Distribution and abundance of herbivorous grazing fishes in the central Great Barrier Reef

A census of herbivorous grazing fishes was undertaken on 9 reefs located across the continental shelf in the central region of the Great Barrier Reef between July 1982 and February 1983. The reefs chosen for surveys were: 3 inshore reefs (Pandora Reef, Phillips Reef and Lorne Reef); 3 mid-shelf reefs (Rib Reef, John Brewer Reef and Lodestone Reef); and 3 outer shelf reefs (Myrmidon Reef, Dip Reef and Bowl Reef). For the mid- and outer shelf reefs, surveys were conducted within each of five reef zones: the windward reef slope, the windward reef crest, the reef flat, the lagoon and the back reef. The inshore reefs lacked distinct patterns of zonation and the perimeters of each reef were censused and treated as a single zone. The census was restricted to a list of 51 species from four families: Acanthuridae (24 species), Zanclidae (1 species), Scaridae (20 species) and Siganidae (6 species). Each species was also assigned to a feeding guild.A visual census technique was used for surveys and abundance was recorded using a log 3 abundance scale from 1 to 7. Each census dive through a zone was 30 minutes long and a distance of between 300 m and 400 m was covered, depending on conditions. Individuals within approximately 5 m either side of the diver were recorded. Juveniles (

1982年7月至1983年2月，研究团队于大堡礁中部大陆架沿线的9座珊瑚礁开展植食性牧食鱼类普查。本次调查选定的珊瑚礁分为三类：3座近岸礁（潘多拉礁（Pandora Reef）、菲利普斯礁（Phillips Reef）与洛恩礁（Lorne Reef））、3座陆架中部礁（里布礁（Rib Reef）、约翰·布鲁尔礁（John Brewer Reef）与磁石礁（Lodestone Reef）），以及3座陆架外缘礁（默米登礁（Myrmidon Reef）、迪普礁（Dip Reef）与博尔礁（Bowl Reef））。针对陆架中部与陆架外缘礁，调查在5个标准礁体分区内开展：迎风礁坡、迎风礁脊、礁坪、泻湖与后礁。近岸礁无明确的分区特征，因此对整座礁体的周边区域开展普查，并将其视为单一分区。本次普查仅纳入4个科的51个物种：刺尾鱼科（Acanthuridae，24种）、镰鱼科（Zanclidae，1种）、鹦嘴鱼科（Scaridae，20种）与篮子鱼科（Siganidae，6种），且每个物种均被划归至相应的摄食功能群（feeding guild）。本次调查采用视觉普查法，鱼类丰度以3为底的对数丰度尺度记录，等级取值范围为1至7。每一次分区普查的潜水时长为30分钟，根据现场作业条件覆盖300米至400米的调查距离，记录潜水员两侧约5米范围内的个体。幼鱼（