Habitat degradation increases functional originality in highly diverse coral reef fish assemblages
Habitat degradation increases functional originality in highly diverse coral reef fish assemblages
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DOI：
10.1002/ecs2.1557
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发表时间：
2016-11-01
期刊：
影响因子：
2.7
通讯作者：
Ceccarelli, Daniela M.
中科院分区：
文献类型：
--
作者：
Brandl, Simon J.;Emslie, Michael J.;Ceccarelli, Daniela M.
随着人为和自然干扰的加剧，人们越来越关注功能重要或独特物种的丧失。功能冗余，或几个不同物种占据相似的功能生态位，可以提供防止多样性丧失的保障，但这种效应的证据很少。同样，功能冗余模式对干扰的响应方式也知之甚少，阻碍了对干扰后社区级动态的彻底理解。在这里，我们使用热带气旋后硬珊瑚覆盖范围的广泛减少来探索高度多样化的珊瑚鱼组合对栖息地退化的反应。我们发现，尽管鱼类对干扰具有明显的性状特异性敏感性，但6个功能指数中的5个（包括功能丰富度和均匀度）与栖息地退化没有关系。相比之下，功能原创性（量化组合内物种的平均功能独特性）在干扰后增加，与珊瑚覆盖减少呈负相关，尽管关系较弱。功能原创性的增加是由易受影响的群体中功能相似的物种（主要是与活珊瑚栖息地相关的小型浮游生物和杂食性物种）的丧失和从干扰中受益的群体中功能独特的物种（以藻类草皮、碎屑和无脊椎动物为食的大型、非领土物种）的增加同时驱动的。我们的研究结果表明，高珊瑚覆盖率的珊瑚礁可以培育低功能原创性（即高功能冗余）的鱼类组合，从而防止一些最常用的功能指标在干扰后发生可检测到的变化。然而，我们警告说，基于性状的方法的有限分辨率可能掩盖了功能独特物种的损失，并且随着功能独创性的增加，后干扰组合可能不太适合在面对未来干扰时充分维持某些生态系统功能。因此，迫切需要进一步探索干扰、功能冗余和生态系统功能之间的动态关系。
As anthropogenic and natural disturbances intensify, there is mounting concern about the loss of functionally important or unique species. Functional redundancy, or the presence of several different species occupying similar functional niches, can provide insurance against diversity loss, but evidence for this effect is rare. Likewise, the ways in which functional redundancy patterns respond to disturbances are poorly known, impeding a thorough understanding of community-level dynamics post disturbance. Here, we use an extensive reduction of hard coral cover following a tropical cyclone to explore the response of a highly diverse reef fish assemblage to habitat degradation. We demonstrate that despite clear trait value-specific susceptibility of fishes to the disturbance, five of six functional indices (including functional richness and evenness) showed no relationship with habitat degradation. In contrast, functional originality, which quantifies the average functional uniqueness of species within an assemblage, increased post disturbance, exhibiting a negative, albeit weak, relationship with decreasing coral cover. The increase in functional originality is simultaneously driven by the loss of functionally similar species in susceptible groups (predominantly small planktivorous and omnivorous species that associate with live coral habitat) and the addition of functionally unique species in groups that benefit from the disturbance (large, non-territorial species feeding on algal turfs, detritus, and invertebrates). Our findings suggest that coral reefs with high coral cover can foster fish assemblages with low functional originality (i.e., high functional redundancy), therefore preventing detectible changes in some of the most commonly applied functional indices post disturbance. However, we caution that the limited resolution of trait-based approaches may mask the loss of functionally unique species and that, with an increase in functional originality, post disturbance assemblages may be less suited to adequately maintain certain ecosystem functions in the face of future disturbances. Thus, there is an urgent need for further exploration of the dynamics between disturbances, functional redundancy, and ecosystem functioning.