A new constraint on the antiquity of ancient haloalkaliphilic green algae that flourished in a ca. 300 Ma Paleozoic lake

Liuwen Xia, Jian Cao*, Carina Lee, Eva E. Stüeken, Dongming Zhi, Gordon D. Love

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

It is established that green algae and land plants progressively colonized freshwater and terrestrial habitats throughout the Paleozoic Era, but little is known about the ecology of Paleozoic saline lakes. Here, we report lipid biomarker and petrographic evidence for the occurrence of a green alga as a major primary producer in a late Paleozoic alkaline lake (Fengcheng Formation; 309–292 Ma). A persistently saline and alkaline lacustrine setting is supported by mineralogical and lipid biomarker evidence alongside extremely enriched δ15Nbulk values (+16 to +24‰) for the lake depocenter. The prominence of C28 and C29 steroids, co-occurring with abundant carotene-derived accessory pigment markers in these ancient rocks, is suggestive of prolific primary production and elevated source inputs from haloalkaliphilic green algae. The high C28/C29-sterane ratios (0.78–1.29) are significantly higher than the typical marine value reported for late Paleozoic rocks (<0.5) and thus are associated with certain groups of chlorophytes. Adaptation to such extreme lacustrine environments, aided by enhanced biosynthesis of certain cell membrane lipids, likely played an important role in the evolution and physiological development of ancient green algae.

Original languageEnglish
JournalGeobiology
Early online date16 Dec 2020
DOIs
Publication statusE-pub ahead of print - 16 Dec 2020

Keywords

  • alkaline (soda) lake
  • extreme environment
  • green alga
  • Junggar Basin
  • Late Paleozoic
  • Mahu Sag
  • β-carotane

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