Parrotfish perform a variety of vital ecological functions on coral reefs, but we have little understanding of how these vary spatially as a result of inter-habitat variability in species assemblages. Here, we examine how two key ecological functions that result from parrotfish feeding, bioerosion and substrate grazing, vary between habitats over a reef scale in the central Maldives. Eight distinct habitats were delineated in early 2015, prior to the 2016 bleaching event, each supporting a unique parrotfish assemblage. Bioerosion rates varied from 0 to 0.84 ± 0.12 kg m⁻² yr⁻¹ but were highest in the coral rubble- and Pocillopora spp.-dominated habitat. Grazing pressure also varied markedly between habitats but followed a different inter-habitat pattern from that of bioerosion, with different contributing species. Total parrotfish grazing pressure ranged from 0 to ~264 ± 16% available substrate grazed yr^-1 in the branching Acropora spp.-dominated habitat. Despite the importance of these functions in influencing reef-scale physical structure and ecological health, the highest rates occurred over less than 30% of the platform area. The results presented here provide new insights into within-reef variability in parrotfish ecological functions and demonstrate the importance of considering how these interact to influence reef geo-ecology.

中文翻译：

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印度洋礁平台上鹦鹉鱼生物侵蚀率和放牧压力的生境间变异性

鹦嘴鱼在珊瑚礁上执行各种重要的生态功能，但我们对这些物种在栖息地间的变异性导致的空间分布变化知之甚少。在这里，我们研究了由鹦鹉鱼摄食，生物侵蚀和基质放牧产生的两个关键生态功能如何在马尔代夫中部一个珊瑚礁规模的生境之间变化。在2016年漂白事件之前的2015年初，划定了八个不同的栖息地，每个栖息地都支持一种独特的鹦嘴鱼组合。生物侵蚀速率从0到0.84±0.12 kg m ^-2 yr ^-1不等，但在珊瑚瓦砾和Pocillopora中最高物种主导的栖息地。不同生境之间的放牧压力也显着不同，但生境间的变化方式不同于生物侵蚀的生境方式，其贡献物种也不同。总鹦嘴鱼放牧压力范围从0到264〜±16％可用的基底擦过年^-1在分支鹿角spp.主导的栖息地。尽管这些功能在影响礁石规模的物理结构和生态健康方面具有重要意义，但在平台面积不到30％的地区，发生率最高。本文介绍的结果提供了对鹦鹉鱼生态功能中礁内变异性的新见解，并说明了考虑这些相互作用如何影响礁石地球生态学的重要性。