Zonation of assemblages of Lutjanidae, Lethrinidae and Serranidae (Ephinephelinae) within and among midshelf and outershelf reefs in the central Great Barrier Reef

In December 1993, visual census surveys were conducted on three midshelf reefs (Rib Reef, John Brewer Reef and Lodestone Reef) and three outershelf reefs (Myrmidon Reef, Dip Reef and Bowl Reef) in the central Great Barrier Reef region.At each of the 6 reefs, surveys were conducted within 3 zones: the windward reef slopes; the lagoon; and the leeward back reef. Each census consisted of a 45 minute swim (on SCUBA) through a zone, recording the total number of each of the target species within approximately 5 m either side of the diver. All target species were surveyed simultaneously. Three replicate non-overlapping censuses, each covering a distance of approximately 400 m, were made in each zone on each reef.Census dives on the windward reef slope were unidirectional, consisting of a meandering swim from the reef crest to a depth of 12 m. In the lagoon and on the back reef, the paths were roughly unidirectional, meandering between bommies and coral outcrops to depths of 2-8 m and 12 m respectively. There was little information available describing the spatial distribution and abundance of demersal reef fish of commercial and recreational fishing significance in Australia. Visual census surveys were used to examine variation in assemblages of species of Lutjanidae, Lethrinidae and Serranidae within and among reefs at similar locations on the continental shelf and within and among reefs at different locations on the continental shelf.

1993年12月，研究团队于大堡礁中部海域开展视觉普查调查，覆盖3个陆架中部礁体：里夫礁（Rib Reef）、约翰·布鲁尔礁（John Brewer Reef）与磁石礁（Lodestone Reef），以及3个陆架外缘礁体：默米登礁（Myrmidon Reef）、迪普礁（Dip Reef）与博尔礁（Bowl Reef）。在6个礁体的每个位点，调查均设置于3类区域内：迎风礁坡、泻湖与背风后礁。每一次普查均需借助水肺潜水（SCUBA）在目标区域完成45分钟的游泳巡测，记录潜水员两侧约5米范围内各目标物种的总个体数，所有目标物种同步开展普查。每个礁体的每类区域均开展3次重复且无重叠的普查，单次巡测覆盖距离约400米。迎风礁坡的普查潜水为单向路线，即从礁顶向12米水深区域蜿蜒行进；在泻湖及背风后礁区域，巡测路线大致为单向，分别在珊瑚丘与珊瑚露头之间蜿蜒穿行，作业水深分别为2-8米与12米。此前澳大利亚境内针对兼具商业与休闲捕捞价值的底层礁栖鱼类的空间分布与丰度的公开研究资料较为匮乏。本次视觉普查调查旨在探究分布于大陆架相似位置的礁体内部、礁体之间，以及大陆架不同位置的礁体内部、礁体之间，笛鲷科（Lutjanidae）、裸颊鲷科（Lethrinidae）与鮨科（Serranidae）物种种群群落组成的差异。