Cunning Ross, Yost Denise M, Guarinello Marisa L, Putnam Hollie M, Gates Ruth D
University of Hawai'i, Hawai'i Institute of Marine Biology, PO Box 1346, Kāne'ohe, Hawaii, 96744, United States of America.
Northwest Knowledge Network, University of Idaho, 875 Perimeter Dr. MS2358, Moscow, Idaho, 83844, United States of America.
PLoS One. 2015 Dec 29;10(12):e0145099. doi: 10.1371/journal.pone.0145099. eCollection 2015.
Reef-building corals host assemblages of symbiotic algae (Symbiodinium spp.) whose diversity and abundance may fluctuate under different conditions, potentially facilitating acclimatization to environmental change. The composition of free-living Symbiodinium in reef waters and sediments may also be environmentally labile and may influence symbiotic assemblages by mediating supply and dispersal. The magnitude and spatial scales of environmental influence over Symbiodinium composition in different reef habitat compartments are, however, not well understood. We used pyrosequencing to compare Symbiodinium in sediments, water, and ten coral species between two backreef pools in American Samoa with contrasting thermal environments. We found distinct compartmental assemblages of clades A, C, D, F, and/or G Symbiodinium types, with strong differences between pools in water, sediments, and two coral species. In the pool with higher and more variable temperatures, abundance of various clade A and C types differed compared to the other pool, while abundance of D types was lower in sediments but higher in water and in Pavona venosa, revealing an altered habitat distribution and potential linkages among compartments. The lack of between-pool effects in other coral species was due to either low overall variability (in the case of Porites) or high within-pool variability. Symbiodinium communities in water and sediment also showed within-pool structure, indicating that environmental influences may operate over multiple, small spatial scales. This work suggests that Symbiodinium composition is highly labile in reef waters, sediments, and some corals, but the underlying drivers and functional consequences of this plasticity require further testing with high spatial resolution biological and environmental sampling.
造礁珊瑚体内共生着多种藻类（共生藻属），其多样性和丰度会随不同条件而波动，这可能有助于珊瑚适应环境变化。珊瑚礁水域和沉积物中自由生活的共生藻的组成也可能受环境影响而不稳定，并且可能通过介导供应和扩散来影响共生组合。然而，不同珊瑚礁栖息地环境对共生藻组成影响的程度和空间尺度尚未得到充分了解。我们利用焦磷酸测序技术，比较了美属萨摩亚两个礁后池（热环境不同）中沉积物、水体以及十种珊瑚中的共生藻。我们发现了A、C、D、F和/或G类共生藻的不同分区组合，水体、沉积物以及两种珊瑚在两个池之间存在显著差异。在温度较高且变化较大的池中，与另一个池相比，各种A类和C类共生藻的丰度有所不同，而D类共生藻在沉积物中的丰度较低，但在水体和细纹扁脑珊瑚中的丰度较高，这揭示了栖息地分布的改变以及不同分区之间的潜在联系。其他珊瑚物种在两个池之间缺乏影响，要么是因为总体变异性较低（如多孔珊瑚），要么是因为池内变异性较高。水体和沉积物中的共生藻群落也显示出池内结构，这表明环境影响可能在多个小空间尺度上起作用。这项研究表明，共生藻的组成在珊瑚礁水体、沉积物和一些珊瑚中高度不稳定，但这种可塑性的潜在驱动因素和功能后果需要通过高空间分辨率的生物和环境采样进行进一步测试。
