As oceans warm, the depth of the upper mixed layer is predicted to decrease, resulting in insufficient nutrient supply and higher solar radiation for phytoplankton. In order to understand the photophysiological responses of the key eukaryotic phytoplankton diatoms to high light and nutrient limitation, we grew two diatoms, Thalassiosira weissflogii and Thalassiosira pseudonana under N starvation conditions and exposed them to high visible light. It showed that the large-sized diatom T. weissflogii can maintain photosynthetic activity for a longer period of time under nitrogen starvation as compared with the small-sized diatom T. pseudonana. The electron transfer reaction was inhibited in both diatoms and the fast closing of reaction centers promoted the development of Q_B non-reducing PSII centers, thus facilitated the rapid induction of NPQ, however, the induction of NPQ depended on the degree of N starvation. N starvation exacerbated the photoinhibition caused by high light. The smaller-sized T. pseudonana had a higher σi value and was more sensitive to high-light, but its PSII repair rate was also higher. In contrast, T. weissflogii was more tolerant to high light with a lower σi value, but the tolerance was severely reduced under N-starvation. This study provides helpful insight into how climate change variables impact diatom's photosynthetic physiology.

随着海洋变暖，预计上层混合层的深度会减少，从而导致营养物质供应不足和浮游植物的太阳辐射增加。为了了解关键的真核浮游植物硅藻对高光和营养限制的光生理反应，我们在N饥饿条件下生长了两个硅藻，即Thalassiosira weissflogii和Thalassiosira pseudonana，并将它们暴露在高可见光下。结果表明，与小型硅藻T. pseudonana相比，大型硅藻T. weissflogii在氮饥饿下可以保持更长的光合活性。。电子传递反应在两个硅藻中均受到抑制，反应中心的快速关闭促进了Q _B非还原性PSII中心的发展，从而促进了NPQ的快速诱导，但是NPQ的诱导取决于N饥饿程度。N饥饿加剧了强光引起的光抑制。假单胞菌较小，其σi值较高，对强光更敏感，但其PSII修复率也较高。相反，魏氏梭菌对较高的光具有较低的σi值耐受性，但在N饥饿条件下其耐受性大大降低。这项研究为气候变化变量如何影响硅藻的光合生理提供了有益的见解。