Dataset: Bleaching of coral communities on nearshore reefs of the central Great Barrier Reef after Cyclone Sadie (1994)


Description

The nearshore reefs, Brook Islands Reef (2 sites), Iris Point Reef at Orpheus Island (1 site) and Pandora Reef (4 sites) were surveyed using swim survey and video techniques in February 1994. The Pandora Reef sites were resurveyed in April 1994.

Meandering SCUBA and/or snorkel swims were used to record an inventory of the coral species at each site and to estimate the severity of coral bleaching. Swims of approximately 100 m were conducted at depths of between 0 to 3 m, 4 to 7 m and 8 to 12 m below approximate mean low water (mlw) level. For each species, the relative abundances of unaffected, partially bleached and totally bleached colonies were estimated to the nearest 20%.

At Iris Point Reef and Pandora Reef, the coral communities were also filmed using a Sony Hi-8 Video camera from about 50 cm above the substrate during the swims, producing video profiles covering about 30-50 cm width of reef substrate. The videos were inspected for additional species not previously recorded during the swims. The perimeter of bleached tissue was filmed on four partially-bleached massive corals and marked with stainless steel nails.

At Pandora Reef, video belt-transects of 50 m length were filmed at three depths (1 to 3 m, 4 to 6 m and 9 to 11 m below approximate mlw level) at four sites around the reef perimeter. The sites were selected haphazardly within areas known to support the range of major coral community types present. Transects were marked with a glass fibre metric tape measure laid along the depth contours. The starting point of each transect was marked with a buoy. The transects were filmed from approximately 50 cm above the substratum, providing a video band-width of 30 to 50 cm. Each transect took about 4 minutes to film. The transects in the second survey (April 1994) were located near the buoyed positions, in the same depth ranges and community types, but did not follow the precise path of the original transects.

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