Surveys of Octocoral communities, benthic cover and environmental factors on coral reefs of Hong Kong

Temporal Range: From 05-Nov-1999 To 15-Nov-1999

Resource Summary

All surveys were carried out by the principal researcher using Rapid Ecological Assessment. The dataset comprises 41 surveys from 21 reef locations, recording 42 species in 23 genera (dominated by azooxanthellate taxa).

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).

Taxa 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 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: Bokhara Rocks, Breakers Rock, Fo Shek Chau, Junk Bay, Kung Chau, Lo Chau Pak Poi, Long Ke Wan, Luk Chau, Luk Chau Wan, North Ninepin, Pak Shau, Ping Chao, Po Toi, Sham Wan, South Ninepin, Tai Tau Chau, Waglan.

To survey the cover of the main benthic groups, richness and abundance of octocorals in the reefs of Hong Kong and related spatial and water quality gradients.

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.

Comparable data are held for the Great Barrier Reef, 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,

Resource Usage

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The data was collected under contract between AIMS and another party(s). Specific agreements for access and use of the data shall be negotiated separately. Contact the AIMS Data Centre ( for further information

Metadata Usage

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Format for citation of metadata sourced from Australian Institute of Marine Science (AIMS) in a list of reference is as follows: "Australian Institute of Marine Science. [year-of-data-download], [Title], [data-access-URL], accessed (date-of-access]".

Resource Usage:

The data is under exclusive access period. Contact the AIMS Data Centre ( for possible access to the data within this period.

Access Constraint: restricted
Use Constraint: restricted
Security classification code: unclassified

Metadata Usage:
Access Constraint: intellectualPropertyRights
Use Constraint: intellectualPropertyRights
Security classification code: unclassified

Cite this Record
Australian Institute of Marine Science (AIMS). (2009), Surveys of Octocoral communities, benthic cover and environmental factors on coral reefs of Hong Kong,, accessed 09-Jul-2020.
General Links
OBIS dataset