Ocean acidification, a process caused by rising levels of carbon dioxide (CO₂) in the atmosphere, may interfere with the ability of diatoms to capture carbon and support marine food webs, according to new research from Flinders University. Published in the journal Marine Ecology, the study used advanced techniques to examine how diatoms—microscopic, single-celled organisms—respond to various environmental stressors, including acidification. The findings suggest that changes in ocean pH could disrupt diatoms' ability to absorb essential trace metals, affecting their health and their role in the global carbon cycle. Diatoms are vital to Earth's ecosystems. Found in oceans, lakes, rivers, and even damp soil, they are responsible for producing a large portion of the oxygen in the atmosphere. In the ocean, they contribute 40% to 50% of primary production, meaning they form the base of the marine food web by converting CO₂ into organic matter. This process helps transport carbon from the surface of the ocean to the deep, playing a key role in regulating atmospheric CO₂ levels. Lead researcher Sophie Leterme, from Flinders University, noted that ocean pH changes can influence diatoms' growth, abundance, and composition. The study emphasizes the importance of understanding how these changes interact with trace elements like iron, zinc, and cadmium, which are essential for diatoms to absorb carbon. Disruptions in diatom health could have far-reaching consequences, including the breakdown of marine food webs, reduced carbon export to the deep ocean, and altered microbial activity. Since the Industrial Revolution, ocean pH has decreased by 0.1 units due to the absorption of excess CO₂. Scientists predict this trend will continue, with pH levels expected to drop another 0.3 to 0.6 units by the end of the century. This acidification can affect how planktonic algae, including diatoms, absorb essential nutrients, potentially weakening their ability to support marine life and the carbon cycle. The research team collected seawater samples from South Australia's Gulf St. Vincent and used a CSIRO algae collection to conduct experiments on two common diatom species. Using neutron activation analysis, a highly sensitive method, the study revealed how diatoms absorb trace metals. These insights could apply to other marine organisms, helping scientists better understand the broader environmental impacts of ocean acidification. Researchers hope this knowledge will lead to innovative solutions, such as developing biofilms to reduce pollution in coastal areas.