Surveys of Octocoral communities, benthic cover and environmental factors on coral reefs of Palau, Micronesia

All surveys were carried out by the principal researcher using Rapid Ecological Assessment. The dataset comprises 58 surveys from 10 reefs.On each reef 1-3 sites were surveyed with up to 5 transects (usually 200-300m long, 1-3m wide for 10-15 minutes) per site at pre-defined depths (1-3m, 3-8m, 8-13m, 13-18m and reef flat).Species recorded: octocorals (63 genera belonging to 24 families and 3 orders - soft corals, gorgonians, sea fans, sea whips, sea pens, leather corals, arborescent octocorals, blue coral, stoloniferans), black and wire coral. Note that species are mostly at generic level.Site variables comprise: visibility (a modified Secchi technique - estimating maximum visible distance of a bright object in metres); depth; exposure (very exposed, protected, exposed, moderate); orientation (E, NNE, etc.); formation (Point, Face, Bay/Inlet, Channel); slope angle (assigned to 5° categories); flowspeed (estimated by 5 timings of the traveling speed of suspended particles along a ruler at cm/second); wave exposure (0=sheltered to 4=very exposed); sediment deposit (0=none, 1=thin layer, 2=considerable, 3=thick layer); rubble % cover; sand % cover.Visual estimates of overall abundance (percent cover) were estimated in 2% increments from 1-10%, 5% increments from 10-30% and 10% increments over 30%). Categories are: hard corals, soft corals, dead coral, turf algae, coralline algae, macroalgae (conspicuous macroalgae - Halimeda and sargassum - were recorded separately), and total percent cover including sand and silt.Octocoral genera (in some cases species) were given a taxon abundance ranking (0=absent, 1=rare, 2=uncommon, 3=common, 4=abundant, 5=dominant).Zooxanthellate and azooxanthellate richness was calculated based on the numbers of octocoral taxa with (or without) zooxanthellae.Where applicable, samples taken for taxonomic purposes are noted.Site locations: Big Dropoff, German Channel, Heliofungia Lake, Ngerdmau, Niko Bay, Peliliu-West, PICRC House reef, Soft coral arc, Taoch Reef, Toachel Mlengui. To survey the cover of the main benthic groups, richness and abundance of octocorals in the reefs of Palau and related spatial and water quality gradients. To examine principal drivers of biodiversity, community composition, and ranges of coral reef benthos. Comparable data are held for the Great Barrier Reef, Hong Kong, Papua New Guinea, Torres Strait, and Rowley Shoals (WA).A subset of the data has been provided to the Ocean Biogeographic Information System (OBIS, http://iobis.org/OBISWEB/DisplayMetaData.jsp?content=meta/1459.html).