Variation in assemblages of Lutjanidae and Lethrinidae among mid-continental shelf reefs in the central Great Barrier Reef


Temporal Range: From 02-Sep-1992 To 25-Jun-1993

Resource Summary

Surveys of fish in the families Lutjanidae and Lethrinidae were carried out on three midshelf reefs (Rib Reef, John Brewer Reef and Lodestone Reef) in the central Great Barrier Reef at approximately 2 monthly intervals between September 1992 and July 1993. The back reef habitat (NW aspect, leeward slopes) of each reef was surveyed and the areas censused on each of the reefs were as similar as possible in terms of their physical characteristics.Six replicate non-overlapping visual censuses of the lutjanid and lethrinid assemblages in the shallow back reef zone (0-10 m) were undertaken at each reef during each of the 6 sampling periods. Dives were conducted haphazardly; transects were not fixed, and no two censuses within any sampling period covered exactly the same census area. Diel differences in catches, large-scale differences among reefs and differences between depths within reefs through time were investigated using fish traps. During each of the 6 sampling periods, 12 traps were set by day and 12 at night in each of two depth zones (shallow: 12-18 m, and deep: 30-40 m) at each reef. Traps were deployed randomly in each depth zone.For day sampling, traps were set in the morning (0600-0830 h) and retrieved in the evening (1630-1830 h), resulting in a soak time of between 9 and 11 hours. For night sampling, traps were set in the evening (1700-1830 h) and retrieved the following morning (0530-0800 h), resulting in a soak time of between 12 and 14 hours. The catch of each trap was identified to species and measured to the nearest millimetre.

Visual census and fish traps were used to investigate assemblages of the Lutjanidae and Lethrinidae from surface waters to the base of the back reef among three replicate reefs at one continental-shelf locality (mid-shelf) in the central Great Barrier Reef to determine whether previously observed spatial patterns in species abundance were persistent through time.

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Australian Institute of Marine Science . 2013, Variation in assemblages of Lutjanidae and Lethrinidae among mid-continental shelf reefs in the central Great Barrier Reef, https://apps.aims.gov.au/metadata/view/a6309abb-687c-4d1f-9813-b47950a2f30f, accessed 18-Aug-2019