Gradients in Primary Production Predict Trophic Strategies of Mixotrophic Corals across Spatial Scales
Gradients in Primary Production Predict Trophic Strategies of Mixotrophic Corals across Spatial Scales
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DOI：
10.1016/j.cub.2018.08.057
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发表时间：
2018-11-05
期刊：
影响因子：
9.2
通讯作者：
Smith, Jennifer E.
中科院分区：
文献类型：
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作者：
Fox, Michael D.;Williams, Gareth J.;Smith, Jennifer E.
混合营养是陆地和海洋生态系统中最成功的营养策略之一。生物体在自养和异养的连续过程中补充主要营养模式的能力促进了营养灵活性，使其能够在可变或压力条件下维持代谢需求。共生造礁珊瑚是分布最广、生态意义最重要的混合营养体之一，但我们对它们如何在食物供应的不同梯度上改变自养和异养的使用缺乏基本的了解。在这里，我们评估了一种珊瑚物种，Pocillopora meandrina，如何通过在一个群岛内的异质营养来补充自养营养，并测试这种模式是否适用于全球不同物种。利用稳定同位素分析(增量C-13)和卫星对近岸初级生产量的估计(叶绿素，作为食物可获得性的替代指标)，我们表明，当中太平洋五个岛屿有更多食物可用时，Meandrina通过异质营养吸收了更大比例的碳。然后，我们利用加勒比海、印度洋和太平洋16个地点的15个珊瑚物种的数据，表明这种模式在全球范围内是一致的。在全球范围内，表层叶绿素a解释了珊瑚异养营养变异的77%，对10个岛屿上的一个属解释了86%，当控制群岛内的珊瑚分类时，解释了94%。这些结果首次表明，卫星对近岸初级生产量的估计提供了一个全球相关的资源可获得性替代指标，可以解释珊瑚营养生态的变化。因此，我们的模型为解决混合营养生物和沿海海洋资源可获得性的空间格局之间的生物物理耦合提供了关键的一步。
Mixotrophy is among the most successful nutritional strategies in terrestrial and marine ecosystems. The ability of organisms to supplement primary nutritional modes along continua of autotrophy and heterotrophy fosters trophic flexibility that can sustain metabolic demands under variable or stressful conditions. Symbiotic, reef-building corals are among the most broadly distributed and ecologically important mixotrophs, yet we lack a basic understanding of how they modify their use of autotrophy and heterotrophy across gradients of food availability. Here, we evaluate how one coral species, Pocillopora meandrina, supplements autotrophic nutrition through heterotrophy within an archipelago and test whether this pattern holds across species globally. Using stable isotope analysis (delta C-13) and satellite-derived estimates of nearshore primary production (chlorophylla, as a proxy for food availability), we show that P. meandrina incorporates a greater proportion of carbon via heterotrophy when more food is available across five central Pacific islands. We then show that this pattern is consistent globally using data from 15 coral species across 16 locations spanning the Caribbean Sea and the Indian and Pacific Oceans. Globally, surface chlorophyll-a explains 77% of the variation in coral heterotrophic nutrition, 86% for one genus across 10 islands, and 94% when controlling for coral taxonomy within archipelagos. These results demonstrate, for the first time, that satellite-derived estimates of nearshore primary production provide a globally relevant proxy for resource availability that can explain variation in coral trophic ecology. Thus, our model provides a pivotal step toward resolving the biophysical couplings between mixotrophic organisms and spatial patterns of resource availability in the coastal oceans.