School of Marine Science and Technology, Newcastle University, Newcastle, NE1 7RU, UK.
Institute for Marine Resources and Ecosystem Studies, IMARES, 1790AD, Den Burg, The Netherlands.
J Anim Ecol. 2015 Nov;84(6):1678-89. doi: 10.1111/1365-2656.12429. Epub 2015 Sep 6.
There has been ongoing flattening of Caribbean coral reefs with the loss of habitat having severe implications for these systems. Complexity and its structural components are important to fish species richness and community composition, but little is known about its role for other taxa or species-specific responses. This study reveals the importance of reef habitat complexity and structural components to different taxa of macrofauna, total species richness, and individual coral and fish species in the Caribbean. Species presence and richness of different taxa were visually quantified in one hundred 25-m(2) plots in three marine reserves in the Caribbean. Sampling was evenly distributed across five levels of visually estimated reef complexity, with five structural components also recorded: the number of corals, number of large corals, slope angle, maximum sponge and maximum octocoral height. Taking advantage of natural heterogeneity in structural complexity within a particular coral reef habitat (Orbicella reefs) and discrete environmental envelope, thus minimizing other sources of variability, the relative importance of reef complexity and structural components was quantified for different taxa and individual fish and coral species on Caribbean coral reefs using boosted regression trees (BRTs). Boosted regression tree models performed very well when explaining variability in total (82·3%), coral (80·6%) and fish species richness (77·3%), for which the greatest declines in richness occurred below intermediate reef complexity levels. Complexity accounted for very little of the variability in octocorals, sponges, arthropods, annelids or anemones. BRTs revealed species-specific variability and importance for reef complexity and structural components. Coral and fish species occupancy generally declined at low complexity levels, with the exception of two coral species (Pseudodiploria strigosa and Porites divaricata) and four fish species (Halichoeres bivittatus, H. maculipinna, Malacoctenus triangulatus and Stegastes partitus) more common at lower reef complexity levels. A significant interaction between country and reef complexity revealed a non-additive decline in species richness in areas of low complexity and the reserve in Puerto Rico. Flattening of Caribbean coral reefs will result in substantial species losses, with few winners. Individual structural components have considerable value to different species, and their loss may have profound impacts on population responses of coral and fish due to identity effects of key species, which underpin population richness and resilience and may affect essential ecosystem processes and services.
加勒比海的珊瑚礁一直在不断退化，生境丧失对这些系统造成了严重影响。复杂性及其结构组成对鱼类物种丰富度和群落组成很重要，但对其他分类群或特定物种的反应知之甚少。本研究揭示了珊瑚礁生境复杂性和结构组成对加勒比地区不同大型动物分类群、总物种丰富度以及珊瑚和鱼类个体的重要性。在加勒比地区的三个海洋保护区内，使用一百个 25 平方米的 25 平方米的斑块，对不同分类群的物种存在和丰富度进行了视觉量化。在五个视觉估计的珊瑚礁复杂程度水平上均匀分布采样，同时记录了五个结构组成部分：珊瑚数量、大型珊瑚数量、坡度角、最大海绵和最大八放珊瑚高度。本研究利用特定珊瑚礁生境（Orbicella 珊瑚礁）内结构复杂性的自然异质性和离散的环境范围，从而最小化其他来源的变异性，利用增强回归树 (BRT) 对加勒比珊瑚礁上不同分类群和单个鱼类和珊瑚物种的珊瑚礁复杂性和结构组成的相对重要性进行了量化。增强回归树模型在解释总物种（82.3%）、珊瑚（80.6%）和鱼类物种丰富度（77.3%）的变异性方面表现非常出色，其中丰富度的最大下降发生在中等珊瑚礁复杂性水平以下。复杂性对八放珊瑚、海绵、节肢动物、环节动物或海葵的变异性影响很小。BRT 揭示了珊瑚礁复杂性和结构组成的物种特异性变异性和重要性。珊瑚和鱼类物种的占有通常在低复杂性水平下降，除了两种珊瑚物种（Pseudodiploria strigosa 和 Porites divaricata）和四种鱼类物种（Halichoeres bivittatus、H. maculipinna、Malacoctenus triangulatus 和 Stegastes partitus）在较低的珊瑚礁复杂性水平下更为常见。国家和珊瑚礁复杂性之间的显著相互作用揭示了低复杂性区域和波多黎各保护区的物种丰富度非加性下降。加勒比海珊瑚礁的扁平化将导致大量物种丧失，几乎没有赢家。单个结构组成部分对不同物种具有相当大的价值，其丧失可能会对珊瑚和鱼类的种群反应产生深远影响，因为关键物种的身份效应支撑着种群丰富度和恢复力，并可能影响重要的生态系统过程和服务。
