A study from the University of Miami found that bacteria living in the intestines of toadfish produce calcium carbonate, called ichthyocarbonates, which act as carbon sinks. This process only happens in saltwater, with peak production in hypersaline conditions. The discovery shows that fish and their gut microbes work together to capture carbon, potentially affecting ocean carbon cycling and climate change models. Researchers identified the bacterium Photobacterium damselae in fish guts that carries genes for calcium crystallization. This symbiosis was previously mistaken for pure fish physiology. Understanding this mechanism could improve predictions of how oceans absorb carbon, especially as salinity and acidity shift with climate change. The findings highlight a new biological pathway for carbon sequestration worth further study.
