Dataset: Organism counts from photo-transects collected during quantitative benthic surveys in Southwest Puerto Rico at 20m during 2013-2014 and 2018-2019.

Quantitative benthic surveys were made during 2013-2014 and 2018-2019 at two outer shelf, spur-and-groove reefs, Buoy (17° 53.380′ N; 66° 59.090′ W) and Weinberg (17° 53.429′ N; 66° 59.320′ W). The two sites are located near the insular slope, 7.2 km offshore. Diving operations involved a team of two divers using NITROX or air. Dives were made to target depths of 20 m at each site.

The modified CARICOMP protocol (Weil et al. 2002, 2009) was used to assess the spatial and temporal variability in the number, distribution along 10 × 2 m band permanent transects. Within each band transect, all coral, octocoral, zoanthid and sponge colonies were counted. Only scleractinian corals and a few octocoral species and other reef invertebrates were identified to species level.