and a mixed area with vegetation transitional between these two habitat types. At each site and habitat type suspended particulate organic matter, was collected from overlying water on the habitat edge and filtered on a combusted GF/C filter.  A 3 cm diameter x 5 cm length core was collected for soil organic matter, surface sediment was extracted for benthic microalgae collection, and aquatic consumers were collected using fyke nets, wire minnow traps, suction sampling, and other quadrat-based and opportunistic methods. Samples were measured, dried, homogenized and then analyzed for carbon, nitrogen, and sulfur elemental concentrations and stable isotope values using an elemental analyzer system coupled to a continuous-flow stable isotope ratio mass spectrometer.