Transect data of coral species and other substrate types collected in the field using line transects in Palau, Yap, the Federated States of Micronesia, Majuro, and Kiritimati from 2017 to 2019

As part of the reef-composition survey of Palau (7°30' N, 134°30' E) and Yap (9°32' N, 138°7' E), 10-meter long, 2 to 5-meter depth transects were conducted. Coral species along the transect were recorded along with substrate types and other organisms present. Surveys in Palau were conducted from June 2nd to June 24th, 2017, and from June 25th to July 6th, 2017 in Yap.

In Pohnpei (6.2°N, 158.2°E) and Kosrae (5.3°N, 162.9°E) FSM, six 10-meter transects were used to measure the benthic composition for every centimeter, at each site of 48 sites in 2018. Corals were recorded to species level, except massive Porites and encrusting Montipora, which were recorded in the field as growth forms. All other organisms along each transect were identified to the highest possible taxonomic resolution.

In Majuro (7.0667° N, 171.2667° E) and Kiritimati (1.8721° N, 157.4278° W), a stratified random sampling approach was used to survey the reefs in2019. At both locations, the sites were stratified as either (i) outer reefs, or (ii) patch reefs in lagoons. The number of sites sampled per habitat varied according to the area of available habitat at each location. Surveys were focused between 2–5 m.