This study examines phenotypically plastic responses in Pocillopora acuta collected from a highly urbanized reef environment to extreme low-light conditions. While among-species differences in how corals cope with low light are well documented, much less is known about within-species responses. It also remains unclear how extreme low light and provision of food may interact and influence coral physiology. Clonal fragments from six colonies (genotypes) of P. acuta were subjected to two light treatments with mean midday irradiances of 4 and 40 μmol photons m⁻² s⁻¹ photosynthetically active radiation (PAR), representing just 0.5 and 5% ambient light level, and were either fed with zooplankton or not fed for nine days. Corals maintained in 4 PAR had lower endosymbiont density but higher cellular chlorophyll a concentration than those in 40 PAR. Feeding rates were similar in both light treatments and had no significant effects on endosymbiont density and chlorophyll a concentrations. While genotypes varied in the level of phenotypic plasticity expressed for both photoacclimation and heterotrophy, most displayed similar directions in their responses, indicating photoacclimation in P. acuta is broadly predictable. Our study demonstrates that P. acuta from Singapore is able to acclimate to very low-light conditions by adjusting their photophysiology, providing additional evidence that this species is resilient to urbanization-related stress.

这项研究检查了从高度城市化的珊瑚礁环境中收集到的Pocillopora acuta对极低光照条件下的表型塑性反应。虽然珊瑚如何应对弱光的物种间差异有据可查，但对物种内反应知之甚少。目前还不清楚极低光照和食物供应如何相互作用并影响珊瑚生理。来自P. acuta 的六个菌落（基因型）的克隆片段进行了两次光处理，平均正午辐照度分别为 4 和 40 μmol 光子 m ^-2  s ^-1光合有效辐射 (PAR)，仅代表 0.5% 和 5% 的环境光水平，并且要么喂食浮游动物，要么不喂食 9 天。维持在 4 PAR 中的珊瑚与 40 PAR 中的珊瑚相比，内共生体密度较低，但细胞叶绿素a浓度较高。两种光照处理的摄食率相似，对内共生体密度和叶绿素a浓度没有显着影响。虽然基因型在光驯化和异养的表型可塑性水平上有所不同，但大多数在其反应中显示出相似的方向，表明P. acuta 的光驯化是广泛可预测的。我们的研究表明P. acuta 来自新加坡的物种能够通过调整它们的光生理学来适应非常低的光照条件，这提供了额外的证据表明该物种能够抵御与城市化相关的压力。