Dataset: Surveys of Octocoral communities, benthic cover and environmental factors on coral reefs of Milne Bay, Papua New Guinea


All surveys were carried out by the principal researcher using Rapid Ecological Assessment. The dataset comprises 41 sites.

Each site was surveyed with up to 5 transects (usually 200-300m long, 1-3m wide for 10-15 minutes) 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 taxa were recorded 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 timing 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 and azooxanthellate richness was calculated based on the numbers of octocoral taxa with (or without) zooxanthellae.

Site locations: Alotau Clubhouse, Barbara Reef, Double Tower, Lauwadi, Manta Station, Michelles, Observation Points (off Pier, off Village, off Volcano Lake), Pinnacle, Sulloviens patch, Wahoo Reef.

General Information