Methane fueled lake pelagic food webs in a Cretaceous greenhouse world

• 成果类型: Article
• 署名作者: Sun, Funing; Luo, Genming; Pancost, Richard D.; Dong, Zhengkun; Li, Zhiguo; Wang, Hongmei; Chen, Zhong-Qiang; Xie, Shucheng
• 署名单位: China University of Geosciences; China University of Geosciences; University of Bristol; China University of Geosciences
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-12770
• DOI: 10.1073/pnas.2411413121
• 发表日期: 2024-10-29
• 关键词: daphnia ephippia; carbon; bacteria; cycle; fractionation; tetrahymanol; gammacerane; biomarkers; dolomite; record

摘要

Methane (CH4) is a potent greenhouse gas but also an important carbon and energy substrate for some lake food webs. Understanding how CH4 incorporates into food webs is, therefore, crucial for unraveling CH4 cycling and its impacts on climate and ecosystems. However, CH4-fueled lake food webs from pre-Holocene intervals, particularly during greenhouse climates in Earth history, have received relatively little attention. Here, we present a long-term record of CH4-fueled pelagic food webs across the Cretaceous Oceanic Anoxic Event 1a (similar to 120 Mya) that serves as a geological analog to future warming. We show an exceptionally strong expansion of both methanogens and CH(4)(-)oxidizing bacteria (up to 87% of hopanoid-producing bacteria) during this Event. Grazing on CH4-oxidizing bacteria by zooplankton (up to 47% of ciliate diets) within the chemocline transferred substantial CH4-derived carbon to the higher trophic levels, representing an important CH4 sink in the water column. Our findings suggest that as Earth warms, microbial CH4 cycling could restructure food webs and fundamentally alter carbon and energy flows and trophic pathways in lake ecosystems.