Supervised classification utilized training texels of 30 x 30 to 90 x 90 pixels cut from GeoTiff orthotiles centered on the coordinates of the grab sample stations. Each texel was assigned to a cluster training set based on that sample’s classification in the original (latent) cluster analysis calculated on similarity of sediment characteristics. However, none of the potential 2470 combinations of backscatter signal characters and their treatments were able to discriminate significantly among these 5 classes, meaning that variation among samples of at least 2 classes overlapped considerably. Recombination into 4 classes (combining Classes 3 and 4) yielded significant discrimination. Mapping of the results showed that one of these classes was likely to be legitimate when applied to the bayside, but additionally was duplicated as an artifact of edge between orthotiles on the oceanside because of fading at the swath margins. This means that backscatter was characteristic of the larger habitat distinctions shown in the latent dendrogram with confidence, and of lesser branches with less confidence. Therefore, the entire oceanside was characterized as one habitat, and classification of the bayside was attempted again in isolation. Recombination into 3 classes (“mud”, “sand”, “gravelly sand”) was able to resolve 3 classes significantly (score = 0.33548) using input factors Contrast, Gray Mean, and Directionality with 30 x 30 pixel (15 x 15 m) texels. Despite good separation in the training texels, with some slight overlap at the 5% confidence ellipsoid for mud and gravel, most areas known to be muddy were classified as being gravelly sand in the resulting classification map. This is likely a function of reflective shell hash in acoustically dark mud having similar contrast to reflective gravel with acoustically dark shadows created by high relief. A test of natural separation (Davies-Bouldin Index) indicated four modes using these characters, so the same factors were used in an unsupervised classification allowing four latent classes. The four latent classes mapped very similar to the previous supervised classification but broke up the latent analog to the “gravelly sand” class. Class error was low at 0.1110. The newly resolved class was clearly mud with shell, based on video ground truthing. This class was combined with the mud class in compiling the final habitat classification map.

This dataset contains sediment grain-size classification data develop from during acoustic surveys completed along the 58‐km long Assateague barrier island stretching from the Ocean City inlet in Maryland, down past Chincoteague Island in northern Virginia. The data was collected June 20th-25th, 2014 and May 12th - 21th, 2015. Full coverage side-scan sonar and partial coverage bathymetry data were collected using an EdgeTech 6205 Multiphase Echosounder. In total, 73 square kilometers were mapped at primarily at 100m line spacing and 80 m swath range per channel (to allow overlap between lines).

Benthic habitat maps were developed for the CACO study areas following the top-down mapping approach, for which habitat map units are geologically defined based on the presumption that geologic environments or features contain distinct biological assemblages. The resulting habitats are classified according to the CMECS framework and are referred to as “biotopes.” The term “biotope” is specific in that it integrates biotic-abiotic characteristics to offer more ecologically meaningful information. In this study, biotopes reflect the relationship between macrofaunal communities and geological features of their associated environments within the defined map units. The resulting biotopes are considered preliminary because the relationships identified have not been repeatedly demonstrated over time.

Benthic habitat maps were developed for the Otis Pike and Sunken Forest study areas following the top-down mapping approach, for which habitat map units are geologically defined based on the presumption that geologic environments or features contain distinct biological assemblages. The resulting habitats are classified according to the CMECS framework and are referred to as “biotopes.” The term “biotope” is specific in that it integrates biotic-abiotic characteristics to offer more ecologically meaningful information. In this study, biotopes reflect the relationship between macrofaunal communities and geological features of their associated environments within the defined map units. The resulting biotopes are considered preliminary because the relationships identified have not been repeatedly demonstrated over time, as this study represents the first of its kind within FIIS.

Mapping extent of acoustic surveys completed along the 58‐km long Assateague barrier island stretching from the Ocean City inlet in Maryland, down past Chincoteague Island in northern Virginia. The data was collected June 20th-25th, 2014 and May 12th - 21th, 2015. Full coverage side-scan sonar and partial coverage bathymetry data were collected using an EdgeTech 6205 Multiphase Echosounder. In total, 73 square kilometers were mapped at primarily at 100m line spacing and 80 m swath range per channel (to allow overlap between lines).

Water-level data used in submerged marine habitat mapping, Assateague Island National Seashore

This dataset summarizes the species information derived from ground-truth survey conducted along Assateague Island National Seashore in October 2014 and October 2015. The ground-truth survey consisted of grab samples taken with a modified Young grab sampler. Grab samples were taken at each site. The attribute table of this dataset contains information about the grab samples, including the name and coordinates for each sample site, date of collection, and the species composition of each sample.

This dataset shows the bathymetry data collected during acoustic surveys completed within and adjacent to the boundaries of Cape Cod National Seashore (CACO) from 2014-2015. Full coverage sidescan and partial coverage bathymetry data were collected using an Edgetech 6205 Phase-Measuring Sidescan Sonar. In total, 668 hectares were mapped at primarily 20 – 40 meter line spacing and 50 meter swath range to allow overlap of lines.