Parrotfishes (Scarini) are considered key agents in coral reef health and recovery, but the drivers of parrotfish–coral dynamics remain contentious. The prevailing view of parrotfishes as ecosystem engineers is based on the perceived removal of algal turf, macroalgae and sediment, but these are effects of feeding, not causes. The recent proposal that most parrotfishes are ‘microphages’ that target microscopic photoautotrophs (particularly cyanobacteria) identifies the need to resolve dietary targets at a microscopic scale. Here, we investigate parrotfish dietary targets by posing the following two questions: (1) are microscopic photoautotrophs the most consistent and dominant elements of the prey community, and (2) do the prey community and substratum taphonomy vary between parrotfish species? In order to identify and quantify dietary targets, five parrotfish species were followed until focused feeding was observed at Lizard Island on the Great Barrier Reef, Australia. Feeding sites were photographed in situ and extracted as substratum bite cores. Cores were analysed microscopically to identify and quantify all epilithic photoautotrophs. Endolithic photoautotrophs accessible to excavating parrotfish were also investigated by vacuum-embedding cores with epoxy resin followed by decalcification to expose endolith microborings. The dominant functional groups of epilithic biota on the cores were tufted cyanobacteria, turfing algae and crustose coralline algae (CCA). The only consistent feature across all cores was the high density of filamentous cyanobacteria, supporting the view that these parrotfishes target microphotoautotrophs. Macroalgae was absent or a minor component on cores, supporting the hypothesis that parrotfishes avoid larger algae. The microchlorophyte Ostreobium was the dominant photoautotrophic euendolith (true borer) in the cores of the excavating parrotfish Chlorurus microrhinos. Significant differences in CCA coverage, turf height and substrate taphonomy were found among the five parrotfish species, suggesting that interspecific resource partitioning is based on successional stage of feeding substrata.

中文翻译：

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使用饲养基质的显微组织学解决鹦鹉鱼（Scarini）的资源分配问题

鹦鹉鱼（Scarini）被认为是珊瑚礁健康和恢复的关键因素，但鹦鹉鱼 - 珊瑚动态的驱动因素仍然存在争议。鹦鹉鱼作为生态系统工程师的普遍观点是基于对藻类草皮、大型藻类和沉积物的感知去除，但这些是摄食的影响，而不是原因。最近提出的大多数鹦鹉鱼是针对微观光合自养生物（特别是蓝藻）的“微噬菌体”，这表明需要在微观尺度上解决饮食目标。在这里，我们通过提出以下两个问题来研究鹦鹉鱼的饮食目标：（1）微观光能自养生物是猎物群落中最一致和占主导地位的元素，（2）鹦鹉鱼物种之间的猎物群落和基质埋藏学是否有所不同？为了确定和量化饮食目标，对五种鹦鹉鱼进行了追踪，直到在澳大利亚大堡礁的蜥蜴岛观察到集中进食。摄食部位原位拍照并提取为基质咬核。用显微镜分析核以鉴定和量化所有附生光能自养生物。还通过用环氧树脂真空嵌入核心然后脱钙以暴露内石微孔来研究可用于挖掘鹦鹉鱼的内石光自养生物。核心上的附生生物群的主要官能团是簇状蓝藻、草坪藻和壳珊瑚藻（CCA）。所有核心中唯一一致的特征是丝状蓝藻的高密度，支持这些鹦鹉鱼针对微型光能自养生物的观点。巨藻不存在或核心上的微量成分，支持鹦鹉鱼避开较大藻类的假设。微叶绿体 Ostreobium 是正在挖掘的鹦嘴鱼 Chlorurus microrhinos 的核心中占主导地位的光合自养真内石（真蛀虫）。五种鹦嘴鱼在 CCA 覆盖率、草坪高度和基质埋藏学方面存在显着差异，表明种间资源分配是基于取食基质的演替阶段。