Foraminifera associated with cold seeps in marine sediments

• Published in: Frontiers in Marine Science
• Main Authors: Lu, Yinghan, Yang, Hailin, Huang, Baoqi, Liu, Yujia, Lu, Hailong
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Frontiers Media SA 2023
• Subjects: Ocean Engineering; Water Science and Technology; Aquatic Science; Global and Planetary Change; Oceanography; Planktonic foraminifera
• Online Access: http://dx.doi.org/10.3389/fmars.2023.1157879; https://www.frontiersin.org/articles/10.3389/fmars.2023.1157879/full

Cold seep foraminifera have attracted considerable attention as they provide valuable insights into the study of cold seeps. This study provides a comprehensive overview of the manifestations of foraminifera in cold seep environments and methane seepage activities. Certain taxa of benthic foraminifera, such as Uvigerina , Bolivina , Bulimina , Chilostomella , Globobulimina , Nonionella , Melonis , Epistominella , Cibicidoides , and Globocassidulina , are known to inhabit geochemical conditions induced by methane-rich environments and may feed on associated methanotrophic microbial communities. Secondary mineralization on foraminifera shells is a widespread manifestation in seep sediments, and alters the microstructure, elementary composition, and isotopic signatures of foraminifera. On one hand, the precipitation of secondary authigenic Mg-rich, Mn-rich, Sr-rich, and Ba-rich calcite coatings have been observed on microfossils. On the other hand, micron-sized crystal pyrite and gypsum aggregates can also grow on the foraminifera walls. The negative δ 13 C and positive δ 18 O anomalies in both planktonic and benthic foraminifera from seep-associated sediments can serve as proxies for tracing past seepage activities, either in their live form or being adulterated by methane-derived authigenic carbonate after deposition. Seeping activities are recognized with a significant impact on benthic foraminifera, and the presence of cold seep-related species and significant isotopic anomalies in shells can be used to reconstruct past methane seepage events. Intensive methane seepage tends to suppress benthic foraminifera populations, while moderate intensity seepage may lead to a thriving benthic foraminiferal community, with hypoxia-enduring taxa such as Uvigerina , Melonis , and Bulimina being predominant. In contrast, oxygen-loving epibenthic taxa such as Cibicidoides often occur in areas of low methane flux. Compared to planktonic foraminifera, the single species of benthic foraminifera can provide a more comprehensive ...