Iron is important for algae growth and photosynthesis in coastal areas. Two types of algae were studied to see how they respond to changes in light and iron levels. The researchers found that both algae species take up iron even in the dark, with higher rates in the dark for some. Adding more iron increased carbon fixation and iron uptake. One of the algae species, Skeletonema costatum, is more likely to dominate blooms because it needs less iron but can take it up quickly. Light and iron levels can affect which algae species thrive in coastal ecosystems.