Relating Coral Skeletal Structures at Different Length Scales to Growth, Light Availability to Symbiodinium, and Thermal Bleaching

作者：Timothy D. Swain, Simon Lax, Natalie Lake, Hannah Grooms, Vadim Backman, Luisa A. Marcelino · 发表于：Frontiers in Marine Science · 年份：2018 · DOI：10.3389/fmars.2018.00450 · 被引用次数：34 · 研究领域：Coral and Marine Ecosystems Studies、Marine and coastal plant biology、Cephalopods and Marine Biology

Light scattering of coral skeletons and tissues increases light availability to photosynthetic endosymbionts to form one of the most efficient biological collectors of solar radiation. Rapid increases in light availability during thermally-induced symbiont loss (bleaching) impair photosynthetic performance of the remaining Symbiodinium and precipitate a more severe bleaching response (optical feedback-loop hypothesis). Here we focus on light scattering of the skeleton, which is determined by light interaction with skeletal components assembled in a hierarchical fractal-like structure from tens of nanometers (e.g., calcium carbonate nanograins) to micro- and milli-meters (septa, corallites, and coenosteum) to centimeters and higher (colony form). We examined the association between skeletal structures, their role in light scattering, and species-specific bleaching responses for 88 coral species using phylogenetically-corrected analysis. We also explored the effect of growth on light scattering by modeling the fractal-like accretive growth of the skeleton (assuming a diffusion limited process of biomineralization) as a function of skeletal density, size of nanograins, fractal range of biomineralized clusters, and overall mass-fractal dimension, and validated the model with experimental data. Our results show that differences in light scattering from the top ~200µm (micro-μ_s^') of the skeleton, and not from the whole skeleton (bulk-μ_s^'), are related to bleaching susceptibilit...