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

Created 23/06/2025

Updated 23/06/2025

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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 ofcoral 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, http://www.iobis.org/OBISWEB/DisplayMetaData.jsp?content=meta/1462.html).

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Additional Info

Field Value
Title Surveys of Octocoral communities, benthic cover and environmental factors on coral reefs of Hong Kong
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/dataset/41110289-4d4c-4a28-997c-a3bdaaab6e93
Contact Point
Australian Ocean Data Network
reception@aims.gov.au
Reference Period 20/11/2017
Geospatial Coverage
Map data © OpenStreetMap contributors
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  "type": "Polygon"
}
Data Portal Australian Oceans Data Network

Data Source

This dataset was originally found on Australian Oceans Data Network "Surveys of Octocoral communities, benthic cover and environmental factors on coral reefs of Hong Kong". Please visit the source to access the original metadata of the dataset:
https://catalogue.aodn.org.au/geonetwork/srv/eng/csw/dataset/surveys-of-octocoral-communities-benthic-cover-and-environmental-factors-on-coral-reefs-of-hong1