Light and iron are critical environmental factors regulating the growth and primary productivity of marine diatoms. However, the quantitative relationship between these factors and intracellular energy metabolism remains unclear, as does the impact of ocean acidification in the context of climate change. Using the marine diatom Phaeodactylum tricornutum and a resource allocation optimization model, we quantitatively estimated the effects of varying light intensity and intracellular iron content on energy metabolism and how ocean acidification influences this process. Intracellular energy is primarily allocated for carbon fixation. Under low light or iron conditions, diatom growth is inhibited, and cells respond by increasing their investment of iron and energy into the photosynthetic system. Ocean acidification alleviates this inhibition by reallocating more iron to the photosynthetic system and improving the efficiency of the nitrate reduction process. 

Model predictions indicate that, if anthropogenic CO₂ emissions continue to rise, ocean acidification will increase the global growth rate of Phaeodactylum tricornutum by 3.17% by the end of this century compared to the 1990s. This study enhances our understanding of marine diatom energy metabolism in response to environmental changes, offering valuable insights for predicting future ocean biogeochemical cycles.
 

cellular model, ocean acidification, diatom, iron