Sura Shayna A, Molina Nury E, Blumstein Daniel T, Fong Peggy
Department of Ecology and Evolutionary Biology, University of California Los Angeles, Los Angeles, CA 90095, USA.
J Exp Mar Biol Ecol. 2021 Mar;536. doi: 10.1016/j.jembe.2020.151508. Epub 2021 Jan 11.
Worldwide, many coral reefs are at risk of shifting to degraded algal-dominated states, due to compromised ecological conditions. Functional diversity of herbivorous fishes maintains coral reef health and promotes reef resilience to disturbances. Given previous evidence, it appears the functional roles of herbivorous fishes differ across geographical locations, indicating a need for further assessment of macroalgal consumption by herbivorous fishes. We assessed functional diversity by examining foraging behavior of herbivorous fish species on macroalgae on a fringing reef in Moorea, French Polynesia. We video-recorded choice experiments containing seven common macroalgae and used Strauss' linear resource selection index to determine macroalgal selectivities. We used cluster analysis to identify any distinct groups within herbivorous fish species, given the macroalgal species they targeted, and fitted generalized linear mixed-effects models to identify factors that best predicted the number of bites taken on macroalgae. Seven species from 3 fish families/tribes took a total of 956 bites. Fish species differed in their selectivity with some species () strongly preferring one or two macroalgal species, while other fish species () were less selective. This resulted in fish species forming two clusters. Only 3 of 7 macroalgae were preferred by any fish species, with two fish species both preferring the same two macroalgae. The limited differences in fish species' preferences for different macroalgae suggests limited functional complementarity. Two models (macroalgal species identity+fish functional group, macroalgal species identity+fish species) best predicted the number of bites taken on macroalgae compared to models incorporating only a single explanatory factor or fish family. In the context of this Moorean fringing reef, there is greater functional redundancy than complementarity of herbivorous fishes consuming macroalgae, and the fishes grouped together according to their relative selectivity. We observed fish species that are not classified as browsers consuming macroalgae, suggesting diets of herbivorous fishes may be broader than previously thought. Finally, we observed macroalgal selectivities and consumption that differed from previous studies for the same fish species. Our results contribute to the understanding of functional diversity of herbivorous fishes across coral reefs, and also highlight the need for additional research to further elucidate the role of context and functional diversity of herbivorous fishes consuming macroalgae on coral reefs.
在全球范围内，由于生态条件受损，许多珊瑚礁正面临转变为以藻类为主的退化状态的风险。草食性鱼类的功能多样性维持着珊瑚礁的健康，并促进珊瑚礁对干扰的恢复力。根据先前的证据，草食性鱼类的功能作用似乎因地理位置而异，这表明需要进一步评估草食性鱼类对大型藻类的消耗情况。我们通过研究法属波利尼西亚莫雷阿岛岸礁上草食性鱼类对大型藻类的觅食行为来评估功能多样性。我们对包含七种常见大型藻类的选择实验进行了视频记录，并使用施特劳斯线性资源选择指数来确定大型藻类的选择性。鉴于草食性鱼类所针对的大型藻类物种，我们使用聚类分析来识别草食性鱼类物种中的任何不同群体，并拟合广义线性混合效应模型以识别最能预测对大型藻类咬食次数的因素。来自3个鱼科/族的7个物种总共咬了956次。鱼类物种的选择性存在差异，一些物种（）强烈偏好一两种大型藻类物种，而其他鱼类物种（）的选择性较低。这导致鱼类物种形成了两个聚类。7种大型藻类中只有3种被任何鱼类物种偏好，有两种鱼类物种都偏好相同的两种大型藻类。鱼类物种对不同大型藻类的偏好差异有限，这表明功能互补性有限。与仅包含单一解释因素或鱼科的模型相比，两个模型（大型藻类物种身份+鱼类功能组，大型藻类物种身份+鱼类物种）最能预测对大型藻类的咬食次数。在这个莫雷阿岛岸礁的背景下，草食性鱼类消耗大型藻类的功能冗余性大于互补性，并且鱼类根据其相对选择性聚集在一起。我们观察到未被归类为食草动物的鱼类物种也在消耗大型藻类，这表明草食性鱼类的饮食可能比以前认为的更广泛。最后，我们观察到大型藻类的选择性和消耗量与之前对相同鱼类物种的研究不同。我们的结果有助于理解珊瑚礁上草食性鱼类的功能多样性，也突出了需要进行更多研究以进一步阐明环境背景的作用以及草食性鱼类消耗大型藻类的功能多样性在珊瑚礁上的作用。
