Structure of fish communities on outer slopes of inshore, mid-shelf and outer shelf reefs of the central Great Barrier Reef

The structure of fish communities on the outer slopes of one inshore reef (Pandora), one mid-shelf reef (Rib) and one outer shelf reef (Myrmidon) in the central region of the Great Barrier Reef was examined using small, standardised plastic explosive charges.Ten collections (5 at a depth of 5m and 5 at 9m), were made on each reef in areas of the outer reef slope with the greatest abundance and diversity of fish and coral. Charges were laid on the bottom and after detonation fish were affected over a area of approximately 150 m².Immediately after detonation of the explosive, dead and stunned fish were collected by divers and from a boat using hand nets. Fish were later identified to species, weighed and assigned to trophic categories and feeding guilds within these categories.
Earlier visual censuses of reef fish across the continental shelf, based on a limited number of species, identified a strong gradient in species composition. In this study, the differences in fish communities among reefs, including biomass measurements and trophic structure were examined for a more comprehensive list of species, by collecting fish using small explosive charges, which is an effective and non-selective collection method.
A total of 323 species belonging to 45 families and comprising 28,537 individuals were collected.

本研究针对大堡礁（Great Barrier Reef）中部区域的3处珊瑚礁展开调查，分别为近岸礁（inshore reef）潘多拉礁（Pandora）、陆架中部礁（mid-shelf reef）里布礁（Rib）以及陆架外缘礁（outer shelf reef）默米登礁（Myrmidon），采用小型标准化塑料炸药对三处礁体的外坡（outer slope）鱼类群落结构进行解析。每处礁体均在鱼类与珊瑚丰度及多样性最高的外坡区域开展10次采样，其中5次设置于5米水深，剩余5次设置于9米水深。炸药被布设至海底，起爆后其影响范围约为150平方米。炸药起爆瞬间，潜水员即刻搭乘小艇手持手抄网收集死亡及昏迷的鱼类样本。后续研究人员将采集到的鱼类鉴定至物种水平，称量其体重，并划分至对应的营养类群（trophic categories）及该类群下的摄食功能群（feeding guilds）。
此前针对陆架（continental shelf）区珊瑚礁鱼类开展的目视调查（visual censuses）仅覆盖有限物种，结果显示物种组成存在显著的梯度变化。本研究采用高效且无选择性的小型炸药采样法，采集覆盖更全面的物种名录，以此对比不同礁体间鱼类群落的差异，包括生物量（biomass）及营养结构特征。
本次研究共采集到隶属于45个科的323个物种，总计28537尾个体。