Surveys of Octocoral communities, benthic cover and environmental factors on coral reefs of the Great Barrier Reef

All surveys were carried out by the principal researcher using Rapid Ecological Assessment. The dataset runs from May 1996: in early 2009 comprising 1636 entries from 180 reef locations, spread relatively evenly along and across the whole Great Barrier Reef (GBR). 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 (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 2.5% 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 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: 13-050, 13-063, 13-120, 13-123, 17-069, 18-023, 18-026, 18-NNN, 19-109, 19-159, 20-154, 20-344, 20-348, 20-385, 21-089, 21-132, 21-141, 21-149, 21-151, 21-155, 21-164, 21-173, 21-433, 21-551, 21-551, 22-101, Agincourt 3, Alexandra, Barnard, Barren, Bewick, Border, Bramble, Britomart, Bugatti, Cape Flattery, Cape Tribulation South, Champagne Bay, Chinaman, Clack, Clerke.Is, Cockburn, Collette, Conical Rock, Curacoa, Davie, Deloraine, Dent, Dido Rock, Digby, Dingo, Double, Double Cone, Douglas, Dumbell, Dunk, East Cay, Eden, Edward, Elizabeth, Ellison, Escape, Esk, Faith, False Nara Inlet, Fantome, Faraday, Fitzroy, Flat, Fly, Gable, Gallan, Garioch, Gilbey, Gloucester, Gould, Grassy, Great.Detached, Great Keppel, Great Palms, Green, Grub PCB, Haggerstone, Halftide, Hannah, Haslewood, Hay, Heath, Henning, Herald, Heron, Hicks, Hideaway Bay, High, High Peak, Hook, Horseshoe, Iris, Jacqueline, James, Joan, John Brewer, Korea, Lindeman, Linnet, Lodestone, Long, Low, Lupton, MacDonalds, Macona Inlet, Magra, Marble, Martha Ridgeway, McSweeny, Miall, Michaelmas, Middle, Middle Keppels, Monsoon, Morris, Murdoch, Myrmidon, Nara Inlet, Needle, Nomad, Normanby, North East Percy, North Keppel, Old, One Tree, Opal, Opp Long, Orpheus, Osborne, Pandora, Pelican (Princess Charlotte Bay), Pelican (Whitsundays), Pelorus, Phillips, Pickersgill, Pine Peak, Pine Percy, Pith, Polmaise, Rattay, Repulse, Rib, Ribbon 10, Richard, Rundle, Russell, Salamander, Saunders, Scott, Shute Bay, Snake, Snapper, Snapper, St Crispin, Stanley, Stark, Switzer, Three, Thrush, Tideway, Tiger, Turner Cay, Undine, Unity, Upolu, Wackett, Wharton, Wheeler, Whitsunday, Whitsunday, Wilkie, Wizard, Yongala Wreck, Yule.

To determine spatial patterns and abiotic controls of soft coral biodiversity: allowing examination of relationships of reef location (in-shore, mid-shelf and off-shore), environmental conditions and depth to taxonomic composition and richness.

Because roughly half Octocorals have photosynthetic symbionts they are ideal to assess how biodiversity is related to spatial and environmental factors, and photosynthetic symbionts and energy supply.

To examine principal drivers of biodiversity, community composition, and ranges of coral reef benthos.

Richness data have been analyzed using aggregated boosted trees (ABTs), an extension of boosted trees that improve predictive performance, particularly for smaller data sets. (Boosted trees are a regression and classification technique based on adaptive learning, and render simple graphical and numerical interpretations of complex data relationships, for ecological studies.

Comparable data are held for Hong Kong, Palau, 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://www.iobis.org/explore/#/dataset/1457).

Data have been used for the e-Atlas: http://e-atlas.org.au/content/octocorals-great-barrier-reef-0