Dataset: Port Fourchon, LA species range data from presence and absence data from 2002, 2014, and 2022

Location description:   All data for this analysis were collected near Port Fourchon, Louisiana, USA (29.10 °N, 90.19 °W). The marshes around the port are microtidal, with a mean tidal range of ~0.37 m. The site sits at the precise edge of black mangrove expansion into saltmarsh habitats and although some land loss in the areas has occurred, mangroves in the area have been expanding since the 1990s (Osland et al., 2013). 

Species Collections

All species in this study were collected using a drop sampler method specifically designed for flooded marsh habitats, providing a standardized approach across sampling years. The design of the drop samplers used in 2005, 2015, and 2022 varied slightly in terms of construction materials and deployment mechanisms to adapt to equipment improvements over time, but the essential structure remained the same. Each sampler employed a 1-m² cylinder, suspended from a boom arm, to minimize disturbance prior to deployment. The cylinder was rapidly lowered to enclose a section of flooded marsh habitat, ensuring precise capture of benthic and water-column organisms (Nelson et al., 2019; Zimmerman et al., 1984).

Once the sampler was in position, a submersible pump was used to evacuate the water inside the cylinder to concentrate captured organisms. Special care was taken to prevent loss of organisms during pumping by filtering the outflow through a fine mesh screen. After the water was removed, captured animals were collected manually or with fine nets, transferred to containers with preservatives appropriate for long-term identification and analysis, such as ethanol or formalin. Each sample was meticulously labeled with the date, location, and environmental parameters at the time of collection to facilitate later analysis. Salinity, water temperature, and depth were also recorded at each sampling event to characterize habitat conditions during collection.

All samples were transported to the laboratory for taxonomic identification. Species were identified to the lowest taxonomic level possible, typically genus or species, with multiple experts cross-validating questionable identifications to ensure data quality.