Molecular diversity of foraminiferal eDNA in sediments and their correlations with environmental factors from the Yellow Sea

Foraminiferal environmental DNA (eDNA) is an efficient and reliable indicator of environmental changes. Here, we investigated the foraminiferal diversity of 25 stations (33-36 degrees N) in the Yellow Sea based on eDNA and presented the first assessment on the correlations between foraminifera diversity and environmental conditions in the region. A total of 71 sediment samples were collected and local environmental parameters were measured. The foraminiferal eDNA was extracted from the samples and part of the small subunit (SSU) rRNA gene was amplified from the samples. After high-throughput sequencing, 1,701,899 amplified reads were detected and clustered into 426 operational taxonomic units (OTUs). The benthic foraminiferal eDNA community diversity and group diversity showed significant positive correlations with water depth and total inorganic carbon (TIC) in sediments, and significant negative correlations with temperature and total organic carbon (TOC) in sediments. However, in terms of the correlation between relative abundance and environmental factors, there were wide variations from species to species. In this work, planktic foraminiferal eDNA was detected in the sediments, and its OTUs number could reflect the changes in ocean currents and upper layer water masses to a certain extent. This is the first study on relationship of foraminiferal eDNA and environmental factors in the Yellow Sea shelf region of the western Pacific Ocean, and it demonstrates that community parameters in foraminiferal eDNA could be a valuable proxy for environmental changes in the shelf sea.