Dataset: Polyp settlement and polyp counts on experimental tiles with different levels of turf algae cover during an in-situ experiment in St. John, US Virgin Islands in August and September of 2019.

Methodology: 

Custom-fired stoneware clay tiles were deployed and conditioned on an octocoral-dominated reef in Grootpan Bay, St. John, U.S. Virgin Islands. One of three treatments was applied to each tile (n = 8 per treatment): a control, referred to as Reef; scrubbed with a soft nylon bristle brush, referred to as Scrubbed; or removed from the reef and maintained in a sea table for 15 days, referred to as Protected. Tiles were placed into 41  29  17 cm plastic containers filled with 12 L of 10 m filtered seawater. Two tiles from the same treatment were placed in each container on top of 1 cm square plastic mesh, rolled into 5 cm tall cylinders so that tiles were lifted off the bottom of the container to provide water circulation underneath. Competent planulae (n = 150) were added to each container and allowed to settle for eight days and then polyps were counted.

Nine days after adding planulae, the tiles were deployed onto the reef at Grootpan Bay, where the tiles were initially conditioned. We counted the number of polyps on the undersides of the tiles on the day of deployment (day 0) and 2, 5, 9, 14, 19, and 57 days after deployment. On 9 of the 24 tiles, polyps were also counted and mapped on days 6, 9, 11, 14, 16, 19, and 57 to assess polyp survival and quantify settlement in the field.

Location: Grootpan Bay, St. John, U.S. Virgin Islands (also known as East Cabritte in other studies) (18.309, -64.719). All tiles were deployed at this site.