Sea ice supports a unique assemblage of microorganisms that underpin Antarctic coastal food-webs, but reduced ice thickness coupled with increased snow cover will modify energy flow and could lead to photodamage in ice-associated microalgae. In this study, microsensors were used to examine the influence of rapid shifts in irradiance on extracellular oxidative free radicals produced by sea-ice algae. Bottom-ice algal communities were exposed to one of three levels of incident light for 10 days: low (0.5 μmol photons m⁻² s⁻¹, 30 cm snow cover), mid-range (5 μmol photons m⁻² s⁻¹, 10 cm snow), or high light (13 μmol photons m⁻² s⁻¹, no snow). After 10 days, the snow cover was reversed (either removed or added), resulting in a rapid change in irradiance at the ice-water interface. In treatments acclimated to low light, the subsequent exposure to high irradiance resulted in a ~400× increase in the production of hydrogen peroxide (H₂O₂) and a 10× increase in nitric oxide (NO) concentration after 24 h. The observed increase in oxidative free radicals also resulted in significant changes in photosynthetic electron flow, RNA-oxidative damage, and community structural dynamics. In contrast, there was no significant response in sea-ice algae acclimated to high light and then exposed to a significantly lower irradiance at either 24 or 72 h. Our results demonstrate that microsensors can be used to track real-time in-situ stress in sea-ice microbial communities. Extrapolating to ecologically relevant spatiotemporal scales remains a significant challenge, but this approach offers a fundamentally enhanced level of resolution for quantifying the microbial response to global change.

海冰支持构成南极沿海食物网的微生物的独特组合，但是减小的冰厚度和增加的积雪将改变能量流，并可能导致与冰相关的微藻的光损伤。在这项研究中，使用微传感器来检查辐照度的快速变化对海冰藻类产生的细胞外氧化自由基的影响。海底藻类群落在三种水平的入射光之一中暴露10天：低（0.5μmol光子m ^-2 s ^-1，积雪30厘米），中范围（5μmol光子m ^-2 s ^-1，10厘米的雪）或高光（13μmol光子m ^-2 s ^-1，没有雪）。10天后，积雪被颠倒（移除或添加），导致冰水界面处的辐照度迅速变化。在适应弱光的处理中，随后暴露于高辐照度导致24小时后过氧化氢（H ₂ O ₂）产量增加约400倍，一氧化氮（NO）浓度增加10倍。观察到的氧化自由基的增加还导致光合电子流，RNA氧化损伤和群落结构动力学的显着变化。相比之下，在强光照射下，然后在24或72 h暴露于低得多的辐照度下，海冰藻类无明显反应。我们的结果表明，微传感器可用于跟踪实时原位海冰微生物群落的压力。推断与生态相关的时空尺度仍然是一个巨大的挑战，但是这种方法从根本上提高了分辨率水平，可以量化微生物对全球变化的响应。