Methodology:

OFOBS Data was collected on the AWI Polarstern cruise PS118 from April-May 2019 in order to assess epibenthic megafauna communities and establishing temporal baselines for comparison with future studies. OFOBS photos contain latitude, longitude, and the water depth at which the photo was taken. Each photograph had three laser dots placed in an equilateral triangle (50 cm sides) near the center of the photograph.

We annotated two profiles: Profile 69_1 (Powell Basin, approx. 2000 m water depth) and Profile_6_9 (Weddell Sea, approx. 420m water depth), as these two profiles provided the maximum variation in substrate and water depth for this cruise. Photo annotations were made on Inkscape. We scaled each photo using the laser dots and used a sample box of 1.5m x 1.5 m for annotations for the Powell Basin, and 2 m x 1.5 m for the Weddell Sea. We identified, at least to class, often to genus and species levels, every macrobenthic organism visible in the photographs. Bounding boxes were ellipses.

Images can be downloaded from PANGAEA.

Annotations are found in the two csv files: "OFOBS_annotations_Powell_Basin.csv", "OFOBS_annotations_Weddell_Sea.csv".

The headers in these files refer to:

Morphotaxa - the best possible ID name for the observed individual

Ids - an object ID assigned by Inkscape when annotating

rx - the length of the ellipse (mm)

ry - the width of the ellipse (mm)

Area - the area of the ellipse (mm2), calculated using (0.5rx)*(0.5ry)*pi

Image - the filename of the annotated image. These images can be downloaded from PANGAEA.

These annotations were then condensed into site-by-taxa matrices in R. These can be found in the two further CSV files: "Abundance_Powell_Basin.csv", "Abundance_Weddell_Sea.csv".

The headers in these files refer to:

Image - the filename of the image.

encrustor_percentage (%) - an estimate of area coverage of the substrate by organisms - they are likely hard parts that settle on/are attached to the seafloor - they may be disarticulated/broken portions of stylasterids, lace corals, cup corals, or urchin spines, i.e., impossible to ascertain provenance.

Other columns - morphotaxa observed.

Data collection:

Inkscape Version 1.1

R

Data quality:

Annotations are made to the lowest taxonomic level possible based on the resolution of the seabed photographs.