Harborne Alastair R, Mumby Peter J, Kappel Carrie V, Dahlgren Craig P, Micheli Fiorenza, Holmes Katherine E, Brumbaugh Daniel R
Marine Spatial Ecology Lab, School of Biosciences, Hatherly Laboratory, University of Exeter, Prince of Wales Road, Exeter EX4 4PS, United Kingdom.
Ecol Appl. 2008 Oct;18(7):1689-701. doi: 10.1890/07-0454.1.
Habitat maps are frequently invoked as surrogates of biodiversity to aid the design of networks of marine reserves. Maps are used to maximize habitat heterogeneity in reserves because this is likely to maximize the number of species protected. However, the technique's efficacy is limited by intra-habitat variability in the species present and their abundances. Although communities are expected to vary among patches of the same habitat, this variability is poorly documented and rarely incorporated into reserve planning. To examine intra-habitat variability in coral-reef fishes, we generated a data set from eight tropical coastal habitats and six islands in the Bahamian archipelago using underwater visual censuses. Firstly, we provide further support for habitat heterogeneity as a surrogate of biodiversity as each predefined habitat type supported a distinct assemblage of fishes. Intra-habitat variability in fish community structure at scales of hundreds of kilometers (among islands) was significant in at least 75% of the habitats studied, depending on whether presence/absence, density, or biomass data were used. Intra-habitat variability was positively correlated with the mean number of species in that habitat when density and biomass data were used. Such relationships provide a proxy for the assessment of intra-habitat variability when detailed quantitative data are scarce. Intra-habitat variability was examined in more detail for one habitat (forereefs visually dominated by Montastraea corals). Variability in community structure among islands was driven by small, demersal families (e.g., territorial pomacentrid and labrid fishes). Finally, we examined the ecological and economic significance of intra-habitat variability in fish assemblages on Montastraea reefs by identifying how this variability affects the composition and abundances of fishes in different functional groups, the key ecosystem process of parrotfish grazing, and the ecosystem service of value of commercially important finfish. There were significant differences in a range of functional groups and grazing, but not fisheries value. Variability at the scale of tens of kilometers (among reefs around an island) was less than that among islands. Caribbean marine reserves should be replicated at scales of hundreds of kilometers, particularly for species-rich habitats, to capture important intra-habitat variability in community structure, function, and an ecosystem process.
栖息地地图常被用作生物多样性的替代物，以辅助海洋保护区网络的设计。地图用于使保护区内的栖息地异质性最大化，因为这可能会使受保护物种的数量最大化。然而，该技术的有效性受到同一栖息地内物种及其丰度的变异性限制。尽管预计群落会在同一栖息地的不同斑块间有所差异，但这种变异性记录不足，很少被纳入保护区规划。为了研究珊瑚礁鱼类的栖息地内变异性，我们利用水下视觉普查从巴哈马群岛的八个热带沿海栖息地和六个岛屿生成了一个数据集。首先，我们进一步支持了栖息地异质性作为生物多样性替代物的观点，因为每种预先定义的栖息地类型都支持着独特的鱼类组合。根据使用的是存在/不存在、密度还是生物量数据，在至少75% 的研究栖息地中，数百公里尺度（岛屿间）的鱼类群落结构的栖息地内变异性很显著。当使用密度和生物量数据时，栖息地内变异性与该栖息地的平均物种数呈正相关。当缺乏详细的定量数据时，这种关系为评估栖息地内变异性提供了一个替代指标。我们对一个栖息地（主要由蒙氏珊瑚视觉主导的前礁）的栖息地内变异性进行了更详细的研究。岛屿间群落结构的变异性是由小型底栖鱼类家族（如领地性雀鲷科和隆头鱼科鱼类）驱动的。最后，我们通过确定这种变异性如何影响不同功能组鱼类的组成和丰度、鹦嘴鱼啃食这一关键生态系统过程以及具有商业重要性的食用鱼价值这一生态系统服务，来研究蒙氏珊瑚礁鱼类组合中栖息地内变异性在生态和经济方面的重要性。在一系列功能组和啃食方面存在显著差异，但在渔业价值方面没有差异。数十公里尺度（岛屿周围的珊瑚礁间）的变异性小于岛屿间的变异性。加勒比海海洋保护区应在数百公里的尺度上进行复制，特别是对于物种丰富的栖息地，以捕捉群落结构、功能和一个生态系统过程中重要的栖息地内变异性。
