Heenan Adel, Williams Ivor D
Joint Institute of Marine and Atmospheric Research, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America.
PLoS One. 2013 Nov 6;8(11):e79604. doi: 10.1371/journal.pone.0079604. eCollection 2013.
Resilience-based management aims to promote or protect processes and species that underpin an ecosystem's capacity to withstand and recover from disturbance. The management of ecological processes is a developing field that requires reliable indicators that can be monitored over time. Herbivory is a key ecological process on coral reefs, and pooling herbivorous fishes into functional groups based on their feeding mode is increasingly used as it may quantify herbivory in ways that indicate resilience. Here we evaluate whether the biomass estimates of these herbivore functional groups are good predictors of reef benthic assemblages, using data from 240 sites from five island groups in American Samoa. Using an information theoretic approach, we assembled a candidate set of linear and nonlinear models to identify the relations between benthic cover and total herbivore and non-herbivore biomass and the biomass of the aforementioned functional groups. For each benthic substrate type considered (encrusting algae, fleshy macroalgae, hard coral and turf algae), the biomass of herbivorous fishes were important explanatory variables in predicting benthic cover, whereas biomass of all fishes combined generally was not. Also, in all four cases, variation in cover was best explained by the biomass of specific functional groups rather than by all herbivores combined. Specifically: 1) macroalgal and turf algal cover decreased with increasing biomass of 'grazers/detritivores'; and 2) cover of encrusting algae increased with increasing biomass of 'grazers/detritivores' and browsers. Furthermore, hard coral cover increased with the biomass of large excavators/bio-eroders (made up of large-bodied parrotfishes). Collectively, these findings emphasize the link between herbivorous fishes and the benthic community and demonstrate support for the use of functional groups of herbivores as indicators for resilience-based monitoring.
基于恢复力的管理旨在促进或保护那些支撑生态系统抵御干扰并从中恢复能力的过程和物种。生态过程管理是一个不断发展的领域，需要能够长期监测的可靠指标。食草作用是珊瑚礁上一个关键的生态过程，基于食草鱼类的摄食模式将它们归为功能组的做法越来越普遍，因为这样做可能会以表明恢复力的方式对食草作用进行量化。在此，我们利用美属萨摩亚五个岛屿群240个地点的数据，评估这些食草动物功能组的生物量估计值是否能很好地预测珊瑚礁底栖生物组合。我们采用信息论方法，构建了一组线性和非线性模型的候选集，以确定底栖生物覆盖率与食草动物和非食草动物总生物量以及上述功能组生物量之间的关系。对于所考虑的每种底栖基质类型（覆盖藻类、肉质大型藻类、硬珊瑚和草皮藻类），食草鱼类的生物量是预测底栖生物覆盖率的重要解释变量，而所有鱼类生物量的总和通常并非如此。此外，在所有四种情况下，覆盖率的变化最好由特定功能组的生物量来解释，而不是由所有食草动物的生物量总和来解释。具体而言：1）大型藻类和草皮藻类的覆盖率随着“食草动物/碎屑食性动物”生物量的增加而降低；2）覆盖藻类的覆盖率随着“食草动物/碎屑食性动物”和啃食者生物量的增加而增加。此外，硬珊瑚覆盖率随着大型挖掘者/生物侵蚀者（由大型鹦嘴鱼组成）的生物量增加而增加。总体而言，这些发现强调了食草鱼类与底栖生物群落之间的联系，并表明支持将食草动物功能组用作基于恢复力监测的指标。
