Authigenic 13C-depleted perylene in marine cold seeps

Perylene is ubiquitous in diverse environments, with its origin largely attributed to the degradation of fungal metabolites—perylenequinones. However, its potential authigenic production in marine environments is often obscured by the geochemical overlap with terrestrial inputs. Marine cold seeps provide an ideal setting to solve this ambiguity, as their unique chemosynthetic ecosystems produce biomarkers with characteristically 13C-depleted signatures. Here, we report the discovery of perylene with extremely low δ13C values (−84‰ to −61‰) in authigenic carbonates from the Haima cold seep in the South China Sea, confirming its authigenic production by fungi. These findings establish perylene as a robust isotopic tracer for subseafloor fungal activity and provide a new tool for reconstructing fungal evolution in ancient chemosynthetic environments.