Benthic foraminiferal community structure and response to environmental factors revealed through eDNA and eRNA...

Benthic foraminifera serve as indicator organisms for changes in the marine environment. Understanding the correlation between their community structure and environmental factors is important for examining marine ecology. In this study, surface sediments from ten stations in the Beiji Archipelago of Zhejiang Province, China, were collected to determine the response of benthic foraminifera to environmental factors. A physicochemical analysis revealed that the sediments predominantly comprised a silt-clay mixture and contained relatively high levels of heavy metal contamination, posing moderate potential ecological risks. Cd posed the highest potential ecological risk, followed by Hg. Environmental DNA (eDNA) and environmental RNA (eRNA) metabarcoding identified seven orders of benthic foraminifera, which primarily comprised Rotaliida, Miliolida, and Allogromida. At the genus level, eDNA metabarcoding revealed a high abundance of Operculina, whereas Parasorites was the most dominant group in the eRNA metabarcoding database. Correlation analysis between benthic foraminifera and environmental factors revealed that Parasorites may exhibit tolerance to Cd, Neoassilina is sensitive to heavy metal contamination, and Operculina prefers sedimentary environments characterized by higher sand content.