Herbivorous fishes consume algae on coral reefs, and this ecological function is pivotal in helping reefs to resist and recover from disturbance. Although numerous studies have differentiated between those fishes that graze on low-profile algae and those that browse on larger fleshy macroalgae, little is known about the feeding behaviours of some herbivorous fishes (e.g. rabbitfishes, Siganidae), limiting our understanding of whether, and how, these species contribute to ecological functions on coral reefs. Here, we examine how the feeding ecology of four species of rabbitfishes that dominate the artisanal fishery in the Seychelles changed spatially and temporally. Siganus argenteus and S. sutor were generalist herbivores feeding on a range of substrata (e.g. turf algae, macroalgae, seagrass and epiphytic algae), whereas S. corallinus and S. stellatus were specialist herbivores feeding primarily on substrata covered in turf algae. Bite rates of S. argenteus and S. sutor were positively correlated with the cover of macroalgae, seagrass and epiphytic algae. By contrast, bite rates of S. corallinus and S. stellatus were not correlated with changes in the cover of turf algae. These findings illustrate possible differences in the ecological contributions among rabbitfish species on coral reefs, and emphasize the need for caution when assigning species to functional groups and assuming within-group functional equivalence. The results also support the classic niche theory that species within a community must use resources differently in order to coexist over evolutionary timescales. These results further provide valuable insights for the management of rabbitfishes in tropical fisheries because it implies that the conservation of different species might result in distinct shifts in the competitive dominance of coral and algae.

中文翻译：

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印度洋珊瑚礁上具有重要商业价值的比目鱼的饮食和觅食行为的差异

食草鱼类以珊瑚礁上的藻类为食，这种生态功能对于帮助珊瑚礁抵御干扰和从干扰中恢复至关重要。尽管许多研究已经将那些以低调藻类为食的鱼类和以较大的肉质大型藻类为食的鱼类区分开来，但对一些食草鱼类（例如兔鱼、Siganidae）的摄食行为知之甚少，限制了我们对是否以及如何，这些物种有助于珊瑚礁的生态功能。在这里，我们研究了主导塞舌尔手工渔业的四种兔鱼的摄食生态如何在空间和时间上发生变化。Siganus argenteus 和 S. sutor 是多才多艺的食草动物，以一系列基质（例如草皮藻类、大型藻类、海草和附生藻类）为食，而 S. corallinus 和 S. stellatus 是专业的食草动物，主要以草皮藻类覆盖的基质为食。S. argenteus 和 S. sutor 的咬食率与大型藻类、海草和附生藻类的覆盖率呈正相关。相比之下，S. corallinus 和 S. stellatus 的咬合率与草皮藻类覆盖的变化无关。这些发现说明了珊瑚礁上兔鱼物种的生态贡献可能存在差异，并强调在将物种分配给功能组和假设组内功能等效时需要谨慎。结果还支持经典的生态位理论，即社区内的物种必须以不同的方式使用资源才能在进化时间尺度上共存。