Selective consumption of macroalgal species by herbivorous fishes suggests reduced functional complementarity on a fringing reef in Moorea, French Polynesia

Sura Shayna A.; Molina Nury E.; Blumstein Daniel T.; Fong Peggy

摘要

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 (Naso lituratus, N. unicornis, Calatomus carolinus) strongly preferring one or two macroalgal species, while other fish species (Acanthurus nigrofuscus, Ctenochaetus striatus, Chlorurus sordidus, Balistapus undulatus) 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.

机译：在全球范围内，由于生态条件损害，许多珊瑚礁有可能转移到降级的藻类占主导地位的国家。食草鱼类的功能多样性维持珊瑚礁健康，促进礁石的弹性对干扰。鉴于以前的证据，它看起来越来越多的地理位置的功能作用，表明需要进一步评估食草鱼类的大类消费。通过检查法国波利尼西亚摩尔尼亚摩尔雷地区的甲状腺凝血鸡草的觅食性鱼类的觅食行为来评估功能多样性。我们录制录制的选择实验，其中包含七种常见的大型宏观，并使用施特劳斯的线性资源选择指标来确定宏观政府选择性。我们使用聚类分析以鉴定食草种中的任何不同群体，鉴于它们所针对的大类物种，并拟合推广的线性混合效果模型，以确定最能预测在大型麦克胶上拍摄的叮咬数量的因素。来自3条鱼族/部落的七种物种共有956个叮咬。鱼类在各种物种（Naso Lituratus，N. Unicornus，Calatomus Carolinus）中的选择性不同，而其他两种大类物种（Acanthurus Nigrofuscus，Ctenochaetus Striatus，Callurus Sydidus，Balistapus Undulatus）的选择性较少。这导致形成两种簇的鱼类。任何鱼类只优选7种大甲藻的3个，两种鱼类均偏爱同一两种大甲虫。鱼类对不同宏观凝游偏好的有限差异表明功能互补有限。两种型号（大型物种身份+鱼官能团，Macroalgal物种身份+鱼种）最佳预测了与仅包含单个解释性因素或鱼类家族的模型相比甲状腺果的咬伤数。在该摩尔铰接礁的背景下，具有比食用宏观格凝游的食草鱼类的互补性更高的功能冗余，并且根据其相对选择性将鱼类分组。我们观察了未被归类为食用宏观格的鱼类的鱼类，表明食草鱼类的饮食可能比以前想象的更广泛。最后，我们观察到近似研究与同一鱼类的研究不同的宏观政府选择性和消费。我们的成果有助于了解珊瑚礁上食鱼类鱼类功能多样性，并突出了额外研究的需要，以进一步阐明食草鱼类消费珊瑚礁的未食子鱼类的语境和功能多样性的作用。

Selective consumption of macroalgal species by herbivorous fishes suggests reduced functional complementarity on a fringing reef in Moorea, French Polynesia

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