Dataset: Organism counts from photo-transects collected during quantitative benthic surveys in Southwest Puerto Rico at 50 and 70 m during 2018 and 2019

Location: Caribbean Sea, Southwest Puerto Rico, Lat. 17.8849 Long. -67.01546

Quantitative benthic surveys were made during 2018-2019 at two mesophotic sites El Hoyo (672.460 W, 1752.530 N) and Hole-in-the-Wall (671.330 W, 1753.070N). The two sites are located along the insular slope 11 km south of La Parguera, 44 km to the west.  The benthic surveys followed the methodology in Appeldoorn et al. (2015). Diving operations involved a team of three technical divers using closed-circuit rebreathers. Dives were made to target depths of 50 and 70 m at each site. Upon reaching the target depth, divers conducted a continuous high-resolution benthic phototransect 10 m long by 40 cm wide. The photo-transect consisted of 16 sequential quadrat photographs, each 40 x 60 cm. For each 40 x 60 cm digital photograph, benthic taxa (e.g. algae and scleractinian corals) were recorded.

For each 40 x 60 cm digital photograph, percent cover was calculated by overlaying 100 random points using Coral Point Count with an Excel extension (CPCe) (Kohler and Gill 2006). Identifications associated with the random points were classified into 29 ‘‘taxa’’ that focused primarily on the algae and scleractinian corals as follows: corals (13 spp.), gorgonians, sponges, algae (12 taxa including cyanobacteria), sand and pavement.