Methodology:

Still imagery was collected using a drop camera built and designed by the BAS marine engineering department (model number). Images were geolocated (using a GPS waypoint at time of image capture), and associated conductivity, temperature and depth (CTD) + turbidity data were collected from a Swift CTD attached the legs of the drop camera frame. Drop cam was lowered to seabed where the first image was taken and assessed for quality. The vessel was allowed to drift approximately 2 metres and then the process was repeated. Twenty images were taken at each site. Images were edited for white balance and contrast. Identification and counts of all taxa were made upon review of the images.

Video was collected using an ROV which was flown at approximately 1 m above the seabed. Transects differed in length, between 15 minutes to over an hour, depending on light levels and power consumption of the ROV. Stills were extracted from the ROV video by a random number generator to decide on which frame of video was used. ROV stills were analysed in the same manner as the drop cam images.

A novel sediment profiler (SeaPen) device was used to measure the hardness of the seabed by depth of penetration of a needle under a weight. As with the Dropcam imagery, the frame was lowered to the seabed, until contact was made, at which point the operator allowed the weighted bar to free fall from the set distance (40cm). The device used a GoPro attached to the legs to film the needle (attached to the weighted bar) penetrating the seabed. This footage was reviewed later to determine the depth of penetration.

Timelapse Cameras were also set up to overlook the survey area from above the operations and flight tower at Rothera Research station. Images were set to an interval of 1 every 10 minutes, which were converted into a timelapse video. Iceberg movement was observed to manually assess water current speed and direction.

There are additional maps that include the Zone sites, including transects of the ROV, Drop Cam, SeaPen and CTD deployments.

Data collection:

The following instruments and software were used:

Drop Cam (Built by BAS Antarctic Marine Engineers)

ROV (Boxfish Luna)

CTD + turbidity (Valeport SWiFT)

Steel sediment hand scoop

SeaPen (Built by BAS project staff and AME)

Endecott Minor 200 sieve shaker with 7 test sieves (4.00 mm, 2.36 mm, 1.0 mm, 500 nanometres, 250 nanometres, 125 nanonetres, 63 nanometres and receiver pot)

Timelapse Cameras (Brinno TLC2020-C)

GoPro (Hero 10)

PRIMER 7.0.24

R Studio 2024.09.1

Data quality:

Still imagery was quality assured in-situ via a live-view screen, this allowed repeated images to be taken assuring enough data from each site. Images were identified twice to allow an overlap for quality control. The CTD was calibrated by Valeport. All taxa in the sediment samples were identified under microscope. Images of and a subsample of taxa were sent to experts for further identification.

The ROV video stills were only accepted under strict criteria. The ROV needed to be at less than 1 m altitude above the seabed, at an angle of 45 degrees or greater. The frame needed to be in focus with adequate lighting for species identification.

The SeaPen required the GoPro's to be reviewed on a computer screen. As such repeat data collection trips were made to certain sites to make sure enough data was collected per site.