Planform change and Fundulus SNP data for small watersheds in South Mississippi and Louisiana

Fluvial geomorphic processes and the resulting patterns of landform morphogenesis affect the distribution and connectivity of habitat patches for aquatic organisms. Human alterations to fluvial geomorphic processes may affect local habitat quality and stability, and affect connectivity of habitat patches by altering the distribution, supply, and movement of landform-generating materials. This dataset examines 17 watersheds in south Mississippi and southeastern Louisiana and was used in preparation of a manuscript addressing the hypothesis that elevated planform movement, indicative of advanced fluvial erosion, would cause fragmentation among populations of a headwater specialist (Blackspotted Topminnow Fundulus olivaceus). The dataset includes numerous spatial features derived from the NHD+ dataset used in planform measurements, spatial features digitized from NAPP and NAIP aerial imagery measuring planform characteristics and dynamics, additional metrics of each watershed, and a population genetics dataset of single nucleotide polymorphisms (SNPs) for multiple individuals at multiple sites per watershed. Associated code to recreate all analyses in the manuscript is provided.

Methods
Fluvial geomorphic measurements were collected using a remote-sensing approach with QGIS (open-source) geospatial software and National Aerial Photogrammetric Program (NAPP, 1995-1998) and National Agricultural Imagery Program (NAIP, 2019-2020) aerial imagery. River mainstems (>100km2 drainage area) were subsampled at 1km intervals with a stratified random approach (3km sampled per 10km of stream). Planform metrics used to estimate planform characteristics or dynamics (i.e., unvegetated channel width and centerlines) were digitized for each sampled reach in each time period (1990s and 2020s) and exported as shapefiles. Associated watershed metrics pertinent to gene flow were extracted directly or calculated from the NHD+ dataset (e.g., watershed size), or the National Land Cover Database 2019 dataset. Blackspotted Topminnows were sampled from multiple localities per watershed by standard fish sampling techniques. Fin clips were taken in the field, and DNA was extracted and sequenced. Raw sequence data was aligned to a reference genome, SNPs were identified, and data were filtered to produce a final SNP dataset for analysis. As filtering utilized the R package “vcfR”, which requires Linux, we additionally provide both the code and the outputs of those portions of the data analysis workflow to facilitate universal use of the dataset.