Feeding behavior of coral reef fishes often determines their species‐specific ecological roles. We studied the two most common Caribbean surgeonfishes (Acanthurus coeruleus and Acanthurus tractus) to examine their species‐specific grazing rates and feeding preferences and how these differed with environmental context. We quantified the feeding activity of both surgeonfishes at four spur and groove reefs in the Florida Keys, USA, that varied in fish abundance, rugosity, algal community composition, and sediment loading. Overall, A. tractus fed twice as fast as A. coeruleus. Both species selected for turf algae but avoided feeding on turf algae that had become laden with sediment. Selectivity for upright macroalgae was more complex with A. tractus targeting Dictyota spp., while A. coeruleus avoided Dictyota spp. relative to the alga's abundance. Both species selected for epiphytes growing on other organisms such as macroalgae and sponges. However, several of these feeding patterns changed with ontogeny. For example, larger individuals of both species fed more frequently on long, sediment‐laden algal turf and less frequently on Dictyota spp. compared to smaller sized individuals. In addition, A. tractus also increased its preference for upright calcareous algae as they attained larger sizes. Overall, the disparity in feeding preferences of surgeonfishes likely indicates subtle differences in species‐specific ecological roles. Both A. coeruleus and A. tractus likely prevent development of turf algae and thus maintain algal communities in the early stages of succession. Additionally, A. tractus may also help reduce macroalgal abundance by targeting common macroalgal species.

中文翻译：

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加勒比海刺尾鱼的摄食行为因鱼的大小，藻类丰度和栖息地特征而异

珊瑚鱼的摄食行为通常决定了其物种特定的生态作用。我们研究了两种最常见的加勒比海刺尾鱼（Acanthurus coeruleus和Acanthurus tractus），以检查它们特定于物种的放牧率和摄食偏好，以及它们与环境之间的差异。我们在美国佛罗里达礁岛的四个正刺和沟礁中定量了两种刺尾鱼的摄食活动，这些活动在鱼的丰度，皱纹度，藻类群落组成和沉积物含量方面有所不同。总体而言，A.孤束喂两次快A.斑。这两个物种都选择了草皮藻，但避免以已经充满沉积物的草皮藻为食。选择性直立海藻是更复杂的A.孤束瞄准Dictyota属，而A.斑避免Dictyota属。相对于藻类的丰度。两种物种都被选为在其他生物（例如大型藻类和海绵）上生长的附生植物。然而，这些进食方式中的几种随着个体发生而改变。例如，两种物种的较大个体在长满泥沙的长草皮上的觅食频率更高，而在鼠尾草上的觅食频率则更低。与较小的个体相比。另外，短小曲霉由于直立钙质藻类的尺寸较大，因此也增加了对直立钙质藻类的偏好。总体而言，刺尾鱼取食偏好的差异可能表明特定物种的生态作用存在细微差异。无论A.斑和A.孤束可能防止草皮藻类的发展，从而在继承早期阶段维持藻类群落。另外，通过将常见的大型藻类作为目标，可将曲霉也有助于减少大型藻类的丰度。