Plant Functional Biology and Climate Change Cluster (C3), Department of Environmental Science, University of Technology, Broadway, Sydney, New South Wales, Australia.
J R Soc Interface. 2011 Dec 7;8(65):1785-95. doi: 10.1098/rsif.2011.0144. Epub 2011 May 20.
The thermal microenvironment of corals and the thermal effects of changing flow and radiation are critical to understanding heat-induced coral bleaching, a stress response resulting from the destruction of the symbiosis between corals and their photosynthetic microalgae. Temperature microsensor measurements at the surface of illuminated stony corals with uneven surface topography (Leptastrea purpurea and Platygyra sinensis) revealed millimetre-scale variations in surface temperature and thermal boundary layer (TBL) that may help understand the patchy nature of coral bleaching within single colonies. The effect of water flow on the thermal microenvironment was investigated in hemispherical and branching corals (Porites lobata and Stylophora pistillata, respectively) in a flow chamber experiment. For both coral types, the thickness of the TBL decreased exponentially from 2.5 mm at quasi-stagnant flow (0.3 cm s(-1)), to 1 mm at 5 cm s(-1), with an exponent approximately 0.5 consistent with predictions from the heat transfer theory for simple geometrical objects and typical of laminar boundary layer processes. Measurements of mass transfer across the diffusive boundary layer using O(2) microelectrodes revealed a greater exponent for mass transfer when compared with heat transfer, indicating that heat and mass transfer at the surface of corals are not exactly analogous processes.
珊瑚的热微环境以及流动和辐射变化的热效应对于理解热致珊瑚白化至关重要，这是珊瑚与其光合作用微藻共生关系破坏所导致的应激反应。对具有不均匀表面形貌的光照石珊瑚（Leptastrea purpurea 和 Platygyra sinensis）进行表面温度和热边界层（TBL）的毫米级测量，揭示了表面温度和 TBL 的毫米级变化，这可能有助于理解单个珊瑚虫群中珊瑚白化的斑片状性质。在流动室内实验中，研究了半球形珊瑚（Porites lobata）和分枝珊瑚（Stylophora pistillata）的水流对热微环境的影响。对于这两种珊瑚类型，TBL 的厚度从准停滞流（0.3 cm s(-1)）下的 2.5 毫米呈指数递减至 5 cm s(-1) 下的 1 毫米，指数约为 0.5，与简单几何物体传热理论的预测一致，也是典型的层流边界层过程。使用 O(2)微电极测量扩散边界层中的传质，发现与传热相比，传质的指数更大，表明珊瑚表面的热传递和传质过程并不完全类似。
